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Frontiers in Bird Science ·

Volume 5 - 2026 | https://doi.org/10.3389/fbirs.2026.1958803

Beyond the frontiers: avian organoid and stem cell models for genetic rescue in bird conservation

  • Sittipon Intarapat1*corresponding author
  • Oleg Gusev2,3,4*corresponding author
  • Guojun Sheng4*corresponding author
  1. 1Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
  2. 2Intractable Disease Research Center, Juntendo University, Tokyo, Japan
  3. 3Institute of Biochemistry and Genetics, Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Ufa, Russia
  4. 4International Research Center for Medical Sciences, Kumamoto University, Kumamoto, Japan
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Abstract

Various threats, including habitat loss, climate change, overexploitation, and human activities, endanger bird species. To combat declining avian populations, cutting-edge technologies have been employed to safeguard species, particularly those that are endangered or critically endangered. From this perspective, we highlight organoid and stem cell models, combined with genomic tools, as a novel approach to genetic rescue in bird populations. Somatic and germline stem cell technologies, such as embryonic stem cells, induced pluripotent stem cells, and primordial germ cells, along with a biobanking platform, are emphasized for avian genetic conservation. Integrating in situ and ex situ conservation through cell-based and genomic studies could bridge the genotype-phenotype gap, thereby enhancing conservation efforts. The theme: From Cells to Conservation is proposed, aiming for real-world conservation impact and reusable outcomes. Overall, cellular models and translational genetic platforms under this theme could inform evidence-based strategies for sustainable genetic rescue of threatened bird populations.

Keywords

1 Introduction

Can the dodo be brought back? Recent reports question whether Colossal secured $200 million to resurrect the dodo (Callaway, 2023). The dodo, extinct for 400 years, has only mummified head skin left, which is held at the Oxford University Museum of Natural History (Nowak-Kemp and Hume, 2017). This idea is part of de-extinction efforts to conserve and recreate bird species (Turner et al., 2025; Hutchison et al., 2026). Instead of focusing on resurrecting extinct birds, a lesson from the dodo is that advances from de-extinction can be redirected to conserve vulnerable live birds. Across all assessed taxonomic groups, 10,443 species were classified as Critically Endangered (CR) on the IUCN Red List in 2025, including 223 bird species (IUCN, 2025), with 85% threatened by predation and disease (Lacher et al., 2025). Human activities like hunting, land change, and invasive species are main drivers of extinction (Cooke et al., 2023). To conserve these species, we must understand their habitats and threats, then develop strategies using emerging technologies, including genomics and stem cell biology (Pukazhenthi et al., 2006; Haig et al., 2011; Nakamura, 2017). In situ conservation faces many challenges; only a few populations of this species still survive in the wild (Braverman, 2014); thus, ex situ methods, particularly organoid and stem cell models, offer solutions (Bourdon et al., 2021; Hutchinson et al., 2024; MastroMonaco et al., 2026). However, applying these in practice is limited. Assisted reproductive technologies such as in vitro fertilization and cloning are difficult in birds due to reproductive differences (Tajima, 2013; Jung et al., 2023). The focus then shifts to conserving germplasm, including embryonic stem cells and primordial germ cells (Petitte, 2006). Ex situ conservation of germline and stem cells, especially PGCs, seems practical (Nakamura, 2016). Genetic conservation with germline and stem cell models may help recover declining bird populations (Katayama et al., 2022; Chen et al., 2025b). Therefore, we propose that multi-faceted approaches—genomic with organoid and stem cell tools—can support genetic rescue strategies within “From Cells to Conservation,” thereby promoting sustainable avian genetic preservation.

2 Conservation challenge and genomic advances

Assessing genetic diversity in endangered birds is essential for conservation as it informs management and recovery efforts (Cortes-Rodriguez et al., 2019). Advances in high-throughput techniques enable non-invasive assessment of population size, inbreeding, movement, diet, and disease (Cassin-Sackett et al., 2019; Husby et al., 2019). Cross-taxonomic gene function comparisons using genomic methods offer alternative conservation strategies. Gene flow-driven genetic rescue is viewed as the most effective way to improve the fitness of endangered bird populations (Pavlova et al., 2023; Beheregaray et al., 2026). Genomic advances are enhancing bird conservation efforts, with technologies like genomic and next-generation sequencing providing crucial data (Cassin-Sackett et al., 2019; Zhou et al., 2026). Transcriptomic studies identify bird genes responding to stressors such as disease and climate change (Jax et al., 2018). Metagenomics and microbiome research offer insights into how bird symbiosis influences survival and population dynamics (Trevelline et al., 2018). These tools are particularly useful for examining genetic diversity in small or captive populations, helping to assess inbreeding and estimate population sizes amid disease concerns (Harrisson et al., 2014; Li et al., 2014a; Nadachowska-Brzyska et al., 2015; Sun et al., 2015; Cassin-Sackett et al., 2019).

Recent advances in genomic research on endangered birds have focused on the family Accipitridae. Notably, the Steppe Eagle (Aquila nipalensis) is classified as endangered (EN) (BirdLife International, 2021a), while the Red-headed Vulture (Sarcogyps calvus) is critically endangered (CR) (BirdLife International, 2021e). Researchers examined the genomes and mitogenomes of these species to clarify their genetic structure and population dynamics, yielding valuable insights for conservation. These findings could inform breeder selection and genetic restoration efforts for endangered raptors (Buthasane et al., 2024, Buthasane et al., 2025, Buthasane et al., 2026). Genomic studies could then be applied to genetic rescue in bird populations, not only within this family but also in other related species being driven to extinction.

A major challenge in avian genetic conservation is the genotype-to-phenotype gap, which concerns the relationship between genetic variation (genotype) and observable traits (phenotype) (Gjuvsland et al., 2013). These traits include disease resistance, reproductive success, thermal tolerance, migration behavior, and developmental fitness. Although large-scale genomic studies reveal genetic diversity, adaptive loci, population structure, and key variants, conservationists often lack information on whether these variants affect survival or fitness (Funk et al., 2012; Rellstab et al., 2021; van der Valk and Dalen, 2024). This limits their ability to prioritize breeding, identify adaptive populations, predict responses to environmental changes, and implement genetic rescue (Frankham, 2010; Hoffmann et al., 2021; Beck et al., 2025). The genotype–phenotype gap highlights the need for functional approaches to determine whether candidate genetic variants identified by population genomic analysis have measurable biological effects. Stem cell and organoid models provide controlled experimental systems in which selected variants can be compared, introduced, or corrected and their effects assessed at the cellular and tissue levels, including changes in gene expression, cellular behavior, differentiation, or tissue-specific function. These approaches can therefore help establish mechanistic links between genetic variation and cellular or tissue phenotypes, providing functional evidence that complements population genomic data and helps prioritize candidate variants and biological pathways for further investigation in threatened populations (Yin et al., 2016; Zhou et al., 2026a). Such functional information can provide biological context for genetic differences, help prioritize genetic resources or potential genetic interventions, and when integrated with genomic data, help evaluate the functional basis of genetic variation associated with adaptive traits, thereby providing additional evidence to inform more sustainable conservation strateg (Supple and Shapiro, 2018; Funk et al., 2019; Huang et al., 2024; Thompson-Brandhagen et al., 2026). However, cellular and organoid phenotypes do not necessarily predict organismal fitness or population survival, as in vitro phenotypes may not fully capture tissue interactions, behavior, and environmental influences (Liu et al., 2025b). Therefore, stem cell and organoid models should be regarded as mechanistic tools that complement, rather than replace, organismal studies, population monitoring, and genetic analysis (Jensen and Little, 2023; Luce and Duclos-Vallee, 2025). The current applications and limitations of avian organoid systems are discussed in subsection 5.2.

Chicken serves as the primary model for avian stem cell and organoid studies because of extensive research on its development, genomics, and cell biology. Conversely, the Green peafowl is presented as a conservation-important species, suggesting that technologies developed for model birds could be applied to threatened or declining species. Thus, this section ends with a case study on how advanced genomic technologies can aid in conserving bird species, especially the endangered green peafowl (Pavo muticus), listed as EN by the IUCN Red List (BirdLife International, 2018). The green peafowl’s numbers decline due to hybridization with the Indian peafowl (Pavo cristatus), creating hybrids (Intarapat et al., 2023; Rackowski, 2025; Wang et al., 2025a; Sukumal et al., 2026). Genome assembly and mitochondrial and nuclear markers enable researchers to distinguish pure green peafowl from hybrids, improving conservation and breeding success (Du et al., 2020; Dong et al., 2021; Zhang et al., 2022). Using genetic tools provides precise insights into genetic diversity and supports better conservation strategies, including selecting genetically pure individuals for habitat release, as described in Figure 1.

A schematic illustrating the concept for bird conservation: from cells to conservation. 1.) Endangered avian species across different groups would be identified to guide urgent conservation efforts for those of interest. 2.) For bird conservation, cellular models can be built using somatic cells such as feathers, blood, and skin from target species, as well as germline cells such as primordial germ cells (PGCs), which can be collected and stored in biobanks. 3.) Somatic cells of interest can be cultured to derive avian stem cells, such as embryonic or pluripotent stem cells. These can be used in 3D cultures to produce avian organoids and to develop stem cell-based cellular models for bird conservation. 4.) Emerging translational platforms facilitate various genomic and omic studies using high-throughput methods such as genomic sequencing and gene editing to explore disease susceptibility, adaptive traits, and developmental processes. These investigations are often performed using cell-based models through genomic and functional screening. 5.) Genomic and functional analysis data can translate genetic variation into biological traits and functions, helping bridge the gap between genotype and phenotype. 6.) Cellular and genomic platforms can support evidence-based conservation by guiding strategic decisions. These decisions may involve genetic rescue, restoration strategies, artificial reproductive technology, disease control, biosecurity measures, population monitoring, and adaptive management as key conservation tools. 7.) Integrated knowledge from different platforms could pave the way for a sustainable conservation plan by ensuring the long-term viability of the avian population, a resilient population in a changing environment, sustainable coexistence with ecosystems, and ex situ and *in situ* conservation, all of which would be ideal conservation outcomes. Considerably, conservation intervention should not be treated as the endpoint of a technology-development pipeline. After implementation, outcomes should be monitored at the genetic, cellular, reproductive, demographic, and ecological levels to determine whether the intervention delivers the intended conservation benefit or produces unintended effects. These observations can inform adaptive conservation management, allowing the intervention to continue, be modified, or be discontinued based on emerging evidence. Thus, integrating stem cell and organoid technologies into conservation should be viewed as an iterative process rather than a linear transition from laboratory development to field application. Created by the authors with assistance from [bioart.niaid.nih.gov/](https://bioart.niaid.nih.gov/) and [Database Center for Life Science](https://dbcls.rois.ac.jp/index-en.html) licensed under CC-BY 4.0.
Figure 1. A schematic illustrating the concept for bird conservation: from cells to conservation. 1.) Endangered avian species across different groups would be identified to guide urgent conservation efforts for those of interest. 2.) For bird conservation, cellular models can be built using somatic cells such as feathers, blood, and skin from target species, as well as germline cells such as primordial germ cells (PGCs), which can be collected and stored in biobanks. 3.) Somatic cells of interest can be cultured to derive avian stem cells, such as embryonic or pluripotent stem cells. These can be used in 3D cultures to produce avian organoids and to develop stem cell-based cellular models for bird conservation. 4.) Emerging translational platforms facilitate various genomic and omic studies using high-throughput methods such as genomic sequencing and gene editing to explore disease susceptibility, adaptive traits, and developmental processes. These investigations are often performed using cell-based models through genomic and functional screening. 5.) Genomic and functional analysis data can translate genetic variation into biological traits and functions, helping bridge the gap between genotype and phenotype. 6.) Cellular and genomic platforms can support evidence-based conservation by guiding strategic decisions. These decisions may involve genetic rescue, restoration strategies, artificial reproductive technology, disease control, biosecurity measures, population monitoring, and adaptive management as key conservation tools. 7.) Integrated knowledge from different platforms could pave the way for a sustainable conservation plan by ensuring the long-term viability of the avian population, a resilient population in a changing environment, sustainable coexistence with ecosystems, and ex situ and in situ conservation, all of which would be ideal conservation outcomes. Considerably, conservation intervention should not be treated as the endpoint of a technology-development pipeline. After implementation, outcomes should be monitored at the genetic, cellular, reproductive, demographic, and ecological levels to determine whether the intervention delivers the intended conservation benefit or produces unintended effects. These observations can inform adaptive conservation management, allowing the intervention to continue, be modified, or be discontinued based on emerging evidence. Thus, integrating stem cell and organoid technologies into conservation should be viewed as an iterative process rather than a linear transition from laboratory development to field application. Created by the authors with assistance from bioart.niaid.nih.gov/ and Database Center for Life Science licensed under CC-BY 4.0.

3 Comparison of mammalian and avian cell-based models

Primordial germ cells (PGCs), induced pluripotent stem cells (iPSCs), and organoids are key tools for studying development, reproduction, and genotype–phenotype links in mammals and birds. PGCs are embryonic precursors to the germline, while iPSCs are pluripotent and can produce various somatic and germline lineages. Organoids mimic tissue structure and functions in 3D cultures. However, species-specific differences make direct application of findings challenging. Research on mammals, particularly mice, has extensively examined PGC specification and migration (Saitou and Yamaji, 2012). PGC-derived models have supported the investigation of germline development, epigenetic reprogramming, and inheritance across generations (Ben Maamar et al., 2021; Lee and Surani, 2024). In mice, PGCs originate in the posterior epiblast and are specified through a BMP and transcription factor-dependent pathway involving PRDM1/BLIMP1, PRDM14, and TFAP2C (Ohinata et al., 2005; Yamaji et al., 2008; Nakaki et al., 2013). After specification, mammalian PGCs migrate to the developing gonads, where they differentiate into spermatogonial or oogonial lineages (Nakatsuji and Chuma, 2001).

Avian PGCs share key features with mammalian PGCs, including their embryonic origin, migration to the gonads, and potential to contribute to the germline under specific conditions. However, their developmental routes differ significantly. In chickens, PGCs are in the central epiblast before gastrulation and migrate via the bloodstream to reach the gonads (Nakamura et al., 2007). This unique migration process has helped isolate and manipulate circulating PGCs, advancing avian germline biotechnology (Nakamura, 2017) (see subsection 4.1). A key point is that PGC biology is largely consistent across species, but developmental processes differ. This difference matters when developing germline technologies for endangered birds: success in chicken PGC culture, transplantation, or germline transmission (van de Lavoir et al., 2006a; Kang et al., 2008; Macdonald et al., 2010) does not ensure success across bird species (see subsection 4.2).

Regarding iPSCs and pluripotency, mammalian iPSCs, notably from mice and humans, are extensively studied (Takahashi and Yamanaka, 2006; Takahashi et al., 2007; Nakagawa et al., 2008; Maekawa et al., 2011). They can be maintained, differentiated, genetically engineered, and used in disease modeling and functional studies. In mammalian species, these techniques also enable germline contribution and, with other methods, support in vitro development of germ cell-like cells (Ben-Nun et al., 2011; Li et al., 2014b; Oikawa et al., 2022). In addition, research on avian iPSCs has advanced but remains in development. Chicken and other types of pluripotent stem cells show pluripotency and differentiation capabilities, and reprogramming methods enable sustainable cell sources (Lu et al., 2012, Lu et al., 2014; Fuet et al., 2018). However, avian pluripotency differs from mammals in developmental stage, culture conditions, and the stability of germline competence (Petitte et al., 2004; Han et al., 2015; Pain et al., 2018) (see subsection 5.1). Expressing pluripotency markers or differentiating into somatic lineages does not ensure germline competence or gene transmission. In conservation, an iPSC line from an endangered bird is valuable as a renewable resource (Katayama et al., 2022; Tong et al., 2026), but its usefulness depends on its ability to produce the necessary cell types and, for reproductive rescue, to develop into functional gametes that yield viable offspring (see subsection 5.1).

In organoid technology, mammalian organoids include intestinal, cerebral, liver, and kidney organoids that replicate tissue architecture, signaling, and function (Clevers, 2016). They are vital for studying development, disease models, drug discovery, and regenerative medicine, serving as an intermediate between single cells and whole organisms (Yao et al., 2024). In mammalian counterparts, avian organoid research is growing but still limited. Studies with chicken-derived intestinal, oviductal, respiratory, neural, and other organoids show avian cells can form 3D structures with tissue-specific traits (Pierzchalska et al., 2012; Katayama et al., 2023b; de Bruin et al., 2025; Santativongchai et al., 2026). These models support studies of developmental biology, infectious diseases, host-pathogen interactions, and toxicology (see subsection 5.2). Recently, focus has shifted to avian germline cells for reproductive and genetic research. Most systems are designed for a few species, mainly chickens, with applications to endangered birds still early. Both mammalian and avian organoids serve as controlled tissue models for studies. Mammalian systems are more mature, offering diverse methods, supported by established protocols, culture platforms, and datasets. In contrast, avian organoid technology is in early stages and requires significant species-specific modifications (see subsection 5.2).

Taken together, mammalian systems are vital models for avian biology, offering valuable insights but requiring caution when translating results. While many aspects, including PGC development and organoid formation, are similar across species, they also have unique features. Chickens are currently the most developed avian model, with limited data on non-avian models and endangered species. Therefore, mammal and chicken studies can demonstrate biological principles, but applying these to endangered birds requires species-specific validation. Evidence supporting cellular pluripotency, germline competence, transmission, gamete production, and viable offspring has become more rigorous and should not be considered equivalent.

4 Germline and reproductive biology

4.1 Developmental foundations of avian stem cell biology

Rather than providing a comprehensive description of avian embryogenesis, this section highlights developmental events that provide the biological framework for understanding stem cell potency, germline specification, lineage differentiation, and the development and interpretation of organoid models. Like mammals, an avian embryo undergoes regulated developmental stages before hatching, occurring both before egg-laying (pre-ovipositional) (Eyal-Giladi and Kochav, 1976; Kochav et al., 1980) and after (post-ovipositional) (Hamburger and Hamilton, 1951). After fertilization and before oviposition, for about a day, a chick embryo proliferates cells that later segregate into epiblast, hypoblast, and area opaca cells (Sheng, 2014, Sheng, 2015a). The area opaca cells are roughly equivalent to mammalian trophoblast cells. After oviposition, epiblast cells undergo planar morphogenesis to form a primitive streak (Sheng et al., 2021), followed by gastrulation events like epithelial-mesenchymal transition (Nakaya et al., 2008; Zhang et al., 2025a), migration, convergent extension (Voiculescu et al., 2007; Saadaoui et al., 2020; Caldarelli et al., 2024; Villedieu et al., 2025), and dorsal-ventral and anterior-posterior specification in ectoderm, mesoderm, and endoderm (Lawson et al., 2001; Yang et al., 2002; Fukuda and Kikuchi, 2005; Alev et al., 2010). Around Day 2 after oviposition, cardiac contraction and blood circulation mark the transition from gastrulation to organogenesis (Nakazawa et al., 2006; Nagai et al., 2018; Wittig and Munsterberg, 2020). The amnion, an extraembryonic tissue and key feature of amniotic vertebrates, encloses the embryo at Day 3 (Fleury et al., 2016; Chuva de Sousa Lopes et al., 2022; Tam et al., 2026). The allantois, another extraembryonic tissue, extends from the embryonic hindgut into the extraembryonic coelomic cavity and fuses with the chorion to form the chorioallantoic membrane (CAM), starting at Day 4 (Nagai et al., 2022). The CAM expands to cover the eggshell’s underside, acting as the embryo’s breathing organ (Ismagulov et al., 2026). From Day 10, tissue and organ growth accelerate. Chick hatching occurs at Day 21 (Hamburger and Hamilton, 1951), but varies among species (Nagai et al., 2011) and is influenced by selection pressure on brooding and parental care durations.

Our understanding of avian stem cell biology lags behind that of the mammalian counterparts. This is largely due to limited tools for culturing and manipulating avian stem cells in vitro. Early development in birds and mammals is very similar, with conserved morphogenetic and molecular regulatory mechanisms (Sheng, 2014, Sheng, 2015a). Concepts of stem cell biology developed using mammalian models can be applied to the avian models. Totipotency refers to stem cell-like cells that can give rise to all intra- and extra-embryonic tissues upon differentiation. In birds, totipotency may be considered to refer to pre-ovipositional blastoderm cells. Pluripotency refers to stem cell-like cells that can give rise to all somatic cells in the three germ layers and the germ cells. In birds, pluripotency refers to early post-ovipositional epiblast cells. Likewise, lineage-restricted multipotent stem cells, applicable in both mammals and birds, can give rise to germ-layer or sub-germ layer-restricted cell types, e.g., neural stem cells, mesenchymal stem cells (Khatri et al., 2009; Sheng, 2015b), and hematopoietic stem cells (Yvernogeau and Robin, 2017). These multipotent stem cells refer to stem cell-like cells after completion of gastrulation, but before organ/tissue maturation. Many such multipotent stem cells, and more restrictively unipotent stem cells, remain in post-hatching development and throughout adult life. Avian totipotent stem cells are still a conceptual term, as they have not been shown experimentally. In vitro derivation and culture of avian pluripotent stem cells has been reported in several publications, and most recently in Nature Biotechnology (Chen et al., 2025b) with a derivation method applicable in many different avian species.

4.2 Germline competence and PGC biology

Terminologically, germline competence, germline transmission, gamete production, and viable offspring production should be distinguished as distinct levels of biological evidence. Germline competence refers to a cell’s capacity to produce a functional gamete and pass complete genetic information to the next generation (Han et al., 2015). Germline transmission provides stronger evidence by demonstrating that donor-derived genetic material is incorporated into the functional germline and transmitted to progeny (Hu et al., 2024; He et al., 2025). Gamete production is a further functional endpoint and requires evidence that sperm or oocytes have been generated, ideally with appropriate developmental, genetic, epigenetic, and reproductive competence (Blesbois, 2012). The strongest evidence is viable offspring production, particularly when donor-derived genetic material can be confirmed in the resulting progeny (Ballantyne et al., 2021).

4.2.1 Establishment and maintenance of germline competence

Germ cells in avian gonads are derived from primordial germ cells (PGC) generated before gonad formation. Avian PGCs are currently considered to be specified by maternally derived germ plasm, enriched in a small subset of blastoderm cells during and soon after epiblast formation at peri-ovipositional stages (Whittle and Extavour, 2017; Kim and Han, 2018; Blank et al., 2026a). More recent data indicated that ESCs derived from early post-ovipositional epiblast are capable of contributing to the PGC lineage (Chen et al., 2025b), suggesting an alternative, inductive route of PGC generation in birds. Among avian species, robust in vitro PGC culture systems have been established primarily in chicken (van de Lavoir et al., 2006a; Choi et al., 2010; Macdonald et al., 2010; Song et al., 2014; Whyte et al., 2015; Tonus et al., 2016; Altgilbers et al., 2021). PGCs have also been isolated and cultured in vitro in a limited number of non-chicken species, including duck (Chen et al., 2019), zebra finch (Jung et al., 2019), goose (Doddamani et al., 2025) and pigeon (Nicholson et al., 2026b); however, these approaches remain comparatively limited and require further validation and optimization before they can be considered broadly established culture systems. Currently, sources for PGC derivation/maintenance include post-circulation blood, young gonad, and precirculation stage blastoderm. Culture of chicken PGCs and their genetic modifications are widely and successfully used for a variety of purposes, including agricultural (pathogen-resistant breeds) (Arango and Fulton, 2026; Sid and Schusser, 2026), food (allergen-free eggs) (Ezaki et al., 2023), and basic research (fluorescence-labeled cells) (Henderson et al., 2025).

Bird germline-competent stem cells include blastodermal cells (BDCs), embryonic stem cells (ESCs), primordial germ cells (PGCs), embryonic germ cells (EGCs), spermatogonial stem cells (SSCs), and oogonial stem cells (OSCs) (Han et al., 2015; Kagami, 2016). PGCs are especially valuable for conserving avian genetics as they contribute directly to the germline and are useful for creating germline chimeras (Petitte, 2006; Tajima, 2013). Cross-species PGC transplantation to produce functional gametes in sterile hosts remains challenging. Notably, Kang and colleagues demonstrated that interspecies PGC transplantation is possible by creating pheasant–chicken germline chimeras. They transplanted pheasant PGCs into chicken embryos and obtained pheasant offspring by mating male chimeras with female pheasants (Kang et al., 2008). This evidence shows that interspecies PGC transplantation can produce offspring of the donor species, which is highly significant for genetic conservation. Additionally, a recent study found that injecting GFP-labeled chicken PGCs into guinea fowl and domestic fowl resulted in nearly all recipient gonads producing sperm (Molnar et al., 2024). Effective methods to remove host germ cells before transplantation and identify suitable recipients are still needed.

4.2.2 Germline preservation and transplantation

Birds have unique PGC development, with PGCs migrating through blood vessels from the extragonadal region to developing gonads (Nakamura et al., 2007; Tagami et al., 2017). This allows chicken PGCs to be collected at various embryonic stages, including the blastoderm (Chen et al., 2025a), germinal crescent (Song et al., 2014; Collarini et al., 2015), blood vessels (van de Lavoir et al., 2006a; Choi et al., 2010; Macdonald et al., 2010; Collarini et al., 2015; Whyte et al., 2015), and gonads (Song et al., 2014; Collarini et al., 2015, Collarini et al., 2019). Cryopreserving avian stem cells like ESCs and PGCs is a conservation strategy for endangered species (Kagami, 2016; Ichikawa and McGrew, 2024). This enables germ cell cryobanks as an alternative to traditional conservation efforts, with new protocols successfully derived in various bird species (Chen et al., 2025b). These protocols facilitate research in in vitro gametogenesis and germ-line development, supporting the conservation and revival of endangered bird populations as outlined in Table 1.

Table 1. Technologies and platforms for genetic rescue in avian genetic conservation using organoids and cell-based models.

Technology/platformSpeciesCurrent applicationsConservation approachesReferences
Organoid models
EnteroidsChickenDisease modeling; intestinal cell biology; host-pathogen interactions; pharmacological testing; innate immunity/[Est]Modeling susceptibility to emerging avian infectious diseases; comparing disease susceptibility acrossgenotypes; screening conservation-relevantpathogens; prioritizing resistant or vulnerable lineages/[Pro](Acharya et al., 2020; Nash et al., 2021; Zhao et al., 2022; Nash et al., 2023)
Intestinal organoidsChick(Pierzchalska et al., 2012, Pierzchalska et al., 2017; Mitchell et al., 2024; Shin et al., 2025;Sun et al., 2025; Teng et al., 2025)
Duck(Tang et al., 2025; Zhang et al., 2026)
Tracheal organoidsChickenAvian influenza virus modeling; innate immune response profiling; antiviral drug screening; avian airway biology; epithelial-endothelial interaction studies/[Est]Predicting wild bird species susceptibility; emerging influenza strains; modeling respiratory disease risk incaptive and wild birds; guiding vaccine or intervention strategies; identifying genotype-linked susceptibility/[Pro](de Bruin et al., 2025)
Lung organoidChicken(Nicholson et al., 2026a; Tarres-Freixas et al., 2026)
Oviductal organoidsChickenTurkeyReproductive physiology; pathogenesis of disease/[Est]Understanding reproductive failure in threatened bird populations/[Pro](Cordeiro et al., 2021; Santativongchai et al., 2024, Santativongchai et al., 2026)
Neural-like organoidsChickenRisk assessment of infectious diseases; host-pathogen interactions/[Est]Assessing neurological impacts of infection or toxic exposures in threatened birds; supporting phenotypescreening of rescuedgenotypes/[Pro](Katayama et al., 2023b)
Germline organoidsZebra finchAvian reproductive development/[Est]Assisting reproduction inwild birds/[Pro](Brown et al., 2026)
Stem cell models
Embryonic stem cells (ESCs)ChickenGermline chimerism; donor-derived germ cells production; germ layer differentiation in vitro andin vivo; transgenic line production; derivation across multiple bird species; in vitro propagation; cryopreservation/[Est]Producing germline-competent cell lines forex situ conservation; generating cross-species chimerism to restore reproduction in sterile surrogates; gene editing for introducing disease-resistance traits; providing a basis for futurede-extinction; cell banking from rare birds; offering future germline recovery; rescuing lost alleles; generating long-term genetic repositoryfor extinction prevention/[Pro](Pain et al., 1996; Petitte et al., 2004; van de Lavoir et al., 2006b; Fuet and Pain, 2017;Chen et al., 2025b)
Quail
Goose
Duck
Turkey
Pheasant
Peafowl
Ostrich
Induced pluripotent stem cells (iPSCs)ChickenCellular reprogramming;in vitro gametogenesis; disease modeling; genome editing;alternative for genetic manipulation; non-invasive genetic preservation; multi-pathway species recovery/[Est]Providing genetic biobanking; generating species-specific models; studying gametogenesisin vitro; providing non-invasive biobanking of threatened species; expanding captivebreeding; increasing genetic diversity across conservation; saving avian species from extinction; enabling germline preservation of endangered species/[Pro](Rosselló et al., 2013; Dai et al., 2014; Lu et al., 2014; Yu et al., 2014; Kim et al., 2017; Fuet et al., 2018; Katayama et al., 2018; Tong et al., 2026)
Quail(Lu et al., 2012; Rosselló et al., 2013; Lu et al., 2015; Tong et al., 2026)
Okinawa railJapanese ptarmiganBlakiston’s fish owl(Katayama et al., 2022)
Duck(Tong et al., 2026)
Peacock(Tong et al., 2026)
Zebra finch(Rosselló et al., 2013; Tong et al., 2026)
Pigeon(Tong et al., 2026)
Germline cells/germline stem cells
Primordial germ cells (PGCs)ChickenGermline transmission; transgenesis; genomeediting; germline-competent cells; chimera production; cryopreservation; biobanking/[Est]Providing genetic rescue; offering endangered avian germline preservation; enabling endangered species biobanking; offeringsurrogate host reproduction; transplanting PGCs to threatened species; restoring extinct geneticlineages from cryobank specimens/[Pro](van de Lavoir et al., 2006a; Choi et al., 2010; Macdonald et al., 2010; Song et al., 2014; Whyte et al., 2015; Tonus et al., 2016; Chen et al., 2018; Collarini et al., 2019; Altgilbers et al., 2021; Chen et al., 2025a; Nayga et al., 2026)
Duck(Chen et al., 2019)
Quail(Nakamura et al., 2013; Sritabtim et al., 2024)
Goose(Doddamani et al., 2025)
Rock dove(Nicholson et al., 2026b)
Pheasant(Kang et al., 2008, Kang et al., 2009;Chaipipat et al., 2021)
Zebra finch(Jung et al., 2019; Biegler et al., 2025)
Spermatogonial stem cells (SSCs)ChickenGermline preservation andTransplantation/[Est]Recovering male fertility; offering a maintenance of rare alleles/[Pro](Jung et al., 2007; Naito, 2011; Trefil et al., 2012; Momeni-Moghaddam et al., 2014; Rasouli-Gharehsaghal et al., 2020; Ibtisham et al., 2024)
Quail(Pramod et al., 2017)
Pheasant(Kim et al., 2014)
Cryopreservation/biobanking
Somatic cells: FFs; FFCs; FPFsChickenNon-invasive cell reprogramming; genetic diversity preservation, cryopreservation, long-term storage repositories; cell toxicity/[Est]Providing a conservation plan; supporting minimally invasive genetic rescue in endangered species; developing cell-based biobanks, in vitro conservation; studying environmental stressorsin wild species/[Pro](Xi et al., 2003; Cardoso et al., 2020b)
Red & Green Macaw(Blank et al., 2025)
Hyacinth Macaw(Nogueira et al., 2025)
Wild birds(Kroglund et al., 2022; Katayama et al., 2023a; Reis et al., 2025)
Germplasm: PGCs; TCs; OT, semenChickenAvian biotechnology; genetic resource conservation; germline chimera; breeding; gamete cryopreservation,biobanking; biorepository; artificial insemination; wildlife conservation/[Est]Generating geneticmodified birds; producing interspecific germline chimera; banking sperm for conservation purpose; enabling semen cryopreservation for endangered species; preserving the fertility of wild female birds/[Pro](Naito et al., 1994; Liu et al., 2012; Nakamura, 2016; Nandi et al., 2016; Tonus et al., 2017; Thelie et al., 2019; Lazar et al., 2021; Fujihara et al., 2022; Santiago-Moreno and Blesbois, 2022; Chaipipat et al., 2023; Hu et al., 2024; Kinoshita et al., 2024; Choi et al., 2025; Liu et al., 2025a)
Quail(Kowalczyk, 2008; Nakamura et al., 2013; Kang et al., 2016; Park et al., 2020)
Duck(Tselutin et al., 1995; Wang et al., 2025b; Zhang et al., 2025b)
Turkey(Tselutin et al., 1995; Blanco et al., 2011;Di Iorio et al., 2020; Paventi et al., 2022)
Pheasant(Saint Jalme et al., 2003; Castillo et al., 2021; Zuha et al., 2024)
Crane(Blanco et al., 2011; Brown et al., 2018; Mooney et al., 2023)
Bustard(Hartley et al., 1999; Carreira et al., 2022)
Falcon(Blanco et al., 2000; Cardoso et al., 2020a)
Wild birds(Rakha et al., 2018; Chaipipat et al., 2021; Bezerra et al., 2024; Khursheed et al., 2025; Blank et al., 2026b)

Est, established technology; FFs, feather fibroblasts; FFCs, feather follicle cells; FPFs, feather pulp fibroblasts; PGCs, primordial germ cells;.

Pro, proposed application; OT, ovarian tissue; TCs, testicular cells.

Additionally, PGC transplantation is a germ cell-mediated technology used in avian models, with evidence showing donor germline contribution and inheritance in certain species (Kuwana et al., 2006; Mucksova et al., 2019; Wernery et al., 2010, Wernery et al., 2011; van de Lavoir et al., 2012). However, this evidence is inconsistent across different bird species. Because chickens are the most well-studied, the practicality and success rate of this method in threatened or endangered species remain uncertain. Furthermore, variations among bird species in development, migration, gonadal colonization, and culture methods are species-specific and may influence the transplantation process (Park and Han, 2013; Cooper et al., 2018; Hu et al., 2024; Molnar et al., 2024; Nayga et al., 2026). Therefore, PGC transplantation should be seen as an experimentally proven germline technology in select avian models, rather than a universally reliable germline rescue technique. Validation for each species is necessary before applying this method to conservation efforts in threatened and endangered birds.

4.2.3 Emerging reproductive technologies

Spermatogonial stem cells (SSCs) pose new challenges for wildlife conservation (Naito, 2011; MastroMonaco et al., 2014; Damyanova et al., 2024; MastroMonaco et al., 2026). Xenotransplantation of germline cells, especially for infertile birds, can potentially rescue endangered avian species by transferring germline stem cells from one species to another (Pereira et al., 2013; Rasouli-Gharehsaghal et al., 2023). This method can address male infertility by generating interspecific germline chimeras through transplantation into domestic hosts (Kim et al., 2014). Transferring SSCs between species has been demonstrated, such as transferring adult quail SSCs into chicken embryos (Roe et al., 2013; Blank et al., 2024). This strategy allows recovery of germline cells from deceased birds, aiding endangered species’ reproduction. Multiple methods for isolating, culturing, and maintaining avian SSCs are documented (Momeni-Moghaddam et al., 2014; Pramod et al., 2017; Rasouli-Gharehsaghal et al., 2020; Ibtisham et al., 2024). Little is currently known about avian oogonial stem cells (OSCs), which are believed to help preserve female germ cells and support reproductive longevity in birds (Ma et al., 2026; Sun et al., 2026). These cells might also be useful for in vitro oogenesis and addressing issues with compromised oocytes in endangered avian species. Identifying and testing germline-competent stem cells could be promising strategies for enhancing fertility management in endangered birds, as demonstrated in Table 1.

5 Cellular platforms and biobanking

5.1 iPSCs and PGC technologies

Avian induced pluripotent stem cells (aiPSCs), such as quail iPSCs (qiPSCs), are the first non-mammalian iPSCs, derived from embryonic fibroblasts (Lu et al., 2012). Other bird species, such as chicken and zebra finch, have also had iPSCs generated from somatic cells (Rosselló et al., 2013; Yu et al., 2014; Choi et al., 2016; Fuet and Pain, 2017; Katayama et al., 2018). Feather follicle cells are another source for iPSC induction (Kim et al., 2017). Compared to mammals, avian species have fewer somatic cell sources, and further research is needed to compare efficiencies and develop protocols for conservation, especially in wildlife and endangered species (Nogueira et al., 2024; Zahoor et al., 2024; Katayama and Fukuda, 2026), as mentioned in Table 1.

Primordial germ cells are ideal for cryopreservation (Glover and McGrew, 2012; Doddamani et al., 2025). While avian PGCs from chickens were first isolated, long-term culture for conserving endangered birds remains difficult. Successful culture depends on growth factors and strain-specific needs, some of which can inhibit growth (Ge et al., 2009; Choi et al., 2010; Miyahara et al., 2014; Whyte et al., 2015; Miyahara et al., 2016; Dehdilani et al., 2023; Yousefi Taemeh et al., 2025). For instance, activin A supports chicken PGC self-renewal but inhibits goose PGCs (Doddamani et al., 2025). More research is needed to develop universal culture media for various avian species, especially endangered ones. A key point about avian PGCs, linked to earlier genetic studies, is the variation among PGCs across bird species (Ichikawa and McGrew, 2026). Transcriptional comparisons between chicken and zebra finch PGCs reveal differences in signaling pathways in gonadal PGCs and surrounding somatic cells (Jung et al., 2023; Ichikawa and McGrew, 2026). Understanding genetic differences between domestic and wild birds is vital for conserving avian genetic resources and restoring endangered species.

Isolating and developing endangered bird species that remain understudied is crucial. For example, studying the green peafowl (listed on CITES Appendix II and the IUCN Red List as endangered within the family Phasianidae) offers valuable insights. Similar families, such as Phasianidae (pheasants), could facilitate the isolation of PGCs from these endangered species. Interestingly, successful methods for deriving avian PGCs from domestic birds such as chickens have also been applied to wild species, including those in the family Phasianidae (Chaipipat et al., 2021). We suggest that protocols established for domestic species within the same bird family could be adapted for use with these endangered birds. One piece of evidence strongly supporting the use of an interspecific system in aves is the practical derivation of a culture system using a chicken culture medium. Such a system has also been applied to avian conservation: interspecific germ cell transplantation in Phasianidae was achieved (Kang et al., 2008, Kang et al., 2009). It has been shown that pheasant PGCs successfully completed gametogenesis and produced functional spermatozoa in chickens (Kang et al., 2008). Applying this culture method from a genetically similar family would offer hope of obtaining PGCs from endangered species such as the green peafowl. A key challenge in working with endangered species is the difficulty of collecting their eggs, including purebred eggs from domesticated species, in captivity. This difficulty arises from their breeding seasons, the number of eggs females lay, and the low fertilization rates. Implementing well-managed protocols and conducting thorough sampling could help researchers obtain genetic material from endangered birds for future use.

Reproductive germ cells, such as PGCs, induced PGCs, and PGC-like cells from endangered species, can be stored in cryobanks. Moreover, indigenous chicken breeds derived from PGCs—whether from embryonic blood or tissue—are also suitable for cryopreservation (Chaipipat et al., 2023). This method promotes ex situ conservation by offering a practical way to safeguard endangered bird species. Assessing the potential of cultured PGCs from endangered bird species is challenging because culture media vary across species. Once a cell line is established, PGC survival and migratory capacity in the embryonic gonad should be confirmed before long-term preservation. Therefore, germline biobanking should include not only cryopreservation but also evidence that thawed PGCs can migrate—a key in vivo trait. We recommend prioritizing the optimization of culture media already established for chicken and related species for PGC-based conservation, a step that warrants further research. Currently, PGC culture media for conservation have been documented using the rock dove (Columba livia) as a model (Nicholson et al., 2026b). This step is essential in avian germ cell biology, where species-specific media and protocols, adapted from other birds, should be applied to endangered species. An omics-guided approach could further refine conditions by identifying crucial factors specific to endangered avian PGCs that are essential for germ cell survival and proliferation. Combining this toolkit with conservation efforts would significantly enhance germ cell-based ex situ preservation. An alternative method for this study is to use the optimized rock dove PGC culture media with the critically depleted (CD) pink pigeon (Nesoenas mayeri), which is currently classified as vulnerable (VU) on the IUCN Red List (BirdLife International, 2021d). The pink pigeon faces a high risk of extinction. Since it belongs to the same family, Columbidae, as the rock dove, employing PGC-mediated and somatic cell biobanks offers a promising conservation strategy. This approach could also benefit other near-threatened (NT) species, such as the Nicobar pigeon (Caloenas nicobarica) (BirdLife International, 2021b), which is within the same family. These findings suggest that Columbidae could be a key family for cell-based conservation efforts.

iPSC technology could aid conservation by producing functional gametes in vitro and generating blastoids for embryo reconstruction (Lou et al., 2025). In vitro gametogenesis from ESCs and iPSCs enables germline cell production for future use, aiding bird species’ genetic conservation (Botigelli et al., 2023; Ma et al., 2026). A challenge is that germline competence has not been demonstrated in iPSCs derived from endangered birds (Katayama et al., 2022).

In avian models, ESCs can differentiate into germ cells, but iPSC-derived PGC-like cells in chickens show limited germline competence (Chen et al., 2025b; Tong et al., 2026). This illustrates the promise of germ cells from ESCs and iPSCs for endangered birds and the potential to reliably obtain bona fide PGCs from iPSCs, pending further verification.

The ability of pluripotent stem cells to generate germline-related cells offers a potential pathway toward future reproductive applications. However, germline competence and the subsequent production of viable offspring remain incompletely demonstrated across avian species, particularly endangered birds.

5.2 Organoid derivation and systems

Unlike mammals, the avian blastula appears as a disc-shaped structure called “the blastodisc,” which is adjacent to the egg yolk. Stem cell-based embryo models (SCBEMs), including blastoids and blastocyst-like structures, have been successfully created in various mammalian species, such as mice (Rivron et al., 2018; Li et al., 2019) and humans (Kagawa et al., 2022). Developing this technology further could enhance conservation efforts through genetic rescue in mammals and facilitate the production of reproductive cells (Hutchinson et al., 2024). Similar to mammals, organoids and stem cell technologies are employed in healthcare, with protocols for differentiating these cells into somatic types for disease treatment developed in birds. Using these therapies outside organisms supports a One Health approach (Gabriel et al., 2024; Fujihara and Comizzoli, 2025).

Research on avian organoids has advanced from simple three-dimensional tissue cultures to more complex systems that mimic specific structural and functional traits of bird tissues. Chicken intestinal organoids were developed using embryonic intestinal tissue, with prostaglandin E2 aiding their growth (Pierzchalska et al., 2012). Microbial signals were later found to influence the growth and proliferation of chicken intestinal organoids, serving as a model for host–microbe interactions (Pierzchalska et al., 2017). The complexity of avian intestinal models has advanced over time. Chicken crypt-villus enteroids, which include goblet, enteroendocrine, and antimicrobial cells, successfully mimic essential aspects of the intestinal lining (Acharya et al., 2020). Moreover, apical-out enteroids containing both epithelial and immune cells provide additional opportunities to explore host–pathogen interactions and immune responses (Nash et al., 2021). Chicken iPSC-derived neural-like organoids have demonstrated innate antiviral responses following poly:IC stimulation (Katayama et al., 2023b). Chicken intestinal organoids have been utilized in nutritional and toxicological research, including studies on feed additives and toxin-induced epithelial barrier disruption (Mitchell et al., 2024), innate immune responses (Shin et al., 2025), intestinal cell biology (Sun et al., 2025), and host-pathogen interactions (Teng et al., 2025). Researchers have used an avian oviductal organoid model in reproductive biology and infectious disease research (Cordeiro et al., 2021; Santativongchai et al., 2024, Santativongchai et al., 2026). Overall, the existing evidence supports the use of avian organoids primarily as ex vivo models for studying tissue development, infection, immunity, toxicology, and reproduction. Although these applications are experimentally validated, they should not yet be considered conservation tools.

Recent studies show that avian organoid research is expanding to various tissues and species beyond chickens. Tracheal organoids from chickens and ducks grown at an air-liquid interface have served as models for avian respiratory epithelium and viral targeting (de Bruin et al., 2025). Duck intestinal organoids have created a species-specific system to study intestinal function and immune responses (Tang et al., 2025; Zhang et al., 2026). Avian lung organoids, derived from adult stem cells, have mimicked key features of the respiratory system and facilitated research into viral infection and disease mechanisms (Nicholson et al., 2026a). Notably, long-term germline organoids from zebra finch gonads that retain primordial germ cell markers have recently been developed, providing a model to explore avian germline development and reproductive biology (Brown et al., 2026). This marks a shift from using organoids mainly for poultry health to models that could support conservation efforts. However, compared with mammalian organoids, avian models remain limited, with most developed in domestic or laboratory species.

Germline organoid systems have been proposed as experimental platforms for studying germline development and reproductive biology, but their application to avian conservation remains at an early, conceptual stage. Several technical challenges must be addressed before organoid systems can be reliably developed for endangered birds, including species-specific requirements for tissue sources and culture conditions, limited validated protocols for non-model birds, incomplete cellular maturation and tissue organization, variability in cellular composition, long-term maintenance, and the absence of native tissue components. Thus, avian organoid research is currently progressing from well-established experimental models toward more species- and tissue-specific systems, with their potential conservation applications remaining to be experimentally demonstrated.

Experience from non-avian endangered species provides useful comparative evidence for this emerging field. Endometrial organoids have been established from the endangered Przewalski’s horse (Thompson et al., 2020), and more recently, from the greater one-horned rhinoceros (Rhinoceros unicornis) and southern black rhinoceros (Diceros bicornis minor) (Thompson-Brandhagen et al., 2026). The rhinoceros study demonstrated species-specific differences in organoid proliferation and morphology, highlighting the need to optimize culture conditions for each species (Thompson-Brandhagen et al., 2026). More broadly, stem cell and organoid approaches have been proposed for investigating germ cell specification and maturation in the context of fertility biotechnology and conservation (Hutchinson et al., 2025). However, comparable applications of avian organoids to endangered-species conservation have not yet been established. These comparative studies therefore provide a precedent for species-specific organoid development, but not evidence that similar systems will function in birds.

Accordingly, findings from chicken-derived organoid and stem cell systems should be interpreted primarily as experimental proof of concept when considering applications to non-model or endangered birds. Species-specific validation will be necessary to determine whether these systems can reproducibly recapitulate relevant cellular and tissue phenotypes. The principal challenge is therefore not simply establishing organoid cultures, but determining their biological validity and practical utility for species-specific research. Organoid models, species-derived organoids, and their current applications are summarized in Table 1.

Ultimately, iPSCs, PGCs, and organoid technologies establish chicken as the most extensively developed avian platform for evaluating the feasibility of cellular and germline technologies. Whether these capabilities can be reproduced in endangered birds remains largely unresolved.

5.3 Cellular biobanking and conservation applications

While assisted technologies help preserve endangered species, integrated stem cell methods offer an alternative for avian conservation (Petitte, 2006; Intarapat and Stern, 2013; Intarapat et al., 2023). In vitro conservation, like biobanking, is a challenge for storing somatic and germ cells as a Genetic Resource Bank (GRB) for future use (Wildt et al., 2010; Holt and Comizzoli, 2021). Somatic tissue-derived stem cells are versatile tools for wildlife conservation. Tissue biopsies from dead and live animals can be transdifferentiated into specific cell types (Mahla, 2016). Bird feather-derived cells can be cryopreserved for conservation (Kjelland and Kraemer, 2012; Cardoso et al., 2020b; Blank et al., 2025; Nogueira et al., 2025). Feather tissues—such as follicle cells and pulp fibroblasts—serve as sources for generating avian iPSCs (Kim et al., 2017; Nogueira et al., 2024).

Conservative approaches involve preserving long-term repositories by biobanking frozen cells and tissues (Monfort, 2014; Bolton et al., 2022; Fujihara and Comizzoli, 2025; Madelaire et al., 2025; Nagashima et al., 2025; Santos et al., 2025). The Frozen Zoo, or CryoZoo, is a biobank preserving genomes and germplasm of endangered species (Benirschke, 1984; Monfort, 2014; Mooney et al., 2023). Both avian embryonic stem cells and primordial germ cells can be cryopreserved for germplasm preservation (Petitte, 2006; Glover and McGrew, 2012). Various avian cell types, including erythrocytes (Bissoyi et al., 2026), feather follicle cells (Reis et al., 2025), and reproductive cells (Hu et al., 2022), have been cryopreserved (Figure 1). Biobanking therefore provides the repository through which cellular and genetic resources can be preserved for future research or conservation applications (Ryder and Onuma, 2018). However, preservation alone does not establish functional competence; the biological properties of thawed cells, including survival, proliferation, and lineage potential, require appropriate validation before their conservation value can be established. Avian somatic cell and germplasm cryopreservation is summarized in Table 1.

6 Functional genomics and genetic rescue

The transition from descriptive genomics to functional genomics is critical for modern avian conservation. While whole-genome sequencing and omics studies, including gene expression, provide vast datasets on population structure and bird genes responding to environmental stressors (Jax et al., 2018; Cassin-Sackett et al., 2019), identifying the causal variants underlying adaptive traits remains a significant bottleneck. This genotype-to-phenotype gap limits the ability to predict responses to environmental changes and implement genetic rescue (Gjuvsland et al., 2013; Rellstab et al., 2021). To bridge this gap, exploiting extensive genomic resources—such as functional annotations of the avian genome (e.g., FAANG initiatives) and regulatory element mapping—is critical. Since non-coding regulatory regions, including enhancers and promoters, control spatial and temporal gene expression (Zhou et al., 2026b), leveraging ATAC-seq alongside transcriptome profiling allows us to decipher how genomic architecture and epigenetic landscapes dictate phenotypic plasticity. Functional genomics addresses this challenge by utilizing in vitro platforms, to empirically test the physiological impact of these specific candidate genes and regulatory variants under controlled conditions (Kar et al., 2021; Pain, 2021; Kwon et al., 2026). By integrating transcriptomic data with these cellular models, we can prioritize the variants conferring resistance to diseases or tolerance to climate change, ensuring that genetic rescue efforts are precisely targeted.

Furthermore, the application of functional genomics opens new avenues for targeted genetic rescue, moving beyond traditional gene flow strategies. Once adaptive alleles and their regulatory networks are functionally validated, genome-editing technologies can be employed within targeted cells. After functional validation of candidate variants and their regulatory effects, genome-editing approaches could be explored in vitro or other systems capable of germline transmission. These applications remain theoretical, especially for endangered bird species, and would require thorough evaluations of germline transmission, offspring viability, fitness impacts, and effects on population dynamics. As demonstrated by successful cross-species PGC transplantations into sterile interspecific avian recipients (Molnar et al., 2024), these functional cells can subsequently generate viable germline chimeras, effectively translating functional genomic discoveries into live, resilient breeding populations.

Looking forward, the integration of functional genomics with stem cell and organoid technologies represents a transformative paradigm for sustainable avian conservation. The proposed “From Cells to Conservation” framework integrates genomic information with functional analysis of relevant cellular and tissue phenotypes to inform potential conservation applications (Monfort, 2014; Mooney et al., 2023). Leveraging functional genomics in tandem with stem cell and organoid models may therefore support proactive management of the evolutionary potential of declining bird species, contributing to their adaptation and long-term survival in rapidly changing ecosystems (Hoffmann et al., 2021; Hutchinson et al., 2024), as shown in Figure 1.

7 From cells to conservation: future perspectives

Organoid and stem cell technologies benefit bird conservation by validating genetic variants, assessing disease risk, studying reproductive biology, and preserving germline cells (Hutchinson et al., 2024; Brown et al., 2026; He and Duan, 2026; Thompson-Brandhagen et al., 2026). Basic genomics reviews should include studies of avian germlines, such as germline transmission, which can be tested in vitro. Organoid technology also advances functional genomics and disease modeling (Cheng et al., 2026).

Translating research into conservation strategies is essential. Climate change threatens species by causing declines (Urban, 2015). Understanding how it influences biological adaptation at cellular and organismal levels is valuable. Birds like green peafowl are vulnerable to climate fluctuations (Dong et al., 2021). Climate change impacts endangered species through range shifts, habitat fragmentation, and reduced connectivity (Cao and Shi, 2022; Asgharzadeh et al., 2023; Intarapat et al., 2023). The cellular and physiological effects of rising temperatures on fertility are unclear. Hyperthermia affects reproductive cells in birds, impairing their function and migration (Gu et al., 2024). Disrupted migration can reduce gamete production and reproductive success. Why is cellular biology crucial for conservation? Understanding this links climate’s cellular effects to avian reproductive preservation and genetic resilience in adaptation, as described in Figure 1.

7.1 Linking platforms to real-world conservation

Researchers recently cultured specialized cells from the rock dove, and this method could extend to cells from the Nicobar pigeon, the dodo’s closest living relative in the same bird family. Harnessing gene-editing and stem cell methods could make resurrecting a bird like the dodo remain a challenge. Recently, stem cell scientists cultivated primordial germ cells—precursors to sperm and eggs—from the rock dove (Columba livia) (Nicholson et al., 2026b). This breakthrough supports the dodo de-extinction project. Since the dodo is related to pigeons and doves, using Nicobar pigeon PGCs with a surrogate chicken could test the feasibility of resurrection (Alexandre et al., 2026). However, the dodo symbolizes that emerging technologies such as genomics and reproductive science could someday revive extinct species. These ideas remain theoretical and are not proven conservation methods. While genomic and cellular techniques could play a role, many biological hurdles remain, such as recreating cellular states, producing germ cells, ensuring reproductive compatibility, supporting embryonic development, and establishing sustainable populations. De-extinction differs from proven conservation and genetic rescue, which focus on maintaining existing genetic diversity. Currently, the dodo mainly illustrates potential future technology integration rather than a validated conservation strategy.

Furthermore, the “Bring Back Blue” project (Zoo Praha, 2026) highlights efforts to reintroduce the Vietnam pheasant (Lophura edwardsi), which has declined and is classified as critically endangered (CR) (BirdLife International, 2024). It includes ex situ conservation, such as relocating individuals from Germany to Vietnam, showing how conservation in one country can support umbrella species elsewhere. This aligns with translocation strategies (Berger-Tal et al., 2020; Collar, 2020). Additionally, we suggest a similar cell-mediated approach for this species. However, applying cell-based conservation strategies to Lophura edwardsi remains an emerging and relatively unexplored area. Preserving somatic and germline cells, along with stem cell technologies and biobanking, may provide complementary resources to safeguard genetic diversity and support future translocation and reintroduction efforts.

Despite the latest technologies and innovations, conservationists benefit most from integrating various approaches. One focus is maintaining global bird populations to ensure survival and gene transmission. This could lead to resurrecting extinct species through genetics, conserving living species to prevent extinctions, and preserving traits for future research. Using advanced techniques, we aim to support reproduction and conservation from cellular to ecological levels, offering hope for safeguarding bird species for future generations, as described in Figure 1.

7.2 Conservation applications and outcomes

Animal populations, including birds, are threatened by factors like climate change (Johnson and Koepfli, 2014), leading to declines and increased inbreeding (Wei et al., 2024). Rising temperatures harm bird survival, and extreme weather raises mortality (Al-Khalaifah and Al-Nasser, 2026). Climate change likely reduces reproductive rates, risking species decline such as the vulnerable houbara bustard (Dolman et al., 2021; Al-Khalaifah and Al-Nasser, 2026). The IUCN Red List classifies the Asian Houbara (Chlamydotis macqueenii) and the African Houbara (Chlamydotis undulata) as Vulnerable (VU) (BirdLife International, 2021c; 2023). Studying the functional genomics and stem cell technologies of hot-climate birds like the houbara can reveal adaptive traits vital for survival in extreme heat (Hemon et al., 2000). Introducing these models could connect cellular research with conservation efforts and climate resilience, offering insights into how these species, physiologically suited to hot environments, could serve as ideal models for tackling climate change-related population declines.

In small populations, such as endangered species, genetic variation is low, raising risks like inbreeding depression, reduced adaptability, and outbreeding depression (Fujihara, 1999). These can cause population decline and extinction. Although genetic rescue can reduce inbreeding depression and boost genetic diversity, it also presents genetic and evolutionary risks (Nichols et al., 2024; Beheregaray et al., 2026). Introducing genetically different material might lead to outbreeding depression by disrupting locally adapted or co-adapted gene combinations, which could lower fitness or reproductive success (Storfer, 1999; Bosse and van Loon, 2022). Additionally, too much introgression may dilute rare or population-specific alleles, eroding locally adapted genetic traits (Maxwell et al., 2021; Ottenburghs, 2022). Therefore, selecting donors should involve considering genetic relatedness, demographic history, ecological adaptation, and the conservation importance of the recipient population’s genetic makeup, rather than focusing solely on increasing genetic diversity. Cell-based and genome-engineering methods can pose additional risks. Extended in vitro culture of germline cells or organoids may cause genetic or epigenetic changes or lead to the growth of abnormal cell populations (Allegrucci et al., 2005; Thalheim et al., 2021). Likewise, genome-editing techniques might result in unintended genetic modifications (Lee et al., 2017; Cooper et al., 2018). These changes could be heritable if modified germline cells are involved in reproduction (Lee et al., 2015; He et al., 2025). Therefore, comprehensive genomic, epigenomic, developmental, and reproductive quality controls are essential before using these technologies in conservation breeding or genetic rescue efforts. Eventually, increased genetic diversity, successful germline transmission, or viable offspring alone do not confirm a successful genetic rescue. Long-term assessments of fitness, reproductive success, survival, adaptation, and population stability are necessary to verify the true conservation benefits of any intervention.

Conservation strategies include in situ (natural habitat) and ex situ (off-site) methods, with in situ conservation involving the maintenance of species within their natural habitats (Robinson, 1992; Braverman, 2014; Comizzoli and Holt, 2019; Fujihara and Inoue-Murayama, 2024). On-site preservation may be challenging for very small or declining populations, making ex situ approaches an important complementary strategy (Fujihara, 1999). Taken together, evidence-based decisions across conservation scenarios can support long-term population viability, resilience to changing environments, sustainable coexistence, and effective integration of ex situ and in situ conservation, as shown in Figure 1.

7.3 Current limitations and technical challenges

A major challenge is the species-specific nature of avian development and stem cell systems. Many current studies focus on controllable species, especially chickens, which may limit applicability to endangered avian species (Li et al., 2018; Dakhel et al., 2021; Zhao et al., 2022; Katayama et al., 2023b). Furthermore, differences in genome organization, developmental timing, germline, and reproductive biology between chickens and endangered birds must be considered (Lu et al., 2012; Woodcock et al., 2019; Huang et al., 2023; Jin et al., 2026). Cellular signaling processes, including the creation and use of species-specific stem cell and organoid systems, are also important. Therefore, validating these findings across a wide range of avian species with diverse phylogenetic and biological characteristics will be essential before advancing this platform, particularly for conservation efforts. When discussing technical challenges, it is crucial to focus on creating reproducible and reliable avian organoids. Considerations should include optimizing species-specific culture conditions, addressing cellular heterogeneity, developing controllable 3D culture systems, and ensuring long-term genome stability, particularly the distinction between germline and somatic cell populations (Suarez-Martinez et al., 2022; Ryoo et al., 2024; Xia et al., 2025). Additional hurdles in germline applications involve achieving proper meiotic progression, gamete maturation, and functional germline competence within germline organoids (Kaltsas et al., 2025; Hayashi et al., 2026; Yang et al., 2026). Before employing these organoids for avian genetic conservation, validated protocols for producing authentic germline organoids must be established.

8 Conclusion

Avian stem cell, organoid, and germline technologies offer valuable opportunities to analyze, conserve, and potentially use the genetic resources of threatened and endangered bird species. However, much of the evidence comes from domestic and experimental models, leaving uncertainty about their applicability to endangered species. Species-level variation in cellular reprogramming, germline development, reproductive biology, and genomic stability requires thorough validation before these methods can be used in conservation efforts. Additionally, achieving cellular or reproductive success does not automatically imply genetic rescue or population recovery; these outcomes must be supported by evidence of organismal fitness, reproductive success, demographic benefits, and sustainable long-term populations. Future development will rely on integrating cellular and genomic technologies with species-specific validation, population genetic analysis, field monitoring, and adaptive management strategies. In this context, stem cell and organoid approaches should be seen as complementary tools rather than replacements for existing conservation methods, broadening options for genetic resource preservation and potential rescue. Finally, a proposed framework, “From Cells to Conservation,” should be implemented to make a difference in real-world bird conservation.

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Footnotes

Edited by: Sangeet Lamichhaney, Kent State University, United States

Reviewed by: Kyung Min Jung, University of Missouri, United States

James Harper, A.T. Still University - Kirksville College of Medicine, United States

Dr. Dhaval J Kamothi, Kamdhenu University, India

Statements

Conflict of interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding

The author(s) declared that financial support was received for this work and/or its publication. The authors declared that the work of GS related to this topic has been supported by Kumamoto University International Research Center for Medical Sciences, Takeda Science Foundation grant, JSPS Kakenhi grant (18H02452 and 21H02490), JST grant (JPMJSC19E5) and Revive and Restore. The Ministry of Science and Higher Education of the Russian Federation Agreement No. 075-15-2025-484 was awarded to OG.

Data availability

The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding authors.

Author contributions

SI: Conceptualization, Writing – original draft, Writing – review & editing, Visualization. OG: Writing – review & editing, Supervision, Funding acquisition, Writing – original draft, Conceptualization. GS: Supervision, Funding acquisition, Writing – review & editing, Writing – original draft, Conceptualization.

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Citation

Intarapat, S., et al. (2026). Beyond the frontiers: avian organoid and stem cell models for genetic rescue in bird conservation. Frontiers in Bird Science, Volume 5. https://doi.org/
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5 - 2026

Copyright

Copyright © 2026 Intarapat, Gusev and Sheng.

License: https://creativecommons.org/licenses/by/4.0/

*Correspondence: Sittipon Intarapat; Oleg Gusev; Guojun Sheng

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