Induced pluripotent stem cells of endangered avian species

Advancing stem cell technologies for conservation of wildlife biodiversity

Wildlife biodiversity is essential for healthy, resilient and sustainable ecosystems. For biologists, this diversity also represents a treasure trove of genetic, molecular and developmental mechanisms that deepen our understanding of the origins and rules of life. However, the rapid decline in biodiversity reported recently foreshadows a potentially catastrophic collapse of many important ecosystems and the associated irreversible loss of many forms of life on our planet. Immediate action by conservationists of all stripes is required to avert this disaster. In this Spotlight, we draw together insights and proposals discussed at a recent workshop hosted by Revive & Restore, which gathered experts to discuss how stem cell technologies can support traditional conservation techniques and help protect animal biodiversity. We discuss reprogramming, in vitro gametogenesis, disease modelling and embryo modelling, and we highlight the prospects for leveraging stem cell technologies beyond mammalian species.

The mechanism of TGF-β mediating BRD4/STAT3 signaling pathway to promote fibroblast proliferation and thus promote keloid progression

The purpose of this study was to investigate the effect of TGF-β on keloid and its molecular mechanism in fibroblasts.

METHODS

The difference between normal tissue and keloid tissue can be detected using HE staining. Fibroblasts were treated with TGF-β, and then treated with the BRD4 inhibitor JQ1 and the STAT3 activator Colivelin TFA. Western blot was used to measure the relative protein expression of TGF-β, BRD4, p-STAT3, p-EZH2, C-myc, KLF2, KLF4, α-SMA, and Collagen-I. Immunofluorescence staining was used to measure the relative fluorescence intensity of BRD4, p-STAT3, α-SMA, and Collagen-I. Cell proliferation ability was evaluated by CCK-8 assay and colony formation assay.

RESULTS

The expression of TGF-β and BRD4 was significantly higher in keloid tissue compared to normal tissue. TGF-β mediated the BRD4/STAT3 signaling pathway to inhibit p-EZH2 and promote the expression of C-myc, KLF2, KLF4, α-SMA, and Collagen-I. Additionally, TGF-β mediated the BRD4/STAT3 signaling pathway to enhance fibroblast proliferation.

CONCLUSION

TGF-β mediates the BRD4/STAT3 signaling pathway to promote fibroblast proliferation and contribute to the progression of keloid.

40 'wild' years: the current reality and future potential of assisted reproductive technologies in wildlife species

Over the past 40 years, assisted reproductive technologies (ARTs) have grown significantly in scale and innovation, from the bovine embryo industry's shift from in vivo derived to in vitro produced embryos and the development of somatic cell-based approaches for embryo production. Domestic animal models have been instrumental in the development of ARTs for wildlife species in support of the One Plan Approach to species conservation that integrates in situ and ex situ population management strategies. While ARTs are not the sole solution to the biodiversity crisis, they can offer opportunities to maintain, and even improve, the genetic composition of the captive and wild gene pools over time. This review focuses on the application of sperm and embryo technologies (artificial insemination and multiple ovulation/in vitro produced embryo transfer, respectively) in wildlife species, highlighting impactful cases in which significant progress or innovation has transpired. One of the key messages following decades of efforts in this field is the importance of collaboration between researchers and practitioners from zoological, academic, governmental, and private sectors.

The impact of induced pluripotent stem cells in animal conservation

It is widely acknowledged that we are currently facing a critical tipping point with regards to global extinction, with human activities driving us perilously close to the brink of a devastating sixth mass extinction. As a promising option for safeguarding endangered species, induced pluripotent stem cells (iPSCs) hold great potential to aid in the preservation of threatened animal populations. For endangered species, such as the northern white rhinoceros (Ceratotherium simum cottoni), supply of embryos is often limited. After the death of the last male in 2019, only two females remained in the world. IPSC technology offers novel approaches and techniques for obtaining pluripotent stem cells (PSCs) from rare and endangered animal species. Successful generation of iPSCs circumvents several bottlenecks that impede the development of PSCs, including the challenges associated with establishing embryonic stem cells, limited embryo sources and immune rejection following embryo transfer. To provide more opportunities and room for growth in our work on animal welfare, in this paper we will focus on the progress made with iPSC lines derived from endangered and extinct species, exploring their potential applications and limitations in animal welfare research.

Cloning for the Twenty-First Century and Its Place in Endangered Species Conservation

Cloning as it relates to the animal kingdom generally refers to the production of genetically identical individuals. Because cloning is increasingly the subject of renewed attention as a tool for rescuing endangered or extinct species, it seems timely to dissect the role of the numerous reproductive techniques encompassed by this term in animal species conservation. Although cloning is typically associated with somatic cell nuclear transfer, the recent advent of additional techniques that allow genome replication without genetic recombination demands that the use of induced pluripotent stem cells to generate gametes or embryos, as well as older methods such as embryo splitting, all be included in this discussion. Additionally, the phenomenon of natural cloning (e.g., a subset of fish, birds, invertebrates, and reptilian species that reproduce via parthenogenesis) must also be pointed out. Beyond the biology of these techniques are practical considerations and the ethics of using cloning and associated procedures in endangered or extinct species. All of these must be examined in concert to determine whether cloning has a place in species conservation. Therefore, we synthesize progress in cloning and associated techniques and dissect the practical and ethical aspects of these methods as they pertain to endangered species conservation.

Establishment of African pygmy mouse induced pluripotent stem cells using defined doxycycline inducible transcription factors

Mus minutoides is one of the smallest mammals worldwide; however, the regulatory mechanisms underlying its dwarfism have not been examined. Therefore, we aimed to establish M. minutoides induced pluripotent stem cells (iPSCs) using the PiggyBac transposon system for applications in developmental engineering. The established M. minutoides iPSCs were found to express pluripotency markers and could differentiate into neurons. Based on in vitro differentiation analysis, M. minutoides iPSCs formed embryoid bodies expressing marker genes in all three germ layers. Moreover, according to the in vivo analysis, these cells contributed to the formation of teratoma and development of chimeric mice with Mus musculus. Overall, the M. minutoides iPSCs generated in this study possess properties that are comparable to or closely resemble those of naïve pluripotent stem cells (PSCs). These findings suggest these iPSCs have potential utility in various analytical applications, including methods for blastocyst completion.

Wnt signaling blockade is essential for maintaining the pluripotency of chicken embryonic stem cells

Activation of Wnt/β-catenin signaling supports the self-renewal of mouse embryonic stem cells. We aimed to understand the effects of Wnt signaling activation or inhibition on chicken embryonic stem cells (chESCs), as these effects are largely unknown. When the glycogen synthase kinase-3 β inhibitor CHIR99021-which activates Wnt signaling-was added to chESC cultures, the colony shape flattened, and the expression levels of pluripotency-related (NANOG, SOX2, SOX3, OCT4, LIN28A, DNMT3B, and PRDM14) and germ cell (CVH and DAZL) markers showed a decreasing trend, and the growth of chESCs was inhibited after approximately 7 d. By contrast, when the Wnt signaling inhibitor XAV939 was added to the culture, dense and compact multipotent colonies (morphologically similar to mouse embryonic stem cell colonies) showing stable expression of pluripotency-related and germline markers were formed. The addition of XAV939 stabilized the proliferation of chESCs in the early stages of culture and promoted their establishment. Furthermore, these chESCs formed chimeras. In conclusion, functional chESCs can be stably cultured using Wnt signaling inhibitors. These findings suggest the importance of Wnt/β-catenin signaling in avian stem cells, offering valuable insights for applied research using chESCs.

Avian iPSC Derivation to Recover Threatened Wild Species: A Comprehensive Review in Light of Well-Established Protocols

Induced pluripotent stem cells (iPSCs) were first generated by Yamanaka in 2006, revolutionizing research by overcoming limitations imposed by the use of embryonic stem cells. In terms of the conservation of endangered species, iPSC technology presents itself as a viable alternative for the manipulation of target genetics without compromising specimens. Although iPSCs have been successfully generated for various species, their application in nonmammalian species, particularly avian species, requires further in-depth investigation to cover the diversity of wild species at risk and their different protocol requirements. This study aims to provide an overview of the workflow for iPSC induction, comparing well-established protocols in humans and mice with the limited information available for avian species. Here, we discuss the somatic cell sources to be reprogrammed, genetic factors, delivery methods, enhancers, a brief history of achievements in avian iPSC derivation, the main approaches for iPSC characterization, and the future perspectives and challenges for the field. By examining the current protocols and state-of-the-art techniques employed in iPSC generation, we seek to contribute to the development of efficient and species-specific iPSC methodologies for at-risk avian species. The advancement of iPSC technology holds great promise for achieving in vitro germline competency and, consequently, addressing reproductive challenges in endangered species, providing valuable tools for basic research, bird genetic preservation and rescue, and the establishment of cryobanks for future conservation efforts.

Generation of induced pluripotent stem cells from Bornean orangutans

Introduction: Orangutans, classified under the Pongo genus, are an endangered non-human primate (NHP) species. Derivation of induced pluripotent stem cells (iPSCs) represents a promising avenue for conserving the genetic resources of these animals. Earlier studies focused on deriving orangutan iPSCs (o-iPSCs) from Sumatran orangutans (Pongo abelii). To date, no reports specifically target the other Critically Endangered species in the Pongo genus, the Bornean orangutans (Pongo pygmaeus). Methods: Using Sendai virus-mediated Yamanaka factor-based reprogramming of peripheral blood mononuclear cells to generate iPSCs (bo-iPSCs) from a female captive Bornean orangutan. In this study, we evaluate the colony morphology, pluripotent markers, X chromosome activation status, and transcriptomic profile of the bo-iPSCs to demonstrate the pluripotency of iPSCs from Bornean orangutans. Results: The bo-iPSCs were successfully derived from Bornean orangutans, using Sendai virus-mediated Yamanaka factor-based reprogramming of peripheral blood mononuclear cells. When a modified 4i/L/A (m4i/L/A) culture system was applied to activate the WNT signaling pathway in these bo-iPSCs, the derived cells (m-bo-iPSCs) manifested characteristics akin to human naive pluripotent stem cells, including high expression levels of KLF17, DNMT3L, and DPPA3/5, as well as the X chromosome reactivation. Comparative RNA-seq analysis positioned the m-bo-iPSCs between human naive and formative pluripotent states. Furthermore, the m-bo-iPSCs express differentiation capacity into all three germlines, evidenced by controlled in vitro embryoid body formation assay. Discussion: Our work establishes a novel approach to preserve the genetic diversity of endangered Bornean orangutans while offering insights into primate stem cell pluripotency. In the future, derivation of the primordial germ cell-like cells (PGCLCs) from m-bo-iPSCs is needed to demonstrate the further specific application in species preservation and broaden the knowledge of primordial germ cell specification across species.

Equine Induced Pluripotent Stem Cell Culture

Groundbreaking work by Takahashi and Yamanaka in 2006 demonstrated that non-embryonic cells can be reprogrammed into pluripotent stem cells (PSCs) by forcing the expression of a defined set of transcription factors in culture, thus overcoming ethical concerns linked to embryonic stem cells. Induced PSCs have since revolutionized biomedical research, holding tremendous potential also in other areas such as livestock production and wildlife conservation. iPSCs exhibit broad accessibility, having been derived from a multitude of cell types and species. Apart from humans, iPSCs hold particular medical promise in the horse. The potential of iPSCs has been shown in a variety of biomedical contexts in the horse. However, progress in generating therapeutically useful equine iPSCs has lagged behind that reported in humans, with the generation of footprint-free iPSCs using non-integrative reprogramming approaches having proven particularly challenging. A greater understanding of the underlying molecular pathways and essential factors required for the generation and maintenance of equine iPSCs and their differentiation into relevant lineages will be critical for realizing their significant potential in veterinary regenerative medicine. This article outlines up-to-date protocols for the successful culture of equine iPSC, including colony selection, expansion, and adaptation to feeder-free conditions.

A Bird's-Eye View of Endangered Species Conservation: Avian Genomics and Stem Cell Approaches for Green Peafowl (Pavo muticus)

Aves ranks among the top two classes for the highest number of endangered and extinct species in the kingdom Animalia. Notably, the IUCN Red List classified the green peafowl as endangered. This highlights promising strategies using genetics and reproductive technologies for avian wildlife conservation. These platforms provide the capacity to predict population trends and enable the practical breeding of such species. The conservation of endangered avian species is facilitated through the application of genomic data storage and analysis. Storing the sequence is a form of biobanking. An analysis of sequence can identify genetically distinct individuals for breeding. Here, we reviewed avian genomics and stem cell approaches which not only offer hope for saving endangered species, such as the green peafowl but also for other birds threatened with extinction.

Induced pluripotent stem cells in companion animals: how can we move the field forward?

Following a one medicine approach, the development of regenerative therapies for human patients leads to innovative treatments for animals, while pre-clinical studies on animals provide knowledge to advance human medicine. Among many different biological products under investigation, stem cells are among the most prominent. Mesenchymal stromal cells (MSCs) are extensively investigated, but they present challenges such as senescence and limited differentiation ability. Embryonic stem cells (ESCs) are pluripotent cells with a virtually unlimited capacity for self-renewal and differentiation, but the use of embryos carries ethical concerns. Induced pluripotent stem cells (iPSCs) can overcome all of these limitations, as they closely resemble ESCs but are derived from adult cells by reprogramming in the laboratory using pluripotency-associated transcription factors. iPSCs hold great potential for applications in therapy, disease modeling, drug screening, and even species preservation strategies. However, iPSC technology is less developed in veterinary species compared to human. This review attempts to address the specific challenges associated with generating and applying iPSCs from companion animals. Firstly, we discuss strategies for the preparation of iPSCs in veterinary species and secondly, we address the potential for different applications of iPSCs in companion animals. Our aim is to provide an overview on the state of the art of iPSCs in companion animals, focusing on equine, canine, and feline species, as well as to identify which aspects need further optimization and, where possible, to provide guidance on future advancements. Following a "step-by-step" approach, we cover the generation of iPSCs in companion animals from the selection of somatic cells and the reprogramming strategies, to the expansion and characterization of iPSCs. Subsequently, we revise the current applications of iPSCs in companion animals, identify the main hurdles, and propose future paths to move the field forward. Transferring the knowledge gained from human iPSCs can increase our understanding in the biology of pluripotent cells in animals, but it is critical to further investigate the differences among species to develop specific approaches for animal iPSCs. This is key for significantly advancing iPSC application in veterinary medicine, which at the same time will also allow gaining pre-clinical knowledge transferable to human medicine.

Organoids containing neural-like cells derived from chicken iPSCs respond to poly:IC through the RLR family

There is still much room for development in pluripotent stem cell research on avian species compared to human stem cell studies. Neural cells are useful for the evaluation of risk assessment of infectious diseases since several avian species die of encephalitis derived from infectious diseases. In this study, we attempted to develop induced pluripotent stem cells (iPSCs) technology for avian species by forming organoids containing neural-like cells. In our previous study, we established two types iPSCs from chicken somatic cells, the first is iPSCs with PB-R6F reprogramming vector and the second is iPSCs with PB-TAD-7F reprogramming vector. In this study, we first compared the nature of these two cell types using RNA-seq analysis. The total gene expression of iPSCs with PB-TAD-7F was closer to that of chicken ESCs than that of iPSCs with PB-R6F; therefore, we used iPSCs with PB-TAD-7F to form organoids containing neural-like cells. We successfully established organoids containing neural-like cells from iPSCs using PB-TAD-7F. Furthermore, our organoids responded to poly:IC through the RIG-I-like receptor (RLR) family. In this study, we developed iPSCs technology for avian species via organoid formation. In the future, organoids containing neural-like cells from avian iPSCs can develop as a new evaluation tool for infectious disease risk in avian species, including endangered avian species.

iPSC Technology: An Innovative Tool for Developing Clean Meat, Livestock, and Frozen Ark

Induced pluripotent stem cell (iPSC) technology is an emerging technique to reprogram somatic cells into iPSCs that have revolutionary benefits in the fields of drug discovery, cellular therapy, and personalized medicine. However, these applications are just the tip of an iceberg. Recently, iPSC technology has been shown to be useful in not only conserving the endangered species, but also the revival of extinct species. With increasing consumer reliance on animal products, combined with an ever-growing population, there is a necessity to develop alternative approaches to conventional farming practices. One such approach involves the development of domestic farm animal iPSCs. This approach provides several benefits in the form of reduced animal death, pasture degradation, water consumption, and greenhouse gas emissions. Hence, it is essentially an environmentally-friendly alternative to conventional farming. Additionally, this approach ensures decreased zoonotic outbreaks and a constant food supply. Here, we discuss the iPSC technology in the form of a "Frozen Ark", along with its potential impact on spreading awareness of factory farming, foodborne disease, and the ecological footprint of the meat industry.