Induced pluripotent stem cells from goat fibroblasts

In vitro generation of trophoblast like stem cells from goat pluripotent stem cells

Since the first mouse induced pluripotent stem cells (iPSCs) was derived, the in vitro culture of domestic iPSCs functionally and molecularly comparable with mouse iPSCs has been a challenge. Here, we established dairy goat iPSCs (giPSCs) from goat ear fibroblast cells with mouse iPSCs morphology, the expression of pluripotent markers and differentiation ability in vitro delivered by piggyBac transposon with nine Dox-inducible exogenous reprogramming factors. These reprogramming factors were bOMSK (bovine OCT4, CMYC, SOX2, and KLF4), pNhL (porcine NANOG and human LIN28), hRL (human RARG and LRH1), and SV40 Large T. Notably, AF-giPSCs (induced in activin A and bFGF condition) were capable of differentiation in embryoid bodies in vitro and could contribute to interspecies chimerism in mouse E6.5 embryos in vitro, demonstrating that AF-giPSCs have the developmental capability to generate some embryonic cell lineages. Moreover, Wnt/β-catenin signaling has an important role in driving goat induced trophoblast-like stem cells (giTLSCs) from Dox-independent giPSCs. This study will support further establishment of the stable giPSC lines without any integration of exogenous genes.

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.

Establishment of Capra hircus somatic cells and induction of pluripotent stem-like cells

Capra hircus (goat) induced pluripotent stem cells (giPSCs) harbor enormous scientific value and contribute to cellular agriculture, animal cloning, etc. Conventional approaches to giPSC generation suffer from complexity and low preparation efficiency. In the present study, we introduced the episomal vectors carrying the human pluripotent genes in goat somatic cells to generate the giPSC-like colonies. Initially, a simple non-enzymatic method was used to isolate the goat dermal fibroblast cells and, further, a cell line was established. Later, goat fibroblast cells were transfected with commercially available episomal vectors carrying the human pluripotent genes and successfully generated the iPSC-like colonies which exhibited the expression of goat endogenous pluripotent genes and positive staining with alkaline phosphatase. Moreover, giPS-like cells formed embryoid bodies (EBs)-like aggregates and weekly expressed the marker genes of two germ layers. Reprogramming of goat fibroblast using episomal vectors carrying human pluripotent genes could lead to the development of an efficient and time- and cost-effective approach to giPSC generation.

Generation, characterization, and differentiation of induced pluripotent stem-like cells in the domestic cat

Induced pluripotent stem (iPS) cells are generated from somatic cells and can differentiate into various cell types. Therefore, these cells are expected to be a powerful tool for modeling diseases and transplantation therapy. Generation of domestic cat iPS cells depending on leukemia inhibitory factor has been reported; however, this strategy may not be optimized. Considering that domestic cats are excellent models for studying spontaneous diseases, iPS cell generation is crucial. In this study, we aimed to derive iPS cells from cat embryonic fibroblasts retrovirally transfected with mouse Oct3/4, Klf4, Sox2, and c-Myc. After transfection, embryonic fibroblasts were reseeded onto inactivated SNL 76/7 and cultured in a medium supplemented with basic fibroblast growth factor. Flat, compact, primary colonies resembling human iPS colonies were observed. Additionally, primary colonies were more frequently observed in the KnockOut Serum Replacement medium than in the fetal bovine serum (FBS) medium. However, enhanced maintenance and proliferation of iPS-like cells occurred in the FBS medium. These iPS-like cells expressed embryonic stem cell markers, had normal karyotypes, proliferated beyond 45 passages, and differentiated into all three germ layers in vitro. Notably, expression of exogenous Oct3/4, Klf4, and Sox2 was silenced in these cells. However, the iPS-like cells failed to form teratomas. In conclusion, this is the first study to establish and characterize cat iPS-like cells, which can differentiate into different cell types depending on the basic fibroblast growth factor.

Induced pluripotent stem cells from domesticated ruminants and their potential for enhancing livestock production

Ruminant livestock, including cattle, sheep, goat, and buffalo, are essential for global food security and serve valuable roles in sustainable agricultural systems. With the limited availability of embryonic stem cells (ESCs) from these species, ruminant induced pluripotent stem cells (iPSCs) and iPSC-like cells provide a valuable research tool for agricultural, veterinary, biomedical, and pharmaceutical applications, as well as for the prospect of translation to human medicine. iPSCs are generated by reprogramming of adult or fetal cells to an ESC-like state by ectopic expression of defined transcription factors. Despite the slow pace the field has evolved in livestock species compared to mice and humans, significant progress has been made over the past 15 years in using different cell sources and reprogramming protocols to generate iPSCs/iPSC-like cells from ruminants. This mini review summarizes the current literature related to the derivation of iPSCs/iPSC-like cells from domesticated ruminants with a focus on reprogramming protocols, characterization, associated limitations, and potential applications in ruminant basic science research and production.

iPSC Therapy for Myocardial Infarction in Large Animal Models: Land of Hope and Dreams

Myocardial infarction is the main driver of heart failure due to ischemia and subsequent cell death, and cell-based strategies have emerged as promising therapeutic methods to replace dead tissue in cardiovascular diseases. Research in this field has been dramatically advanced by the development of laboratory-induced pluripotent stem cells (iPSCs) that harbor the capability to become any cell type. Like other experimental strategies, stem cell therapy must meet multiple requirements before reaching the clinical trial phase, and in vivo models are indispensable for ensuring the safety of such novel therapies. Specifically, translational studies in large animal models are necessary to fully evaluate the therapeutic potential of this approach; to empirically determine the optimal combination of cell types, supplementary factors, and delivery methods to maximize efficacy; and to stringently assess safety. In the present review, we summarize the main strategies employed to generate iPSCs and differentiate them into cardiomyocytes in large animal species; the most critical differences between using small versus large animal models for cardiovascular studies; and the strategies that have been pursued regarding implanted cells' stage of differentiation, origin, and technical application.

Induced pluripotent stem cells from farm animals

The development of the induced pluripotent stem cells (iPSCs) technology has revolutionized the world on the establishment of pluripotent stem cells (PSCs) across a great variety of animal species. Generation of iPSCs from domesticated animals would provide unrestricted cell resources for the study of embryonic development and cell differentiation of these species, for screening and establishing desired traits for sustainable agricultural production, and as veterinary and preclinical therapeutic tools for animal and human diseases. Induced PSCs from domesticated animals thus harbor enormous scientific, economical, and societal values. Although much progress has been made toward the generation of PSCs from these species, major obstacles remain precluding the exclamation of the establishment of bona fide iPSCs. The most prominent of them remain the inability of these cells to silence exogenous reprogramming factors, the obvious reliance on exogenous factors for their self-renewal, and the restricted development potential in vivo. In this review, we summarize the history and current progress in domestic farm animal iPSC generation, with a focus on swine, ruminants (cattle, ovine, and caprine), horses, and avian species (quails and chickens). We also discuss the problems associated with the farm animal iPSCs and potential future directions toward the complete reprogramming of somatic cells from farm animals.

Perspectives of pluripotent stem cells in livestock

The recent progress in derivation of pluripotent stem cells (PSCs) from farm animals opens new approaches not only for reproduction, genetic engineering, treatment and conservation of these species, but also for screening novel drugs for their efficacy and toxicity, and modelling of human diseases. Initial attempts to derive PSCs from the inner cell mass of blastocyst stages in farm animals were largely unsuccessful as either the cells survived for only a few passages, or lost their cellular potency; indicating that the protocols which allowed the derivation of murine or human embryonic stem (ES) cells were not sufficient to support the maintenance of ES cells from farm animals. This scenario changed by the innovation of induced pluripotency and by the development of the 3 inhibitor culture conditions to support naïve pluripotency in ES cells from livestock species. However, the long-term culture of livestock PSCs while maintaining the full pluripotency is still challenging, and requires further refinements. Here, we review the current achievements in the derivation of PSCs from farm animals, and discuss the potential application areas.

Generation of transgene-free induced pluripotent stem cells from cardiac fibroblasts of goat embryos

Induced pluripotent stem cells (iPSCs) hold a great potential for therapeutic regenerative medicine. The aim of this study was to generate induced pluripotent stem cells from goat embryonic cardiac tissue derived fibroblasts. The isolated cardiac fibroblasts from the cardiac tissue of goat embryos were positive for alfa smooth muscle actin, vimentin and discoidin domain receptor2. From these cells, we generated transgene free iPSCs using piggyBac transposons / transposase using five transcription factors (Oct4, Sox2, Klf, Myc and Lin 28). The generated iPSCs were SSEA1, SSEA4 and Oct4 positive. They were cultured on neofeeders using 20% Serum replacement - IMDM with bFGF. They could form cystic and compact embryoid bodies that showed differentiated ectodermal and mesodermal like cells when cultured using 20% FBS-IMDM without bFGF. The iPSCs, generated in the frame of this approach were produced without the use of integrating virus and the reprogramming transgenes were removed at the end of the process. Though there were limitations in the approach used, a substantial sign of reprogramming was obtained.

The use of induced pluripotent stem cells in domestic animals: a narrative review

Induced pluripotent stem cells (iPSCs) are undifferentiated stem cells characterized by the ability to differentiate into any cell type in the body. iPSCs are a relatively new and rapidly developing technology in many fields of biology, including developmental anatomy and physiology, pathology, and toxicology. These cells have great potential in research as they are self-renewing and pluripotent with minimal ethical concerns. Protocols for their production have been developed for many domestic animal species, which have since been used to further our knowledge in the progression and treatment of diseases. This research is valuable both for veterinary medicine as well as for the prospect of translation to human medicine. Safety, cost, and feasibility are potential barriers for this technology that must be considered before widespread clinical adoption. This review will analyze the literature pertaining to iPSCs derived from various domestic species with a focus on iPSC production and characterization, applications for tissue and disease research, and applications for disease treatment.

Livestock pluripotency is finally captured in vitro

Pluripotent stem cells (PSCs) have demonstrated great utility in improving our understanding of mammalian development and continue to revolutionise regenerative medicine. Thanks to the improved understanding of pluripotency in mice and humans, it has recently become feasible to generate stable livestock PSCs. Although it is unlikely that livestock PSCs will be used for similar applications as their murine and human counterparts, new exciting applications that could greatly advance animal agriculture are being developed, including the use of PSCs for complex genome editing, cellular agriculture, gamete generation and invitro breeding schemes.

Inducing Pluripotency in the Domestic Cat (Felis catus)

Domestic cats suffer from a range of inherited genetic diseases, many of which display similarities with equivalent human conditions. Developing cellular models for these inherited diseases would enable drug discovery, benefiting feline health and welfare as well as enhancing the potential of cats as relevant animal models for translation to human medicine. Advances in our understanding of these diseases at the cellular level have come from the use of induced pluripotent stem cells (iPSCs). iPSCs can differentiate into virtually any cell type and can be derived from adult somatic cells, therefore overcoming the ethical implications of destroying embryos to obtain embryonic stem cells. No studies, however, report the generation of iPSCs from domestic cats [feline iPSCs (fiPSCs)]. Feline adipose-derived fibroblasts were infected with amphotropic retrovirus containing the coding sequences for human Oct4, Sox2, Klf4, cMyc, and Nanog. Isolated iPSC clones were expanded on inactivated mouse embryonic fibroblasts in the presence of feline leukemia inhibitory factor (fLIF). Retroviral delivery of human pluripotent genes gave rise to putative fiPSC colonies within 5-7 days. These iPS-like cells required fetal bovine serum and fLIF for maintenance. Colonies were domed with refractile edges, similar to mouse iPSCs. Immunocytochemistry demonstrated positive staining for stem cell markers: alkaline phosphatase, Oct4, Sox2, Nanog, and SSEA1. Cells were negative for SSEA4. Expression of endogenous feline Nanog was confirmed by quantitative polymerase chain reaction. The cells were able to differentiate in vitro into cells representative of the three germ layers. These results confirm the first generation of induced pluripotent stem cells from domestic cats. These cells will provide valuable models to study genetic diseases and explore novel therapeutic strategies.

MiR-378 promoted cell proliferation and inhibited apoptosis by enhanced stem cell properties in chronic myeloid leukemia K562 cells

Dysregulation of miR-378 has been found in diverse types of tumors as well as in leukemia. The role of miR-378 in chronic myeloid leukemia (CML) remains unclear. The aim of the study was to reveal the potential effects of miR-378 in the pathological process and progress in CML. Our results showed general level of miR-378 was significant higher in CML patients compared to controls. Overexpression of miR-378 dramatically promoted cell proliferation and drug-resistance. Additionally, apoptosis was inhibited in cells transfected with miR-378. More and bigger stem cell sphere formation was observed in miR-378 transfected cells. Furthermore, enhanced expression of miR-378 was associated with upregulation of stem-cell makers OCT4 and c-Myc. Further study validated that miR-378 inhibited the expression of FUS1. Our research demonstrated the oncogenic nature of miR-378 in CML, and might contribute to the progress of CML.

Stem cells on regenerative and reproductive science in domestic animals

Stem cells are undifferentiated and self-renewable cells that present new possibilities for both regenerative medicine and the understanding of early mammalian development. Adult multipotent stem cells are already widely used worldwide in human and veterinary medicine, and their therapeutic signalling, particularly with respect to immunomodulation, and their trophic properties have been intensively studied. The derivation of embryonic stem cells (ESCs) from domestic species, however, has been challenging, and the poor results do not reflect the successes obtained in mouse and human experiments. More recently, the generation of induced pluripotent stem cells (iPSCs) via the forced expression of specific transcription factors has been demonstrated in domestic species and has introduced new potentials in regenerative medicine and reproductive science based upon the ability of these cells to differentiate into a variety of cells types in vitro. For example, iPSCs have been differentiated into primordial germ-like cells (PGC-like cells, PGCLs) and functional gametes in mice. The possibility of using iPSCs from domestic species for this purpose would contribute significantly to reproductive technologies, offering unprecedented opportunities to restore fertility, to preserve endangered species and to generate transgenic animals for biomedical applications. Therefore, this review aims to provide an updated overview of adult multipotent stem cells and to discuss new possibilities introduced by the generation of iPSCs in domestic animals, highlighting the possibility of generating gametes in vitro via PGCL induction.

Functional characterization of NANOG in goat pre-implantation embryonic development

Nanog as a novel pluripotent cell-specific gene plays important roles in regulation of signaling pathways for maintenance and induction of pluripotency in inner cell mass (ICM) and embryonic stem cells (ESC) in mouse. The molecular features and transcription regulation of NANOG gene in domestic animals are not well defined. In this study, we performed knockdown of NANOG mRNA in goat embryos and examined its effect on early embryonic development. Presumptive zygotes were injected with a volume of 8-10 pl NANOG or scrambled (SCR) siRNA, and subsequently cleavage and blastocyst formation rate were assessed. Furthermore, gene expression analysis was carried out in 6-8 cell and blastocyst derived embryos from non-injected controls, SCR - and siRNA-injected presumptive zygotes. Cleavage and blastocyst rates in siRNA groups were insignificantly lower than the control and SCR groups. Embryos with reduced expression of NANOG showed decrease in number of trophectoderm (TE) and total cells in blastocysts. Analysis of expression of developmentally important genes (SOX2, OCT4 and NANOG), which work as a network, showed that NANOG knockdown results in significant increase in expression of SOX2 and OCT4 and among the possible target genes (CDX2, REX1 and GATA4) of this network, only GATA4 showed increased expression. Our results suggest that NANOG is likely to be required for proliferation of trophoblastic cells.

The current perspectives of dromedary camel stem cells research

Camels have cultural value in the Arab society and are considered one of the most important animals in the Arabian Peninsula and arid environments, due to the distinct characteristics of their meat and milk. Moreover, there is a great interest in camel racing and beauty shows. Therefore, treatment of elite animals, increasing the number of camels as well as genetic improvement is an essential demand. Because there are unique camels for milk production, meat, or in racing, the need to propagate genetically superior camels is urgent. Recent biotechnological approaches such as stem cells hold great promise for biomedical research, genetic engineering, and as a model for studying early mammalian developmental biology. Establishment of stem cells lines from camels would tremendously facilitate regenerative medicine for genetically superior camels, permit the gene targeting of the camel genome and the generation of genetically modified animal and be a mean for genome conservation for the elite breeds. In this mini-review, we show the current research, future horizons and potential applications for camel stem cells.

Bovine trophectoderm cells induced from bovine fibroblasts with induced pluripotent stem cell reprogramming factors

Thirteen independent induced bovine trophectroderm (iBT) cell lines were established by reprogramming bovine fetal liver-derived fibroblasts after viral-vector transduction with either six or eight factors, including POU5F1 (OCT4), KLF4, SOX2, MYC, NANOG, LIN28, SV40 large T antigen, and hTERT. Light- and electron-microscopy analysis showed that the iBT cells had epithelial cell morphology typical of bovine trophectoderm cells. Reverse-transcription-PCR assays indicated that all of the cell lines expressed interferon-tau (IFNT) at passages 1 or 2. At later passages (≥ passage 8), however, immunoblot and antiviral activity assays revealed that more than half of the iBT cell lines had stopped expressing IFNT. Messenger RNAs specific to trophectoderm differentiation and function were found in the iBT cell lines, and 2-dimensional-gel analysis for cellular proteins showed an expression pattern similar to that of trophectoderm cell lines derived from bovine blastocysts. Integration of some of the human reprogramming factors, including POU5F1, KLF4, SOX2, MYC, NANOG, and LIN28, were detected by PCR, but their transcription was mostly absent in the iBT cell lines. Gene expression assessment of endogenous bovine reprogramming factor orthologs revealed endogenous bLIN28 and bMYC transcripts in all; bSOX2 and bNANOG in none; and bKLF4 and bPOU5F1 in less than half of the iBT cell lines. These results demonstrate that bovine trophectoderm can be induced via reprogramming factor expression from bovine liver-derived fibroblasts, although other fibroblast populations-e.g., derived from fetal thigh tissue-may produce similar results, albeit at lower frequencies.

Big Animal Cloning Using Transgenic Induced Pluripotent Stem Cells: A Case Study of Goat Transgenic Induced Pluripotent Stem Cells

Using of embryonic stem cells (ESCs) could improve production traits and disease resistance by improving the efficiency of somatic cell nuclear transfer (SCNT) technology. However, robust ESCs have not been established from domestic ungulates. In the present study, we generated goat induced pluripotent stem cells (giPSCs) and transgenic cloned dairy goat induced pluripotent stem cells (tgiPSCs) from dairy goat fibroblasts (gFs) and transgenic cloned dairy goat fibroblasts (tgFs), respectively, using lentiviruses that contained hOCT4, hSOX2, hMYC, and hKLF4 without chemical compounds. The giPSCs and tgiPSCs expressed endogenous pluripotent markers, including OCT4, SOX2, MYC, KLF4, and NANOG. Moreover, they were able to maintain a normal karyotype and differentiate into derivatives from all three germ layers in vitro and in vivo. Using SCNT, tgFs and tgiPSCs were used as donor cells to produce embryos, which were named tgF-Embryos and tgiPSC-Embryos. The fusion rates and cleavage rates had no significant differences between tgF-Embryos and tgiPSC-Embryos. However, the expression of IGF-2, which is an important gene associated with embryonic development, was significantly lower in tgiPSC-Embryos than in tgF-Embryos and was not significantly different from vivo-Embryos.

Generation of Arbas Cashmere Goat Induced Pluripotent Stem Cells Through Fibroblast Reprogramming

Various factors affect the process of obtaining stable Arbas cashmere goat embryonic stem cells (ESCs), for example, the difficulty in isolating cells at the appropriate stage of embryonic development, the in vitro culture environment, and passage methods. With the emergence of induced pluripotent stem cell (iPSC) technology, it has become possible to use specific genes to induce somatic cell differentiation in PSCs. We transferred OCT4, SOX2, c-MYC, and KLF4 into Arbas cashmere goat fetal fibroblasts, then induced and cultured them using a drug-inducible system to obtain Arbas goat iPSCs that morphologically resembled mouse iPSCs. After identification, the obtained goat iPSCs expressed ESC markers, had a normal karyotype, could differentiate into embryoid bodies in vitro, and could differentiate into three germ layer cell types and form teratomas in vivo. We used microarray gene expression profile analysis to elucidate the reprogramming process. Our results provide the experimental basis for establishing cashmere goat iPSC lines and for future in-depth studies on molecular mechanism of cashmere goat somatic cell reprogramming.

Generation of Induced Pluripotent Stem Cells from Bovine Epithelial Cells and Partial Redirection Toward a Mammary Phenotype In Vitro

In contrast to adult stem cells, induced pluripotent stem cells (iPSCs) can be grown robustly in vitro and differentiated into virtually any tissue, thus providing an attractive alternative for biomedical applications. Although iPSC technology is already being used in human biomedicine, its potential in animal production has not been investigated. Herein, we investigated the potential application of iPSCs in dairy production by generating bovine iPSCs and establishing their ability to generate mammary epithelial tissue. iPSCs were derived by retrovirus-mediated expression of murine Oct4, Sox2, Klf4, and c-Myc in mammary epithelium and dermal fibroblasts. The resulting reprogrammed cells stained positive for alkaline phosphatase and showed renewed expression of pluripotency genes, including Lin28, Rex1, Oct4, Sox2, and Nanog. In addition, injection of epithelial- or fibroblast-derived reprogrammed cells into nonobese diabetic (NOD/NOD) mice resulted in the formation of teratomas containing differentiated derivatives of the three germ layers, including cartilage, membranous ossification, stratified squamous epithelial tissue, hair follicles, neural pinwheels, and different types of glandular tissue. Finally, mammary epithelium-derived iPSCs could be induced to differentiate back to a mammary phenotype characterized by epithelial cells expressing cytokeratin 14 (CK14), CK18, and smooth muscle actin (SMA) as a result of treatment with 10 nM progesterone. This study reports for the first time the generation of iPSCs from bovine epithelial cells and demonstrates the potential of using iPSCs technology for generating bovine mammary tissue in vitro.

Cellular reprogramming in farm animals: an overview of iPSC generation in the mammalian farm animal species

Establishment of embryonic stem cell (ESC) lines has been successful in mouse and human, but not in farm animals. Development of direct reprogramming technology offers an alternative approach for generation of pluripotent stem cells, applicable also in farm animals. Induced pluripotent stem cells (iPSCs) represent practically limitless, ethically acceptable, individuum-specific source of pluripotent cells that can be generated from different types of somatic cells. iPSCs can differentiate to all cell types of an organism’s body and have a tremendous potential for numerous applications in medicine, agriculture, and biotechnology. However, molecular mechanisms behind the reprogramming process remain largely unknown and hamper generation of bona fide iPSCs and their use in human clinical practice. Large animal models are essential to expand the knowledge obtained on rodents and facilitate development and validation of transplantation therapies in preclinical studies. Additionally, transgenic animals with special traits could be generated from genetically modified pluripotent cells, using advanced reproduction techniques. Despite their applicative potential, it seems that iPSCs in farm animals haven’t received the deserved attention. The aim of this review was to provide a systematic overview on iPSC generation in the most important mammalian farm animal species (cattle, pig, horse, sheep, goat, and rabbit), compare protein sequence similarity of pluripotency-related transcription factors in different species, and discuss potential uses of farm animal iPSCs. Literature mining revealed 32 studies, describing iPSC generation in pig (13 studies), cattle (5), horse (5), sheep (4), goat (3), and rabbit (2) that are summarized in a concise, tabular format.

Pluripotent stem cells and livestock genetic engineering

The unlimited proliferative ability and capacity to contribute to germline chimeras make pluripotent embryonic stem cells (ESCs) perfect candidates for complex genetic engineering. The utility of ESCs is best exemplified by the numerous genetic models that have been developed in mice, for which such cells are readily available. However, the traditional systems for mouse genetic engineering may not be practical for livestock species, as it requires several generations of mating and selection in order to establish homozygous founders. Nevertheless, the self-renewal and pluripotent characteristics of ESCs could provide advantages for livestock genetic engineering such as ease of genetic manipulation and improved efficiency of cloning by nuclear transplantation. These advantages have resulted in many attempts to isolate livestock ESCs, yet it has been generally concluded that the culture conditions tested so far are not supportive of livestock ESCs self-renewal and proliferation. In contrast, there are numerous reports of derivation of livestock induced pluripotent stem cells (iPSCs), with demonstrated capacity for long term proliferation and in vivo pluripotency, as indicated by teratoma formation assay. However, to what extent these iPSCs represent fully reprogrammed PSCs remains controversial, as most livestock iPSCs depend on continuous expression of reprogramming factors. Moreover, germline chimerism has not been robustly demonstrated, with only one successful report with very low efficiency. Therefore, even 34 years after derivation of mouse ESCs and their extensive use in the generation of genetic models, the livestock genetic engineering field can stand to gain enormously from continued investigations into the derivation and application of ESCs and iPSCs.

Pluripotent Stem Cells from Domesticated Mammals

This review deals with the latest advances in the study of embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC) from domesticated species, with a focus on pigs, cattle, sheep, goats, horses, cats, and dogs. Whereas the derivation of fully pluripotent ESC from these species has proved slow, reprogramming of somatic cells to iPSC has been more straightforward. However, most of these iPSC depend on the continued expression of the introduced transgenes, a major drawback to their utility. The persistent failure in generating ESC and the dependency of iPSC on ectopic genes probably stem from an inability to maintain the stability of the endogenous gene networks necessary to maintain pluripotency. Based on work in humans and rodents, achievement of full pluripotency will likely require fine adjustments in the growth factors and signaling inhibitors provided to the cells. Finally, we discuss the future utility of these cells for biomedical and agricultural purposes.

Generation of induced pluripotent stem cells from domestic goats

The creation of genetically modified goats provides a powerful approach for improving animal health, enhancing production traits, animal pharming, and for ensuring food safety all of which are high-priority goals for animal agriculture. The availability of goat embryonic stem cells (ESCs) that are characteristically immortal in culture would be of enormous benefit for developing genetically modified animals. As an alternative to long-sought goat ESCs, we generated induced pluripotent stem cells (iPSC) by forced expression of bovine POU5F1, SOX2, MYC, KLF4, LIN-28, and NANOG reprogramming factors in combination with a MIR302/367 cluster, delivered by lentiviral vectors. In order to minimize integrations, the reprogramming factor coding sequences were assembled with porcine teschovirus-1 2A (P2A) self-cleaving peptides that allowed for tri-cistronic expression from each vector. The lentiviral-transduced cells were cultured on irradiated mouse feeder cells in a semi-defined, serum-free medium containing fibroblast growth factor (FGF) and/or leukemia inhibitory factor (LIF). The resulting goat iPSC exhibit cell and colony morphology typical of human and mouse ESCs-that is, well-defined borders, a high nuclear-to-cytoplasmic ratio, a short cell-cycle interval, alkaline phosphatase expression, and the ability to generate teratomas in vivo. Additionally, these goat iPSC demonstrated the ability to differentiate into directed lineages in vitro. These results constitute the first steps in establishing integration and footprint-free iPSC from ruminants. Mol. Reprod. Dev. 82: 709-721, 2015. © 2015 Wiley Periodicals, Inc.

Induced pluripotent stem cells: Mechanisms, achievements and perspectives in farm animals

Pluripotent stem cells are unspecialized cells with unlimited self-renewal, and they can be triggered to differentiate into desired specialized cell types. These features provide the basis for an unlimited cell source for innovative cell therapies. Pluripotent cells also allow to study developmental pathways, and to employ them or their differentiated cell derivatives in pharmaceutical testing and biotechnological applications. Via blastocyst complementation, pluripotent cells are a favoured tool for the generation of genetically modified mice. The recently established technology to generate an induced pluripotency status by ectopic co-expression of the transcription factors Oct4, Sox2, Klf4 and c-Myc allows to extending these applications to farm animal species, for which the derivation of genuine embryonic stem cells was not successful so far. Most induced pluripotent stem (iPS) cells are generated by retroviral or lentiviral transduction of reprogramming factors. Multiple viral integrations into the genome may cause insertional mutagenesis and may increase the risk of tumour formation. Non-integration methods have been reported to overcome the safety concerns associated with retro and lentiviral-derived iPS cells, such as transient expression of the reprogramming factors using episomal plasmids, and direct delivery of reprogramming mRNAs or proteins. In this review, we focus on the mechanisms of cellular reprogramming and current methods used to induce pluripotency. We also highlight problems associated with the generation of iPS cells. An increased understanding of the fundamental mechanisms underlying pluripotency and refining the methodology of iPS cell generation will have a profound impact on future development and application in regenerative medicine and reproductive biotechnology of farm animals.

PRMT5 enhances generation of induced pluripotent stem cells from dairy goat embryonic fibroblasts via down-regulation of p53

OBJECTIVES

Protein arginine methyltransferase 5 (PRMT5), is thought to play a role in epigenetic reprogramming of mouse germ cells. However, up to now there has been little information concerning its expression profile and effects on generation of induced pluripotent stem cells (iPSCs) from somatic cells, in livestock. Here, we have explored PRMT5 expression profiles in dairy goats and its consequences to derivation of iPSCs from dairy goat embryonic fibroblasts (GEFs).

MATERIALS AND METHODS

We investigated effects of PRMT5 on iPS-like cells production in vitro. alkaline phosphatase (AP) staining, QRT-PCR and western blotting analysis of expression of related markers were used to evaluate efficiency of generation of iPSCs derived from GEFs.

RESULTS

These showed PRMT5 to be a conservative gene widely expressed in various tissues and different-aged testes. PRMT5 overexpression in combination with OCT3/4, SOX2, KLF4 and C-MYC (POSKM) significantly increased number of AP positive iPS-like colony-derived GEFs compared to OSKM alone, in our dairy goats. Moreover, our results demonstrated that PRMT5 overexpression stimulated GEF proliferation and down-regulated p53, p21 (a target gene of p53) and the apoptotic marker caspase 3, to enhance somatic cell reprogramming.

CONCLUSION

This study provides an efficient model for future studies on mechanisms underlying goat somatic cell reprogramming and differentiation.