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Jin Gyoung Jung, Young Mok Lee, Jin Nam Kim, Tae Min Kim, Ji Hye Shin, Tae Hyun Kim, Jeong Mook Lim, and Jae Yong Han

We recently developed bimodal germline chimera production approaches by transfer of primordial germ cells (PGCs) or embryonic germ cells (EGCs) into embryos and by transplantation of spermatogonial stem cells (SSCs) or germline stem cells (GSCs) into adult testes. This study was undertaken to investigate the reversible developmental unipotency of chicken germ cells using our established germline chimera production systems. First, we transferred freshly isolated SSCs from adult testis or in vitro cultured GSCs into stage X and stage 14–16 embryos, and we found that these transferred SSCs/GSCs could migrate to the recipient embryonic gonads. Of the 527 embryos that received SSCs or GSCs, 135 yielded hatchlings. Of 17 sexually mature males (35.3%), six were confirmed as germline chimeras through testcross analysis resulting in an average germline transmission efficiency of 1.3%. Second, PGCs/EGCs, germ cells isolated from embryonic gonads were transplanted into adult testes. The EGC transplantation induced germline transmission, whereas the PGC transplantation did not. The germline transmission efficiency was 12.5 fold higher (16.3 vs 1.3%) in EGC transplantation into testis (EGCs to adult testis) than that in SSC/GSC transfer into embryos (testicular germ cells to embryo stage). In conclusion, chicken germ cells from different developmental stages can (de)differentiate into gametes even after the germ cell developmental clock is set back or ahead. Use of germ cell reversible unipotency might improve the efficiency of germ cell-mediated germline transmission.

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Seok Hee Lee, Hyun Ju Oh, Min Jung Kim, and Byeong Chun Lee

Oviduct cells produce a favorable environment for the development of gametes by generating multiple growth factors. Particularly, in canine species, immature oocytes undergo serial maturation processes in the oviduct, while the other mammals already possess matured oocytes in ovulatory follicles. However, little is known about the potential effect exhibited by the components released from canine oviduct cells (OCs) for modulating the biological function of oocytes. Recently, exosomes are regarded as promising extracellular vesicles because they represent considerable data for molecular cargo. Therefore, we first investigated the effect of canine oviductal exosomes (OC-Exo) on oocyte development via EGFR/MAPK pathway. Our results showed that OC-Exo labeled with PHK67 are successfully incorporated with cumulus cells and oocytes during IVM. Also, OC-Exo markedly increased the proportion of cumulus-oocyte complexes (COCs) exhibiting cumulus expansion as well as cumulus cell proliferation and maturation rate of oocytes (P < 0.05). Furthermore, gene expression patterns related with EGFR/MAPK pathway including EGFR, PKA, TACE/ADAM17, MAPK1/3, MAPK14, PTGS2, TNFAIP6, GDF9, and BMP15 were positively modified in COCs cultured with OC-Exo (P < 0.05). In addition, OC-Exo significantly up-regulated the protein expression levels of p-EGFR, p-MAPK1/3, GDF9 and BMP15 in COCs (P < 0.05). Consequently, the current study provides a model for understanding the roles of OC-Exo as bioactive molecules for canine oocyte maturation via EGFR/MAPK pathway, which would open a new avenue for the application of exosomes to improve assisted reproductive technology in mammals, including humans.

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Jung Bok Lee, Ji Min Song, Jeoung Eun Lee, Jong Hyuk Park, Sun Jong Kim, Soo Man Kang, Ji Nie Kwon, Moon Kyoo Kim, Sung Il Roh, and Hyun Soo Yoon

Mouse embryonic fibroblasts (MEFs) have been previously used as feeder cells to support the growth of human embryonic stem cells (hESCs). In this study, human adult uterine endometrial cells (hUECs), human adult breast parenchymal cells (hBPCs) and embryonic fibroblasts (hEFs) were tested as feeder cells for supporting the growth of hESCs to prevent the possibility of contamination from animal feeder cells. Cultured hUECs, hBPCs and hEFs were mitotically inactivated and then plated. hESCs (Miz-hES1, NIH registered) initially established on mouse feeder layers were transferred onto each human feeder layer and split every 5 days. The morphology, expression of specific markers and differentiation capacity of hESCs adapted on each human feeder layer were examined. On hUEC, hBPC and hEF feeder layers, hESCs proliferated for more than 90, 50 and 80 passages respectively. Human feeder-based hESCs were positive for stage-specific embryonic antigen (SSEA)-3 and -4, and Apase; they also showed similar differentiation capacity to MEF-based hESCs, as assessed by the formation of teratomas and expression of tissue-specific markers. However, hESCs cultured on hUEC and hEF feeders were slightly thinner and flatter than MEF- or hBPC-based hESCs. Our results suggest that, like MEF feeder layers, human feeder layers can support the proliferation of hESCs without differentiation. Human feeder cells have the advantage of supporting more passages than when MEFs are used as feeder cells, because hESCs can be uniformly maintained in the undifferentiated stage until they pass through senescence. hESCs established and/or maintained under stable xeno-free culture conditions will be helpful to cell-based therapy.