• Reproductive and Developmental Biology
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• v.38 no.2
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• pp.85-91
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• 2014

Despite many researches related with in-vitro culture of porcine spematogonial stem cells (SSCs), adherent culture system widely used has shown a limitation in the maintenance of porcine SSC self-renewal. Therefore, in order to overcome this obstacle, suspension culture, which is known to have numerous advantage over adherent culture, was applied to the culture of porcine SSCs. Porcine SSCs retrieved from neonatal testes were suspension-cultured for 5 days or 20 days, and characteristics of suspension-cultured porcine SSCs including proliferation, alkaline phosphatase (AP) activity, and self-renewal-specific gene expression were investigated and compared with those of adherent-cultured porcine SSCs. As the results, the suspension-cultured porcine SSCs showed entirely non-proliferative and significantly higher rate of AP-positive cells and expression of self-renewal-specific genes than the adherent-cultured porcine SSCs. In addition, long-term culture of porcine SSCs in suspension condition induced significant decrease in the yield of AP staining-positive cells on post-day 10 of culture. These results showed that suspension culture was inappropriate to culture porcine SSCs, because the culture of porcine SSCs in suspension condition didn't stimulate proliferation and maintain AP activity of porcine SSCs, regardless of culture periods.

• Journal of Embryo Transfer
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• v.31 no.1
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• pp.89-95
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• 2016

The present study was conduct to examine the $H_2O_2$ expression level and apoptosis-related gene expression levels inporcineskin-derived stem cell-like cells (pSSCs) after adipogenic, chondrogenic, and osteogenic differentiation induction. The pSSCs were obtained by digestion of porcine ear skin biopsy and cultured in each induction medium for 21 to 26 days to induce adipogenic, chondrogenic, and osteogenic differentiation, respectively. The $H_2O_2$ levels of pSSCs after induction culture were evaluated by staining with 2'7'-dichlorodihydrofluorescein diacetate ($H_2DCFDA$). The apoptotic gene expression of pSSCs after induction culture was also estimated by RT-PCR. The pSSCs have a potential to differentiate into three mesodermal cell types (adipocytes, chondrocytes, and osteoblasts). Non-induced control and chondrogenic-induced cells were showed higher $H_2DCFDA$ intensity (P<0.05) than adipogenic- and osteogenic-induced cells. The relative expression of Bax/Bcl-2 level was significantly low (P<0.05) in adipogenic- and osteogenic-induced cells compared to non-induced control. However, there was no difference in the relative expression of Bax/Bcl-2 level among differentiation induction groups. The result of the present study shows that the apoptosis of pSSCs is not detrimentally increased by differentiation induction culture, although chondrogenic-induced pSSCs showed high ROS generation level and apoptotic index similarly to those of non-induced cells.

• Journal of Embryo Transfer
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• v.32 no.3
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• pp.193-200
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• 2017

The purpose of this study is to confirm whether spontaneous adipocyte generation during chondrogenic induction culture affects the chondrogenic differentiation of porcine skin-derived stem cells (pSSCs). For this purpose, chondrogenic differentiation characteristics and specific marker gene expression were analyzed using cell lines showing different characteristics of spontaneous adipocyte formation. Of the four different lines of pSSCs, the pSSCs-IV line showed higher Oil red O (ORO) and glycosaminoglycan (GAG) extraction levels. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the levels of adipogenic markers peroxisome proliferator-activated receptor gamma 2 ($PPAR{\gamma}2$) and adipocyte Protein 2 (aP2) mRNAs were significantly higher in pSSCs-IV than those of the other pSSC lines (P<0.05). Among three chondrogenic markers, collagen type II (Col II) and sex determining region Y-box (Sox9) mRNAs were strongly expressed in pSSCs-IV (P<0.05), but not in aggrecan (Agg), which was significantly higher in pSSCs-II (P<0.05). These results demonstrate that the spontaneous adipocyte generation during chondrogenic differentiation has a positive effect on the chondrogenesis of pSSCs. More research is needed on the correlation between adipocyte generation and cartilage formation.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.10
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• pp.1398-1406
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• 2016

In general, the seminiferous tubule basement membrane (STBM), comprising laminin, collagen IV, perlecan, and entactin, plays an important role in self-renewal and spermatogenesis of spermatogonial stem cells (SSCs) in the testis. However, among the diverse extracellular matrix (ECM) proteins constituting the STBM, the mechanism by which each regulates SSC fate has yet to be revealed. Accordingly, we investigated the effects of various ECM proteins on the maintenance of the undifferentiated state of SSCs in pigs. First, an extracellular signaling-free culture system was optimized, and alkaline phosphatase (AP) activity and transcriptional regulation of SSC-specific genes were analyzed in porcine SSCs (pSSCs) cultured for 1, 3, and 5 days on non-, laminin- and collagen IV-coated Petri dishes in the optimized culture system. The microenvironment consisting of glial cell-derived neurotrophic factor (GDNF)-supplemented mouse embryonic stem cell culture medium (mESCCM) (GDNF-mESCCM) demonstrated the highest efficiency in the maintenance of AP activity. Moreover, under the established extracellular signaling-free microenvironment, effective maintenance of AP activity and SSC-specific gene expression was detected in pSSCs experiencing laminin-derived signaling. From these results, we believe that laminin can serve as an extracellular niche factor required for the in vitro maintenance of undifferentiated pSSCs in the establishment of the pSSC culture system.

• Journal of Embryo Transfer
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• v.29 no.3
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• pp.221-228
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• 2014

Despite that porcine spermatogonial stem cells (pSSCs) have been regarded as a practical tool for preserving eternally genetic backgrounds derived from pigs with high performance in the economic traits or phenotypes of specific human diseases, there were no reports about precise definition of niche conditions promoting proliferation and maintenance of pSSCs. Accordingly, we tried to determine niche conditions supporting proliferation and maintenance of undifferentiated pSSCs for short-term. For these, undifferentiated pSSCs were progressively cultured in different composition of culture medium, seeding density of pSSCs, type of feeder cells and concentration of growth factors, and then total number of and alkaline phosphatase (AP) activity of pSSCs were investigated at post-6 day culture. As the results, the culture of $4{\times}10^5$ pSSCs on mitotically in activated $2{\times}10^5$ STO cells in the mouse embryonic stem cell culture medium (mESCCM) supplemented with 30 ng/ml glial cell line-derived neurotrophic factor (GDNF) was identified as the best niche condition supporting effectively the short-term maintenance of undifferentiated pSSCs. Moreover, the optimized short-term culture system will be a basis for developing long-term culture system of pSSCs in the following researches.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.343-351
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• 2017

Porcine spermatogonial stem cells (SSCs) prefer three-dimensional (3D) culture systems to 2D ones for the maintenance of self-renewal. Of the many 3D culture systems, agar-based hydrogels are candidates for supporting porcine SSC self-renewal, and there are various types of agar powder that can be used. In this study, we sought to identify an agar-based 3D hydrogel system that exhibited strong efficacy in the maintenance of porcine SSC self-renewal. First, 3D hydrogels with different mechanics were prepared with various concentrations of Bacto agar, lysogeny broth (LB) agar, and agarose powder, and the 3D hydrogel with the strongest alkaline phosphatase (AP) activity and greatest increase in colony size was identified for the different types of agar powder. Second, among the porcine SSCs cultured in the different 3D hydrogels, we analyzed the colony formation, morphology, and size; AP activity; and transcription and translation of porcine SSC-related genes, and these were compared to determine the optimal 3D hydrogel system for the maintenance of porcine SSC self-renewal. We found that 0.6% (w/v) Bacto agar-, 1% (w/v) LB agar-, and 0.2% (w/v) agarose-based 3D hydrogels showed the strongest maintenance of AP activity and the most pronounced increase in colony size in the culture of porcine SSCs. Moreover, among these hydrogels, the strongest transcription and translation of porcine SSC-related genes and largest colony size were detected in porcine SSCs cultured in the 0.2% (w/v) agarose-based 3D hydrogel, whereas there were no significant differences in colony formation and morphology. These results demonstrate that the 0.2% (w/v) agarose-based 3D hydrogel can be effectively used for the maintenance of porcine SSC self-renewal.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.67-75
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• 2011

The faulty regulation of imprinting gene lead to the abnormal development of reconstructed embryo after nuclear transfer. However, the correlation between the imprinting status of donor cell and preimplantation stage of embryo development is not yet clear. In this study, to determine this correlation, we used the porcine spermatogonial stem cell (pSSC) and fetal fibroblast (pFF) as donor cells. As the results, the isolated cells with laminin matrix selection strongly expressed the GFR ${\alpha}$-1 and PLZF genes of SSCs specific markers. The pSSCs were maintained to 12 passages and positive for the pluripotent marker including OCT4, SSEA1 and NANOG. The methylation analysis of H19 DMR of pSSCs revealed that the zinc finger protein binding sites CTCF3 of H19 DMRs displayed an androgenic imprinting pattern (92.7%). Also, to investigate the reprogramming potential of pSSCs as donor cell, we compared the development rate and methylation status of H19 gene between the reconstructed embryos from pFF and pSSC. This result showed no significant differences of the development rate between the pFFs ($11.2{\pm}0.8%$) and SSCs ($13.3{\pm}1.1%$). However, interestingly, while the CTCF3 methylation status of pFF-NT blastocyst was decreased (36.3%), and the CTCF3 methylation status of pSSC-NT blastocyst was maintained. Therefore, this result suggested that the genomic imprinting status of pSSCs is more effective than that of normal somatic cells for the normal development because the maintenance of imprinting pattern is very important in early embryo stage.

• Journal of Embryo Transfer
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• v.33 no.3
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• pp.177-183
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• 2018

The identification of biomarkers of a living tissues is essentially required to understand specific functions of the cells. In previous study, we reported IGFBP 3 as one of the putative biomarkers, by showing specific expression at porcine spermatogonial stem cells (SSCs) of early stage of porcine testis. In this study, we analyzed the expression of seven members of IGFBP family (IGFBPs) in SSCs and histological expression pattern of pregnancy-associated plasma protein-A (PAPP-A), which plays a role on the growth promoting enzyme by cleavage of IGFBPs in testis of 5 days old pig. RT-PCR analysis showed that IGFBP 1, 2, 3, 4, and 6 were expressed at high level specifically in porcine SSCs compared with whole testis. We performed immunohisotochemical staining of testis sections with PAPP-A and protein gene product 9.5 (PGP9.5) which are the known biomarkers for SSCs. We were not able to find co-expression of PAPP-A and PGP9.5; PAPP-A was expressed only in Sertoli cells and PGP9.5 expression was confirmed in spermatogonium. Additionally, we were able to confirm the GATA4 expression in Sertoli and Leydig cells as a regulator of Sertoli cell function was not detected PGP9.5 expressing cells, indicating indirect evidence of that cytolocalization of PAPP-A expression is limited in Sertoli cells. These results suggested that the PAPP-A expressed in Sertoli cells may play role on regulation of development and differentiation of testicular cells through the IGF axis in neonatal porcine testis.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.171-177
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• 2009

Spermatogonial stem cells(SSCs) only are responsible for the generation of progeny and for the transmission of genetic information to the next generation in male. Other in vitro studies have cultured SSCs for proliferation, differentiation, and genetic modification in mouse and rat. Currently, information regarding in vitro culture of porcine Germline Stem Cell(GSC) such as gonocyte or SSC is limited and is in need of further studies. Therefore, in this study, we report development of a successful culture system for gonocytes of neonatal porcine testes. Testis cells were extracted from $10{\sim}14$-day-old pigs. These cells were harvested using enzymatic digestion, and the harvested cells were purified with combination of percoll, laminin, and gelatin selection techniques. The most effective culture system of porcine gonocytes was established through trial experiments which made a comparison between different feeder cells, medium, serum concentrations, temperatures, and $O_2$ tensions. Taken together, the optimal condition was established using C166 or Mouse Embryonic Fibroblast(MEF) feeder cell, Rat Serum Free Medium(RSFM), 0% serum concentration, $37^{\circ}C$ temperature, and $O_2$ 20% tension. Although we discovered the optimal culture condition for proliferation of porcine gonocytes, the gonocyte colonies ceased to expand after one month. These results suggest inadequate acquirement of ingredients essential for long term culture of porcine GSCs. Consequently, further study should be conducted to establish a successful long-term culture system for porcine GSCs by introducing various growth factors or nutrients.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.11
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• pp.1529-1539
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• 2012

A whole genome association (WGA) study was performed to detect significant polymorphisms for meat quality traits in an $F_2$ cross population (N = 478) that were generated with Korean native pig sires and Landrace dams in National Livestock Research Institute, Songwhan, Korea. The animals were genotyped using Illumina porcine 60k SNP beadchips, in which a set of 46,865 SNPs were available for the WGA analyses on ten carcass quality traits; live weight, crude protein, crude lipids, crude ash, water holding capacity, drip loss, shear force, CIE L, CIE a and CIE b. Phenotypes were regressed on additive and dominance effects for each SNP using a simple linear regression model, after adjusting for sex, sire and slaughter stage as fixed effects. With the significant SNPs for each trait (p<0.001), a stepwise regression procedure was applied to determine the best set of SNPs with the additive and/or dominance effects. A total of 106 SNPs, or quantitative trait loci (QTL) were detected, and about 32 to 66% of the total phenotypic variation was explained by the significant SNPs for each trait. The QTL were identified in most porcine chromosomes (SSCs), in which majority of the QTL were detected in SSCs 1, 2, 12, 13, 14 and 16. Several QTL clusters were identified on SSCs 12, 16 and 17, and a cluster of QTL influencing crude protein, crude lipid, drip loss, shear force, CIE a and CIE b were located between 20 and 29 Mb of SSC12. A pleiotropic QTL for drip loss, CIE L and CIE b was also detected on SSC16. These QTL need to be validated in commercial pig populations for genetic improvement in meat quality via marker-assisted selection.