To date, there are no protocols optimized to the effective separation of spermatogonial stem cells (SSCs) from testicular cells derived from mouse testes, thus hindering studies based on mouse SSCs. In this study, we aimed to determine the most efficient purification method for the isolation of SSCs from mouse testes among previously described techniques. Isolation of SSCs from testicular cells derived from mouse testes was conducted using four different techniques: differential plating (DP), magnetic-activated cell sorting (MACS) post-DP, MACS, and positive and negative selection double MACS. DP was performed for 1, 2, 4, 8, or 16 h, and MACS was performed using EpCAM (MACSEpCAM), Thy1 (MACSThy1), or GFR α1 (MACSGFRα1) antibodies. The purification efficiency of each method was analyzed by measuring the percentage of cells that stained positively for alkaline phosphatase. DP for 8 h, MACSThy1 post-DP for 8 h, MACSGFRα1, positive selection double MACSGFRα1/EpCAM, and negative selection double MACSGFRα1/α-SMA were identified as the optimal protocols for isolation of SSCs from mouse testicular cells. Comparison of the purification efficiencies of the optimized isolation protocols showed that, numerically, the highest purification efficiency was obtained using MACSGFRα1. Overall, our results indicate that MACSGFRα1 is an appropriate purification technique for the isolation of SSCs from mouse testicular cells.

Microenvironments surrounded with various extracellular matrix (ECM) components can decide specifically the fate of spermatogonial stem cells (SSCs) and integrin heterodimers recognizing directly ECM proteins play an important role in transporting ECM-derived signals into cytoplasm, resulting in inducing a variety of biological functions such as cell attachment, self-renewal and differentiation. However, to date, studies on type of integrin heterodimers expressed functionally on the undifferentiated SSCs derived from mouse with hybrid strain remain unclear. Therefore, we tried to investigate systematically what kind of integrin heterodimers are expressed transcriptionally, translationally and functionally in the SSCs derived from testis of hybrid (B6CBAF1) mouse. For these, magnetic activated cell sorting (MACS) using Thy1 antibody was used for isolating SSCs from testis, and real-time PCR or fluorescence immunoassay was conducted for measuring transcriptional or translational level of integrin α and β subunits in the isolated SSCs. Subsequently, antibody inhibition assay was conducted for confirming functionality of presumed integrin heterodimers. As the results, transcriptional levels of genes encoding total 25 integrin subunits were quantified, 7 integrin α (α4, α6, α7, α9, αV, αL and αE) and 2 integrin β (β1 and β5) subunit genes showed significantly increased transcriptional up-regulation, compared to the other integrin subunit genes. In contrast, integrin α3, α5, α10 and α11, and integrin β2, β3, β4 and β7 were weakly transcribed. When translational levels of the integrin α subunits showing high transcription level (α4, α6, α7, α9, αV, αL and αE) were measured, significantly strong translational up-regulation of integrin α6, α7, α9, αV and αL subunit genes were detected, whereas integrin α4 and αE subunit genes were weakly. In case of integrin β subunit, β1 evaluated more expression than β5. Based on these results, we speculated that the undifferentiated SSCs derived from B6CBAF1 mouse might express integrin α4β 1, α6β1, α7β1, α9β1, αVβ1 or αVβ5 on plasma membrane. Subsequently, the hybrid strain SSCs showed significantly increased adhesion to fibronectin, laminin, tenascine-C and vitronectin and functional blocking of integrin α4β1, α6β1, α9β1, and αVβ1 or αVβ5 in SSCs significantly inhibited attachment to fibronectin, laminin, tenascin-C and vitronectin, respectively. Accordingly, we could identify that the hybrid (B6CBAF1) mouse-derived SSCs had integrin α4β1, α6β1, α9β1, αVβ1 or αVβ5 on plasma membrane. Moreover, this information will greatly contribute to constructing non-cellular niche supporting self-renewal of SSCs in the future.

Spermatogonial stem cells (SCCs) is foundation for spermatogenesis throughout male adult life because they have ability of self-renewal and differentiation into spermatozoa. Storage of such SSCs is very important to study on male reproduction, which would contribute human male infertility to be treated. However, during cryopreservation, the most cells are damaged by cryoinjury such as apoptosis, necrosis, osmotic stress, oxidative stress and so on. For the reason, in cryopreservation technique, targeting purpose is what cells are stored stably without cryoinjury. The purpose of this study was to develop the cryoprotectant for decrease in cryoinjury of SSCs by using melatonin and necrostatin-1 as additive cryoprotectant. The SSCs with melatonin or necrostatin-1 was frozen for 1 month, and then thawed to evaluate survival, recovery and proliferation rate. The result showed that necrostatin-1 50 mM was significantly greater than DMSO control. Furthermore, we conducted the characterization of cryo-thawed SSCs with necrostatin-1 50 mM to confirm whether the SSCs could maintain the undifferentiated state. As a result, the normal expression of each marker, which is PLZF, GFRa1 and VASA, was observed except for C-kit, meaning that the cells could maintain the undifferentiated state regardless of cryopreservation. Therefore, the result indicates that the cryo-thawed SSCs have ability of proliferation and self-renewal. In conclusion, our finding verifies that cryopreservation of SSC with necrostatin-1 50 mM could be helpful to preserve the SSCs stably, contributing to various studies on male reproduction and infertility treatment

A tremendous increase in the human population has put poultry industry under an increased pressure to meet steep increase in the demand. Poultry is contributing 25% of the total world’s meat production and lesser cost of investment per bird makes it more suitable for the further breeding programmes. Major poultry diseases frequently lead to cardiac damage and cause huge economic losses to poultry industry due to mortality. The in vitro embryonic stem cell (ESC) technology has a futuristic approach for homogeneous populace of differentiated cells, for their further transplantations. During in vitro conditions the differentiated cell populace can be used in grafting and transplantation processes to regenerate damaged tissues. Therefore, the current study targeted the use of spermatogonial stem cells (SSCs) in the poultry production system through cardiac regeneration. The current study will also open new boulevard for the similar kind of research in other livestock species for the management of heart diseases.

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 4x105 pSSCs on mitotically in activated 2x105 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.

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-cul-tured 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.

Spermatogenesis is initiated from spermatogonial stem cells (SSCs) that has an ability of self-renewal and unipotency to generate differentiating germ cells. The objective of this study is to develop the simple method for derivation of SSCs using non-sorting of both spermatogonia and feeder cells. Simply uncapsulated mouse testes were treated with enzymes followed by surgical mincing, and single cells were cultured in stempro-34TM cell culture media at 37℃. After 5 days of culture, aciniform of SSC colony was observed, and showed a strong alkaline phosphatase activity. Molecular characterization of mouse SSCs showed that most of the mouse SSC markers such as integrin α6 and β1, CD9 and Stra8. In addition, pluripotency embryonic stem cell (ESC) marker Oct4 were expressed, however Sox2 expression was lowered. Interestingly, expression of SSC markers such as Vasa, Dazl and PLZF were stronger than mouse ESC (mESC). This data suggest that generated mouse SSCs (mSSCs) in this study has at least similar biomarkers expression to mESC and mSSCs derived from other study. Immunocytochemistry using whole mSSC colony also confirmed that mSSCs generated from this study expressed SSC specific biomarkers such as c-kit, Thy1, Vasa and Dazl. In conclusion, mSSCs from 5 days old mouse testes were successfully established without sorting of spermatogonia, and this cells expressed both mESC and SSC specific biomarkers. This simple derivation method for mSSCs may facilitate the study of spermatogenesis.

Spermatogonial stem cells (SSC) undergo self-renewal division and generate spermatogenesis to produce mature spermatozoa. Very recently in some species, include rodent and farm animals, SSC has been isolated and cultured in vitro. In this study, we analysed SSC marker of both 5 days old and pubertal pig testis by histological method. In 5day pig testis, prior to set of spermatogenic differentiation, the seminiferous tubules contain a relatively large number of SSCs than in pubertal pig testis. Then putative pig SSCs were successfully isolated from 5 day pig testis, and cultured long term using CD34 positive cell culture media contained GDNF, bFGF, LIF and EGF. The SSC colonies were appeared at 3 days after cells were seed. The SSC colonies were alkaline phosphatase positive and strongly expressed PGP 9.5, PLZF and DBA, but not expressed GATA4 and LH receptors. The SSC colonies were stably proliferated in GDNF, bFGF, LIF and EGF contained CD34 positive cell culture media up to 60 days. This study will be facilitated to study of in vitro and ex vivo spermatogenesis and of production of transgenic pigs using sperm vector.

Spermatogenesis is a series of complex processes that produce spermatozoa in male testis and it occurs through consecutive cell divisions and differentiation of germ cells (Russell et al., 1990). This process is initiated by a small number of spermatogonial stem cells (SSCs) that are only two or three per 104 testis cells in mouse case, and finally gives rise to many functional spermatozoa. Similar to the characteristics found in other adult stem cells, SSCs have the capability of self‐renewal and differentiation (Meistrich and van Beek, 1993). SSCs that have these two capabilities are the source of maintaining male postnatal fertility for lifetime. SSCs that exist inside the male testis maintain the numerical equilibrium through self‐renew after birth and they are the only germ‐line stem cell that can transfer the genetic information to the next generation through spermatogenesis. Therefore, when genetic modification is performed at the SSC stage, it can produce transgenic offspring in the next generation as well as germ‐line modification so that it can deliver the transformed character stably to the descendants. Past studies regarding the SSC had been dependent on morphological observations due to the absence of a marker system that can distinguish the SSCs. Brinster et al. (1994) published a groundbreaking turning point in identifying characteristics of SSC by developing SSC transplantation technique (Brinster and Avarbock, 1994; Brinster and Zimmermann, 1994). Utilizing the SSC transplantation technique, the self‐renew and production capability of differentiated tissue derived from transplanted SSC within the recipient’s seminiferous tubule can be directly analyzed. The biological activity of SSCs can also be investigated objectively by the SSC transplantation technique. Since the advent of the SSC transplantation technique, there have been a lot of progresses in the biological field of SSC. Recently, the enrichment technique of SSCs using FACS and specific surface marker, in vitro culture, and genetic modification techniques of SSCs have been developed in rodents. These techniques have potential to enhance the practical applications of SSCs. Characterization and development of useful technique for SSCs are now extending to livestock species.

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 GFRα-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±0.8%) and SSCs (13.3±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.

The HMG box containing protein (HBP) has a high mobility group domain and involved in the regulation of proliferation and differentiation of tissues. We screened HBP2 in glioblastoma using Suppression Subtractive Hybridization (SSH) and isolated human spermatogonial stem cell‐like cells (hSSC‐like cells) derived from patients of nonobstructive azoospermia (NOA). Expression of HBP2 was analyzed by RT‐PCR in undifferentiated stem cells (human Embryonic Stem Cells, hSSC‐like cells 2P) and spontaneous differentiated stem cells (hSSC‐like cells 4P). It was overexpressed in hESC and hSSC‐like cells 2P but not in hSSC‐like cells 4P. Also, the expression level of HBP2 was downregulated in colon tumor tissues compared to normal tissues. Specifically in synchronized WI‐38 cells, HBP2 was highly upregulated until the G1 phase of the cell cycle and gradually decreased during the S phase. Our results suggest that HBP2 was downregulated during the spontaneous differentiation of hSSC‐like cells. HBP2 was differently expressed in colon tissues and was related to G1‐progression in WI‐38 cells. It may play a role in the maintenance of an undifferentiated hSSC‐like cell state and transits from G1 to S in WI‐38 cells. This research was important that it identified a biomarker for an undifferentiated state of hSSC‐like cells and characterized its involvement to arrest during cell cycle in colon cancer.