RESUMO
Isolation and culture of spermatogonial stem cells (SSCs) are attractive for production of genetic modified offspring. In the present study, buffalo spermatogonial stem-like cells were isolated, cultured and expression pattern of different germ cell marker genes were determined. To recover spermatogonia, testes from age 3 to 7 months of buffalo were decapsulated, and seminiferous tubules were enzymatically dissociated. Two types of cells, immature sertoli cell and type A spermatogonia were observed in buffalo testes in this stage. Germ cell marker genes, OCT3/4 (Pou5f1), THY-1, c-kit, PGP9.5 (UCHL-1) and Dolichos biflorus agglutinin, were determined to be expressed both in mRNA and protein level by reverse transcription polymerase chain reaction and immunostaining in buffalo testes and buffalo spermatogonial stem-like cells, respectively. In the following, when the isolated buffalo buffalo spermatogonial stem-like cells were cultured in the medium supplemented 2.5% fetal bovine serum and 40 ng/mL glial cell-derived neurotrophic factor medium, SSCs proliferation efficiency and colony number were significantly improved than those of other groups (p<0.05). These findings may help in isolation and establishing long term in vitro culture system for buffalo spermatogonial stem-like cells, and accelerating the generation of genetic modified buffaloes.
RESUMO
Ectopically, expression of defined factors could reprogram mammalian somatic cells into induced pluripotent stem cells (iPSCs), which initiates a new strategy to obtain pluripotent stem cell lines. Attempts have been made to generate buffalo pluripotent stem cells by culturing primary germ cells or inner cell mass, but the efficiency is extremely low. Here, we report a successful method to reprogram buffalo fetal fibroblasts (BFFs) into pluripotent stem cells [buffalo induced pluripotent stem cell (biPSCs)] by transduction of buffalo defined factors (Oct4, Sox2, Klf4, and c-Myc) using retroviral vectors. The established biPSCs displayed typical morphological characteristics of pluripotent stem cells, normal karyotype, positive staining of alkaline phosphatase, and expressed pluripotent markers including Oct4, Sox2, Nanog, Lin28, E-Cadherin, SSEA-1, SSEA-4, TRA-1-81, STAT3, and FOXD3. They could form embryoid bodies (EBs) in vitro and teratomas after injecting into the nude BALB/C mice, and 3 germ layers were identified in the EBs and teratomas. Methylation assay revealed that the promoters of Oct4 and Nanog were hypomethylated in biPSCs compared with BFFs and pre-biPSCs, while the promoters of Sox2 and E-Cadherin were hypomethylated in both BFFs and biPSCs. Further, inhibiting p53 expression by coexpression of SV40 large T antigen and buffalo defined factors in BFFs or treating BFFs with p53 inhibitor pifithrin-a (PFT) could increase the efficiency of biPSCs generation up to 3-fold, and nuclear transfer embryos reconstructed with biPSCs could develop to blastocysts. These results indicate that BFFs can be reprogrammed into biPSCs by buffalo defined factors, and the generation efficiency of biPSCs can be increased by inhibition of p53 expression. These efforts will provide a feasible approach for investigating buffalo stem cell signal pathways, establishing buffalo stem cell lines, and producing genetic modification buffaloes in the future.