In vitro culture and characterization of spermatogonial stem cells on Sertoli cell feeder layer in goat (Capra hircus)

To develop an efficient protocol for isolation, purification and long-term culture of spermatogonial stem cell (SSC) in goat. The isolation of SSC was performed by testicular disaggregation by enzymatic digestion using collagenase IV, trypsin and DNase I. Further SSCs were enriched using Percoll density gradient centrifugation. The purity of SSCs was assessed by immunocytochemistry (ICC) using alpha 6 integrin. The SSCs were co-cultured on Sertoli cell feeder layer. The SSC colonies were characterized by studying the expression of SSC specific markers (viz., alpha 6 integrin and PLZF) using ICC. The abundance of mRNAs encoding the markers of SSC (viz., beta 1 integrin and Oct-4) and Sertoli cells (viz., vimentin) was also assayed using quantitative real-time PCR (qPCR). The viability of isolated testicular cells was > 90 % and the Percoll density gradient method resulted in 3.65 folds enrichment with a purity of 82.5 %. Co-culturing of SSCs with Sertoli cell feeder layer allowed the maintenance of stable SSC colonies even after one and half months of culture. The results of ICC analysis showed the expression of alpha 6 integrin and PLZF in almost all the SSC colonies. qPCR analysis revealed a differential expression of mRNAs encoding beta 1 integrin, Oct-4 and vimentin markers. Results of this study demonstrate a simple enzymatic digestion and Percoll density gradient method for isolation and enrichment of SSCs, and suitability of Sertoli cell feeder layer for long term in vitro culture of SSC in goats. Results also suggest the possible application of non-caprine antibodies against SSC specific markers for the identification and subsequent assessment of SSCs in goats.