ABSTRACT
<p><b>OBJECTIVE</b>To isolate, identify and culture human spermatogonial stem cells (SSC) and then obtain purified and enriched human SSCs for research and application.</p><p><b>METHODS</b>We detected the expression of CD90 in the human testis using the immunofluorescence technique and isolated human testicular spermatogenic cells by two-step enzymatic digestion, followed by differential plating and magnetic-activated cell sorting (MACS) with CD90 as an SSC marker. Then we identified the isolated CD90-positive spermatogenic cells by RT-PCR and immunocytochemistry, and meanwhile cocultured them with Sertoli cells in SG medium in vitro.</p><p><b>RESULTS</b>The isolated CD90-positive cells showed a relatively homogeneous characteristic in size and morphology and expressed the genes specific for human SSCs, with high expressions (90.5%) of GFRA1, GPR125, and UCHL1. After coculture with Sertoli cells in the SG medium for 2 weeks, the isolated CD90-positive cells maintained a good activity.</p><p><b>CONCLUSION</b>CD90 can be regarded as a speci- fic marker for human SSCs and used to obtain highly enriched human SSCs by differential plating and MACS. Furthermore, the isolated human SSCs can be cultured in SG medium in vitro.</p>