ABSTRACT
<p><b>OBJECTIVE</b>To study the ability of bone marrow mesenchymal stem cells (BMSCs) to repair the internal environment of the testis in male azoospermia rats.</p><p><b>METHODS</b>We established azoospermia models in 22 six-week-old male SD rats by intraperitoneal injection of busulfan at 20 mg per kg body weight. We transplanted allogeneic rat BMSCs (rBMSCs) into the testicular seminiferous tubules of the model rats and, 30 days after transplantation, observed the composition and structure of the seminiferous tubular cells by HE staining and detected the expressions of CD44, CD106, and c-kit in the rBMSCs by immunohistochemistry.</p><p><b>RESULTS</b>The number of epididymal sperm was significantly reduced in the model rats as compared with the normal controls (P < 0.01). CD44 and CD106, but not c-kit, were expressed in the isolated rBMSCs. At 30 days after transplantation of rBMSCs, lots of new cells were observed in the seminiferous tubules, some expressing CD106 and some expressing the germ cell surface marker c-kit.</p><p><b>CONCLUSION</b>BMSCs can transdifferentiate into germ cells and repair the damaged seminiferous tubules of sterile rats.</p>