Phenotype and steroidogenic potential peritubular cells

Platelet-derived growth factor receptor alpha (PDGFR alpha)-positive peritubular cells (PTCs) are suggested to be putative stem Leydig cells. At present little is known about their phenotype and steroidogenic potential. We isolated highly purified PDGFR alpha-positive neonatal PTCs by magnetic cell sorting (MACS) from 8dpp rat testes and characterized them in vitro. We have demonstrated that PDGFR alpha-positive PTCs have a mixed phenotype. They expressed PTC-specific genes (alpha Sma, Myh11), pluripotency markers (Pou5f1, nestin, Lifr) and genes encoding steroidogenic enzymes. Treatment with the cAMP-analog (Bu)(2)cAMP for 7 days upregulated steroidogenic enzyme gene expression and significantly increased their steroidogenic potential. The main end-point steroid was progesterone due to rapid inactivation of CYP17 and 17 beta HSD. Long-term culturing of PDGFRa-positive PTCs increased the expression of Myh11, and treatment with (Bu)(2)cAMP attenuated this process. All together, our findings support the hypothesis that neonatal PDGFR alpha-positive PTCs are steroidogenic competent progeny of stem Leydig cells (SLCs) which give rise to the adult Leydig cell lineage. (C) 2013 Elsevier Ireland Ltd. All rights reserved.