Phenotype and steroidogenic potential of PDGFRα-positive rat neonatal peritubular cells

Platelet-derived growth factor receptor α (PDGFRα)-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 PDGFRα-positive neonatal PTCs by magnetic cell sorting (MACS) from 8dpp rat testes and characterized them in vitro. We have demonstrated that PDGFRα-positive PTCs have a mixed phenotype. They expressed PTC-specific genes (αSma, Myh11), pluripotency markers (Pou5f1, nestin, Lifr) and genes encoding steroidogenic enzymes. Treatment with the cAMP-analog (Bu)2cAMP 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 17βHSD. Long-term culturing of PDGFRα-positive PTCs increased the expression of Myh11, and treatment with (Bu)2cAMP attenuated this process. All together, our findings support the hypothesis that neonatal PDGFRα-positive PTCs are steroidogenic competent progeny of stem Leydig cells (SLCs) which give rise to the adult Leydig cell lineage.