AB199. Human germ cell secreting factor Nodal regulates Sertoli cell functions

OBJECTIVES: To explore the regulatory effects of germ cells and germ cells secreting factor Nodal on the function of Sertoli cells derived from obstructive azoospermia and non-obstructive azoospermia patients. DESIGN: Comparative and controlled study. MATERIALS AND METHODS: Human Sertoli cells and germ cells were isolated using two-steps enzymatic digestions from the testes of obstructive azoospermia and non-obstructive azoospermia patients respectively. Expressions of Nodal signaling components in human Sertoli cells and germ cells were identified by PCR and immunochemistry. Human germ cells and Sertoli cells were cocultured in vitro to evaluate their effects on Sertoli cells. Human recombinant nodal and its receptor inhibitor SB431542 were added in the Sertoli cells culture medium to study their effects on Sertoli cell functions. CCK8 measurement was used to evaluate the proliferative activity. Q-PCR and western blot were applied to assess the expression of functional Sertoli cell genes. RESULTS: Human germ cells down-regulated blood-testis-barrier associated genes (CLDN11, OCLN) expressions of Sertoli cells in co-culture system. Nodal was expressed in germ cells but not in Sertoli cells, whereas its receptors ALK4, ALK7, and ActR-IIB were detected on Sertoli cells, which indicated Nodal signaling pathway, may play roles in the regulation of germ cells to Sertoli cells. Human recombinant nodal could promote the proliferation of human Sertoli cells, while the proliferative activity was inhibited by SB431542. Nodal could enhance the expressions of functional Sertoli cell genes (GDNF, SCF, BMP4, and ABP), while SB431542 decreased their expressions. In contrast, Nodal decreased the expression of blood-testis-barrier associated genes (CLDN11, OCLN), while SB431542 increase their expressions. CONCLUSIONS: Human Sertoli cell functions could be regulated by germ cells via paracrine pathway. Human germ cells secrete Nodal which could regulate Sertoli cell functions.