The functional and predictive roles of miR-210 in cryptorchidism.

Idiopathic diseases of the reproductive system are important factors leading to male infertility. Many studies have shown that microRNAs (miRNAs) regulate the expression of multiple genes that play a significant role in spermatogenesis and development. We previously showed that microRNA-210 (miR-210) is one of the markedly upregulated microRNAs in the testes of sterile males with maturation arrest (MA). However, the role of miR-210 in spermatogenesis remains unknown. In this study, we found that miR-210 is highly expressed not only in patients with MA but also in patients with cryptorchidism. In addition, miR-210 inhibits the expression of Nuclear Receptor Subfamily 1, Group D, Member 2 (NR1D2) both in vitro and in vivo, particularly in cryptorchidic tissues. To facilitate further research, we established a mouse model of cryptorchidism and were surprised to discover that the miR-210 expression pattern was in accordance with that of patients with cryptorchidism. Thus, we propose that miR-210 may serve as a biomarker of cryptorchidism in clinical tests.