Abstract: BACKGROUND: At present, many drugs used in the treatment of polycystic ovary syndrome are super-designated drugs, and the treatment of patients with polycystic ovary syndrome still faces great challenges. Studies have shown that human umbilical cord mesenchymal stem cells can repair ovarian function, but few studies have reported their therapeutic effect on polycystic ovary syndrome.  
OBJECTIVE: To investigate the therapeutic effect of human umbilical cord mesenchymal stem cells on polycystic ovary syndrome, and to preliminarily explore the correlation between mitochondrial autophagy and the improvement of polycystic ovary syndrome by human umbilical cord mesenchymal stem cells.  
METHODS: Polycystic ovary syndrome mouse model was established by subcutaneous injection of dehydroepiandrosterone for 20 days into C57BL/6J mice. Human umbilical cord mesenchymal stem cells (2×106) were injected through the caudal vein. After treatment, vaginal secretions were collected for 10 consecutive days to detect the estrus cycle of mice. At 2 weeks after treatment, the levels of sex hormones in the peripheral blood of mice, including luteinizing hormone and follicle-stimulating hormone, were detected by ELISA. Hematoxylin-eosin staining was used to evaluate ovarian histopathology. Finally, mitochondrial autophagy in ovaries was observed by transmission electron microscopy. 
RESULTS AND CONCLUSION: (1) After human umbilical cord mesenchymal stem cell therapy, follicles at different stages (primitive follicles, primary follicles, and secondary follicles) appeared in the ovary of polycystic ovary syndrome mice, and luteal tissue could be seen, indicating that ovulation function of mice was effectively improved. (2) Polycystic ovary syndrome mice treated with human umbilical cord mesenchymal stem cells had sex hormone levels. (3) Untreated polycystic ovary syndrome mice were found to be in the estrous stage for a long time, lacking estrous interphase and estrous phase, but after human umbilical cord mesenchymal stem cell therapy, the estrous cycle returned to a normal level. (4) After treatment with human umbilical cord mesenchymal stem cells, the mitochondrial autophagy of polycystic ovary syndrome mice was significantly reduced. (5) The results show that human umbilical cord mesenchymal stem cells can effectively improve the symptoms of endocrine disorders and promote ovulation in polycystic ovary syndrome mice, which may be related to the inhibition of mitochondrial autophagy.

Key words: umbilical cord mesenchymal stem cell, polycystic ovary syndrome, ovulatory dysfunction, endocrine disorder, mitochondrial autophagy