Peroxiredoxin 4 secreted by cumulus cells ameliorates the maturation of oocytes in vitro.

BACKGROUND: Peroxiredoxin 4 (Prdx4) in the endoplasmic reticulum (ER) is the only secretory member of the antioxidant Prdx family. Our previous studies demonstrated that Prdx4 in cumulus cells (CCs) ameliorated the maturation of oocytes in vitro and enhanced oocyte developmental competence by preventing CCs apoptosis caused by oxidative stress (OS) through gap junctions. In this study, we aimed to determine whether Prdx4 released by CCs can repair meiotic defects in mouse oocytes by co-culturing immature (germinal vesicle) oocytes with CCs from mature oocytes in the absence of gap junctions. RESULTS: The OS-induced meiotic defects in mouse oocytes were impeded by co-culture with CCs, as evidenced by the increased first polar body (PB1) extrusion rate and decreased ROS level. CCs increased Prdx4 expression and lowered IRE1α, Bip expression in H2O2-treated oocytes. After knockdown of Prdx4 expression in CCs, the rate of PB1 extrusion in the oocytes was significantly reduced to the level detected in H2O2 group, and ER stress was not alleviated. CO-IP and immunofluorescence co-localization experiments demonstrated that Prdx4 interacted with PDIA6 in the oocytes and the Pearson's R value was 0.69 calculated using ImageJ. CONCLUSIONS: Cumulus cells can promote the maturation of oocytes in vitro by secreting Prdx4 in a paracrine manner and serve as a promising therapeutic antioxidant for improving the quality of oocytes, especially aging oocytes, in clinical in vitro maturation (IVM).

Human amnion-derived mesenchymal stem cells improved the reproductive function of age-related diminished ovarian reserve in mice through Ampk/FoxO3a signaling pathway.

BACKGROUND: Age-related diminished ovarian reserve (AR-DOR) reduced the quality of oocytes, resulting in decreased female fertility. Aging is tightly related to abnormal distribution and function of mitochondria, while mitophagy is a major process to maintain normal quality and quantity of mitochondria in cells, especially in oocytes which containing a large number of mitochondria to meet the demand of energy production during oocyte maturation and subsequent embryonic development. Ampk/FoxO3a signaling is crucial in the regulation of mitophagy. It is reported mesenchymal stem cells (MSCs) can improve ovarian function. Here we aim to explore if human amnion-derived mesenchymal stem cells (hAMSCs) are effective in improving ovarian function in AR-DOR mice and whether Ampk/FoxO3a signaling is involved. METHODS: The AR-DOR model mice were established by 32-week-old mice with 3-8 litters, significantly low serum sex hormone levels and follicle counts. The old mice were divided into 5 treatment groups: normal saline (NS, control), 1% human serum albumin (HSA, resolver), low dose (LD, 5.0 × 106cells/kg), middle dose (MD, 7.5 × 106cells/kg), and high dose (HD, 10.0 × 106cells/kg). The prepared hAMSCs were injected through tail vein. Serum sex hormone level, follicle counts, fertilization rate, gestation rate, little size, apoptosis of granulosa and stromal cells, expression level of Sod2, Ampk, and ratio of phosphorylated FoxO3a to total FoxO3a in ovaries were examined. RESULTS: Our results show that after hAMSC transplantation, the ovarian function in AR-DOR mice was significantly improved, meanwhile the apoptosis of granulosa and stromal cells in the ovaries was significantly repressed, the expression level of Ampk and the ratio of phosphorylated FoxO3a to total FoxO3a both were significantly increased, meanwhile increased Sod2 expression was also observed. CONCLUSION: Our results demonstrate hAMSC transplantation via tail-injection can improve ovarian function of AR-DOR mice through Ampk/FoxO3a signaling pathway.