Conservative Hypomethylation of Mesenchymal Stem Cells and Their Secretome Restored the Follicular Development in Cisplatin-Induced Premature Ovarian Failure Mice

Abstract

Premature ovarian failure (POF) is one of the main causes of infertility in women under the age of 40 years. Recently, epigenetic reprogramming, particularly DNA hypomethylation, has emerged as a promising strategy to enhance the therapeutic potential of mesenchymal stem cells (MSCs). Thus, it is crucial to elucidate how far global hypomethylation of MSCs genome can maintain their pluripotency and viability and improve their therapeutic effect in chemotherapy-induced POF mice. Herein, the genomic DNA of bone marrow-derived MSCs (BM-MSCs) was hypomethylated by the DNA methyltransferase inhibitor (5-Aza-dC), and the degree of global hypomethylation was assessed by methylation-sensitive HepII/MspI restriction analysis. Next, mildly hypomethylated cells and their secretome were independently transplanted (or infused) in POF mice, established via cisplatin-mediated gonadotoxicity. We found that conservative global hypomethylation of BM-MSCs genome with low doses of 5-Aza-dC (≤0.5 μM) has maintained cell viability and MSCs-specific clusters of differentiation (CD). Engraftment of mildly hypomethylated cells in POF mice, or infusion of their secretome, improved the concentrations of estradiol (E2), follicle-stimulating hormone (FSH), and anti-Mullerian hormone (AMH). Furthermore, mice restored their normal body weight, ovarian size, and ovarian follicle count. This was associated with improved follicular development, where the populations of healthy primordial, primary, secondary, and tertiary follicles were significantly ameliorated, relative to mice transplanted with normally methylated cells. This observational study suggests that transplantation of mildly hypomethylated BM-MSCs cells and their secretome can restore the structural and functional integrity of the damaged ovaries in POF mice. Also, it presents conservative hypomethylation of BM-MSCs and their secretome as a promising alternative to MSCs transplantation.Graphical Transplantation of partially hypomethylated BM-MSCs improved the follicular count and integrity in the POF mouse model. Gonadotoxic drug (cisplatin) was used to establish the POF mouse model. In parallel, BM-MSCs were isolated, authenticated, and then incubated with the DNMTs inhibitor (5-Aza-dC). Partially hypomethylated cells and their secretome were independently transplanted into the POF mice, and both the follicular count, ovarian histology, and the serum levels of the fertility-related hormones (E2, AMH, and FSH) were assessed 1 week after transplantation or infusion. Hypomethylated BM-MSCs and their secretome increased the follicular count, increased the number of healthy follicles, and restricted apoptosis of the granulose cells. Also, the hormonal profile was improved compared to their corresponding level in mice transplanted with normally methylated cells.