Umbilical cord mesenchymal stem cells and their extracellular vesicles attenuate cryopreservation-induced ovarian injury via the suppression of ferroptosis in an in vitro culture system

Ovarian tissue cryopreservation is a vital fertility preservation technique. However, cryopreservation-induced injury significantly limits its efficacy in frozen-thawed ovarian tissue transplantation. This study investigated the therapeutic potential of umbilical cord mesenchymal stem cells (UC-MSCs) and their derived extracellular vesicles (MSC-EVs) for repairing cryopreservation-induced ovarian injury via ferroptosis in an <i>in vitro</i> culture system. RNA sequencing revealed ferroptosis as a key regulatory pathway in cryopreserved ovarian tissue. This was characterized by downregulation of GPX4, upregulation of ACSL4, elevated Fe²⁺ levels, glutathione depletion, and enhanced lipid peroxidation. UC-MSCs and MSC-EVs effectively suppressed ferroptosis, restored GPX4 expression, and reduced lipid peroxidation, mirroring the effects of the ferroptosis inhibitor ferrostatin-1. In an <i>in vitro</i> culture system, UC-MSCs and MSC-EVs enhanced follicular survival and angiogenesis, while reducing apoptosis. Transplantation experiments demonstrated improved graft vascularization, hormone secretion, and oocyte retrieval in treated groups. Notably, MSC-EVs demonstrated comparable efficacy to UC-MSCs, suggesting their potential as a nanoscale therapeutic strategy. These findings elucidate ferroptosis as a critical mechanism in cryopreservation-induced injury and highlight UC-MSCs and MSC-EVs as promising therapeutic agents for improving ovarian tissue cryopreservation outcomes.