Protective properties of heme oxygenase-1 expressed in umbilical cord mesenchymal stem cells help restore the ovarian function of premature ovarian failure mice through activating the JNK/Bcl-2 signal pathway-regulated autophagy and upregulating the circulating of CD8+CD28- T cells

Background: Umbilical cord-derived mesenchymal stem cell (UCMSCs) transplantation has been widely studied in premature ovarian failure (POF). However, the underlying mechanism remains elusive. This study aims to investigate the protective properties and mechanisms of heme oxygenase-1 (HO-1) expressed in UCMSCs in restoring the ovarian function of POF mice.

Methods: In in vitro and in vivo experiments, mice were treated with the presence or absence of the HO-1/shHO-1-transfected UCMSCs, and the administration of SP600125 or anisomycin, the inhibitor or activator of JNK. The viability and Apoptosis of granulosa cells (GCs) at different time points of co-cultivation were assessed in vitro. In in vivo experiments, mouse ovarian function was assessed by detecting the serum levels of hormone and observing the ovarian morphological changes. Multiple molecular indices of JNK/Bcl-2 signal pathway were performed. And the Autophagy changes in GCs were assessed by detecting the associated cytokines and observing the intracellular autophagosome accumulation. Additionally, the spleen levels of CD8⁺CD28^- T cells and serum levels of interleukin 10 (IL-10) were tested to evaluate the immune mechanisms involved.

Results: UCMSCs transfected with shHO-1 or treated with SP600125 inhibited GCs' viability and promoted its Apoptosis in a time-dependent manner in vitro. In in vivo experiments, mice in both groups showed little therapeutic efficiency which presented as the increased extent of ovarian fibrosis with decreased number of functional follicles, and disordered hormone production. Additionally, the JNK/Bcl-2-associated cytokines were obviously declined. The inhibited autophagy-related cytokines, the chromatin condensation and abound vacuolar autophagosome in GCs, and weakened fluorescence intensity by MDC were observed. The downregulated levels of CD8⁺CD28^- T cells and serum levels of IL-10 were also detected. The damages above can be alleviated with HO-1-MSCs treatment or anisomycin administration.

Conclusions: HO-1 expressed in UCMSCs is critical in restoring the ovarian function in POF mice with UCMSC transplantation, which is mediated by the activation of JNK/Bcl-2 signal pathway-regulated Autophagy and upregulating the circulating of CD8⁺CD28^- T cells.