Sustained release of miR-21 carried by mesenchymal stem cell-derived exosomes from GelMA microspheres inhibits ovarian granulosa cell apoptosis in premature ovarian insufficiency

Premature ovarian insufficiency (POI) refers to the severe decline or failure of ovarian function in women younger than 40 years of age. It is a serious hazard to women's physical and mental health, but current treatment options are limited. Mesenchymal stem cell-derived exosomes (MSC-Exo) exhibit promising potential as a therapeutic approach for POI. However, their clinical application is hindered by their instability and low long-term retention rate in vivo. In this study, miR-21 was identified as the predominant miRNA with low-expression in follicular fluid exosomes of POI patients and was shown to possess antiapoptotic activity. Next, we loaded miR-21 agomir to MSC-Exo to form Agomir21-Exo, which significantly reversed the apoptosis of granulosa cells in vitro. Moreover, we successfully developed GelMA hydrogel microspheres for encapsulating Agomir21-Exo through microfluidic technology, named GelMA-Ag21Exo, which had good injectability and significantly enhanced the stability and long-term retention of Agomir21-Exo in mice through sustained release. The release of Agomir21-Exo from GelMA-Ag21Exo notably alleviated the apoptosis of ovarian granulosa cells and improved the ovarian reserve and fertility in POI mice. Our findings illustrate that activating miR-21 through Agomir21-Exo could improve the function of ovarian granulosa cells. The GelMA-Ag21Exo enhanced the exosome-based therapeutic efficacy of the Agomir21-Exo in vivo. These findings provide a novel and promising treatment strategy for POI patients.