Injectable antioxidant hyaluronan/chitosan hydrogel as a platelet-rich plasma and stem cell carrier to promote endometrial regeneration and fertility restoration.

Severe damage to the uterine endometrium can lead to thin endometrium and intrauterine adhesions (IUAs), resulting in infertility or complications during pregnancy. Therapies utilizing mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) represent promising strategies for restoring thin endometrium. However, the low homing rate and functionality of transplanted cells, along with the rapid release of PRP growth factors, limit their therapeutic efficacy. In this study, we developed an in-situ formable and redox-responsive hydrogel composed of thiolated hyaluronan (tHA) and thiolated chitosan (tChi) (tHA-tChi) for encapsulating PRP and mouse adipose-derived stem cells (ADSCs). Our results demonstrate that the tHA-tChi hydrogel exhibits appropriate swelling, injectability, self-healing, and antioxidant properties, alongside a sustained release of PRP growth factors. In vitro experiments indicated that the PRP and ADSCs encapsulated within the hydrogel (ADSCs/tHA-tChi/PRP) stimulated angiogenesis in endothelial cells. In a mouse model of thin endometrium, the ADSCs/tHA-tChi/PRP significantly enhanced endometrial regeneration, as evidenced by increased endometrial thickness and reduced fibrosis. This improvement markedly enhanced endometrial receptivity and pregnancy rates in damaged endometria, correlating with increased angiogenesis and endometrial cell proliferation via activation of the VEGF/AKT/BAD pathway, as shown by Western blotting assays. Overall, the combination of antioxidant hydrogel, PRP, and ADSCs demonstrates promising potential for promoting endometrial regeneration and restoring fertility, offering new minimally invasive therapeutic options for endometrial diseases. STATEMENT OF SIGNIFICANCE: This research presents a potent approach to the treatment of thin endometrium, employing an injectable, biodegradable and antioxidant hydrogel comprising thiolated hyaluronic acid (tHA) and thiolated chitosan (tChi). The antioxidant capacity of the hydrogel improves the oxidative microenvironment of the injured uterus, while the hydrogel is designed to release adipose-derived stem cells (ADSCs) and growth factors from platelet-rich plasma (PRP) sustainably, promoting tissue regeneration by enhancing angiogenesis and endometrium cell proliferation. Demonstrated efficacy in a mouse model of thin endometrium indicates its great potential to significantly improve fertility restoration treatments. The administration of antioxidant hydrogel containing ADSCs and PRP represents a promising therapeutic strategy for patients with endometrial disease.