A smart therapeutic approach for improving thin endometrium in rodent models – A maiden intra uterine preclinical approach

Abstract

Recurrent endometrial injuries, such as those caused by miscarriages, curettage, or infections, leading to thin endometrium, are one of the main causes of female infertility. The current treatments for endometrial injury offer limited clinical benefits and cannot improve endometrial receptivity and pregnancy outcomes. Stem cell therapies, or regenerative medicine, are considered potential solutions to address this concern and may offer effective treatment methods for the regeneration of thin endometrium. This study spots light on a combined therapeutic approach conjoining vasculogenesis, angiogenesis, proliferation, and remodelling of cells of the uterine endometrium studied in Wistar albino rat models. The ultimate objective of this research was to regenerate the thin endometrium using commercially obtained bone marrow derived rat mesenchymal stem cells with hormone 17-beta estradiol incorporated into a thermosensitive injectable hydrogel PluronicF127 by a novel minimally invasive intrauterine approach, ensuring a controlled release of hormone estradiol from the hydrogel invitro and the delivery of stem cells to regenerate the thin endometrium. Combining the proven ability of the hydrogel PF127, oestradiol, and rat mesenchymal stem cells to regenerate the endometrial basalis layer and Functionalis layers by inducing vascularization & angiogenesis, subsequently triggering the endometrial stem cells residing in the basalis layer. The injectable hydrogel (PluronicF127) showed satisfactory biocompatibility when loaded with oestradiol and rat mesenchymal stem cells. A thin endometrial rat model was established using 1 % Lugol's iodine rather than the traditional ethanol-induced method with the concept to preserve the endometrial basalis layer. The treatment with rat mesenchymal stem cells and oestradiol-loaded injectable hydrogel significantly enhanced the thickness of the endometrium and increased the abundance of blood vessels and glands in the injured endometrium compared to the control group. The rat mesenchymal stem cells and oestradiol-loaded injectable hydrogel treatment significantly reduced endometrial fibrosis; collagen deposits and increased the presence of endometrial glands. Endometrial thickness, angiogenesis, and molecular markers were assessed at 14- and 21-days post-treatment. Histological analysis revealed that PF127/E2/rMSCs significantly improved endometrial thickness, gland density, and vascularization compared to other groups. The PF127/E2/rMSCs group showed a significant decrease in collagen deposits, which Masson's trichrome staining confirmed. Angiogenesis markers (VEGFA, EGF) and genes linked to stem cells (SOX9, AXIN1, SSEA1) were found to be upregulated in molecular analysis, indicating increased vascularization and stem cell activation in the endometrial basalis layers. Oestradiol was released continuously by the encapsulated delivery system, which also promoted cellular integration and decreased inflammatory reactions. These results demonstrate that PF127/E2/rMSCs have the capacity to repair endometrial structure and function, providing a potentially effective treatment approach for diseases such as thin endometrium. Larger-scale research is advised for additional validation in order to support these findings and ease clinical translation.