Human umbilical cord blood-derived MSCs trans-differentiate into endometrial cells and regulate Th17/Treg balance through NF-κB signaling in rabbit intrauterine adhesions endometrium

Abstract Purpose: The fundamental cause of intrauterine adhesions (IUAs) is the destruction and reduction of stem cells in endometrial basal layer, resulting in endometrial reconstruction very difficult. The purpose of this study was to investigate the effects and underlying mechanism of human umbilical cord blood derived mesenchymal stem cells (hUCB-MSC) on the endometrial reconstruction after transplantation.Methods: hUCB-MSCs were isolated and identified successfully. The rabbit IUA models were established and set five groups (control, 14/28th day after surgery, estrogen and hUCB-MSCs treatment).The number of endometrial glands and the fibrosis rate were evaluated using HE and Masson staining, respectively. Endometrial proliferation, angiogenesis and inflammation was evaluated by immunohistochemical staining of ER, Ki-67and TGF-β1, respectively. Single-cell RNA sequencing (scRNA-seq) was applied to explore the cell differentiation trajectory after hUCB-MSCs transplanted into IUA endometrium. Finally, molecular mechanism of hUCB-MSCs repairing damaged endometrium was investigated by RNA sequencing.Results: After transplantation of the hUCB-MSCs, the increase of endometrial gland number, estrogen receptor(ER) and Ki-67expression,and the decrease of fibrosis rate and TGF-β expression(P＜0.05), suggested the endometrial repair, angiogenesis and inflammatory suppression. The therapeutic effect of hUCB-MSCs was significantly improved compared with 28th day after surgery and estrogen group. ScRNA-seq demonstrated that the transplanted hUCB-MSCs can trans-differentiate into endometrial cells: epithelial, fibroblast, and macrophage. RNA Sequencing of six IUA samples further revealed that hUCB-MSCs may regulate Th17/Treg balance through NF-kB signaling, thus inhibiting the immune response of damaged endometrium.Conclusions: Our study demonstrated that hUCB-MSCs can repair damaged endometrium through trans-differentiation, immunomodulatory capacities, and NF-κB signaling, suggesting the treatment value of hUCB-MSCs in IUA.