[Effect of mesenchymal stem cell derived from umbilical cord blood on rabbit intrauterine adhesion model]

Objective: To investigate the repair effect of human umbilical cord blood mesenchymal stem cells (hUCB-MSC) on endometrium of intrauterine adhesion (IUA) by establishing animal model. Methods: Eighteen healthy female New Zealand white rabbits were divided into a control group, an IUA group and an hUCB-MSC transplantation group according to random number table method. The control group underwent laparotomy only. The IUA group underwent IUA modeling surgery using curettage and lipopolysaccharide (LPS) cotton placed in uterine cavity for double injury. The hUCB-MSC transplantation group received the same IUA modeling surgery followed by multipoint injection of hUCB-MSC suspension (2×10⁶ cells/ml, 500 μl) into the bilateral uterine myometrium one week after surgery. Four weeks after the IUA modeling surgery, the rabbits were euthanized and samples were collected. Hematoxylin and eosin (HE) staining and Masson staining were used to assess the number of endometrial glands and the fibrosis rate. RNA sequencing was performed on the endometrium of the IUA group and hUCB-MSC transplantation group.The mRNA and protein expression of the fibrosis markers [transforming growth factor β1 (TGF-β1) and tissue inhibitors of metalloproteinase 1 (TIMP1)] and RNA sequencing-related parameters were detected by quantitative real-time PCR (qRT-PCR) and Western blot. Results: Compared with the control group, the number of glands in IUA group decreased (26.33±1.53 vs 4.33±1.53, P<0.001), and the fibrosis rate increased (18.01%±2.21% vs 69.55%±2.42%, P<0.001), indicating successful modeling. HE and Masson staining revealed that the number of glands in the hUCB-MSC transplantation group was increased compared with that in IUA group (17.33±2.52 vs 4.33±1.53, P<0.001), and the fibrosis rate decreased (69.55%±2.42% vs 41.55%±1.99%,P=0.001). Western blot analyses of fibrosis-related proteins (TGF-β1 and TIMP1) showed elevated levels of TGF-β1 (0.91±0.05) and TIMP1 (0.99±0.01) proteins in the IUA group compared to control group (0.61±0.04, 0.68±0.07) (P=0.001, 0.015). The hUCB-MSC transplantation group exhibited reduced expression of TGF-β1 (0.69±0.04) and TIMP1 (0.62±0.08) proteins compared to the IUA group (P=0.005, 0.014). Western Blot results related to the PI3K/AKT signaling pathway [phosphorylated phosphatidylinositol 3-kinase (p-PI3K), phosphorylated protein kinase B (p-AKT)] showed that the expression of p-PI3K(1.05±0.05) and p-AKT(1.17±0.06) in the IUA group increased compared to the control group (0.78±0.03, 0.85±0.05) (P=0.002, 0.002). The expression of p-PI3K (0.74±0.02) and p-AKT (0.93±0.04) proteins in the hUCB-MSC transplantation group decreased compared to the IUA group (P=0.003, 0.005). Conclusion: hUCB-MSC can repair the damaged endometrium in rabbit intrauterine adhesion model by increasing the number of endometrial glands and improving its level of fibrosis.