Synergistic effects of electroacupuncture and bone marrow mesenchymal stem cell transplantation on rat intrauterine adhesion： an observation.

Objectives: To investigate the effects of electroacupuncture(EA) combined with bone marrow mesen-chymal stem cells(BMSCs) transplantation on the endometrium of rats with intrauterine adhesions(IUA), so as to explore the possible mechanisms underlying their combined therapeutic effects.

Methods: Forty adult female SD rats were randomly divided into control, model, cell, and combined groups. The IUA rat model was established using a dual injury method of mechanical scratching and lipopolysaccharide infection. After successful modeling, on days 1, 3, and 7, rats in the model group received tail vein injection of phosphate buffered solution, while rats in the cell group received tail vein injection of BMSCs suspension for BMSCs transplantation；and rats in the combined group received BMSCs transplantation combined with EA treatment (2 Hz/15 Hz, 1-2 mA), targeting the "Guanyuan"(CV4), bilateral "Zusanli"(ST36) and "Sanyinjiao"(SP6) for 20 min daily for 3 consecutive estrous cycles. After intervention, uterine tissue was collected from 5 rats in each group. Histological analysis was performed using hematoxylin and eosin staining to evaluate endometrial thickness and glandular number. Masson staining was used to assess endometrial fibrosis area. Immunohistochemistry was performed to detect the positive expressions of vascular endothelial growth factor(VEGF), proliferating cell nuclear antigen(PCNA), and estrogen receptor(ER). Western blot analysis was conducted to determine the protein expressions of homeobox A10(HoxA10) and leukemia inhibitory factor(LIF), both key regulators of endometrial receptivity. The remaining 5 rats in each group were co-housed with male rats, and the uterine function recovery was evaluated by assessing the number of embryo implantations.

Results: Compared with the control group, the model group showed thinning endometrium(<0.001), decreased glandular number(<0.001), increased endometrial fibrosis area(<0.001), reduced positive expressions of VEGF, PCNA, ER, expressions of HoxA10 and LIF, and decreased embryo implantation number (<0.001) on the injured side of the uterus. Compared with the model group, the combined group showed a reversal of the aforementioned indicators(<0.001, <0.01)；the cell group exhibited thicker endometrium(<0.001) and reduced endometrial fibrosis area(<0.001). Compared with the cell group, the combined group showed increased endometrial thickness(<0.01), elevated glandular number(<0.05), significantly decreased endometrial fibrosis area(<0.05), enhanced positive expressions of VEGF, PCNA and ER, expressions of HoxA10 and LIF in the endometrium, and a significant increase in embryo implantation number (<0.001, <0.05, <0.01) on the injured side of the uterus, indicating better results than the cell group.

Conclusions: The combination of EA and BMSCs synergistically promotes the repair of damaged endometrium, improves endometrial morphology, reduces fibrosis levels, enhances vascular regeneration and matrix cell proliferation, improves endometrial receptivity, which ultimately facilitates embryo implantation.