Bushen Huoxue Formula Enema Improves Embryo Implantation: Promoting Epithelial–Mesenchymal Transition via the LXA4R/NF‐κB Pathway

PROBLEM: Embryo implantation failure remains a significant challenge in reproductive medicine. This study investigates the therapeutic potential and underlying mechanism of a Chinese medicine Bushen Huoxue Formula (BHF) enema in improving embryo implantation. METHOD OF STUDY: A rat model of embryo implantation disorder was established, with uterine tissues collected on the sixth and eighth days post coition (dpc). Implanted embryo counts were recorded, and endometrial morphology and pinopode development were assessed using hematoxylin-eosin staining and scanning electron microscopy. Western blotting and immunofluorescence measured lipoxin A4 receptor (LXA4R), nuclear factor kappa-B (NF-κB) p65, and epithelial-mesenchymal transition (EMT) marker expressions. An in vitro model was also used, where adhesion assays, Western blotting, and RT-qPCR were conducted before and after NF-κB p65 silencing via lentiviral transfection to evaluate BHF enema-containing serum (BHFE-CS) effects. RESULTS: BHF enema significantly increased endometrial thickness, improved pinopode development, and enhanced the number of implanted embryos in model rats. Molecularly, BHF upregulated p-NF-κB p65 and N-cadherin while downregulating LXA4R and E-cadherin, promoting a pro-inflammatory microenvironment and EMT process essential for embryo implantation. Consistently, BHFE-CS enhanced embryo adhesion in vitro. Crucially, the pro-implantation effects of BHFE-CS were abolished upon NF-κB p65 silencing, confirming the pathway's indispensability. CONCLUSIONS: BHF enema improves embryo implantation by modulating the LXA4R/NF-κB pathway to promote EMT, highlighting its potential as a treatment for embryo implantation disorders.