De-tensioning of collagen fibers optimizes endometrial receptivity and improves the rate of embryo implantation
Successful embryo implantation within the uterine wall requires intricate endometrial remodeling. Impaired endometrial receptivity, a common cause of infertility, often results from ineffective remodeling processes. Here, we demonstrate that a single dose of human collagenase-1 administered into the mouse uterus enhances embryo implantation rates. Mechanistically, collagenase-1 induces remodeling of the endometrial extracellular matrix (ECM), leading to the degradation of collagen fibers and proteoglycans. This process releases matrix-bound bioactive factors, such as VEGF, which facilitates local vascular permeability and angiogenesis. Furthermore, collagenase-1 treatment increases NK cell infiltration and elevates levels of the cytokine LIF, a key factor in embryo implantation. Remarkably, the overall structural integrity of the uterine tissue remains uncompromised, even in the presence of reduced tension in endometrial collagen fibers. To assess pre-clinical potential, in-uteri application of collagenase-1 successfully rescued implantation in mouse models subjected to heat stress and embryo transfer, conditions known for their adverse impact on implantation rates. Importantly, ex-vivo exposure of human uterine tissue to collagenase-1 induced collagen de-tensioning and the release of VEGF, demonstrating similar processes observed in the mouse settings, and the potential relevance of this treatment to human conditions. Our findings underscore the immense clinical potential and feasibility of collagenase treatment to enhance uterine receptivity for embryo implantation, offering a controlled and minimally invasive intervention. This innovative approach not only demonstrates the potential to enhance efficiency in livestock breeding but, more importantly, signifies a substantial promise in supporting medical interventions for human reproduction in clinical settings.