Inhibition of erythropoietin-producing hepatoma receptor B4 (EphB4) signalling suppresses the vascularisation and growth of endometriotic lesions.

The development of endometriotic lesions is crucially dependent on the formation of new blood vessels. In the present study, we analysed whether this process is regulated by erythropoietin-producing hepatoma receptor B4 (EphB4) signalling. We first assessed the anti-angiogenic action of the EphB4 inhibitor NVP-BHG712 in different in vitro angiogenesis assays. Then, endometriotic lesions were surgically induced in the dorsal skinfold chamber and peritoneal cavity of NVP-BHG712- or vehicle-treated BALB/c mice. This allowed to study the effect of EphB4 inhibition on their vascularisation and growth by means of intravital fluorescence microscopy, high-resolution ultrasound imaging, histology and immunohistochemistry. Non-cytotoxic doses of NVP-BHG712 suppressed the migration, tube formation and sprouting activity of both human dermal microvascular endothelial cells (HDMEC) and mouse aortic rings. Accordingly, we also detected a lower blood vessel density in NVP-BHG712-treated endometriotic lesions. This was associated with a reduced lesion growth due to a significantly lower number of proliferating stromal cells when compared to vehicle-treated controls. Inhibition of EphB4 signalling suppresses the vascularisation and growth of endometriotic lesions. Hence, EphB4 represents a promising pharmacological target for the treatment of endometriosis.