Inducible deletion of endothelial cell Efnb2 delays capillary regeneration and attenuates myofibre reinnervation following myotoxin injury in mice

• The relationship between microvascular regeneration and motor nerve regeneration following skeletal muscle injury remains undefined. Expression of Efnb2 in endothelial cells (ECs) is essential to vascular development and promotes neurovascular regeneration in the adult. • To test the hypothesis that EfnB2 in ECs is required for microvascular regeneration and myofibre reinnervation, conditional knock out of (CKO) Efnb2 was performed in ECs of mice (age, 3-6 months) followed by injection of BaCl2 into gluteus maximus (GM), tibialis anterior (TA), or extensor digitorum longus (EDL) muscle. • Capillary regeneration was reduced at 5 days post-injury (dpi) in GM of CKO vs. CON with neither different from uninjured at 10 dpi. Sciatic nerve stimulation revealed neuromuscular transmission failure (NMTF) in TA with perturbed neuromuscular junction (NMJ) morphology. Satellite cell counts along EDL myofibres did not differ between CKO vs. CON. • CKO of EC Efnb2 delays capillary regeneration and attenuates recovery of NMJ structure and function.