Covalently immobilized recombinant humanized collagen type III (rhCol III) for enhanced anticoagulation and endothelialization.

Given the significant prevalence of mitral regurgitation, transcatheter edge-to-edge repair with mitral valve clips has become a critical area of research, focusing on innovative, minimally invasive treatment strategies. However, as a blood-contacting device, device-induced thrombosis and difficulty in endothelialization of its surface after implantation are potential factors that limit the long-term service of the device. In this study, a protective coating with enhanced anticoagulation and endothelialization was prepared via the covalent immobilization of recombinant humanized collagen type III (rhCol III) along with the co-deposition of tannic acid (TA) and 1,6-hexanediamine (HD), named TA-HD@rhCol III. The coating presented anti-thrombotic and anti-platelet adhesion abilities compared to unmodified substrates. Subcutaneous implantation in rats and macrophage culture experiments demonstrated its anti-inflammatory properties. The potential of the coating to promote endothelialization process was confirmed by both in vitro cell proliferation tests and in vivo experiments (pig model). In this proof-of-concept large-animal experiment, TA-HD@rhCol III-coated and uncoated mitral valve clips were implanted simultaneously in the porcine mitral valve. The modified clip elicited higher expression of the endothelial markers eNOS and CD31 than the uncoated control. In conclusion, these results suggest that the anticoagulation, anti-inflammation, pro-endothelialization properties of the coating may further improve the safety of the mitral valve clip, providing valuable evidence for the potential application of coated functionalized mitral valve clips in the future.