Transition from Procoagulation to Antiplatelet Effect: Application and Mechanism of Aspirin-Modified Chitosan in Small-Diameter Vascular Grafts

Chitosan is generally considered to be a procoagulant effect, which may cause adverse phenomena such as blood clotting when used in small-diameter vascular grafts. However, it also shows good biocompatibility and anti-inflammatory properties, which can facilitate vascular reconstruction. Therefore, it is significant to transition the effect of chitosan from coagulation promotion to antiplatelet while still harnessing its bioactivity. The procoagulant mechanism of chitosan is primarily attributed to the presence of protonated amino groups in the molecular chain. If the number of amino groups in chitosan is reduced, the procoagulant effect will be diminished as well. Aspirin has a strong antiplatelet function, and its molecular structure contains numerous active carboxyl groups, which can couple with the amino groups in chitosan. Aspirin-modified chitosan retains the biological activity of chitosan while also imparting an antiplatelet effect. In our study, we used a heparinized electrospun graft as the substrate and coated it with aspirin-modified chitosan to create a functional vascular graft. The blood clotting index of the graft remained above 80% after 45 min, and the platelet activation degree was only 4.03%. Additionally, the graft maintained complete patency with stable blood flow after 4 weeks of implantation and the vascular structure was largely rebuilt.