Biodegradable Mg alloy modified with bioactive exosomes for cardiovascular stent application

Cardiovascular stent has been widely applied to treat cardiovascular disease (CVD), which is the major disease contribution to mortality in the world wide. Biodegradable magnesium (Mg) alloys are the encouraging materials in cardiovascular stents benefit from absorbability and biocompatibility. While, the ability of degradation is a double-edged sword for manufacture stent, modifying the surface to decrease the excessive degradation rate and promote the surface endothelialization could expand the prospect of the further application. In this work, the biodegradable Mg-Zn-Y-Nd alloy was modified by MgF₂ and dopamine polymer film (PDA) as the corrosion resistance layer and the bonding layer respectively, and then the exosome, a natural nanoparticle contains mRNAs and proteins, was tailored to give the surface better biocompatibility. The electrochemical test and weight loss test reflected the MgF₂-PDA/exosome coating increase the corrosion resistance of the Mg-Zn-Y-Nd alloy. The cytocompatibility data indicated the novel MgF₂-PDA/exosome coating selectively reduced the tumor necrosis factor (TNF-α) expression and ROS release from macrophage, and promoted the α-SMA expression of smooth muscle cells. In addition, the MgF₂-PDA/exosome coating also improved the adhesion, proliferation, CD31 expression and nitric oxide (NO) release of vascular endothelial cells (ECs), all of which contribute to the surface endothelialization. And the mechanism experiments showed the exosome released from the coating uptake by the ECs and assemble around the lysosome and mitochondria, and the released rate of the exosome on the coating is around 5 to 7 days, indicating excellent multi-functions of MgF₂-PDA/exosome coating in cardiovascular stent.