Revealing the silver and red lining in drug-eluting stents with angioscopy

Survivin modulates stiffness-induced vascular smooth muscle cell motility

Arterial stiffness is a key contributor to cardiovascular diseases, including atherosclerosis, restenosis, and coronary artery disease, it has been characterized to be associated with the aberrant migration of vascular smooth muscle cells (VSMCs). However, the underlying molecular mechanisms driving VSMC migration in stiff environments remain incompletely understood. We recently demonstrated that survivin, a member of the inhibitor of apoptosis protein family, is highly expressed in both mouse and human VSMCs cultured on stiff polyacrylamide hydrogels, where it modulates stiffness-mediated cell cycle progression and proliferation. However, its role in stiffness-dependent VSMC migration remains unknown. To assess its impact on migration, we performed time-lapse video microscopy on VSMCs seeded on fibronectin-coated soft and stiff polyacrylamide hydrogels, mimicking the physiological stiffness of normal and diseased arteries, with either survivin inhibition or overexpression. We observed that VSMC motility increased under stiff conditions, while pharmacologic or siRNA-mediated inhibition of survivin reduced stiffness-stimulated migration to rates similar to those observed under soft conditions. Further investigation revealed that cells on stiff hydrogels exhibited greater directional movement and robust lamellipodial protrusion compared to those on soft hydrogels. Interestingly, survivin-inhibited cells on stiff hydrogels showed reduced directional persistence and lamellipodial protrusion compared to control cells. We also examined whether survivin overexpression alone is sufficient to induce cell migration on soft hydrogels, and found that survivin overexpression modestly increased cell motility and partially rescued the lack of directional persistence compared to GFP-expressing control VSMCs on soft hydrogels. In conclusion, our findings demonstrate that survivin plays a key role in regulating stiffness-induced VSMC migration, suggesting that targeting survivin and its signaling pathways could offer therapeutic strategies for addressing arterial stiffness in cardiovascular diseases.

Surface engineering at the nanoscale: A way forward to improve coronary stent efficacy

Coronary in-stent restenosis and late stent thrombosis are the two major inadequacies of vascular stents that limit its long-term efficacy. Although restenosis has been successfully inhibited through the use of the current clinical drug-eluting stent which releases antiproliferative drugs, problems of late-stent thrombosis remain a concern due to polymer hypersensitivity and delayed re-endothelialization. Thus, the field of coronary stenting demands devices having enhanced compatibility and effectiveness to endothelial cells. Nanotechnology allows for efficient modulation of surface roughness, chemistry, feature size, and drug/biologics loading, to attain the desired biological response. Hence, surface topographical modification at the nanoscale is a plausible strategy to improve stent performance by utilizing novel design schemes that incorporate nanofeatures via the use of nanostructures, particles, or fibers, with or without the use of drugs/biologics. The main intent of this review is to deliberate on the impact of nanotechnology approaches for stent design and development and the recent advancements in this field on vascular stent performance.