ENDOGENOUS CELL SEEDING - REMNANT ENDOTHELIUM AFTER STENTING ENHANCESVASCULAR REPAIR

Background Endothelial integrity is essential for maintaining Vascular homeostasis, and endothelial denudation results in neointimal thicken ing. Balloon-expandable endovascular stents provide a luminal scaffold ing within atherosclerotic arteries with minimal direct contact betwee n balloon and endothelium. We wondered whether stents cause diminished endothelial ablation, and if so, whether the degree of endothelial da mage might deter mine later proliferative sequelae. Methods and Result s Stainless steel stents were expanded in normal or previously denuded iliac arteries of New Zealand White rabbits. Stented arteries were ha rvested 15 minutes, 1 hour, 3 days, or 14 days later. En face staining of the luminal surfaces of stented arteries demonstrated that endothe lial cell loss began immediately after stent expansion and was restric ted to interstices between stent struts. Remnant endothelium adjacent to struts provided the foundation for complete endothelial regeneratio n of the stented segment within 3 days. Both early monocyte adhesion a nd later intimal macrophage accumulation were reduced >80% in nonballo oned but stented arteries, in concert with a twofold reduction in inti mal thickening after 14 days, compared with ar teries completely denud ed with a balloon before stent expansion. Conclusions It is accepted t hat deep injury caused by balloon-expanded endovascular stents is a cr itical contributor to experimental stent-induced neointimal hyperplasi a. Our data indicate that the degree of endothelial injury may also be an important component of vascular repair after stenting and an impor tant consideration in stent and balloon design and use. The use of ste nts for primary endovascular intervention may allow partial retention of endothelium within treated arteries, thereby modulating vascular re pair with less need for adjunctive pharmacological therapy.