Healthy Endothelial Accelerated Lining Inhibits Neointimal Growth

Currently available coronary stents are prone to thrombosis and restenosis. It is believed that the accelerated re-establishment of a functional endothelial layer on damaged stented vascular segments may help to prevent potentially serious complications by providing a barrier to circulating cytokines, and by the ability of endothelial cells to produce substances that passivate the underlying smooth muscle cell layer.

By recruiting the patient's own EPCs to the site of vascular injury (e.g. the site of a coronary stent implant), an acceleration of the normal endothelialization process would occur. It is theorized that the rapid establishment of a functioning endothelial layer may promote the transformation of the injured site to a healthy state. For example, in the case of coronary stent implantation, rapid re-endothelialization may reduce inflammation, thrombosis and potentially eliminate restenosis.

The influences of EPC recruitment and reendothelialization on restenosis range from the effects on the vascular repair response, to the prevention of platelet aggregation and activation, angiogenesis, and enhancement of vasomotor response. Recently it has been shown that the integrity and functional activity of the endothelial monolayer play a crucial role in the prevention of atherosclerosis. However, risk factors for coronary artery disease such as age, hypertension, hypercholesterolemia, and diabetes reduce the number and functional activity of these circulating EPCs, thus limiting the regenerative capacity. The impairment of stem cells by risk factors in CAD patients may contribute to the limited regenerative capacity of diseased endothelium, as well as to atherogenesis and atherosclerotic disease progression. Therefore, relating the number and function of circulating EPCs to the functional outcome of stent technology is crucial to identify a beneficial effect on in-stent restenosis formation and vascular (dys) function.

The HEALING FIM and HEALING II clinical studies sought to define the safety and efficacy of a stent designed to sequester circulating endothelial progenitor cells to the luminal surface of the stent struts by an anti-CD34 antibody coating, thereby promoting reendothelialization of the coronary stent and the vascular healing response following stent deployment. Enhanced vascular healing will reinstate vascular integrity, prevent platelet aggregation and sub-acute in-stent thrombosis, reinstate vasoreactivity and inhibit restenosis formation. In the HEALING II study, a correlation was found between EPC levels and angiographic/IVUS outcomes in patients receiving the Genous stent. Patients with normal EPC titers had significantly less in-stent late loss compared to those with low EPCs (0.53 vs 1.02mm). This is consistent with the results from drug eluting stent trials, thereby establishing proof of concept of the EPC capturing technology, provided adequate EPC target cell population is available.

There are several animal studies demonstrating that statin therapy was associated with a 2.5 to 3 fold increase of circulating EPCs leading to accelerated reendothelialization, vascular repair and improved angiogenesis. In addition, Dimmeler and co-workers found similar results in a small cohort of cardiovascular patients receiving atorvastatin therapy (n=7, Circulation 2001), suggesting an angiotrophic effect of atorvastatin therapy in addition to its previously defined pleiotrophic properties. Similarly, Drexler and co-workers described similar EPC recruiting properties of simvastatin in CAD patients unrelated to/ irrespective of LDL reduction (n=10, Circulation 2005).

The current study seeks to confirm the safety and optimize the effectiveness of the EPC capture technology (Genous Bio-engineered R stent) by incorporating a high dose statin therapy, specifically atorvastatin 80mg, for at least two weeks prior to the index procedure.