Re-endothelialization

However, we have no data to support the concept of prolonged (>l year) dual antiplatelet treatment except in patients who underwent vascular brachytherapy for in-stent re-stenosis. Due to the lack of re-endothelialization, this small group of patients should receive the dual treatment for life (49,50). 

Time-course analysis in a rabbit iliac artery model disclosed <20% stent re-endothelialization at four days, <40% at seven days, and near-complete endothelialization at 28 days following stent implantation (18). The re-endothelialization process has been studied in several other animal models using different types of injuries with very controversial results, suggesting, in part, a diversity in the response and capacity of vascular healing. 

The clinical utility of this approach will depend on the results of these initial clinical trials evaluating l7(3-estradiol and the outcomes of current DESs in higher-risk patients, Speculations about the clinical results are that an improved healing and re-endothelialization, although not completely abolishing neointima formation, will allow a controlled... 

The effects of VEGF that have led to most research interest in the field of cardiovascular disease can be broadly divided in two categories re-endothelialization and angiogenesis. 

Vascular endothelial growth factor delivery to promote re-endothelialization... 

Percutaneous coronary intervention (PCI) inevitably causes extensive denudation of the vascular endothelium at the stenosis site, In animal models of stent placement, re-endothelialization begins to occur in the first two to seven days postplacement, Full re-endothelialization of the stent takes three or four weeks, This process has been called stent passivation, It is thought that a similar or longer time course occurs in humans, although this has been difficult to quantify from the rarity of available autopsy specimens from patients poststent insertion (3), In animals, endothelial dysfunction is seen up to three months poststenting (4),... 

To promote re-endothelialization, VEGF has been administered in animal studies by a variety of means, using varying isoforms of the VEGF family either in protein form or as a plasmid. 

Locally delivered VEGF infusion appeared to accelerate re-endothelialization of damaged arteries in the rat carotid artery (14). A 30-minute infusion of VEGF into the carotid artery at the site of balloon injury caused superior re-endothelialization and reduced intimal hyperplasia. Antibodies against VEGF inhibited this effect on re-endothelialization (15). 

These VEGF-eluting stents were tested in vivo in a rabbit iliac artery model. After seven days, median clot demonstrated was 12.5 mg in control stents versus Omg [P = 0.0142 95% confidence interval (Cl) 8.49, 55.99] in VEGF stents. Quantifiable re-endothelialization was poor in both groups (Fig. 2), with no significant differences between them. Neointimal cross-sectional area at 28 days showed no statistically significant differences (Table I) (24). 

The VEGF-eluting stent did not lead to the expected rapid re-endothelialization, which may well explain the lack of effect in reducing restenosis. The reduction in thrombosis may be because of the antithrombotic effects of VEGF discussed... 

At therapeutic dosimetries in vivo, the main photodynamic mechanism for vascular SMC depletion is apoptosis (10). Re-endothelialization appears to be accelerated after PDT and may contribute to the sustained inhibition of neointimal formation (26,45-47). If so, this would be an important advantage over other restenosis prevention strategies such as brachytherapy or certain drug-eluting stents. 

Waksman R, Leitch I, Roessler J, et al. Intracoronary photodynamic therapy reduces neointimal growth without suppressing re-endothelialization in a porcine model. Heart 2006 (e-Pub). 

Re-endothelialization promoting coating. When designing and applying permanent (whole life) implants like artificial vascular grafts, artificial hearts, or artificial heart valves, more attention and effort has been paid to... 

Catheter-based, plasmid with Human iNOS fusigenic liposome Gene transfer for rapid re-endothelialization Phase I, human coronary artery REGENT-I... 

Vascular proliferative disease 235 Vascular re-endothelialization 319 Vascular smooth muscle cell (VSMC) 313 Vasoactive intestinal peptide (VIP)... 

Another example of a biodegradable stent is the REVA (Reva Medical Inc., San Diego, CA), a tyrosine-derived polycarbonate, which after metabolism produces amino acids, ethanol, and carbon dioxide. The REVA is balloon expandable with a slide and lock design which allows the expansion of the stent without deformation (Figure 5C). Iodine is its source of radiopacity. It has thick struts of 200 microns. Preclinical data show complete re-endothelialization [81]. Currently, the paclitaxel-eluting REVA stent is under development. 

F. Hess. History of (micro) vascular surgery and the development of small-caliber blood vessel prostheses (with some notes on patency rates and re-endothelialization), Microsurgery. 6 (2) 59-69, 1985. 

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