Doyle, Brendan

Site specific targeting remains an elusive goal for stem cell and gene therapies in the cardiovascular field. One promising option involves use of modified 3D stent designs that deliver larger cell/gene payloads to specific disease sites using the versatility of percutaneous vascular access. Here, we engineered smooth muscle cells (SMCs) placed in a 3D metallic stent scaffold to deliver high local concentrations of an angiogenic gene (VEGF165) in a porcine model of chronic total occlusion involving ameroid placement on the proximal left circumflex (LCx) artery(n≥8 per group). Engineered SMCs were retained within the mesh stent structure (479 ± 47.4 SMC/mm2) and were competent for VEGF production in vitro (8.8 ± 1.8 ng/ml in media). Following implantation, micro CT analyses revealed that stents loaded with VEGF producing SMCs significantly enhanced vasa vasora microvessel density (5.43 ± 0.46 vs 2.14 ± 0.19 vessels/mm2, p<0.001) with a concomitant increase in tissue VEGF protein levels (277.9 ± 85.7 vs 18.8 ± 4.4 pg/mg protein, p<0.0001). Formation of endothelial cell colonies from peripheral blood mononuclear cells was significantly increased with the implantation of VEGF-secreting cells suggesting increased angiogenic potential (7.0 ± 2.0 versus 41.6 ± 4.5, EC:CFU p<0.0001). VEGF secreting mesh stent placement enhanced regional blood flow analyses determined by microsphere analyses as well as improving regional wall motion in the LCx-related territory (p<0.05) as well as left ventricular function assessed in terms of ejection fraction (34.2 ± 6.7% vs 61.2 ± 5.2% P<0.001) and dp/dt (p<0.001) Our data indicate robust clinically relevant angiogenesis can be achieved in a human scale porcine chronic vascular occlusion model following stent based delivery of angiogenic cells. This may have implications for percutaneous delivery of stem cells, genes and secreted therapeutic factors in cardiovascular disease in general and in creation of percutaneous microvascular bypass networks in the setting of chronic vaso-occlusive disease in particular.

AbstractThe fundamental mechanisms underlying erosive oesophagitis and subsequent development of Barrett's oesophagus (BO) are poorly understood. Here, we investigated the contribution of specific components of the gastric refluxate on adhesion molecules involved in epithelial barrier maintenance. Cell line models of squamous epithelium (HET‐1A) and BO (QH) were used to examine the effects of bile acids on cell adhesion to extracellular matrix proteins (Collagen, laminin, vitronectin, fibronectin) and expression of integrin ligands (α3, α4, α5, α6 and αν). Experimental findings were validated in human explant oesophageal biopsies, a rat model of gastroesophageal reflux disease (GORD) and in patient tissue microarrays. The bile acid deoxycholic acid (DCA) specifically reduced adhesion of HET‐1A cells to vitronectin and reduced cell‐surface expression of integrin‐αν via effects on endocytic recycling processes. Increased expression of integrin‐αv was observed in ulcerated tissue in a rat model of GORD and in oesophagitis and Barrett's intestinal metaplasia patient tissue compared to normal squamous epithelium. Increased expression of integrin‐αν was observed in QH BO cells compared to HET‐1A cells. QH cells were resistant to DCA‐mediated loss of adhesion and reduction in cell‐surface expression of integrin‐αν. We demonstrated that a specific component of the gastric refluxate, DCA, affects the epithelial barrier through modulation of integrin αν expression, providing a novel mechanism for bile acid‐mediated erosion of oesophageal squamous epithelium and promotion of BO. Strategies aimed at preventing bile acid‐mediated erosion should be considered in the clinical management of patients with GORD.

Background— Concern regarding risk of late thrombosis after “off-label” treatment with drug-eluting stents has prompted increased use of bare-metal stents (BMS) in current practice. The sequelae of late BMS failures, however, have been poorly characterized. Methods and Results— We performed a retrospective study of 4503 consecutive patients treated with at least 1 BMS and dual antiplatelet therapy between 1994 and 2000. The cumulative incidence of stent thrombosis was 0.5% at 30 days (95% CI, 0.3% to 0.7%), 0.8% at 1 year (95% CI, 0.6% to 1.1%), and 2.0% at 10 years (95% CI, 1.5% to 2.5%). Risk of late (30 days to 1 year) and very late (>1 year) BMS thrombosis was increased among patients considered off label for drug-eluting stent use ( P =0.024). When saphenous vein graft interventions were excluded, however, risk after off-label use was not significantly increased ( P =0.23). Other correlates included vein graft intervention, prior myocardial infarction (MI), peripheral vascular disease, and ulcerated lesion ( P <0.001). Mortality was markedly increased after late and very late BMS thrombosis, particularly during the first 30 days (hazard ratios, 22 [95% CI, 3.1 to 159] and 40 [95% CI, 15 to 107], respectively). The 10-year incidence of clinical restenosis was 18.1% (95% CI, 16.5% to 19.7%), presenting with MI in 2.1% (95% CI, 1.6% to 2.6%). Restenosis presenting with MI was associated with increased mortality compared with no restenosis (hazard ratio, 2.37; P <0.001) and with restenosis with a non-MI presentation (hazard ratio, 2.42; P <0.001). Conclusions— The incidence of BMS thrombosis and of MI caused by restenosis during extended follow-up is significant. Both complications are associated with mortality.