MESENCHYMAL STEM CELLS IN THE PREVENTION OF THROMBOSIS AND NEOINTIMAL HYPERPLASIA

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DESCRIPTION (provided by applicant): Drug-eluting stents cause less intimal hyperplasia and less late luminal loss, but inhibit re- endothelialization of the stented segment making it more susceptible to thrombosis. Thus, there is trade-off between restenosis and late stent thrombosis requiring longer periods of anti-platelet therapy. Clearly, a better therapeutic approach that can prevent intimal hyperplasia and induce re-endothelialization would be useful to provide long-term symptom-free control of coronary artery disease without the need for prolonged anti- platelet therapy. Since PTEN modulates cell signaling and cell growth, PTEN transgene overexpression in arterial smooth muscle cells would prevent the development of neointimal hyperplasia. In addition, thrombosis could be prevented by the repair of endothelial cells with mesenchymal stem cells (MSCs) which have been primed to differentiate into endothelial cells. We hypothesize that the delivery of MSCs and PTEN transgene locally to the site of angioplasty and stent injury prevents thrombosis and the development of neointimal hyperplasia. Down-regulation of Wnt/2 catenin signaling in MSCs promotes endothelial cell differentiation and re-endothelialization. This hypothesis has been supported by our data demonstrating that vascular endothelial growth factor (VGEF)-primed MSCs differentiate into endothelial cells and PTEN overexpression inhibits proliferation of arterial smooth muscle cells. We will do these studies in a well-established and routinely used in our laboratory the swine model of hyperlipidemia and atherosclerosis with angioplasty and in-stent restenosis. Aim 1: Test the hypothesis that overexpression of PTEN transgene with MSCs at the site of balloon angioplasty in atherosclerotic coronary artery prevents thrombosis and the development of neointimal hyperplasia. Aim 2: Test the hypothesis that overexpression of PTEN transgene with MSCs at the site of bare metal stenting in atherosclerotic coronary artery prevents thrombosis and in-stent restenosis and this would be superior to the effect of drug-eluting stent alone. Aim 3: Test the hypothesis that down-regulation of Wnt/2-catenin signaling promotes MSC differentiation to endothelial cells at the injury site in coronary arteries. We will examine the role of Wnt/¿-catenin signaling molecules, particularly ¿-catenin, LRP5 and Kremen1, as the underlying mechanism of MSCs differentiation into ECs and re-endothelialization both in vitro and in vivo in swine coronary arteries. These studies would position us to translate our investigation into a clinical phase 1 study for the use of PTEN-engineered autologous MSCs for the treatment of the complications due to coronary interventional procedures, and PTCA with PTEN-engineered autologous MSCs might eliminate the need of stents in coronary artery disease.