Abstract 16601: Novel Tissue Engineered Angiogenic Construct to Enhance Endothelial Progenitor Cell Mediated Vasculogenic Activity and Normalize Myocardial Biomechanics
Objective: Cell mediated angiogenic therapy for ischemic heart disease has had disappointing results. The lack of clinical translatability may be due to cell death and systemic dispersion with cell injection. We propose a novel tissue engineered therapy, whereby extracellular matrix scaffold seeded with EPCs (endothelial progenitor cell) can overcome these limitations using an environment in which the cells can thrive, enabling an insult free myocardial cell delivery.
Methods: EPCs (DiLDL+, VEGFR2+, cKit+) were isolated from Wistar Rat bone marrow. There was 79.5±6.5% EPC purity (Flow Cytometry; CD34+VEGFR2+). The cells were cultured for 7 days in media as control or seeded at a density of 5x106 cells/cm2 on a collagen/vitronectin matrix (CVM), n=5/group. Seeded EPCs underwent ex-vivo modification with stromal cell derived factor-1α (100ng/ml) to potentiate angiogenic properties and enhance paracrine qualities prior to CVM formation. Scanning electron microscopy confirmed EPC-CVM adhesion. In vitro vasculogenic potential was assessed by quantifying EPC cell migration and vascular differentiation. The construct was then implanted onto ischemic myocardium in a rat model of acute myocardial infarction (LAD ligation) for 6 wks. Myocardial biomechanical properties were uniaxially quantified by elastic modulus at 5-25% strain.
Results: There was a marked increase in EPC migration in the presence of CVM (26.0±8.0 cells) as compared to control (0.2±0.4, p=0.00005) or acellular matrix (1.4±2.6, p=0.00009) by Boyden chemotaxis assay. An increase in vascular differentiation and tubule formation was noted in the presence of CVM as compared to control by 3D matrigel angiogenesis assay (vascular length 3687±387 vs 2006±106µm, p=0.001; branches 8.3±1.5 vs 3.7±1.1, p=0.007). Enhanced paracrine, chemokine secretion was noted with CVM versus control by ELISA (VEGF= 277±9 vs 183±3 pg/ml,p=0.00000002; SDF= 4073±332 vs. 227±24pg/ml, p=0.000002). Myocardial elasticity normalized in the CVM group (227±44kPa vs. normal=201±61, p=NS; control, no CVM=305±110, p=0.03.
Conclusion: We demonstrate enhanced angiogenic potential of a tissue engineered EPC construct. Myocardial analysis demonstrated a restoration of biomechanics with this therapy.
- © 2012 by American Heart Association, Inc.