Synergistic effect of fibronectin and hepatocyte growth factor on stable cell-matrix adhesion, re-endothelialization, and reconstitution in developing tissue-engineered heart valves

Stable cell-matrix adhesion, re-endothelialization, and reconstitution represent important issues in creating autologous living heart valve, a close collaboration between growth factors and the extracellular matrix in these processes appears crucial. To prove this action, porcine decellularized valve constructs were precoated with fibronectin and seeded with hepatocyte growth factor-transferred marrow stromal cells (MSCs) and grown in vitro in a pulsatile-flow bioreactor. Results showed hepatocyte growth factor stimulated adhesion of MSCs to fibronectin in a time-dependent manner with a range of 8-128 ng/ml. Histological observation demonstrated a time course of MSC growth on decellularized valve constructs. A handful of cells, a loose cellular layer, a confluent monolayer coverage, a 2-layer structure and a 3-layer structure were observed at weeks 2, 3, 4, 6, and 8, respectively. Immunohistochemical analysis revealed cellular reconstitution of endothelial cells (von Willebrand factor positive) and myofibroblasts (alpha-smooth muscle actin and vimentin double-positive) at week 8. Importantly, endothelial cell retention (17.3 +/- 2.6/mm) remained high under exposure to high flow and pressure conditions in a bioreactor. These results demonstrated that the combination of fibronectin and hepatocyte growth factor contributed to creating autologous living heart valve.