Covalently Bonded Heparin to Alter the Pericardial Calcification

Abstract

Calcification is the leading cause of failure of a wide spectrum of cardiovascular and non-cardiovascular medical devices. In this study our aim was to immobilize polyethylene glycol (PEG) and heparin on multiple crosslinked bovine pericardium with Glutaraldehyde (GA) and carbodiimide. Grafting of PEG and heparin through an intermediate tissue bound substrate containing aldehyde and imide functional groups showed reduction in calcification. In this experimental protocol, we used Golomb and Wagner's in vitro model for studying pericardial calcification and a diffusion cell with two compartments for evaluating the diffusion of calcium across the BP. The results showed that heparin immobilization on the surface reduces calcification independent of its concentration in the incubating medium. It is conceivable that inactivation of unpaired aldehydic moieties present in pericardium after exposure to GA act as potential site for PEG grafting and imide functionalities of EDC can covalently bind heparin, would be the key step in the prevention of calcification. It is wellestablished fact that heparin has a potent antithrombotic effect. But the exact role of heparin in the anticalcification process of bioprostheses still remain elusive.