Aortic and pulmonary bioprosthetic heart valves: an insight on glycosaminoglycan distribution and fine structure in decellularized porcine scaffolds for tissue engineering purposes

Cardiac valves are dynamic structures, that remodel in response to changes in local mechanical forces, and exhibit a complex architecture highly specialized, consisting of cells and extracellular matrix enriched in proteoglycans, glycosaminoglycans (GAGs), collagen and elastic fibers. Typical valve substitutes are mechanical prostheses and bioprostheses. During the last 15 years, tissue engineering (TE) approaches emerged in response to limitations associated to valve bioprostheses. This study was designed to identify the specific GAGs in the leaflet and commissure of aortic and pulmonary valves and to interpret their maintenance in relation to a decellularization procedure finalized to obtain a scaffold for cell repopulation. Free GAGs were obtained from selected portions of leaflets, sinuses, and artery wall from 24 porcine valves freed from proteins by papain treatment. GAG content and distribution were assessed on both fresh and decellularized specimens. GAG structural analysis was performed after depolimerization and fluorescent derivatization of the products. The disaccharide analysis was conducted by fluorophore-assisted polyacrilamide gel electrophoresis (FACE). Results obtained show that total GAG concentration was reduced after decellularization and that the loss mainly regards hyaluronan and an undersulphate condroitin sulfate isomer. The functional consequence of this selective depletion on cell repopulation potential of the scaffold deserves further studies.