Glycosaminoglycan-targeted fixation for improved bioprosthetic heart valve stabilization

Numerous crosslinking chemistries and methodologies have been investigated as alternative fixatives to glutaraldehyde (GLUT) for the stabilization of bioprosthetic heart valves (BHVs). Particular attention has been paid to valve leaflet collagen and elastin stability following fixation. However, the stability of glycosaminoglycans (GAGs), the primary component of the spongiosa layer of the BHV, has been largely overlooked despite recent evidence provided by our group illustrating their structural and functional importance. In the present study we investigate the ability of two different crosslinking chemistries: sodium metaperiodate (NaIO4) followed by GLUT (PG) and 1-Ethyl-3-(3 dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) followed by GLUT (ENG) to stabilize GAGs within BHV leaflets and compare resulting leaflet characteristics with that of GLUT-treated tissue. Incubation of fixed leaflets in GAG-degrading enzymes illustrated in vitro resistance of GAGs towards degradation in PG and ENG treated tissue while GLUT fixation alone was not effective in preventing GAG loss from BHV leaflets. Following subdermal implantation, significant amounts of GAGs were retained in leaflets in the ENG group in comparison to GLUT-treated tissue, although GAG loss was evident in all groups. Utilizing GAG-targeted fixation did not alter calcification potential of the leaflets while collagen stability was maintained at levels similar to that observed in conventional GLUT-treated tissue.