Tissue reactions to epoxy-crosslinked porcine heart valves post-treated with detergents or a dicarboxylic acid

Calcification limits the long-term durability of xenograft glutaraldehyde ( GA)-crosslinked heart valves. Previously, a study in rats showed that epoxy -crosslinked heart valves reduced lymphocyte reactions to the same extent a s the GA-crosslinked control and induced a similar foreign-body response an d calcification reaction. The present study was aimed at reducing the occur rence of calcification of epoxy-crosslinked tissue. Two modifications were carried out and their influence on cellular reactions and the extent of cal cification after 8 weeks' implantation in weanling rats was evaluated. Firs t, epoxy-crosslinked valves were post-treated with two detergents to remove cellular elements, phospholipids and small soluble proteins, known to act as nucleation sites for calcification. The second approach was to study the effect of the impaired balance between negatively and positively charged a mino acids by an additional crosslinking step with a dicarboxylic acid. The detergent treatment resulted in a washed-out appearance of especially the cusp tissue. With the dicarboxylic acid, both the cusps and the walls had a limited washed-out appearance. The wall also demonstrated some detachment of the subendothelium. After implantation, both detergent and dicarboxylic acid post-treatment histologically resulted in reduced calcification at the edges of cusps and walls. However, total amounts of calcification, measure d by atomic emission spectroscopy, were not significantly reduced. Data con cerning the presence of lymphocytes varied slightly, but were in the same r ange as the GA-crosslinked control, i.e., clearly reduced compared with a n oncrosslinked control. It is concluded that both the double detergent and t he dicarboxylic acid post-treatment of epoxy-crosslinked heart valve tissue do not represent a sound alternative in the fabrication of heart valve bio prostheses. (C) 2001 John Wiley & Sons, Inc.