Epoxy compounds as a new cross-linking agent for porcine aortic leaflets: subcutaneous implant studies in rats

The epoxy group of the epoxy compounds has an oxygen arm that can work as a flexible joint in a cross-linking bridge and can block not only the amino group but also the carboxy group of collagen peptide. The purpose of this study is to evaluate the anticalcification efficacy of the epoxy compounds as a cross-linking agent for xenograft bioprostheses. Porcine aortic leaflets were treated with 2% epoxy compounds and implanted in subcutaneous layer of 4-week-old rats. Measurement of calcium content showed that epoxy-treated implants received a minimal calcification: mean 0.64 micrograms/mg dry weight leaflet tissue (range 0.5-0.8; N = 7) at 1 month; mean 0.94 microgram/mg (range 0.3-1.3; N = 9) at 2 months; and mean 1.2 micrograms/mg (range 0.5-2.1; N = 10) at 3 months. Natural leaflets contained calcium of mean 0.43 microgram/mg. By contrast, glutaraldehyde-preserved implants were severely calcified: mean 91 micrograms/mg (range 41-130; N = 11) at 1 month; mean 136 micrograms/mg (range 73-205; N = 16) at 2 months; and mean 170 micrograms/mg (range 90-214; N = 21) at 3 months. The epoxy compounds provide more pronounced anticalcification effects than the glutaraldehyde under pressure load-free subcutaneous circumstances.