Evaluation of calcification in porcine valves treated by ultraviolet ray and glutaraldehyde

Porcine aortic valve, of which tissue structural collagen matrix is cross-linked by glutaraldehyde (GA) to enhance mechanical property, is widely used in clinics, but gradual calcification occurs after implantation. Cross-linking the valve by 24 h of ultraviolet (UV) ray irradiation that induces collagen fibrous cross-link resulted in less calcium deposition than GA-pretreated leaflets. After 3 days, calcium level in GA-treated leaflets was distinctively higher than in leaflets cross-linked by UV irradiation for 24 h and in the non-treated control leaflets. The exposure time of UV irradiation was not significantly correlated with the extent of calcification. In all the test groups, molar [Ca]/[P] ratio gradually decreased as time went by, and UV-irradiated and control leaflets demonstrated molar [Ca]/[P] ratio close to apatite as the predominant mineral phase and GA-treated leaflet reached the similar molar ratio after 30 days. In animal experiment, the leaflet treated by UV irradiation demonstrated a stable surface without calcification after 2 months of implantation.