Protein adsorption of calcified and noncalcified valvular bioprostheses after human implantation

Background. The incidence of calcification of porcine valve bioprostheses s hows important, and as yet unexplained, variations. Previous studies by oth ers showed that osteopontin and osteocalcin are expressed in calcified porc ine valve bioprostheses. However, no study has yet explored other proteins that could also be involved. Methods. Twelve porcine valve bioprostheses were retrieved from 12 patients and were separated into two groups. Group 1 (n = 6) had early calcificatio n after 4 to 9 years (mean, 6 +/- 2.3 years). The mean age of the patients at the time of implantation was 46 +/- 9 years. Group 2 (n = 6) had no calc ification after 8 to 14 years (mean, 12 +/- 2.8 years). The mean age was 47 +/- 13.4 years. These valves were analyzed by electrophoresis, and the ban ds were quantified by densitometry. Results. A 14-kd protein showed a 50% increase in the calcified group. A 31 -kd protein found in the calcified group was not detected in the noncalcifi ed group. Three other proteins (45, 39, and 28 kd) showed reduced adsorptio n in the calcified group. Conclusions. Important differences were found in the proteins adsorbed in c alcified and noncalcified bioprostheses after implantation in patients. Bes ides osteopontin and osteocalcin, several other proteins may play a role in the process of calcification of valvular bioprostheses. (C) 2001 by The So ciety of Thoracic Surgeons.