Role of Glutaraldehyde in Calcification of Porcine Aortic Valve Fibroblasts

Glutaraldehyde-treated porcine aortic valve xenografts frequently fail due to calcification. Calcification in the prostheses begins intracellularly. In a previous study, various types of cell injury to canine valvular fibroblasts, including glutaraldehyde treatment, led to calcification. An influx of extracellular Ca 2+ into the phosphate-rich cytosol was theorized to be the mechanism of calcification. To test the Ca 2+ influx theory, cytosolic Ca 2+ and P i concentrations were assessed in glutaraldehyde-treated porcine aortic valve fibroblasts, and their relationship to a subsequent calcification was studied. Glutaraldehyde caused an immediate and sustained massive cytosolic Ca 2+ increase that was dose dependent and a several-fold increase in P i. Calcification of cells followed within a week. The earliest calcification was observed in blebs formed on glutaraldehyde-treated cells. Live control cells or cells fixed with glutaraldehyde in Ca 2+-free solution did not calcify under the same conditions. Concomitant increases in Ca 2+ and P i in glutaraldehyde-treated cells appear to underlie the mechanism of calcification, and the presence of extracellular Ca 2+ during glutaraldehyde fixation promotes calcification.