DETOXIFIED GLUTARALDEHYDE CROSS-LINKED PERICARDIUM - TISSUE PRESERVATION AND MINERALIZATION MITIGATION IN A SUBCUTANEOUS RAT MODEL

Background and aim of the study: Glutaraldehyde is considered a promot er of calcification by the action of toxic aldehyde group residuals fr om cross-linking. Post-fixation treatment with homocysteic acid (HA)I besides bonding aldehyde groups and neutralizing toxicity, should enha nce biocompatibility due to the strongly electronegative sulfonic grou p. The aim of this investigation was to evaluate HA efficacy on tissue preservation and dystrophic calcification mitigation in glutaraldehyd e cross-linked bovine pericardium (BP) using a subcutaneous rat model. Methods: Four samples of BP, two with glutaraldehyde-HA and two with glutaraldehyde treatment, were implanted in each of 24 male Sprague-Da wley rats. Three rats were killed at 14 days, eight at 28 days, eight at 56 days and five at 84 days. Unimplanted glutaraldehyde-HA- and glu taraldehyde-treated samples served as controls. All samples were studi ed by gross examination, mammography, light, transmission and scanning electron microscopy, and atomic absorption spectroscopy. The nature o f mineralization was investigated by coupling techniques of scanning e lectron microscopy, electron microprobe analysis and X-ray powder diff raction. Results: No histological and ultrastructural differences were found between glutaraldehyde-HA-and glutaraldehyde-treated BP, whethe r implanted or unimplanted. In both groups, calcification progressed w ith time, but significantly less after glutaraldehyde-HA treatment tha n after glutaraldehyde alone and at all time intervals (14.63 +/- 21.3 4 versus 43.17 +/- 15.99 at 28 days, p = 0.003; 56.42 +/- 40.20 versus 90.59 +/- 32.90 at 56 days, p = 0.008; 91.68 +/- 67.68 versus 156.23 +/- 17.85 at 84 days, p = 0.01). Differences were evident by mammograp hy and histology (von Kossa stain). Electron microprobe analysis in bo th groups showed the composition of calcified nuclei to be calcium pho sphate, stoichiometrically close to apatite (Ca-5(PO4)(3)(OH)). The-oc currence of crystallized apatite was supported by X-ray powder diffrac tion findings, the amount of crystallized apatite being higher in glut araldehyde-treated samples. Conclusions: Post-fixation treatment with HA preserves BP structural properties and significantly mitigates mine ralization of long-term subcutaneous implants.