TIME-DEPENDENT EFFECT OF GLUTARALDEHYDE ON THE TENDENCY TO CALCIFY OFBOTH AUTOGRAFTS AND XENOGRAFTS

To determine mechanisms responsible for the reduced calcification in s hort-term glutaraldehyde (Glu)-treated autologous pericardial bioprost heses, we studied the time effect of Glu on subsequent calcification a nd differences in calcification of autograft and xenograft implants in a rat subcutaneous implantation model. In experiment 1, four groups o f bovine pericardial pieces (1 cm(2)) were prepared: (A) fresh bovine pericardium without Glu, (B) with 15-minute Glu, (C) with 60-minute Gl u, and (Df with 120-minute Glu. Seven young male Sprague-Dawley rats w ere used; each received four bovine pericardial pieces from group A, B , C, or D for subcutaneous implantation. Calcium content of the implan ts (mu g/mg dry weight) 45 days later was 4.8 +/- 2.9, 29.8 +/- 13.6, 106.3 +/- 13.7, and 176.3 +/- 85.5 in groups A, B, C, and D, respectiv ely (p < 0.05 between any two groups). Experiment 2 used 8 young male Sprague-Dawley rats from different mothers. Each received five subcuta neous skin implants. The five skin implants were prepared as follows: (1) fresh self skin, (2) self skin with 30-minute Glu, (3) self skin w ith 48-hour Glu, (4) fresh skin of others, and (5) skin of others with 48-hour Glu. After 45 days of implantation, the calcium content of th e implants was 1.4 +/- 1.1, 57.9 +/- 35.4, 142.7 +/- 61.4, 1.5 +/- 1.1 , and 94.9 +/- 24.1 mu g/mg dry weight in groups 1, 2, 3, 4, and 5, re spectively (p < 0.05 for 1 versus 2, 3, or 5; 2 versus 3, 4, or 5; 3 v ersus 4; and 4 versus 5). Neither self nor other skin implants without Glu fixation calcified; however, once treated with Glu, calcification developed in both types of implants. In this model, the extent of cal cification of bovine pericardial pieces or skin implants was solely Gl u fixation time-dependent. Autologous tissues treated with Glu behave biologically like Glu-treated xenogenic tissues; there was no differen ce between them regarding the degree of calcification that makes one p referable to the other. A short duration of Glu fixation of autologous tissue used in valve repair is important to avoid calcification.