Calcification and identification of metalloproteinases in bovine pericardium after subcutaneous implantation in rats.

The purpose of this study was to evaluate the influence of two anticalcification pre-treatments (chloroform/methanol and ethanol) and serum conditioning of glutaraldehyde-crosslinked bovine pericardium on the calcification degree and the presence of gelatinase activities in a subcutaneous implantation model in rats. Regarding calcification of the implants, glutaraldehyde control treatments showed a significatively higher calcification degree than pericardium treated with anticalcification reagents. Serum conditioning of glutaraldehyde treated tissues did not influence the calcification degree; moreover, no differences were found in these samples with the time of implantation (30 and 90 days). On the other hand, anticalcification treatments resulted in a very significant decrease in the calcium content in the implanted membranes. Gelatinase activities were detected by gelatin zymography in almost all the implanted samples. However, control tissues with and without serum conditioning showed less gelatinase activities than those samples pre-treated with anticalcification treatments. Metalloproteinase (MMP-2) activity was detected in all the samples analyzed but a higher expression of MMP-9 was detected in those implants treated with chloroform/methanol and ethanol. Additional gelatinase activities showing lower molecular weight than MMP-2 were also detected in both anticalcification treated samples. The presence of these gelatinase activities is probably due to host cellular infiltrates and could contribute to the biomaterial degradation.