SELECTING VALID IN-VITRO BIOCOMPATIBILITY TESTS THAT PREDICT THE IN-VIVO HEALING RESPONSE OF SYNTHETIC VASCULAR PROSTHESES

We have investigated the usefulness of six in vitro biocompatibility t ests in predicting the healing performance of polyester vascular prost heses as observed in previous canine in vivo trials. Vascular grafts w ere evaluated by using (i) a direct contact (DC) assay, (ii) an extrac t dilution (ED) assay on murine fibroblast cells, (iii) a DC assay on endothelial cells, (iv) a complement activation study, (v) a leucocyte activation study of CD18 integrin subunit expression on human polymor phonuclear cells (PMNs) and (vi) interleukin-2 receptor expression on lymphocytes. Uncleaned polyester grafts had previously been associated with poor healing and gelatin-impregnated polyester grafts with delay ed but satisfactory healing, whereas commercially cleaned polyester gr afts had demonstrated excellent healing. Lightweight and heavyweight k nitted and woven polyester grafts supplied specifically for this proje ct were studied, each with a different surface condition, i.e. commerc ially available (CP), uncleaned (UP) and impregnated with gelatin (GP) . The UP grafts induced fibroblast cytotoxicity according to the ED as say, poor migration and viability of endothelial cells, and an elevate d expression of CD18 and interleukin-2 receptor on PMNs and lymphocyte s, respectively. In contrast, the CP grafts promoted good endothelial cell growth, no evidence of cytotoxicity and a weaker cell activation, and the GP grafts were found to be non-cytotoxic, to exhibit a good c ellular response and to moderate cell activation. The complement activ ation assay and the DC assay on fibroblasts were found to be less usef ul and less discriminating. From this, it is concluded that the two ce ll activation measurements, the DC assay an endathelial cells and ED e ssay on fibroblasts, are useful in predicting the in vivo healing resp onse of arterial polyester substitutes. (C) 1995 Elsevier Science Limi ted