IDENTIFICATION OF MULTIPLE GENES WITH ALTERED EXPRESSION AT THE DISTAL ANASTOMOSIS OF HEALING POLYTETRAFLUOROETHYLENE GRAFTS

Purpose: Anastomotic intimal hyperplasia remains a significant cause o f delayed prosthetic arterial graft failure. Prior studies have identi fied several genes with altered expression within the hyperplastic reg ion at the downstream polytetrafluoroethylene arterial anastomosis as compared with normal arteries. The purpose of the current study was to determine the sequence of early gene-related events at the distal ana stomosis of an in vivo prosthetic arterial graft model. Messenger RNA (mRNA) differential display was used to screen for alterations in gene expression between anastomotic sites and control arterial segments. M ethods: Six carotid interposition 6-mm expanded polytetrafluoroethylen e grafts were placed in mongrel dogs, with the intervening carotid art ery segment serving as the baseline control. Five days after graft imp lantation, the distal anastomotic artery segments were harvested and t otal RNA was isolated from both the intervening normal arteries and an astomotic segments. Differential mRNA display was used to identify can didate complementary DNA (cDNA) clones with expression that differed i n anastomotic segments as compared with normal intervening arteries. N orthern blot analysis confirmed alteration of gene expression. The cDN A clones were sequenced, and gene databases were searched. Novel seque nces were used as probes for screening human cDNA Libraries. Results: Approximately 7000 mRNA species were screened, and 26 candidate clones were obtained. Northern blot analysis showed altered gene expression in 10 (38%) of the clones, undetectable signals in 13 (50%), and nonre gulation in 3 (12%). Seven clones with 92% homology at the nucleotide level to human eel (III) procollagen gene and a novel sequence were ex pressed only at the distal anastomosis. A clone representing apolipopr otein J and a novel sequence had increased expression at the distal an astomosis of 364% +/- 236% and 156% +/- 47%, respectively (mean percen tage, control +/- standard deviation). Conclusions: These studies iden tified genes with expressions that increased or were exclusive to the distal anastomosis of healing prosthetic arterial grafts in an in vivo prosthetic arterial graft model. Type III collagen may contribute sig nificantly to the composition of the extracellular matrix associated w ith intimal hyperplasia by increasing lesion volume. Apolipoprotein J, through its association with proteases, may modulate some of the matr ix changes seen early after grafting.