FGF-1 AFFIXATION STIMULATES EPTFE ENDOTHELIALIZATION WITHOUT INTIMAL HYPERPLASIA

The affixation of FGF-1 to porous vascular grafts has been reported to stimulate capillary ingrowth and surface endothelialization. The current study further characterizes responses to fibroblast growth factor (FGF)-1 affixation to 30-cm-long grafts followed 140 days. ePTFE grafts (30 cm X 8 mm i.d.), 60 mu m internodal distance, were impregnated with fibrin glue (FG) suspensions containing FGF-1 and heparin. Two negative control groups were treated either with FG with heparin alone or left untreated. Grafts were explanted from the canine thoracoabdominal aortic position after 10, 30, or 140 days (n = 3/time/group) 10 hr after im injection of tritiated thymidine (0.5 mu Ci/kg). Specimens were studied by light and electron microscopy, immunohistochemistry, morphometric analyses, and cross-sectional autoradiography. RNA preparations from inner capsule tissues were used for reverse transcription-polymerase chain reaction (RT-PCR) analyses of FGF-1, FGF-2, transforming growth factor-beta(1), (TGF-beta(1)) and FGF receptor mRNA species. Inner capsule collagen was quantitated by hydroxyproline colorimetry. Histologic analyses of perianastomotic regions were performed for comparison purposes. All explants were patent and without intimal hyperplasia. Progressive capillarization of the internodal spaces occurred over time and was significantly more extensive in the FGF-1-treated group. Endothelialization of the luminal surface increased with time, at 140 days covering 86.7 +/- 11.6% of the FGF-1 explants vs 46.1 +/- 7.5% and 48.1 +/- 13.3% in the other groups, P < 0.007 and P < 0.04, respectively. Inner capsule thickness at 140 days differed significantly (P < 0.05) between the FGF-1 group (138.8 mu m) vs either control group (93 and 67 mu m, respectively), which did not significantly differ from each other. Cross-sectional autoradiography demonstrated an FGF-1-induced mitotic index increase at 30 days, 9.6 +/- 4.4% compared to 2.5 +/- 1.0 and 0 +/- 0%, respectively, with both myofibroblasts and endothelial cells incorporating the [H-3]thymidine label. The mitotic index returned to quiescent levels at 140 days (< 1% in all groups). Collagen content increased with time in all groups, significantly greater in both FG groups vs untreated controls at 30 and 140 days. RT-PCR analyses revealed FGF-1, FGF-2, FGFR-1 (flg), and TGF-beta(1) mRNA in all samples without evidence of modulation by FGF-1 affixation. These data demonstrate FGF-1-induced graft capilIarization and surface endothelialization without functionally significant intimal hyperplasia in this model. (C) 1994 Academic Press, Inc.