SELECTIVE STIMULATION OF ENDOTHELIAL-CELL PROLIFERATION WITH INHIBITION OF SMOOTH-MUSCLE CELL-PROLIFERATION BY FIBROBLAST GROWTH-FACTOR-I PLUS HEPARIN DELIVERED FROM FIBRIN GLUE SUSPENSIONS

Background. Pretreatment of expanded polytetrafluoroethylene grafts with fibrin glue (FG) containing fibroblast growth factor-1 (FGF-) (10 ng/ml) and heparin (50 units/ml) has been shown to induce a transmural angiogenesis with proliferation of both endothelial cells (ECs) and smooth muscle cells (SMCs) in dogs. To induce EC without SMC proliferation, we studied the effects of different FGF-1:heparin ratios within FG in vitro. Methods. First passage human umbilical vein ECs (factor VIII+) or primary canine carotid artery SMCs (alpha-actin +) were seeded onto 96-well plates coated with FG containing 10 ng/ml FGF-1 and 0, 5, 50, or 500 units/ml heparin;. Control wells were coated with FG without FGF- or heparin. Cells were fed standard growth medium without soluble FGF- or heparin. Tritiated thymidine (1 mu Ci/well) was added after 1, 5 or 3 days, and proliferation was assayed by scintillation counting 48 hours later. Results. For both ECs and SMCs, proliferation on FG containing FGF-1 but no heparin was not different from control. EC proliferation on FG containing FGF- was significantly increased by addition of 5, 50, or 500 units/ml heparin (+68%, +99%, and +106%, respectively; p < 0.0001 for all), reflecting the synergism of FGF-1 by heparin. SMC proliferation was also significantly increased by the addition of 5 or 50 units/ml heparin (+85 % and +66%, respectively; p ( 0.0001 for both). However, SMC proliferation with 500 units/ml heparin was significantly decreased from control (-12 %; p = 0.014), reflecting heparin's SMC growth inhibitory activity. Conclusions. FG containing 10 ng/ml FGF-1 and 500 units/ml heparin stimulates EC proliferation whit inhibiting SMC proliferation in vitro. Application of this modified FG to vascular grafts or to arteries after direct or transcutaneous interventions may promote endothelialization without intimal hyperplasia.