epidermal-growth-factor and Graft-Occlusion--Vascular

About a quarter of peripheral vein grafts fail due in part to intimal hyperplasia. The proliferative capacity and response to growth inhibitors of medial smooth muscle cells and adventitial fibroblasts in vitro were studied to test the hypothesis that intrinsic differences in cells of vein grafts are associated with graft failure.. Cells were grown from explants of the medial and adventitial layers of samples of vein grafts obtained at the time of implantation. Vein graft patency and function were monitored over the first 12 months using ankle pressures and Duplex ultrasound to determine vein graft status. Cells were obtained from veins from 11 patients whose grafts remained patent (non-stenotic) and from seven patients whose grafts developed stenosis. Smooth muscle cells (SMCs) derived from media and fibroblasts derived from adventitia were growth arrested in serum-free medium and then stimulated with 1 muM sphingosine-1-phosphate (S1P), 10 nM thrombin, 10 ng/ml epidermal growth factor (EGF), 10 ng/ml platelet-derived growth factor-BB (PDGF-BB), PDGF-BB plus S1P, or PDGF-BB plus thrombin for determination of incorporation of [(3)H]-thymidine into DNA. Cells receiving PDGF-BB or thrombin were also treated with or without 100 microg/ml heparin, which is a growth inhibitor. Cells receiving thrombin were also treated with or without 150 nM AG1478, an EGF receptor kinase inhibitor.. SMCs and fibroblasts from veins of patients that developed stenosis responded more to the growth factors, such as PDGF-BB alone or in combination with thrombin or S1P, than cells from veins of patients that remained patent (P = .012). In addition, while PDGF-BB-mediated proliferation of fibroblasts from grafts that remained patent was inhibited by heparin (P < .03), PDGF-BB-mediated proliferation of fibroblasts from veins that developed stenosis was not (P > .5).. Inherent differences in the proliferative response of vein graft cells to PDGF-BB and heparin may explain, in part, the variability among patients regarding long term patency of vein grafts.

Topics: Aged; Ankle; Becaplermin; Blood Pressure; Cell Proliferation; Cells, Cultured; Constriction, Pathologic; DNA Replication; Epidermal Growth Factor; Female; Fibroblasts; Graft Occlusion, Vascular; Heparin; Humans; Hyperplasia; Lower Extremity; Lysophospholipids; Male; Middle Aged; Myocytes, Smooth Muscle; Peripheral Vascular Diseases; Platelet-Derived Growth Factor; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-sis; Quinazolines; Saphenous Vein; Sphingosine; Thrombin; Time Factors; Tyrphostins; Ultrasonography, Doppler, Duplex; Vascular Patency

Recently we found that the incidence of restenosis after carotid endarterectomy was significantly higher in patients homozygous for the normal genotype of mannose-binding lectin (MBL2) than in with patients with MBL2 variant genotypes. Several growth factors are also known to contribute to restenosis. Therefore, we investigated whether early postoperative changes in serum vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and platelet-derived growth factor (PDGF) concentrations and MBL2 genotypes interact in the development of restenosis.. Eighty-two patients who underwent carotid eversion endarterectomy and were followed up by carotid duplex scan sonography for 14 months were studied. Growth factors were measured preoperatively and 4 days after surgery.. Pronounced significant increases in both VEGF and PDGF predicted restenosis but only in patients who were homozygous for the normal MBL2 genotype. In this group, the adjusted odds ratios of restenosis at 14 months in patients with high versus low early VEGF and PDGF increases were 27.73 (2.42 to 317.26) and 9.23 (1.45 to 58.70), respectively.. These findings indicate that the development of restenosis depends on both complement activation regulated by the MBL2 gene and pathologic processes leading to enhanced production of VEGF and PDGF during the very early postoperative period.

Topics: Aged; Carotid Arteries; Carotid Stenosis; Complement System Proteins; DNA Mutational Analysis; Endarterectomy, Carotid; Epidermal Growth Factor; Female; Genetic Markers; Genetic Predisposition to Disease; Genetic Testing; Genotype; Graft Occlusion, Vascular; Humans; Male; Mannose-Binding Lectin; Middle Aged; Platelet-Derived Growth Factor; Prospective Studies; Up-Regulation; Vascular Endothelial Growth Factor A

Angioplasty stimulates proliferation and migration of vascular smooth muscle cells (VSMC), leading to neointimal thickening and vascular restenosis. In a rat model of balloon catheter injury (BCI), we investigated whether alterations in expression of Ca2+-activated K+ channels (KCa) contribute to intimal hyperplasia and vascular restenosis.. Function and expression of KCa in mature medial and neointimal VSMC were characterized in situ by combined single-cell RT-PCR and patch-clamp analysis. Mature medial VSMC exclusively expressed large-conductance KCa (BKCa) channels. Two weeks after BCI, expression of BKCa was significantly reduced in neointimal VSMC, whereas expression of intermediate-conductance KCa (IKCa1) channels was upregulated. In the aortic VSMC cell line, A7r5 epidermal growth factor (EGF) induced IKCa1 upregulation and EGF-stimulated proliferation was suppressed by the selective IKCa1 blocker TRAM-34. Daily in vivo administration of TRAM-34 to rats significantly reduced intimal hyperplasia by approximately 40% at 1, 2, and 6 weeks after BCI. Two weeks of treatment with the related compound clotrimazole was equally effective. Reduction of intimal hyperplasia was accompanied by decreased neointimal cell content, with no change in the rate of apoptosis or collagen content.. The switch toward IKCa1 expression may promote excessive neointimal VSMC proliferation. Blockade of IKCa1 could therefore represent a new therapeutic strategy to prevent restenosis after angioplasty.

Topics: Angioplasty, Balloon; Animals; Cell Line; Cells, Cultured; Clotrimazole; Epidermal Growth Factor; Graft Occlusion, Vascular; Hyperplasia; Intermediate-Conductance Calcium-Activated Potassium Channels; Large-Conductance Calcium-Activated Potassium Channels; Muscle, Smooth, Vascular; Patch-Clamp Techniques; Potassium Channel Blockers; Potassium Channels; Potassium Channels, Calcium-Activated; Pyrazoles; Rats; Rats, Sprague-Dawley; RNA, Messenger; Tunica Intima