Human vascular smooth muscle cells of diabetic origin exhibit increased proliferation, adhesion, and migration.

PURPOSE: Patients with diabetes mellitus (DM) experience progressive macrovascular atherosclerosis and intimal hyperplastic restenosis with increased frequency as compared with nondiabetic patients. These observations suggest that vascular smooth muscle cells (VSMCs) behave in a phenotypically different and more aggressive manner in diabetic patients. In this study, we compared the in vitro rates of proliferation, adhesion, and migration of human VSMCs obtained from diabetic and nondiabetic patients. METHODS: Human VSMC cultures were isolated from 23 diabetic patients (9 artery, 14 vein) and 15 nondiabetic patients (9 artery, 6 vein) with extensive lower extremity atherosclerosis. All patients were between 61 and 78 years of age (average: 68.4 years [diabetic]; 67.3 years [nondiabetic]). All diabetic patients had type 2 DM. Vascular specimens were obtained at the time of amputation from infragenicular arteries and during arterial revascularization from saphenous veins. Cells from passages 2 and 3 were assayed for their proliferative capacity with total DNA fluorescence photometry and for adhesion and migration with a modified Boyden chamber. RESULTS: The average duration of diabetes was 11.6 +/- 4.1 years. The average number of diabetic complications (retinopathy, neuropathy, nephropathy, coronary artery disease) was 2.8 +/- 0.7 per patient. Diabetic VSMCs exhibited abnormal morphology in cell culture with loss of the normal hill and valley configuration. Proliferation was significantly increased in VSMCs of diabetic origin (156 +/- 57 absorption units) as compared with those of nondiabetic origin (116 +/- 42 absorption units) (P <.001). Diabetic VSMCs demonstrated significantly greater adhesion (63.6 +/- 24 per high-power field vs 37.9 +/- 13 per high-power field; P =.002) and migration (397 +/- 151 per low-power field vs 121 +/- 99 per low-power field; P =.001) rates. CONCLUSIONS: Diabetic VSMCs exhibit significantly increased rates of proliferation, adhesion, and migration as well as abnormal cell culture morphology suggestive of abnormal contact inhibition. These observations of human VSMCs in culture are consistent with the increased rate of infragenicular atherosclerosis and the increased rates of restenosis observed clinically in diabetic patients. The atherosclerosis- and intimal hyperplasia-promoting behavior exhibited appears to be intrinsic to the DM-VSMC phenotype and must be considered when designing methods to limit atherosclerosis and intimal hyperplasia in diabetic patients.

Relationship of the 20S proteasome and the proteasome activator PA28 to atherosclerosis and intimal hyperplasia in the human vascular system.

Down-regulation of the proteasome activator PA28 results in abnormal proteasome activation and has been implicated in the development of intimal hyperplasia (IH) in animal models. Demonstration of proteasome and PA28 expression has not yet been documented in the human vascular system. This study sought to define the distribution of the 20S proteasome and its activator PA28 in human vessels and determine the relationship between the expression of the proteasome and PA28 and the development of atherosclerosis and IH. Vascular biopsies were obtained from 70 patients at the time of surgery, were snap frozen and sectioned in 5-micron sections, and prepared using standard histological techniques. The immunoperoxidase technique was used to identify 20S proteasome and PA28 expression in diseased and normal human arteries and veins as well as in patent bypass grafts with and without IH. Expression was graded by a blinded pathologist (scale: 1-4). Repeat quantification of the immunopositive cells was also performed. Expression of 20S proteasome and PA28 was identified in all vascular tissues examined. The proteins were identified predominately within the cytoplasm of vascular smooth muscle cells and endothelial cells. PA28 was more intensely expressed in quiescent regions of the vessel wall as compared to areas undergoing active proliferation and remodeling. PA28-mediated activation of the proteasome may be necessary to maintain normal cellular homeostasis and prevent excessive cellular proliferation in the human vascular system. Abnormalities of proteasome activation may have a significant role in the development of atherosclerosis and IH.

Arm vein conduit is superior to composite prosthetic-autogenous grafts in lower extremity revascularization.

PURPOSE: Various alternative conduits have been used for lower extremity revascularization when an adequate ipsilateral greater saphenous vein is absent. This study compared the effectiveness of all-autogenous multisegment arm vein bypass grafts with that of composite grafts composed of combined prosthetic and autogenous conduits. METHODS: One hundred fifty-three lower extremity revascularization procedures performed between 1990 and 1998 were followed up prospectively using a computerized vascular registry. The grafts were composed of spliced arm vein segments with venovenostomy in 122 and of composite prosthetic-autogenous conduit in 31. Arm vein conduit was prepared by means of intraoperative angioscopy for valve lysis and identification of luminal abnormalities in 47.7% of cases. RESULTS: Bypass graft configurations were as follows: femoropopliteal (12 arm vein, 2 composite); femorotibial (75 arm vein, 23 composite); femoropedal (14 arm vein, 6 composite), and popliteo-tibial/pedal (21 arm vein, 0 composite). The indication for surgery was limb salvage in 98% and disabling claudication in 2% of cases. The mean follow-up was 25.1 months (range, 1 month to 7.9 years). Overall survival at 4 years was 51%. Overall patency and limb salvage rates were as follows: primary patency, at 1 year-arm vein, 76.9% +/- 4.8%; composite, 59. 5% +/- 9.6% (P =.02); at 3 years-arm vein, 70.0% +/- 8.0%; composite, 43.7% +/- 12.4% (P <.01); and at 5 years-arm vein, 53.8% +/- 8.7%; composite, 0%; secondary patency, at 1 year-arm vein, 77.5% +/- 4. 6%; composite, 59.8% +/- 9.5% (P =.02); at 3 years-arm vein, 70.7% +/- 7.5%, composite, 44.9% +/- 13.1% (P <.01); at 5 years-arm vein, 57.7% +/- 8.0%; composite, 0%; limb salvage, at 1 year-arm vein, 89. 3% +/- 3.7%; composite, 73.9% +/- 8.9% (P <.01); at 3 years-arm vein, 80.5% +/- 7.0%; composite, 49.6% +/- 14.3% (P <.01); at 5 years-arm vein, 76.3% +/- 9.9%; composite, 0%. CONCLUSION: In this study, multisegment autogenous arm vein was used successfully in a wide variety of lower extremity revascularization procedures and achieved good long-term patency and limb salvage rates, well in excess of those achieved with composite prosthetic-autogenous grafts. The use of autogenous conduit appears to offer superior results to composite conduit in lower extremity revascularization. The superior durability of arm vein makes it one of the alternative conduits of choice when an adequate greater saphenous vein is not available.

The use of arm vein in lower-extremity revascularization: results of 520 procedures performed in eight years.

PURPOSE: The absence of an adequate ipsilateral saphenous vein in patients requiring lower-extremity revascularization poses a difficult clinical dilemma. This study examined the results of the use of autogenous arm vein bypass grafts in these patients. METHODS: Five hundred twenty lower-extremity revascularization procedures performed between 1990 and 1998 were followed prospectively with a computerized vascular registry. The arm vein conduit was prepared by using intraoperative angioscopy for valve lysis and identification of luminal abnormalities in 44.8% of cases. RESULTS: Seventy-two (13. 8%) femoropopliteal, 174 (33.5%) femorotibial, 29 (5.6%) femoropedal, 101 (19.4%) popliteo-tibial/pedal, and 144 (27.7%) extension "jump" graft bypass procedures were performed for limb salvage (98.2%) or disabling claudication (1.8%). The average age of patients was 68.5 years (range, 32 to 91 years); 63.1% of patients were men, and 36.9% of patients were women. Eighty-five percent of patients had diabetes mellitus, and 77% of patients had a recent history of smoking. The grafts were composed of a single arm vein segment in 363 cases (69. 8%) and of spliced composite vein with venovenostomy in 157 cases (30.2%). The mean follow-up period was 24.9 months (range, 1 month to 7.4 years). Overall patency and limb salvage rates for all graft types were: primary patency, 30-day = 97.0% +/- 0.7%, 1-year = 80.2% +/- 2.1%, 3-year = 68.9% +/- 3.6%, 5-year = 54.5% +/- 6.6%; secondary patency, 30-day = 97.0% +/- 0.7%, 1-year = 80.7% +/- 2.1%, 3-year = 70.3% +/- 3.4%, 5-year = 57.5% +/- 6.2%; limb salvage, 30-day = 97.6% +/- 0.7%, 1-year = 89.8% +/- 1.7%, 3-year = 82.1% +/- 3.3%, 5-year = 71.5% +/- 6.9%. Secondary patency and limb salvage rates were greatest at 5 years for femoropopliteal grafts (69.8% +/- 12.8%, 80.7% +/- 11.8%), as compared with femorotibial (59.6% +/- 10. 3%, 72.7% +/- 10.5%), femoropedal (54.9% +/- 25.7%, 56.8% +/- 26.9%, ) and popliteo-tibial/pedal grafts (39.0% +/- 7.3%, 47.6% +/- 15.4%). The patency rate of composite vein grafts was equal to that of single-vein conduits. The overall survival rate was 54% at 4 years. CONCLUSION: Autogenous arm vein has been used successfully in a wide variety of lower-extremity revascularization procedures and has achieved excellent long- and short-term patency and limb salvage rates, higher than those generally reported for prosthetic or cryopreserved grafts. Its durability and easy accessibility make it an alternative conduit of choice when an adequate saphenous vein is not available.