Perspectives on Cognitive Phenotypes and Models of Vascular Disease.

Clinical investigations have established that vascular-associated medical conditions are significant risk factors for various kinds of dementia. And yet, we are unable to associate certain types of vascular deficiencies with specific cognitive impairments. The reasons for this are many, not the least of which are that most vascular disorders are multi-factorial and the development of vascular dementia in humans is often a multi-year or multi-decade progression. To better study vascular disease and its underlying causes, the National Heart, Lung, and Blood Institute of the National Institutes of Health has invested considerable resources in the development of animal models that recapitulate various aspects of human vascular disease. Many of these models, mainly in the mouse, are based on genetic mutations, frequently using single-gene mutations to examine the role of specific proteins in vascular function. These models could serve as useful tools for understanding the association of specific vascular signaling pathways with specific neurological and cognitive impairments related to dementia. To advance the state of the vascular dementia field and improve the information sharing between the vascular biology and neurobehavioral research communities, National Heart, Lung, and Blood Institute convened a workshop to bring in scientists from these knowledge domains to discuss the potential utility of establishing a comprehensive phenotypic cognitive assessment of a selected set of existing mouse models, representative of the spectrum of vascular disorders, with particular attention focused on age, sex, and rigor and reproducibility. The workshop highlighted the potential of associating well-characterized vascular disease models, with validated cognitive outcomes, that can be used to link specific vascular signaling pathways with specific cognitive and neurobehavioral deficits.

High-level expression of Egr-1 and Egr-1-inducible genes in mouse and human atherosclerosis.

To understand the mRNA transcript profile in the human atherosclerotic lesion, RNA was prepared from the fibrous cap versus adjacent media of 13 patients undergoing carotid endarterectomy. cDNA expression arrays bearing 588 known genes indicated that lesions express unexpectedly high levels of the early growth response gene, Egr-1 (NGFI-A), a zinc-finger transcription factor that modulates a cluster of stress-responsive genes including PDGF and TGF-beta. Expression of Egr-1 was an average of 5-fold higher in the lesion than in the adjacent media, a result confirmed by RT-PCR, and many Egr-1-inducible genes were also strongly elevated in the lesion. Time-course analyses revealed that Egr-1 was not induced ex vivo. Immunocytochemistry indicated that Egr-1 was expressed prominently in the smooth muscle-actin positive cells, particularly in areas of macrophage infiltration, and in other cell types, including endothelial cells. Induction of atherosclerosis in LDL receptor-null mice by feeding them a high-fat diet resulted in a progressive increase in Egr-1 expression in the aorta. Thus, induction of Egr-1 by atherogenic factors may be a key step in coordinating the cellular events that result in vascular lesions.

Peripheral vascular complications of directional coronary atherectomy and stenting: predictors, management, and outcome.

The hospital course of 688 patients consecutively treated with directional coronary atherectomy (375 procedures) or Palmaz-Schatz stenting (376 procedures) was evaluated to identify incidence, predictors, and outcome of major vascular complications. Major vascular complications (defined as surgical repair, major hematoma, or bleeding with a > 10-point hematocrit decrease requiring transfusion alone, or nonsurgically managed arteriovenous fistula, pseudoaneurysm, retroperitoneal hematoma or femoral neuropathy) occurred in 11.7% of procedures, and were more common after stenting than after directional coronary atherectomy (16.8% vs 6.7%, p < 0.001). In particular, surgical repair was required after 10.1% of stenting procedures, versus 5.1% of directional coronary atherectomies (p < 0.02). Multivariable analysis identified age > 70 years, coronary stenting, female gender, multiple procedures during the index hospitalization, and a low nadir platelet count as independent predictors of major vascular complications (all p < 0.03). In the stent subgroup, excessive anticoagulation, nadir platelet count, hypertension, and sheath removal protocol (other than a same-day, activated clotting time-guided protocol) were all independent predictors of vascular complications. Thus, the overall risk of vascular complications with new device procedures (stenting, directional atherectomy) is greater than that traditionally seen with balloon angioplasty alone, and is determined by patient-related factors, procedure type, and management parameters.

Cross-sectional pattern of collateral vessels in patients with superficial femoral artery occlusion.

RATIONALE AND OBJECTIVES: The purpose of this study was to identify the cross-sectional location of collateral vessels in patients with peripheral vascular disease on three-dimensional magnetic resonance angiograms (3D MRAs) to suggest sites for intravascular or transcutaneous angiogenesis gene delivery in the lower extremity. METHODS: The axial locations were measured and categorized by tissue compartments, as well as by radial coordinates with respect to the femur. RESULTS: Collateral vessels in the thigh were identified in 24 of 93 consecutive patients who underwent peripheral 3D MRA. Ninety-one percent (99/109) of the observed collaterals were located near the adductor canal level of the thigh, with 78% (31/46) of these collaterals located in the fat in or surrounding the posterior muscle. CONCLUSIONS: The majority of collateral vessels in the thigh are located in the fat or muscle within the posterior compartment near the femur at the level of the adductor canal.

Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions.

UNLABELLED: Wang Y, Winchester PA, Khilnani NM, et al. Contrast-enhanced peripheral MR angiography from the abdominal aorta to the pedal arteries: Combined dynamic two-dimensional and bolus-chase three-dimensional acquisitions. Invest Radiol 2001;36:170-177. RATIONALE AND OBJECTIVES: To obtain reliable contrast-enhanced peripheral MR angiography for imaging peripheral vascular disease from the abdominal aorta to the pedal arteries. METHODS: A protocol consisting of contrast-enhanced, dynamic two-dimensional (2D) acquisition at the feet and calf and bolus-chase three-dimensional (3D) acquisition from the abdominal aorta to the calf was developed and applied in patients with peripheral vascular disease. The performance of this integrated protocol was assessed in 89 consecutive patients. RESULTS: The bolus-chase 3D acquisition was of diagnostic quality in 100% of the acquisitions in the abdomen, 96% in the thigh, and 43% in the calf. The poor quality of the calf acquisitions was due to insufficient spatial resolution, poor arterial signal, and venous contamination. Diagnostic-quality images were obtained in 100% of the dynamic 2D acquisitions of the calf and 98% of the feet. CONCLUSIONS: The combined dynamic 2D and bolus-chase 3D contrast-enhanced MR angiography technique provides diagnostic images of the entire lower extremity.

Transforming growth factor-beta inhibits human vascular smooth muscle cell growth and migration.

BACKGROUND: Transforming growth factor-beta (TGF-beta) is released after vascular injury and may influence the healing response of the vessel wall. We investigated the effect of this growth factor on proliferation and migration of human venous smooth muscle cells (SMC) and the signal transduction mechanisms through which TGF-beta exerts this effect. METHODS: SMC derived from human saphenous vein were used in a 72-hour proliferation assay and a 6-day migration assay. Cells were exposed to TGF-beta alone and in the presence of platelet-derived growth factor (PDGF), basic fibroblast growth factor (b-FGF), epidermal growth factor, and serum. The ability of TGF-beta to activate tyrosine kinases, phosphatases, or protein kinase C was evaluated by use of Western blotting with an antiphosphotyrosine antibody. RESULTS: In a concentration-dependent manner, TGF-beta inhibited proliferation induced by PDGF, b-FGF, epidermal growth factor, and serum. This inhibitory effect was independent of SMC density. TGF-beta also inhibited migration induced by PDGF and b-FGF. Exposure of cells to TGF-beta did not lead to tyrosine phosphorylation of cellular substrates or activation of protein kinase C. CONCLUSIONS: TGF-beta inhibits both migration and proliferation of human SMC. This inhibitory effect is not mediated through protein kinase C, mitogen-activated protein kinase, or tyrosine kinases.

Platelet attachment stimulates endothelial cell regeneration after arterial injury.

BACKGROUND: Arterial injury is associated with endothelial disruption and attachment of platelets to an exposed subintimal layer. A variety of factors released by platelets may affect the ability of endothelial cells bordering an injury to regenerate. In this study an organ culture model of arterial injury was used to investigate the relationship between attachment of platelets to a superficial arterial injury and endothelial regeneration. METHODS: A defined superficial endothelial injury was made in whole vessel wall explants of rabbit thoracic aorta. Injured explants were treated with either fresh whole platelets, the supernatant of platelets aggregated by collagen, or basic fibroblast growth factor. Four days after injury and treatment, the average distance of endothelial regeneration was determined. RESULTS: A dramatic increase in the rate of endothelial cell regeneration was observed when injured vessels were exposed to fresh whole platelets (p = 0.003). This increase in regeneration was comparable to that observed with fibroblast growth factor. No increase in the regenerative rate was found after exposure of explants to the supernatant of aggregated platelets (p = 0.69). CONCLUSIONS: Platelets stimulate endothelial regeneration at a rate equal to that observed with the potent endothelial mitogen basic fibroblast growth factor. Because this effect was not demonstrated with the supernatant of aggregated platelets, endothelial regeneration may be dependent on attachment of the platelets to the area of injury.

The effect of protein kinase C and its alpha subtype on human vascular smooth muscle cell proliferation, migration and fibronectin production.

BACKGROUND: Vascular smooth muscle cell (SMC) migration, proliferation and extracellular matrix protein production are key steps in the formation of intimal hyperplasia, a process that leads to failure of vascular reconstructions. Protein kinase C (PKC) may be involved in all 3 cellular events. PKC consists of a family of 11 isotypes, 8 of which we have identified in human vascular SMCs. In this study we evaluate the role of PKCalpha as a second messenger for proliferation, migration and fibronectin production induced by human saphenous vein SMCs. METHODS: DNA synthesis was evaluated by using (3)H-thymidine incorporation. Mitogen-activated protein kinase (MAP-K) activation was quantified by Western blotting with an antibody to its phosphorylated substrate, Elk-1. Chemotaxis was evaluated by using a microchemotaxis chamber. SMC fibronectin was measured by Western blotting. For all experiments, PKCalpha was blocked with a selective inhibitor, Gö6976. RESULTS: Gö6976, at concentrations that allow selective inhibition of PKCalpha, inhibited platelet-derived growth factor-stimulated SMC proliferation and MAP-K activation by 30% to 40% and 30% to 60%, respectively. SMC chemotaxis was stimulated approximately 2-fold by the PKCalpha inhibitor. Neither basal nor transforming growth factor-betaI induced fibronectin production was affected by Gö6976. CONCLUSIONS: Our data suggest that PKCalpha is a positive mediator of SMC proliferation and MAP-K activity, a negative regulator of migration and has no effect on SMC fibronectin production. These data suggest that modulating activities of specific PKC isotypes might be useful in both the study and control of intimal hyperplasia.

Is lower extremity revascularization worthwhile in patients with end-stage renal disease?

BACKGROUND: The purpose of this study was to review the results of lower extremity revascularization in patients with end-stage renal disease and to determine in these patients the functional benefit and cost of an aggressive approach to limb preservation. METHODS: During a 5-year period at our institution, 33 bypass operations were performed on 31 limbs of 23 dialysis-dependent patients. Indications for revascularization were limited (18) or extensive (12) tissue loss or ischemia without tissue loss (3). Procedures included aortobifemoral bypass (1), femoropopliteal bypass (10), and femorotibial/pedal bypass (22). A digital or transmetatarsal amputation was performed in 57% of limbs. RESULTS: The 30-day primary patency was 100%. Cumulative primary and secondary patency rates at 2 years were 65% and 79%, respectively. Limb salvage was 67% and 59% at 1 and 2 years, respectively. Patient survival was poor (47% at 2 years). Peritoneal dialysis was predictive of poor survival (P <.001). Four of 5 patients on peritoneal dialysis died within 3 months of intervention. Extensive tissue loss was predictive of a diminished rate of limb salvage (P =.027). Only 39% of limbs with extensive tissue loss were salvaged at 1 year compared with 78% and 100% of limbs with limited and no tissue loss, respectively. The average hospital cost was $44,308 per year of limb salvage. CONCLUSIONS: Although revascularization of ischemic limbs in dialysis patients can be achieved with an excellent initial graft patency and reasonable limb salvage, patient survival is poor and costs are high. A selective approach to revascularization in these complicated patients may be indicated. For patients treated with peritoneal dialysis and for those with extensive tissue loss, primary amputation may be the preferred approach.

Is routine duplex ultrasound surveillance after carotid endarterectomy cost-effective?

BACKGROUND: Although duplex ultrasound surveillance of patients after carotid endarterectomy (CEA) is routinely performed, the use of this policy has been questioned. We evaluated the cost-effectiveness of this strategy. METHODS: Using a decision-analytic Markov model that depicts the natural history of patients after CEA, we compared a strategy of duplex ultrasound surveillance to a strategy of no surveillance. Probability estimates were derived from the literature and costs were obtained from the hospital's cost accounting system. Sensitivity analyses were performed to test the robustness and stability of our base-case conclusion to variations in the underlying assumptions. RESULTS: Using baseline estimates we determined that duplex ultrasound surveillance after CEA reduced the incidence of stroke; however, this required significant additional expense, which resulted in an incremental cost-effectiveness ratio of $126,950. This ratio could decrease to a more acceptable level (less than $100,000) if a subset of patients could be identified whose rate of progression to greater than 80% stenosis exceeded 6% per year or whose stroke rate associated with uncorrected asymptomatic stenosis exceeded 2.6% per year. Also, the cost-effectiveness ratio was reduced to less than $100,000 if patients were younger than 55 years old at the time of initial CEA or if the cost of CEA could be reduced to less than $7,000. CONCLUSIONS: Duplex ultrasound surveillance after CEA is associated with an unfavorable cost-effectiveness ratio. However, this strategy may be cost-effective in younger patients or in those patients who have a more progressive form of disease.

Prospective study of wound complications in continuous infrainguinal incisions after lower limb arterial reconstruction: incidence, risk factors, and cost.

BACKGROUND: Wound complications after lower extremity arterial reconstruction can range from a minor lymphatic leak that causes minimal disability to a severe infection that jeopardizes the limb and life of the affected patient. This study was designed to define more clearly the incidence, severity, and the cost of these complications. METHODS: During a 1-year period the infrainguinal incisions of all patients undergoing lower limb arterial reconstruction were evaluated prospectively. One hundred fifty-six infrainguinal incisions were monitored serially for the presence of infection, hematoma, seroma, serous leak, necrosis, or wound dehiscence. The need for additional treatment or services related to these complications and the cost of these services were determined. RESULTS: Complications occurred in 10% of 77 infrainguinal incisions that were isolated to the groin (groin incisions) e.g., after aortobifemoral bypass, femoral endarterectomy). In only one of these patients was significant cost related to treatment of a complication. Complications occurred in 44% of 79 incisions used for femoral popliteal/tibial and pedal bypasses (distal incisions). In this latter group independent predictors of any complication were age (p=0.02) and obesity (p=0.05); predictors of in-hospital infection were preoperative evidence of venous stasis (p=0.01) and preoperative infection in the same extremity (p=0.08). Fifteen distal wound complications provided additional expense related to reoperation, extended hospitalization or rehospitalization, and rehabilitation or visiting nurse services, with a mean cost per patient undergoing reconstruction of $688. CONCLUSIONS: After lower limb arterial reconstruction, infrainguinal wound complications in isolated groin incisions produce minimal morbidity and cost, whereas complications in incisions after distal bypass are both frequent and associated with significant additional expense.

Differential effects of platelet-derived growth factor isotypes on human smooth muscle cell proliferation and migration are mediated by distinct signaling pathways.

BACKGROUND: Platelet-derived growth factor (PDGF) is a potent mitogen and chemoattractant for vascular smooth muscle cells (SMCs). Three isotypes of PDGF (BB, AB, and AA) have been identified; each of these isotypes may have differing effects on the behaviour of vascular SMCs. In this study we evaluated the influence of PDGF isotypes on proliferation and migration of human venous SMCs and explored the signaling pathways through which these effects are mediated. METHODS: Proliferation was measured by a 72-hour assay of cell number, and migration was evaluated by a 4-hour microchemotaxis assay. The effects of PDGF isotypes on the activities of the signaling proteins mitogen-activated protein kinase (MAP-K), p 125 focal adhesion kinase (p125FAK), and tensin were measured by immunoprecipitation of these proteins and subsequent phosphorylation on myelin basic protein (in MAP-K) and Western blotting with antiphosphotyrosine (in tensin and p125FAK). RESULTS: All three isotypes stimulated SMC proliferation (PDGF-BB > AB > AA). PDGF-BB and -AB, but not -AA, stimulated chemotaxis. All three isotypes activated MAP-K with an intensity that corresponded to their proliferative effects. PDGF-BB and -AB tyrosine phosphorylated tensin and p125FAK, whereas PDGF-AA had no effect on either of these proteins. CONCLUSIONS: For human vascular SMCs the physiologic effects and the signaling pathways that mediate these effects are specific for each of the three PDGF isotypes. These data also suggest an association between MAP-K and SMC proliferation and between the proteins, p125FAK and tensin, and migration.

Activation of pp60c-src is necessary for human vascular smooth muscle cell migration.

BACKGROUND: The most widely distributed nonreceptor tyrosine kinase is pp60c-src (src), yet the role of this intracellular signaling protein in cell migration has not been defined. Given that smooth muscle cell (SMC) migration is essential for the development of intimal hyperplasia, we investigated the importance of src in locomotion of human vascular SMC. METHODS: SMC migration was evaluated using a microchemotaxis chamber assay and videomicroscopy. Src kinase activity was determined by measuring phosphorylation of a synthetic derivative of p34cdc2, a specific substrate for src. Blocking antibodies to src were introduced using a cytoplasmic microinjection technique. RESULTS: Stimulation of SMC with platelet-derived growth factor (PDGF)-BB and AB resulted in an increase in src activation, whereas PDGF-AA did not consistently enhance src activity. These findings correlated with the ability of the PDGF isotypes to stimulate SMC chemotaxis; PDGF-BB and AB produced 7.4 +/- 0.3- and 5.3 +/- 0.5-fold increases in SMC chemotaxis, whereas PDGF-AA inhibited chemotaxis. SMC migration in response to PDGF-BB and serum was significantly inhibited by intracellular injection of a blocking antibody. CONCLUSIONS: Our findings reveal an association between agonist-induced src activation and chemotaxis. Moreover, an antibody that inhibits src activation dramatically inhibits migration of individual SMC. We conclude that activation of src is necessary for SMC migration. Because of its importance in SMC migration, either molecular or pharmacologic inhibitors of src may be useful in the control of intimal hyperplasia.

Do neck incisions influence nerve deficits after carotid endarterectomy?

OBJECTIVES: To determine whether transverse neck incisions for carotid endarterectomy were associated with a similar or greater incidence of cranial nerve complications when compared with vertical skin incisions, and to assess the patient's perception of the appearance of the incision. DESIGN: Prospective, but not randomized. SETTING: A university-affiliated tertiary care hospital. PATIENTS/INTERVENTIONS: Eighty-five consecutive carotid endarterectomy procedures were evaluated prospectively in 80 patients. Although patients were not randomly assigned, consideration was given to having approximately the same number of patients who had carotid endarterectomy performed through transverse neck incision as through vertical neck incision. Forty-four carotid endarterectomies were performed with a vertical incision and 41 procedures were performed with a transverse incision. MAIN OUTCOME MEASURE: To determine the incidence of cranial nerve dysfunction (primarily nerves VII and XII) after operation. RESULTS: The incidence of palsies of cranial nerves VII and XII in the two groups was similar; there was no statistical significance (the seventh nerve palsy, 32% transverse vs 25% vertical; the 12th nerve palsy, 15% transverse vs 20% vertical). Seventy-two percent of the deficits had disappeared by the 3- to 6-month follow-up. Patients expressed a clear preference for the transverse incision (P = .04). CONCLUSIONS: Although surgical exposure was simpler with the vertical incision, adequate exposure with the transverse incision was always possible. The incidence of mostly temporary deficits of cranial nerves VII and XII was similar. Patients favored the transverse incision.

Femoropopliteal reconstruction for claudication. The risk to life and limb.

The current study was undertaken to examine the results of femoropopliteal bypass grafting with intermittent claudication as the indication. Of 1173 infrainguinal reconstructions carried out on our service during the past decade, 249 (21%) consecutive femoropopliteal grafts were performed for disabling claudication in 191 patients. The primary five-year cumulative patency rates were 78% for autogenous vein and 52% for polytetrafluoroethylene grafts. There were two (0.8%) 30-day operative deaths and a subsequent five-year amputation rate of 2.4% for both groups. Femoropopliteal reconstruction for claudication may therefore be carried out with acceptably low operative mortality and a subsequent amputation rate comparable with that anticipated from the natural history of the disease. While the five-year patency rate is significantly higher utilizing autogenous vein grafts, symptomatic relief may be expected with prosthetic grafts in approximately half the patients without incurring a higher risk of limb loss.

Improving cost efficiency on a vascular surgery service.

BACKGROUND: A vascular task force (VTF) consisting of two vascular surgeons and other key personnel was established to reduce costs and improve efficiency in the management of patients on a vascular surgery service. METHODS: The VTF met monthly beginning in 1994 to study and implement changes in the management of patients with (1) abdominal vascular, (2), carotid endarterectomy (3) distal bypass, and (4) other vascular procedures, including amputations. Length of stay, and fixed and variable costs were assessed for change over time using Pearson correlation coefficients. RESULTS: Improvements in efficiency (length of stay) and decreases in costs (fixed and variable costs) from fiscal year 1993 to fiscal year 1996 were significant for the total group of vascular patients (P

Risk factors and their role in the diseases of the arterial wall.

The leading cause of death and disability in developed nations is atherosclerosis. Multiple risk factors, including hyperlipidemia, cigarette smoking, diabetes mellitus, and hypertension, predispose to the development of atherosclerosis. The mechanisms by which these risk factors exacerbate atherosclerosis involve the potentiation of endothelial and smooth muscle cell dysfunction as well as disturbances in coagulation. These mechanisms are discussed in detail in this chapter. Understanding the pathophysiology of how risk factors accelerate the progression of atherosclerosis will aid the clinician in attempts to treat the atherosclerotic patient.

Piggy-back mesenteric arterial reconstruction.

Reimplantation of stenotic or occluded visceral arteries into the aorta is one solution to symptomatic chronic visceral ischemia. We report a patient in whom the associated problem of small bowel infarction precluded prosthetic reconstruction and saphenous vein was unavailable. Reimplantation of the celiac artery into the aorta was combined with piggy-back reimplantation of the superior mesenteric artery into the side of the celiac artery to provide successful revascularization of the small bowel. A 16-month angiographic and 5-year clinical follow-up is provided.

Selecting stent grafts for the endovascular treatment of abdominal aortic aneurysms.

Minimally invasive endovascular techniques for the treatment of abdominal aortic aneurysms (AAA) have significantly reduced the morbidity of these procedures as compared with standard surgical repair. In addition, patients with extensive comorbid medical illnesses in whom standard operative repair is contra-indicated, may be successfully treated using endovascular means. A variety of endovascular stent grafts are currently being used clinically for endovascular AAA repair. The characteristics of these stent grafts vary significantly. In selecting the specific stent graft to be used for endovascular AAA repair, these specific characteristics must be considered particularly with regard to the individual patient's anatomic and physiologic characteristics. In addition, the indications for use of endovascular grafts as compared to standard open surgery have not yet been fully defined. Endovascular stent grafts in current use have limitations and their use must be tempered accordingly, until their long-term effectiveness is more completely evaluated. This article describes the general principles of use for endovascular devices for the repair of AAA. It details the features and results for the devices in current use and highlights the factors that influence the selection of specific stent graft types.

TGF-ß/Smad3 inhibit vascular smooth muscle cell apoptosis through an autocrine signaling mechanism involving VEGF-A.

We have previously shown that in the presence of elevated Smad3, transforming growth factor-ß (TGF-ß) transforms from an inhibitor to a stimulant of vascular smooth muscle cell (SMC) proliferation and intimal hyperplasia (IH). Here we identify a novel mechanism through which TGF-ß/Smad3 also exacerbates IH by inhibiting SMC apoptosis. We found that TGF-ß treatment led to inhibition of apoptosis in rat SMCs following viral expression of Smad3. Conditioned media from these cells when applied to naive SMCs recapitulated this effect, suggesting an autocrine pathway through a secreted factor. Gene array of TGF-ß/Smad3-treated cells revealed enhanced expression of vascular endothelial growth factor (VEGF), a known inhibitor of endothelial cell apoptosis. We then evaluated whether VEGF is the secreted mediator responsible for TGF-ß/Smad3 inhibition of SMC apoptosis. In TGF-ß/Smad3-treated cells, VEGF mRNA and protein as well as VEGF secretion were increased. Moreover, recombinant VEGF-A inhibited SMC apoptosis and a VEGF-A-neutralizing antibody reversed the inhibitory effect of conditioned media on SMC apoptosis. Stimulation of SMCs with TGF-ß led to the formation of a complex of Smad3 and hypoxia-inducible factor-1α (HIF-1α) that in turn activated the VEGF-A promoter and transcription. In rat carotid arteries following arterial injury, Smad3 and VEGF-A expression were upregulated. Moreover, Smad3 gene transfer further enhanced VEGF expression as well as inhibited SMC apoptosis. Finally, blocking either the VEGF receptor or Smad3 signaling in injured carotid arteries abrogated the inhibitory effect of Smad3 on vascular SMC apoptosis. Taken together, our study reveals that following angioplasty, elevation of both TGF-ß and Smad3 leads to SMC secretion of VEGF-A that functions as an autocrine inhibitor of SMC apoptosis. This novel pathway provides further insights into the role of TGF-ß in the development of IH.