The challenges of treating peripheral arterial disease

Clinical investigation of the GORE Drug-Coated PTA Balloon Catheter for CE Mark Approval

OBJECTIVES

Paclitaxel-coated balloon angioplasty has been established as the first-line therapy of femoropopliteal artery disease. The primary objectives of the study were to evaluate the performance and the safety of the GORE-DCB Catheter in the treatment of atherosclerotic femoropopliteal lesions of patients with peripheral artery disease for CE-Mark approval.

METHODS

Prospective, single-arm, multicenter study with 24 months follow-up. The GORE-DCB Catheter consists of a drug-coated nylon (inner layer)/ePTFE (outer layer) composite balloon. The ePTFE layer is coated with paclitaxel (concentration: 3.5μg/mm²), and the excipients stearic acid/tromethamine (tris). The primary endpoints were 6-month late lumen loss (LLL) and 30-day of freedom from Major Adverse Events (MAE).

RESULTS

Fifty-two subjects were enrolled, 69% men, median age 69 (49-83) years. Acute device success was 100%, the 30-day MAE rate was zero. Study primary endpoint of LLL (-0.17 mm) showed significant superiority compared to the performance goal of uncoated PTA balloon catheters from literature. At 1 and 2 years primary patency rates were 81.8% and 68.7%, respectively, and freedom from clinical driven target lesion revascularization rates were 87.9% and 83.4%, respectively.

CONCLUSION

The study demonstrates that the treatment of lesions in femoropopliteal arteries with the GORE-DCB Catheter is safe and effective.

Usefulness of Lipoprotein(a) for Predicting Clinical Outcomes After Endovascular Therapy for Aortoiliac Atherosclerotic Lesions

PURPOSE

To evaluate the usefulness of serum lipoprotein(a) as a biomarker of clinical outcomes after endovascular therapy (EVT) for atherosclerotic aortoiliac lesions.

METHODS

Serum lipoprotein(a) concentrations were measured at admission in 189 consecutive patients (median age 72 years; 160 men) with peripheral artery disease who underwent EVT for aortoiliac occlusive disease. The patients were dichotomized into 2 groups based on serum lipoprotein(a) levels ≤40 mg/dL (LOW; n=135) or >40 mg/dL (HIGH; n=54). After EVT, the incidences of major adverse limb events (MALE) were analyzed. Predictors of MALE were sought with a Cox proportional hazards analysis; results are presented as the hazard ratio (HR) and 95% confidence interval.

RESULTS

At the median follow-up of 33 months (interquartile range 11, 54), MALE occurred in 44 (23.3%) patients. The MALE-free survival estimate was significantly lower in patients in the HIGH group (55.6% vs 85.2%, p<0.001). Independent predictors of MALE after EVT were hemodialysis (HR 2.23, 95% CI 1.04 to 4.78, p=0.039) and high lipoprotein(a) levels (HR 2.80, 95% CI 1.44 to 5.45, p=0.003).

CONCLUSION

High lipoprotein(a) levels were associated with a higher incidence of MALE after EVT for patients with aortoiliac lesions.

Cost-effectiveness of medical, endovascular and surgical management of peripheral vascular disease

Peripheral arterial disease (PAD) is responsible for 20% of all US hospital admissions. Management of PAD has evolved over time to include many medical and transcatheter interventions in addition to the traditional surgical approach. Non-invasive interventions including supervised exercise programs and antiplatelets use are economically attractive therapies that should be considered in all patients at risk. While surgery offers so far a clinically and economically appropriate option, the improvement of percutaneous transluminal angioplasty (PTA) technique with the addition of drug-coated balloons offers a reasonably clinically and economically attractive alternative that will continue to evolve in the future.

Small dense low density lipoprotein particles are associated with poor outcome after angioplasty in peripheral artery disease

Purpose

In patients suffering from symptomatic peripheral artery disease (PAD), percutaneous revascularization is the treatment of choice. However, restenosis may occur in 10 to 60% in the first year depending on a variety of factors. Small dense low density lipoprotein (sdLDL) particles are associated with an increased risk for cardiovascular events, but their role in the process of restenosis is not known. We conducted a prospective study to analyze the association of sdLDL particles with the outcome of balloon angioplasty in PAD. The composite primary endpoint was defined as improved walking distance and absence of restenosis.

Methods

Patients with angiographically documented PAD of the lower extremities who were scheduled for lower limb revascularization were consecutively recruited for the study. At baseline and at three month follow-up triglyceride, total cholesterol, LDL size and subclasses and HDL cholesterol and ankle-brachial index (ABI) were measured. Three months after the intervention duplex sonography was performed to detect restenosis.

Results

Sixty-four patients (53% male) with a mean age of 68.6±9.9 years were included. The proportion of small- dense LDL particles (class III and IV) was significantly lower (33.1±11.0% vs. 39.4±12.1%, p = 0.038) in patients who reached the primary end-point compared with those who did not. Patients with improved walking distance and without restenosis had a significantly higher LDL size at baseline (26.6±1.1 nm vs. 26.1±1.1 nm, p = 0.046) and at follow-up (26.7±1.1 nm vs. 26.2±0.9 nm, p = 0.044) than patients without improvement.

Conclusions

Small-dense LDL particles are associated with worse early outcome in patients undergoing percutaneous revascularization for symptomatic PAD.

Zinc finger protein 191 deficiency attenuates vascular smooth muscle cell proliferation, migration, and intimal hyperplasia after endovascular arterial injury

OBJECTIVE

Restenosis engenders surgical vascular intervention failure. Zinc finger protein 191 (ZFP191) is a novel member of the SCAN domain family of Krüppel-like zinc finger transcription factors. Previous work reveals that ZFP191 is a pleiotropic factor that plays important roles in hematopoiesis, brain development, and tumor growth. Here, we sought to determine whether intimal hyperplasia was affected by the activity of ZFP191 and to investigate the molecular mechanisms that may underpin the process.

METHODS

Intimal hyperplasia was induced by guidewire injury in mouse femoral arteries. The arteries were harvested for morphometric assessment and determination of ZFP191 expression. Next, ZFP191 knockdown in cultured mouse aortic vascular smooth muscle cells (VSMCs) was achieved by lentiviral transduction of short-hairpin RNA. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay, [(3)H]thymidine incorporation assay, scratch assay, and transwell migration assay were used to evaluate the effects of ZFP191 knockdown on VSMC growth and migration. In addition, β-catenin, c-myc, cyclin D1, matrix metalloproteinase (MMP) 9, MMP2, and MMP7 were measured by Western blotting in the absence of ZFP191 in vitro and in vivo. Zymography was used to evaluate MMP activity in cell culture-conditioned media. Lastly, artery injury was performed in wild-type (WT) and heterozygous ZFP191 knockout (KO) mice, and morphometric analysis of the arteries was determined.

RESULTS

Guidewire injury was associated with development of intimal hyperplasia, and ZFP191 expression was enhanced by 51% in the injured arteries. Cultured primary VSMCs transfected with lentiviral shZFP191 displayed reduced proliferation and migration compared with controls. Mechanically, ZFP191 knockdown potently decreased the level of β-catenin and its downstream targets c-myc and cyclin D1. ZFP191 knockdown downregulated the expression of MMP9, MMP2, and MMP7, and zymography confirmed that ZFP191 knockdown reduced the activity of MMPs. Consistent with the in vitro data, elevated expression of β-catenin, c-myc, cyclin D1, MMP9, MMP2, and MMP7 accompanied upregulation of ZFP191 after injury in the femoral arteries of mice, and these levels were downregulated in ZFP191 KO vessels. Finally, intimal hyperplasia was greatly blocked in heterozygous ZFP191 KO mice compared with WT mice (intima/media ratio, 0.124 vs 0.412; P < .05).

CONCLUSIONS

ZFP191 played an essential role in aggressive proliferation and migration of VSMCs, which in turn facilitated intimal hyperplasia. Our findings offer the first genetic evidence of ZFP191 as a potential therapeutic target to prevent restenosis.

Neo-intimal hyperplasia, diabetes and endovascular injury

Diabetes is a significant major risk factor for peripheral arterial disease (PAD) and critical limb ischaemia (CLI), the latter which is also the most common cause of amputation in these patients. Revascularisation of the lower extremities of such patients is imperative for limb salvage and has become First-line therapy. However, the incidence of restenosis following endovascular stenting is very high and is largely due to neo-intimal hyperplasia (NIH), the regulation of which is for the greater part not understood. This article therefore reviews our understanding on the regulation of NIH following stent-induced vascular injury, and highlights the importance of future studies to investigate whether the profile of vascular progenitor cell differentiation, neo-intimal growth factors and lumen diameters predict the severity of post-stent NIH in the peripheral arteries. Results from future studies will (1) better our understanding of the regulation of NIH in general, (2) determine whether combinations of any of the vascular factors discussed are predictive of the extent of NIH postoperatively, and (3) potentially facilitate future therapeutic targets and/or change preventive strategies.

Prevention of diabetic microangiopathy by prophylactic transplant of mobilized peripheral blood mononuclear cells

AIM

To investigate whether the prophylactic local delivery of mobilized peripheral blood mononuclear cells (M-PBMNC) could prevent peripheral microangiopathy in diabetic nude mice.

METHODS

Diabetic nude mice were induced with intraperitoneal injections of streptozotocin. With the time course of diabetes, we detected the capillary and arteriole density of mice adductor muscles by immunohistopathy. In situ apoptosis was detected by using TdT-mediated dUTP nick end labeling (TUNEL) methods. M-PBMNC were labeled and locally delivered to the adductor muscles. Mononuclear cells were also isolated and cultured in vitro for the detection and counting of endothelial progenitor cells(EPC).

RESULTS

Rarefication of capillaries and arterioles, enhanced apoptosis in adductor muscles, and reduced circulating EPC in diabetic nude mice. Prophylactic local delivery of M-PBMNC halted the progression of microvascular rarefaction in hind-limb skeletal muscles by inhibiting apoptosis. We detected the survival, migration and incorporation of transplanted M-PBMNC into the murine vasculature in vivo. In addition, more EPC were available from M-PBMNC than non-mobilized cells.

CONCLUSION

These results suggested that the prophylactic local delivery of M-PBMNC may represent a novel approach for the treatment of microvascular complications in diabetics.

Endothelial progenitor cells transfected with PDGF: cellular and molecular targets for prevention of diabetic microangiopathy

Microvascular insufficiency represents a major cause of end-organ failure among diabetics. Prevention at early stage of disease is therefore necessary and is a focus of current investigations. Progression of diabetes is complicated by endothelial cell apoptosis as well as occlusion of arteriole and capillary leading to microvascular rarefaction. This favors the formation of non-healing limb ulcers and limits the benefit of revascularization. Recent study indicated that reduction of platelet derived growth factor (PDGF) expression was indeed critical, in causing functional and morphological vascular changes, namely the dissociation of pericytes from the capillaries in muscles. Diabetic microangiopathy is a result of pericytes dissociation from reduced PDGF as well as vessel rarefaction from reduced number of endothelial progenitor cells (EPCs) and EPC dysfunction. Since blood vessels develop through the assembly of these two principal cell types--endothelial cells and pericytes/smooth muscle cells, prevention of diabetic microangiopathy requires interventions targeting at both cell types in a complementary and synergistic manner. An improved recruitment of EPCs will help repair of injured endothelium while molecular targeting with PDGF will enhance pericytes recruitment. EPCs modified with PDGF therefore hold promise as the next generation of agents for prevention of microangiopathy.

Autologous transplantation of granulocyte colony-stimulating factor-mobilized peripheral blood mononuclear cells improves critical limb ischemia in diabetes

OBJECTIVE

To assess the application of autologous transplantation of granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood mononuclear cells (PBMNCs) in the treatment of critical limb ischemia (CLI) of diabetic patients and to evaluate the safety, efficacy, and feasibility of this novel therapeutic approach.

RESEARCH DESIGN AND METHODS

Twenty-eight diabetic patients with CLI were enrolled and randomized to either the transplant group or the control group. In the transplant group, the patients received subcutaneous injections of recombinant human G-CSF (600 microg/day) for 5 days to mobilize stem/progenitor cells, and their PBMNCs were collected and transplanted by multiple intramuscular injections into ischemic limbs. All of the patients were followed up after at least 3 months.

RESULTS

At the end of the 3-month follow-up, the main manifestations, including lower limb pain and ulcers, were significantly improved in the patients of the transplant group. Their laser Doppler blood perfusion of lower limbs increased from 0.44 +/- 0.11 to 0.57 +/- 0.14 perfusion units (P < 0.001). Mean ankle-brachial pressure index increased from 0.50 +/- 0.21 to 0.63 +/- 0.25 (P < 0.001). A total of 14 of 18 limb ulcers (77.8%) of transplanted patients were completely healed after cell transplantation, whereas only 38.9% of limb ulcers (7 of 18) were healed in the control patients (P = 0.016 vs. the transplant group). No adverse effects specifically due to cell transplantation were observed, and no lower limb amputation occurred in the transplanted patients. In contrast, five control patients had to receive a lower limb amputation (P = 0.007, transplant vs. control group). Angiographic scores were significantly improved in the transplant group when compared with the control group (P = 0.003).

CONCLUSIONS

These results provide pilot evidence indicating that the autologous transplantation of G-CSF-mobilized PBMNCs represents a simple, safe, effective, and novel therapeutic approach for diabetic CLI.