Therapy For Critical Limb Ischemia Research Articles

Rationale and design of the JUVENTAS trial for repeated intra-arterial infusion of autologous bone marrow-derived mononuclear cells in patients with critical limb ischemia

Critical limb ischemia (CLI) continues to form a substantial burden on Western healthcare. Many patients still face amputation as a last treatment option. Autologous bone marrow (BM)-derived cell administration has emerged as a potential new treatment, but proof for sustainable clinical effects of BM-derived cell therapy in CLI is still lacking. The JUVENTAS (reJUVenating ENdothelial progenitor cells via Transcutaneous intra-Arterial Supplementation) trial is the first randomized, placebo-controlled, double-blinded clinical trial on repeated intra-arterial BM mononuclear cell (MNC) infusion in 110 to 160 CLI patients, designed to provide definite proof for the efficacy of stem cell therapy. Primary outcome is the incidence of major amputation at 6 months. Inclusion of patients is well underway. If BM-MNC cells therapy is beneficial, it could become a novel treatment to prevent amputation in patients with CLI.

TCT-535: Contrast-Induced Nephropathy & Targeted Renal Therapy During Peripheral Vascular Interventions: Results of the Louisiana Targeted Renal Therapy in Critical Limb Ischemia (TRT-CLI) Registry

TCT-535: Contrast-Induced Nephropathy & Targeted Renal Therapy During Peripheral Vascular Interventions: Results of the Louisiana Targeted Renal Therapy in Critical Limb Ischemia (TRT-CLI) Registry

Long-term outcomes after medical and interventional therapy of critical limb ischemia

Background Recommendations of clinical guidelines for the treatment of critical limb ischemia (CLI) are based on randomized controlled trials. Recent data from clinical practice are however lacking. Therefore a prospective observational study in patients with critical limb ischemia (CLI) in 3 hospitals with a specialized vascular medicine department was conducted to document the clinical course and outcome of patients with critical limb ischemia (CLI) in clinical practice. Methods 155 patients were stratified: 56 received endovascular intervention, 82 prostanoids and 17 antibiotic treatment. Patients with surgical revascularisation and primary amputation were excluded. All patients received structured wound treatment, analgesia and vascular risk factor treatment during hospital stay. Results Age 72.0 ± 12.7 years, hospitalisation 23.2 ± 20.3 days. 56.1% had Diabetes, 9.7% multiresistant staphylococcus aureus infection. 40% patients had rest pain, 60% ischemic tissue loss. At discharge 40.0% had no ulcers, 48.4% ongoing trophic alterations, 10.3% received major amputation and 4.5% had stable necrosis. After 18 month rate of major amputation was 6.3% (prostanoids), 14.5% (endovascular treatment; p = n.s. vs. prostanoids) and 26.7% (antibiotics; p = 0.0323 vs. prostanoids). Major amputations were not different in logistic regression analyses adjusting for baseline characteristics. Wound healing and mortality rate was not different between groups (26.8, 25.0 and 23.5%). Conclusion Structured therapy at specialized vascular centres in combination with interventional or conservative treatment is beneficial in patients with critical limb ischemia. Survival without amputation is higher than expected over 18 months.

Mesenchymal stem cell-based gene therapy with prostacyclin synthase enhanced neovascularization in hindlimb ischemia

ObjectiveBone marrow cell therapy contributes to collateral formation through the secretion of angiogenic factors by progenitor cells and muscle cells per se, thereby presenting a novel option for patients with critical limb ischemia. However, some cases are refractory to this therapy due to graft failure. Therefore, we used genetic modification of mesenchymal stem cells (MSCs) to overexpress a vasoregulatory protein, prostacyclin (PGI2), to examine whether it could enhance engraftment and neovascularization in hindlimb ischemia. Methods and resultsWe engineered the overexpression of PGI2 synthase (PGIS) within MSCs, which resulted in higher expression levels of phosphorylated Akt and Bcl-2 than in control. Under hypoxic conditions, the overexpression of PGIS led to upregulated expression of cyclooxigenase-2 and peroxisome proliferator-activated receptor δ, following a 40% increased rate of proliferation in MSCs. We then produced unilateral hindlimb ischemia in C57BL6/J mice, which were injected either with MSCs transfected with GFP, with MSCs overexpressing PGIS, or with vehicle. Laser Doppler analyses demonstrated that the administration of MSCs effectively recovered blood perfusion, and that the peak blood flow was reached within 7 days of surgery in mice with MSCs overexpressing PGIS, which was earlier than that in mice with MSCs transfected with GFP. This beneficial effect was correlated to enhanced collateral formation and muscle bundle proliferation. ConclusionSustained release of PGI2 enhanced the proangiogenic function of MSCs and subsequent muscle cell regrowth in the ischemic tissue suggesting potential therapeutic benefits of cell-based gene therapy for critical limb ischemia.

24-Carat Gold, 14-Carat Gold, or Platinum Standards in the Treatment of Critical Limb Ischemia:

Critical limb ischemia (CLI) remains a poorly understood, rarely reported, and inconsistently treated major global healthcare epidemic. The incidence in the US is estimated at 1% of the population aged 50 years and older and at approximately double that rate in the over-70 age group. These frequencies are expected to increase significantly with the aging population and the expected increase in diabetes. Within 1 year of being diagnosed with CLI, 40% to 50% of the now 20 million US diabetics will experience an amputation, and 20% to 25% will die. The estimate for treating CLI in the US alone is $10 to $20 billion per year, but just a 25% reduction in amputations could save $2.9 to $3.0 billion annually. Infrainguinal bypass surgery (IBS) utilizing autogenous saphenous vein has been considered the "24-carat gold standard" treatment for CLI, but over the last decade, endovascular therapy has emerged to seriously challenge IBS, which has created considerable controversy. Despite an overall lack of "hard" level I data, many interventionists are questioning the role of IBS as a first-line CLI therapy or are at least now considering IBS a "tainted" gold standard ("14-carat"). This review will examine the available evidence, but there should be no doubt regarding the huge global clinical and economic impact of CLI and amputations.

Atherosclerotic Peripheral Vascular Disease Symposium II

Peripheral vascular diseases are important components of cardiovascular medicine. The high prevalence of these disorders in the clinical setting mandates effective communication among healthcare providers. The public health significance of these conditions requires clear and consistent terminology for community audiences. Therefore, the goal of this writing group was to suggest definitions, usage, and nomenclature of specific terms commonly used to describe vascular diseases by cardiovascular specialists and primary care communities. The need for clarity is driven by 2 major challenges: (1) the need for use of common keywords for literature searches; and (2) the need for healthcare professionals to use common, reasoned terminology when communicating with each other and with the public. The major structural components of the vascular system are the veins, lymphatic vessels, and arteries. These serve as the basis of the nomenclature system for vascular diseases (Figure). Figure. Major classification of vascular diseases. *Includes inflammatory, artery dysplasias, congenital, traumatic, and infections. In this report, the writing group focuses only on nomenclature that applies to non–coronary artery diseases. Venous and lymphatic diseases were outside the scope of this conference. Diseases of arteries are classified further into atherosclerotic occlusive disorders, nonatherosclerotic occlusive disorders, and aneurysms. …

Design and rationale of a randomized, double-blind, placebo-controlled phase III study for autologous bone marrow cell transplantation in critical limb ischemia: the BONe Marrow Outcomes Trial in Critical Limb Ischemia (BONMOT-CLI)

Critical limb ischemia (CLI) is the end-stage of peripheral artery disease. Only about two thirds of patients with CLI can be revascularised, one third progresses to leg amputation with high associated morbidity and mortality. Therapeutic angiogenesis with bone marrow cells has shown promising improvement in less severe stages of peripheral ischemia. Our study evaluates the therapeutic value of bone marrow cell induced angiogenesis and arteriogenesis in severe, limb-threatening ischemia. the BONe Marrow Outcome Trial in Critical Limb Ischemia (BONMOT-CLI) is a investigator-initiated, double-blinded, 1:1 randomized, placebo-controlled multi-centre study at 4 sites in Germany. Only patients with no option for revascularisation or after failed revascularisation will be included. A total of 90 patients is to be included. One arm with 45 subjects will be treated with a concentrate of autologous bone marrow cells which will be injected at 40 sites into the ischemic limb. In the placebo arm, study subjects will undergo a sham bone marrow punction and 40 saline injections. At three months, a combined primary endpoint of major amputation or persisting critical limb ischemia (no clinical or perfusion improvement) will be evaluated. Secondary endpoints are death, changes in perfusion, quality of life, walking distance, minor amputations, wound healing, collateral density and cancer incidence. Post-study follow-up is up to two years. The results of this first randomized placebo-controlled trial for autologous bone marrow cell therapy in CLI will clarify the value of this new therapeutic modality in a patient population with no other alternatives except major amputation.

Interventional Management of Critical Limb Ischemia in Renal Patients

Critical limb ischemia (CLI) represents the most severe clinical manifestation of peripheral arterial disease (PAD), defined as the presence of chronic ischemic rest pain, ulcers, or gangrene attributable to objectively proven arterial occlusive disease. The occurrence of CLI in patients with kidney insufficiency portends a strikingly high rate of subsequent morbidity and mortality. Generally, the primary therapy for CLI is revascularization of the affected limb. However, patients with CLI and kidney insufficiency represent a unique and challenging patient subset, and data from surgical series suggest reduced rates of limb salvage and higher medium and long-term mortality rates for patients with kidney insufficiency compared with those with normal kidney function. In contemporary practice, endovascular techniques are fast replacing surgical bypass as the first-line revascularization strategy for CLI, based on high technical success rates and low rates of procedure-related morbidity and mortality. However, a large series on endovascular outcomes for the treatment of CLI in patients with kidney insufficiency is lacking. Based on the severely reduced long-term survival rates of patients with CLI and kidney insufficiency, future efforts should focus on early detection of PAD in patients with kidney insufficiency and institution of aggressive medical therapy to prevent progression in the global burden of atherosclerosis in this patient population.

Infrapopliteal angioplasty for critical limb ischemia: Relation of TransAtlantic InterSociety Consensus class to outcome in 176 limbs

Recent data suggest that percutaneous transluminal angioplasty (PTA) may be appropriate primary therapy for critical limb ischemia (CLI). However, little data are available regarding infrapopliteal angioplasty outcomes based on TransAtlantic InterSociety Consensus (TASC) classification. We report our experience with infrapopliteal angioplasty stratified by TASC lesion classification. From February 2004 to March 2007, 176 consecutive limbs (163 patients) underwent infrapopliteal angioplasty for CLI. Stents were placed for lesions refractory to PTA or flow-limiting dissections. Patients were stratified by TASC classification and suitability for bypass grafting. Primary outcome was freedom from restenosis, reintervention, or amputation. Primary patency, freedom from secondary restenosis, limb salvage, reintervention by repeat angioplasty or bypass, and survival were determined. Median age was 73 years (range, 39-94 years). Technical success was 93%. Average follow-up was 10 months (range, 1-41 months). At 1 and 2 years, freedom from restenosis, reintervention, or amputation was 39% and 35%, conventional primary patency was 53% and 51%, and freedom from secondary restenosis and reintervention were 63% and 61%, respectively. Limb salvage was 84% at 1, 2, and 3 years. Within 2 years, 15% underwent bypass and 18% underwent repeat infrapopliteal PTA. Postoperative complications occurred in 9% and intraprocedural complications in 10%. The 30-day mortality was 5% (9 of 181). Overall survival was 81%, 65%, and 54% at 1, 2, and 3 years. TASC D classification predicted diminished technical success (75% D vs 100% A, B, and C; P < .001), primary restenosis, reintervention, or amputation (hazard ratio [HR], 3.4; 95% confidence interval [CI], 2.1-5.5, P < .001), primary patency (HR, 2.2; 95% CI, 1.3-3.9, P < .004), secondary restenosis (HR, 3.2; 95% CI, 1.6-6.4, P = .001), and limb salvage (HR, 2.6; 95% CI, 1.1-6.3, P < .05). Unsuitability for surgical bypass also predicted restenosis, reintervention, or amputation, secondary restenosis, need for repeated angioplasty, and inferior primary patency and limb salvage rates. Infrapopliteal angioplasty is a reasonable primary treatment for CLI patients with TASC A, B, or C lesions. Restenosis, reintervention, or amputation was higher in patients who were unsuitable candidates for bypass; however, an attempt at PTA may be indicated as an alternative to primary amputation. Although restenosis, reintervention, or amputation is high after tibial angioplasty for CLI, excellent limb salvage rates may be obtained with careful follow-up and reinterventions when necessary, including bypass in 15%.

Patterns of artery disease in 450 patients undergoing revascularization for critical limb ischemia: Implications for clinical trial design

The pattern and distribution of arterial occlusions and stenoses in patients with critical limb ischemia presenting at two academic medical centers was described. From January 1998 to December 2006, 450 consecutive critical limb ischemia patients who underwent arteriography and infrainguinal revascularization at the University of Colorado Health Sciences Center or Southern Illinois University were retrospectively evaluated. Demographics, clinical morbidities, and Fontaine stage were recorded. The arterial tree was categorized into three groups: the aorta and iliac arteries (A-I); the common femoral, superficial femoral, and profunda femoral arteries (Fem); and the popliteal and tibial arteries (Pop-Tib). Arterial segments within groups were categorized as subcritical stenoses (patent or <50% stenoses), critical stenoses (single or multiple >50% stenoses), or occluded (segmental occlusions of any length). Patients with diabetes mellitus, end-stage renal disease, and Fontaine stage (III vs IV) were analyzed for differing disease patterns according to their chart history. Occlusive disease was present in 5% in all arterial segments (A-I + Fem + Pop-Tib), in 1% in the A-I + Fem group, in 2% in the A-I + Pop-Tib group, in 3% in A-I group, in 4% in the Fem group, in 30% in the Fem + Pop-Tib group, and in 55% in the Pop-Tib group. Descriptive comparisons among subgroups demonstrated a 61% to 69% prevalence of popliteal and tibial occlusive patterns in patients with diabetes mellitus, end-stage renal disease, and Fontaine stage IV. Furthermore, 65% of patients with Pop-Tib occlusions had associated critical stenoses in the proximal arterial groups. More than half of critical limb ischemia patients undergoing infrainguinal revascularization have arterial occlusions in the popliteal or tibial arterial segments, or both, with associated critical stenoses in the femoral arterial segments, which is even greater in the subgroups with diabetes mellitus, end-stage renal disease, and Fontaine stage IV. Knowledge of such occlusive patterns is important for the development of novel infrainguinal endovascular and angiogenesis therapies for critical limb ischemia.

Autologous Transplantation of Granulocyte Colony–Stimulating Factor–Mobilized Peripheral Blood Mononuclear Cells Improves Critical Limb Ischemia in Diabetes

Huang et al. (1), in their small seminal clinical trial of cellular therapy for critical limb ischemia in diabetic patients, did not include presence of diabetic retinopathy among their exclusion criteria. It is known that individuals with diabetes are subjected to poor blood vessel growth in ischemic hearts and limbs and increased angiogenesis in retinal complications. This so-called “diabetic paradox” has been attributed …

Hepatocyte growth factor as potential cardiovascular therapy

Hepatocyte growth factor is a mesenchyme-derived pleiotropic factor that regulates the growth, motility and morphogenesis of various types of cells, and is also a member of the angiogenic growth factors. Hepatocyte growth factor is secreted by vascular endothelial cells and smooth muscle cells, and the hepatocyte growth factor receptor, c-met, was also observed in these vascular cells. Treatment of human aortic endothelial cells with recombinant hepatocyte growth factor resulted in a significant increase in cell proliferation, accompanied by mitogen-activated protein kinase and Akt/protein kinase B phosphorylation. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As preclinical study of gene therapy using hepatocyte growth factor to treat peripheral arterial disease, naked hepatocyte growth factor plasmid was intramuscularly injected into the ischemic hind limb of rabbits in order to evaluate its angiogenic activity. Intramuscular injection of hepatocyte growth factor plasmid once on day 10 following surgery, produced significant augmentation of collateral vessel development in the ischemic limb on day 30. In the clinical setting, the authors further investigated the safety and efficacy of hepatocyte growth factor plasmid DNA in patients with critical limb ischemia, in a prospective open-labeled trial. Intramuscular injection of naked plasmid DNA was performed in the ischemic limbs of six patients with critical limb ischemia with arteriosclerosis obliterans (n = 3) or Buerger disease (n = 3) graded as Fontaine III or IV. In the efficacy evaluation, a reduction of pain scale of more than 1 cm on a visual analog pain scale was observed in five out of six patients. An increase in ankle pressure index of more than 0.1 was observed in five out of five patients. The long diameter of eight out of 11 ischemic ulcers in four patients was reduced by more than 25%. Intramuscular injection of naked hepatocyte growth factor plasmid is safe, feasible and can achieve successful improvement of ischemic limbs. Although the present data were obtained to demonstrate safety in a Phase I/early Phase II trial, the initial clinical outcome with hepatocyte growth factor gene transfer seems to indicate its usefulness as sole therapy for critical limb ischemia. Randomized placebo-controlled clinical trials of alternative dosing regimens of gene therapy will be required to define the efficiency of this therapy.

The effect of gradual or acute arterial occlusion on skeletal muscle blood flow, arteriogenesis, and inflammation in rat hindlimb ischemia

Current experimental models of critical limb ischemia are based on acute ischemia rather than on chronic ischemia. Human peripheral vascular disease is largely a result of chromic ischemia. We hypothesized that a model of chronic hindlimb ischemia would develop more collateral arteries, more blood flow, and less necrosis and inflammation than would acute hindlimb ischemia. We therefore developed a rat model of chronic hindlimb ischemia and compared the effects of chronic ischemia with those of acute ischemia on hindlimb skeletal muscle. Acute or chronic ischemia was induced in 36 male Sprague-Dawley rats. Chronic ischemia caused blood flow, as measured by laser Doppler scanning and confirmed by muscle oxygen tension measurements, to gradually decrease over 1 to 2 weeks after operation. Histologic analysis showed chronic hindlimb ischemia better preserved muscle mass and architecture and stimulated capillary angiogenesis, while lacking the muscle necrosis and inflammatory cell infiltrate seen after acute ischemia. Surprisingly, the chronic ischemia group recovered dermal blood flow more slowly and less completely than did the acute ischemia group, as measured by laser Doppler (0.66 +/- 0.02 vs 0.76 +/- 0.04, P < .05) and tissue oxygen tension (0.61 +/- 0.06 vs 0.81 +/- 0.05, P < .05) at 40 days postoperatively. Consistent with poorer blood flow recovery, chronic ischemia resulted in smaller diameter collateral arteries (average diameter of the five largest collaterals on angiogram was 0.01 +/- 0.0003 mm vs 0.013 +/- 0.0007 mm for acute, P < .005 at 40 days postoperatively). Acute ischemia resulted in decreased tissue concentrations of vascular endothelial growth factor (VEGF) (0.96 +/- 0.23 pg/mg of muscle for acute vs 4.4 +/- 0.75 and 4.8 +/- 0.75 pg/mg of muscle for unoperated and chronic, respectively, P < .05 acute vs unoperated), and in increased tissue concentrations of interleukin (IL)-1beta (7.3 +/- 4.0 pg/mg of muscle for acute vs undetectable and 1.7 +/- 1.6 pg/mg of muscle for unoperated and chronic, respectively, P < 0.05 acute vs unoperated). We describe here the first model of chronic hindlimb ischemia in the rat. Restoration of blood flow after induction of hindlimb ischemia is dependent on the rate of arterial occlusion. This difference in blood flow recovery correlates with distinct patterns of muscle necrosis, inflammatory cell infiltration, and cytokine induction in the ischemic muscle. Differences between models of acute and chronic hindlimb ischemia may have important consequences for future studies of mechanisms regulating arteriogenesis and for therapeutic approaches aimed at promoting arteriogenesis in humans suffering from critical limb ischemia. Despite the substantial clinical differences between acute and chronic ischemia, researchers attempting to develop molecular therapies to treat critical limb ischemia have only tested those therapies in experimental models of acute hindlimb ischemia. We present here a novel model of chronic hindlimb ischemia in the rat. We further demonstrate that when hindlimb ischemia is developed chronically, collateral artery development is poorer than when hindlimb ischemia is developed acutely. These findings suggest that further tests of molecular therapies for critical limb ischemia should be performed in chronic hindlimb ischemia models rather than in acute hindlimb ischemia models.

Safety Evaluation of Clinical Gene Therapy Using Hepatocyte Growth Factor to Treat Peripheral Arterial Disease

Therapeutic angiogenesis using angiogenic growth factors is expected to be a new treatment for patients with critical limb ischemia (CLI). Because hepatocyte growth factor (HGF) has potent angiogenic activity, we investigated the safety and efficiency of HGF plasmid DNA in patients with CLI as a prospective open-labeled clinical trial. Intramuscular injection of naked HGF plasmid DNA was performed in ischemic limbs of 6 CLI patients with arteriosclerosis obliterans (n=3) or Buerger disease (n=3) graded as Fontaine III or IV. The primary end points were safety and improvement of ischemic symptoms at 12 weeks after transfection. Severe complications and adverse effects caused by gene transfer were not detected in any patients. Of particular importance, no apparent edema was observed in any patient throughout the trial. In addition, serum HGF concentration was not changed throughout the therapy period in all patients. In contrast, a reduction of pain scale of more than 1 cm in visual analog pain scale was observed in 5 of 6 patients. Increase in ankle pressure index more than 0.1 was observed in 5 of 5 patients. The long diameter of 8 of 11 ischemic ulcers in 4 patients was reduced >25%. Intramuscular injection of naked HGF plasmid is safe, feasible, and can achieve successful improvement of ischemic limbs. Although the present data are conducted to demonstrate the safety as phase I/early phase IIa, the initial clinical outcome with HGF gene transfer seems to indicate usefulness as sole therapy for CLI.

Tubes, Branches, and Pillars

The angiogenic cascade is getting increasingly complex. A few years ago, vasculogenesis and angiogenesis were considered as the primary mechanisms leading to the formation of new blood vessels. The original definition of vasculogenesis denotes the formation of a primary embryonic vascular network from in situ differentiating angioblastic cells.1 In contrast, angiogenesis primarily referred to the sprouting of blood vessels from preexisting vessels.1 Recent advances in the identification of molecules that regulate angiogenesis and vascular remodeling have shown that the simplistic model of an invading capillary sprout is not sufficient to appreciate the whole spectrum of morphogenic events that are required to form a neovascular network (Figure 1).1–3 Undoubtedly, vascular endothelial growth factor (VEGF) acts at an early point in the hierarchical order of morphogenic events and probably fulfills all criteria to be considered as a master switch of the angiogenic cascade. In contrast, the angiopoietins and their receptor Tie-2 as well as the ephrins and their corresponding Eph receptors appear to act at a somewhat later stage of neovessel formation. These molecules orchestrate a number of related, yet functionally and molecularly not well understood, processes such as vessel assembly (network formation and formation of anastomoses), vessel maturation (recruitment of mural cells [pericytes and smooth muscle cells], and extracellular matrix assembly, pruning of the primary vascular bed), and acquisition of vessel identity (formation of arteries, capillaries, and veins)3,4 (Figure 2). Lastly, the mechanisms of organotypic differentiation of the vascular tree (continuous endothelium, discontinuous endothelium, fenestrated endothelium) are not at all understood and the first molecules that govern subpopulation-specific vascular growth and differentiation are just being uncovered.5,6 Figure 1. Change of paradigm. From sprouting angiogenesis to vascular morphogenesis. Basement membrane degradation, directed endothelial cell migration, and proliferation (left) were considered as the primary mechanisms of angiogenesis. …

Fibroblast growth factor as therapy for critical limb ischemia: a case report

Fibroblast growth factor as therapy for critical limb ischemia: a case report