Current state and perspective on medical treatment of critical leg ischemia: gene and cell therapy

Stem Cell Therapy for Vascular Disorders

Peripheral vascular disease results from narrowing of the peripheral arteries that supply oxygenated blood and nutrients to the legs and feet. This pathology causes symptoms such as intermittent claudication (pain with walking), painful ischaemic ulcerations, or even limbthreatening gangrene. It is generally believed that the vascular endothelium, a monolayer of endothelial cells (ECs) that lines the luminal surface of all blood and lymphatic vessels, plays a dominant role in vascular homeostasis and vascular regeneration. As a result, stem cell-based regeneration of the endothelium may be a promising approach for the treatment of PAD. Critical limb ischaemia (CLI) is an advanced form of peripheral artery disease which is responsible for about 100,000 amputations each year in the US. Trials to date have reported clinical improvement and reduced need for amputation in patients with CLI who receive autologous bone marrow or mobilised peripheral blood stem cells for stimulation of angiogenesis. There is no effective treatment for lower limb ischaemia caused by peripheral vascular disease and it is necessary to amputate the limb at the end stage. Therefore, the concept of effective therapeutic angiogenesis has become widely accepted during the past few years and it has emerged as a strategy to treat tissue ischaemia by promoting collateral growth using drug, gene or cell therapy. This article provides an overview of current therapeutic challenges for the treatment of critical limb ischaemia, the basic mechanisms of stem cell therapy, the most relevant clinical trials as well as future directions for translational research in this area.

Neurolitic block of the lumbar sympathetic chain improves chronic pain in a patient with critical lower limb ischemia

Background and objectives

Sympathectomy is one of the therapies used in the treatment of chronic obstructive arterial disease (COAD). Although not considered as first-line strategy, it should be considered in the management of pain difficult to control. This clinical case describes the evolution of a patient with inoperable COAD who responded properly to the lumbar sympathetic block.

Case report

A female patient, afro-descendant, 69 years old, ASA II, admitted to the algology service due to refractory ischemic pain in the lower limbs. The patient had undergone several surgical procedures and conservative treatments without success. Vascular surgery considered the case as out of therapeutic possibility, unless limb amputation. At that time, sympathectomy was indicated. After admission to the operating room, the patient was monitored, positioned and sedated. The blockade was performed with the aid of radioscopy, bilaterally, at L2–L3–L4 right and L3 left levels. On the right side, at each level cited, 3 mL of absolute alcohol with 0.25% bupivacaine were injected without vasoconstrictor, and on the left side only local anesthetic. The procedure was performed uneventfully. The patient was discharged with complete remission of the pain.

Conclusion

Neurolitic block of the lumbar sympathetic chain is an effective and safe treatment option for pain control in patients with critical limb ischemia patients in whom the only possible intervention would be limb amputation.

Human Stem Cells Overexpressing miR-21 Promote Angiogenesis in Critical Limb Ischemia by Targeting CHIP to Enhance HIF-1α Activity

Critical limb ischemia (CLI) is a severe blockage in the arteries of the lower extremities. However, the effective and optimal treatment for CLI remains to be elucidated. Previous therapeutic research is mainly focused on proangiogenic growth factors administrations. Recently, miR-21 has been revealed to play a crucial role in angiogenesis. Thus, we hypothesize that miR-21 over-expression in human umbilical cord blood-derived mesenchymal stem cells (UCBMSCs) can effectively treat CLI. Herein, UCBMSCs were transduced with lentivirus-miR-21-Luciferase (Lenti-miR-21) or lentivirus- LacZ-Luciferase (Lenti-LacZ). The results indicated that miR-21 induced UCBMSCs proliferation, migration, and angiogenesis in vitro. Subsequently, general observation and laser Doppler perfusion imaging were introduced to detect perfusion in muscles of CLI-nude mice on 1, 4, 7, 14, and 28 day postoperation. There was a significant improvement in blood vessels of the ischemic limb in Lenti-miR-21 group at 7 day compared with the saline or Lenti-LacZ groups. At 28 day, histological analysis confirmed that UCBMSCs over-expressing miR-21 increased neovascularization in CLI. Furthermore, carboxyl terminus of Hsc70-interacting protein (CHIP) was found to be the target gene for miR-21-mediated activation of hypoxia-inducible factor 1α (HIF-1α) in UCBMSCs. In summary, our study demonstrated that over-expressing miR-21 in UCBMSCs could improve neovascularization in CLI through enhancing HIF-1α activity by targeting CHIP, which may hold great therapeutic promise in treating CLI.

[Neurolitic block of the lumbar sympathetic chain improves chronic pain in a patient with critical lower limb ischemia]

BACKGROUND AND OBJECTIVES

Sympathectomy is one of the therapies used in the treatment of chronic obstructive arterial disease (COAD). Although not considered as first-line strategy, it should be considered in the management of pain difficult to control. This clinical case describes the evolution of a patient with inoperable COAD who responded properly to the lumbar sympathetic block.

CASE REPORT

A female patient, afro-descendant, 69 years old, ASA II, admitted to the algology service due to refractory ischemic pain in the lower limbs. The patient had undergone several surgical procedures and conservative treatments without success. Vascular surgery considered the case as out of therapeutic possibility, unless limb amputation. At that time, sympathectomy was indicated. After admission to the operating room, the patient was monitored, positioned and sedated. The blockade was performed with the aid of radioscopy, bilaterally, at L2-L3-L4 right and L3 left levels. On the right side, at each level cited, 3mL of absolute alcohol with 0.25% bupivacaine were injected without vasoconstrictor, and on the left side only local anesthetic. The procedure was performed uneventfully. The patient was discharged with complete remission of the pain.

CONCLUSION

Neurolitic block of the lumbar sympathetic chain is an effective and safe treatment option for pain control in patients with critical limb ischemia patients in whom the only possible intervention would be limb amputation.

Regenerative medicine in critical limb ischemia

Critical limb ischemia (CLI) is commonly caused by atherosclerotic arterial obstruction or stenosis in the leg, as demonstrated by rest pain, skin ulcers and gangrene (Fontaine III or IV), often fails to respond to conservative treatments, and carries a high risk for limb amputation, with a particularly dismal prognosis. Although surgical revascularization techniques may be used for certain CLI patients, such techniques are not indicated for most CLI patients due to the diffuse nature of the responsible lesions, distal location of the obstruction, or coexisting systemic comorbidities. For such CLI patients with no alternative treatments, the potential utility of cell therapies has been investigated. Indeed many clinical trials are being carried out by academic sectors, and their achievements will facilitate clinical development by pharmaceutical companies.In order to understand the situation regarding competitive international R&D of revascularization seeds for CLI, we surveyed the status of clinical trials. As a result, we identified 58 clinical trials on revascularization for CLI, with the majority in the early phase (<phase II: 82.7%). Revascularization seeds for CLI are in the development and competition phase, and promising seeds are expected to appear in the near future.In this review, we discuss how to develop optimal regenerative medicine concerning the selection of cell origin, cell type, combination with growth factor, and the influence of concomitant disease.

Therapeutic effect of fucoidan-stimulated endothelial colony-forming cells in peripheral ischemia

BACKGROUND

Fucoidan, an antithrombotic polysaccharide, can induce endothelial colony-forming cells (ECFC) to adopt an angiogenic phenotype in vitro.

OBJECTIVES

We evaluated the effect of fucoidan on vasculogenesis induced by ECFC in vivo.

METHODS

We used a murine hindlimb ischemia model to probe the synergic role of fucoidan-treatment and ECFC infusion during tissue repair.

RESULTS

We found that exposure of ECFC to fucoidan prior to their intravenous injection improved residual muscle blood flow and increased collateral vessel formation. Necrosis of ischemic tissue was significantly reduced on day 14, to 12.1% of the gastronecmius cross-sectional surface area compared with 40.1% in animals injected with untreated-ECFC. ECFC stimulation with fucoidan caused a rapid increase in cell adhesion to activated endothelium in flow conditions, and enhanced transendothelial extravasation. Fucoidan-stimulated ECFC were resistant to shear stresses of up to 21 dyn cm(-2). Direct binding assays showed strong interaction of fucoidan with displaceable binding sites on the ECFC membrane. Bolus intramuscular administration of fucoidan 1 day after surgery reduces rhabdomyolysis. Mice injected with fucoidan (15 mg kg(-1)) had significantly lower mean serum creatine phosphokinase (CPK) activity than control animals. This CPK reduction was correlated with muscle preservation against necrosis (P < 0.001).

CONCLUSIONS

Fucoidan greatly increases ECFC-mediated angiogenesis in vivo. Its angiogenic effect would be due in part to its transportation to the ischemic site and its release after displacement by proteoglycans present in the extracellular matrix. The use of ECFC and fucoidan together, will be an efficient angiogenesis strategy to provide therapeutic neovascularization.

Application of autologous bone marrow mononuclear cells in six patients with advanced chronic critical limb ischemia as a result of diabetes: our experience

BACKGROUND AIMS

Previous clinical studies have reported that the injection of bone marrow (BM)-derived mononuclear cells (MNC) results in improvement in symptoms and healing of ulcers in patients with critical limb ischemia (CLI) up to stage IV of Fontaine's classification. However, most patients with Fontaine stage IV CLI limbs had to undergo amputation even after stem cell therapy. We report on six patients, who had poorly controlled diabetes with extensive ulceration and gangrene of limbs because of Fontaine stage IV CLI and had been advised amputation elsewhere, who underwent injection of autologous BM MNC.

METHODS

In all six patients, BM was aspirated and the isolated MNC from the BM were injected intralesionally at various sites of the ulcer and its surroundings after necessary debridement. The patients were followed up at regular intervals for at least 6 months.

RESULTS

At the end of the 6-month follow-up, the lower limb pain and ulcers had improved significantly in all patients. The mean toe-brachial index had increased from 0.26 to 0.36. One patient died a month after therapy because of causes unrelated to the procedure. Limb salvage was possible in the remaining five patients and they had a pain-free walking distance of 100 m within 6 months.

CONCLUSIONS

Limb salvage was possible in all six diabetic patients with Fontaine stage IV CLI following autologous BM MNC injection. The procedure was safe without any adverse outcomes.

MAPC transplantation confers a more durable benefit than AC133+ cell transplantation in severe hind limb ischemia

There is a need for comparative studies to determine which cell types are better candidates to remedy ischemia. Here, we compared human AC133(+) cells and multipotent adult progenitor cells (hMAPC) in a mouse model reminiscent of critical limb ischemia. hMAPC or hAC133(+) cell transplantation induced a significant improvement in tissue perfusion (measured by microPET) 15 days posttransplantation compared to controls. This improvement persisted for 30 days in hMAPC-treated but not in hAC133(+)-injected animals. While transplantation of hAC133(+) cells promoted capillary growth, hMAPC transplantation also induced collateral expansion, decreased muscle necrosis/fibrosis, and improved muscle regeneration. Incorporation of differentiated hAC133(+) or hMAPC progeny into new vessels was limited; however, a paracrine angio/arteriogenic effect was demonstrated in animals treated with hMAPC. Accordingly, hMAPC-conditioned, but not hAC133(+)-conditioned, media stimulated vascular cell proliferation and prevented myoblast, endothelial, and smooth muscle cell apoptosis in vitro. Our study suggests that although hAC133(+) cell and hMAPC transplantation both contribute to vascular regeneration in ischemic limbs, hMAPC exert a more robust effect through trophic mechanisms, which translated into collateral and muscle fiber regeneration. This, in turn, conferred tissue protection and regeneration with longer term functional improvement.

Therapeutic angiogenesis in the management of critical limb ischemia: current concepts and review

Critical limb ischemia (CLI) represents the most severe form of peripheral arterial disease. Manifestations of CLI include rest pain, ischemic ulcers, and/or gangrene. The presence of CLI frequently leads to amputation, and furthermore, patients with CLI are at an increased risk of cardiovascular events including death. Treatment options for CLI when revascularization is not possible are extremely limited. Therapeutic angiogenesis is a promising new tool in the management of CLI. There is a growing body of evidence demonstrating the safety and efficacy of therapeutic angiogenesis with gene and cell therapy. Many factors must be considered in formulating clinically efficacious gene and/or cell therapies. The dosing regimen, route of delivery, and choice of growth factor or cell population must be decided. Although the optimal regimen of therapeutic angiogenesis has yet to be identified, building on the knowledge gained from the early pioneering studies may help to identify the best combination.

Bone marrow-derived mononuclear cell therapy induces distal angiogenesis after local injection in critical leg ischemia

Critical leg ischemia is associated with a high risk of amputation when revascularization is not possible. Cell therapy based on bone marrow-derived mononuclear cells or with peripheral mononuclear cells, collected after stimulation with G-CSF has been used in an attempt to stimulate angiogenesis. Although several studies have raised the hope that such cell therapy may be effective in critical leg ischemia, no direct demonstration of angiogenesis induced by bone marrow-derived mononuclear cell/peripheral mononuclear cell injection has been reported in man. The aim of this study was to identify and to evaluate the extent of the angiogenic process associated with cell therapy in critical leg ischemia in man. To address this question, this pathological study was conducted in patients enrolled in the OPTIPEC clinical trial (Optimization of Progenitor Endothelial Cells in the Treatment of Critical leg ischemia), an interventional cell therapy study in critical leg ischemia. Amputation specimens from these patients were submitted to a standardized dissection protocol. In three patients, an active angiogenesis was observed in the distal part of the ischemic limb but not in the gastrocnemius muscle, the site of bone marrow cell injection. All the newly formed vessels were positive for endothelial cell markers (CD31, CD34, von Willebrand factor) and negative for markers of lymphatic vessels (podoplanin). Immunohistochemical staining for Ki-67 and c-kit showed extensive endothelial cell proliferation within the new vessels. Bone marrow-derived mononuclear cell therapy in patients with critical leg ischemia induces an active, substained angiogenesis in the ischemic and distal parts of the treated limb, although this may not prevent amputation in some patients with very severe ischemia.

Autologous transplantation of bone marrow mononuclear cells for limb ischemia in a caucasian population with atherosclerosis obliterans

BACKGROUND

Autologous transplantation of bone marrow mononuclear cells (ATBMMNC) has been used successfully in critical limb ischemia. All reported patients were of Asian descent, however, and several studies included only young patients with thromboangiitis obliterans. Whether the beneficial results can be extrapolated to older Caucasian patients with atherosclerosis obliterans and a heavy burden of cardiovascular risk factors remains unclear.

METHODS

We enrolled 16 patients (age 78 +/- 2 year) with critical limb ischemia and a high prevalence of hypertension, smoking, diabetes, hypercholesterolemia and uremia. Mononuclear cells were isolated from the bone marrow and injected in the gastrocnemius muscle of the affected limb.

RESULTS

Four patients died because of progressive gangrene (two) or unrelated causes (two). Three patients required an amputation and one patient a femorocrural bypass within 12 weeks. The remaining eight patients had a modest improvement of resting pain and/or trophic lesions. Transcutaneous oxygen pressure (ratio lesion/reference) improved from 0.51 +/- 0.11 before to 0.86 +/- 0.03 (P < 0.001) after 12 weeks, whereas ankle-brachial index did not change significantly (0.42 +/- 0.15 vs. 0.59 +/- 0.1; P = 0.23). The number of visible collateral vessels on digital subtraction angiography changed with 0.89 +/- 0.86 on a scale of 1-4 (P = 0.33). Capillary surface area in a biopsy of gastrocnemius, evaluated by immunostaining for endothelial nitric oxide synthase, increased from 0.61 +/- 0.07% to 2.38 +/- 0.73% (P < 0.05).

CONCLUSIONS

Although ATBMMNC was associated with objective signs of neovascularization, symptomatic improvement was only modest and restricted to the least affected patients. The discrepancy with previous findings may be related to the high prevalence of cardiovascular risk factors which causes endothelial progenitor cell dysfunction.

Multipotent adult progenitor cells sustain function of ischemic limbs in mice

Despite progress in cardiovascular research, a cure for peripheral vascular disease has not been found. We compared the vascularization and tissue regeneration potential of murine and human undifferentiated multipotent adult progenitor cells (mMAPC-U and hMAPC-U), murine MAPC-derived vascular progenitors (mMAPC-VP), and unselected murine BM cells (mBMCs) in mice with moderate limb ischemia, reminiscent of intermittent claudication in human patients. mMAPC-U durably restored blood flow and muscle function and stimulated muscle regeneration, by direct and trophic contribution to vascular and skeletal muscle growth. This was in contrast to mBMCs and mMAPC-VP, which did not affect muscle regeneration and provided only limited and transient improvement. Moreover, mBMCs participated in a sustained inflammatory response in the lower limb, associated with progressive deterioration in muscle function. Importantly, mMAPC-U and hMAPC-U also remedied vascular and muscular deficiency in severe limb ischemia, representative of critical limb ischemia in humans. Thus, unlike BMCs or vascular-committed progenitors, undifferentiated multipotent adult progenitor cells offer the potential to durably repair ischemic damage in peripheral vascular disease patients.

Cell therapy for diabetes mellitus: an opportunity for stem cells?

Diabetes is a chronic disease characterized by a deficit in beta cell mass and a failure of glucose homeostasis. Both circumstances result in a variety of severe complications and an overall shortened life expectancy. Thus, diabetes represents an attractive candidate for cell therapy. Reversal of diabetes can be achieved through pancreas and islet transplantation, but shortage of donor organs has prompted an intensive search for alternative sources of beta cells. This achievement has stimulated the search for appropriate stem cell sources. Both embryonic and adult stem cells have been used to generate surrogate beta cells or otherwise restore beta cell functioning. In this regard, several studies have reported the generation of insulin-secreting cells from embryonic and adult stem cells that normalized blood glucose values when transplanted into diabetic animal models. Due to beta cell complexity, insulin-producing cells generated from stem cells do not possess all beta cell attributes. This indicates the need for further development of methods for differentiation and selection of completely functional beta cells. While these problems are overcome, diabetic patients may benefit from therapeutic strategies based on autologous stem cell therapies addressing late diabetic complications. In this article, we discuss the recent progress in the generation of insulin-producing cells from embryonic and adult stem cells, together with the challenges for the clinical use of diabetes stem cell therapy.

[Non-surgical treatment of critical limb ischemia]

In critical limb ischemia, the aim of the treatment is to increase the arterial blood flow in the affected limb in order to relieve pain, heal trophic lesions, and avoid amputation. In patients in whom revascularization is not possible, medical treatment can occasionally be considered although it may not prevent limb loss in many patients. Medical strategies include the use of antalgics frequently opioids, antiplatet agents and prevention of venous thromboembolism. Selected patients may benefit from intravenous prostanoids, although their efficacy is unconstant. Maintenance of the bed in a dependant position may increase blood perfusion in the affected limbs. Gene and cell therapies, although promissing strategies, are currently evaluated in large clinical trials.

An Introduction to Genetics and Application to Crohnʼs Disease

Gene-based diagnostics and therapeutics are being explored for application in many areas of healthcare. An understanding of the principles of genomics has become fundamental to patient care within all specialties of nursing and is expected to be included in certification exams in the near future. This introductory article is designed to provide practicing Wound, Ostomy, and Continence nurses with basic information to enhance their abilities to comprehend genetics information, apply it to practice, and translate it to colleagues and patients. Specifics about the genetic basis of Crohn's disease are used to illustrate the application of the concepts described in the article.

Autologous bone-marrow mononuclear cell implantation in patients with severe lower limb ischaemia: a comparison of using blood cell separator and Ficoll density gradient centrifugation

Different studies have provided evidence that implantation of bone-marrow mononuclear cells (BM-MNC) into ischaemic limbs can improve tissue vascularization. Based on these results we performed a pilot study in patients with critical lower limb ischaemia to assess efficacy and safety of implantation of autologous BM-MNC. The amount and efficacy of BM-MNC purified either by an automated method or by a manual procedure were compared. Twelve patients with severe unilateral lower limb ischaemia were entered into this study. They were randomly assigned to be injected with BM-MNC sorted on a blood cell separator or isolated by density gradient on Ficoll-Hypaque. BM-MNC were implanted into the ischaemic legs. Patients were monitored with resting ankle-brachial pressure index (ABI), arterial oxygen saturation (SaO(2)), pain-free walking time and rest pain scale evaluation. The automated and manual methods used for mononuclear cell separation gave results not significantly different. Monitored variables improved in both groups. Improvement of ischaemic condition persisted during 24 weeks follow-up. Limb salvage was achieved in five cases. Our results indicate that BM-MNC implantation into ischaemic limbs is a practical, safe and effective method that may significantly contribute to the management of patients with limb ischaemia. The Ficoll method is a simple and effective procedure for BM-MNC concentration that may be useful, mainly in hospitals without sophisticated facilities.