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

Reference Probe for TcpO2 at Rest: A Systematic Review

(1) Background: Transcutaneous oxygen pressure (TcpO₂) is used to determine the severity of lower extremity arterial disease (LEAD). Many authors used a ratio of limb to chest TcpO₂, also called the regional perfusion index (RPI), which should be independent of variations in oxygen delivery and reflective of local limb oxygen supply. The relevance of a reference probe-positioned TcpO₂ electrode is debated. We aimed to review the relevance of the reference probe in previous studies using rest TcpO₂. (2) Methods: We searched Medline and the Cochrane Central Register of Controlled Trials on 22 September 2022 using keywords related to TcpO₂, reference probe and LEAD. (3) Results/Discussion: Fifteen studies were included in the review. Nine studies investigated LEAD severity (n = 9), amputation healing predication (n = 4), surgical outcome prediction (n = 2), therapeutic effect (n = 3) and difference according to diabetic status (n = 1). Four studies investigated more than 1 indication. Among 12 (16.7%) studies using RPI, only two authors found a benefit of using RPI instead of absolute TcpO₂. Using only univariate analysis, one author reported that RPI was significantly related to viability at 1 year, while distal TcpO₂ was not, on 13 limbs. The following year, the same author published a new study including 118 limbs that reported that RPI and absolute TcPO₂ were both prognostic factors for limb viability at 1 year using a multivariate model. (4) Conclusions: Only one study firmly supporting the use of RPI, calculated using a reference probe on the arm, to predict BKA healing. Prospective studies are needed to validate this result; for other indications there is insufficient data supporting the use of a TcpO₂ reference probe at rest.

Stem Cell Therapies in Peripheral Vascular Diseases — Current Status

Peripheral artery diseases include all arterial diseases with the exception of coronary and aortic involvement, more specifically diseases of the extracranial carotids, upper limb arteries, mesenteric and renal vessels, and last but not least, lower limb arteries. Mononuclear stem cells, harvested from various sites (bone marrow, peripheral blood, mesenchymal cells, adipose-derived stem cells) have been studied as a treatment option for alleviating symptoms in peripheral artery disease, as potential stimulators for therapeutic angiogenesis, thus improving vascularization of the ischemic tissue. The aim of this manuscript was to review current medical literature on a novel treatment method — cell therapy, in patients with various peripheral vascular diseases, including carotid, renal, mesenteric artery disease, thromboangiitis obliterans, as well as upper and lower limb artery disease.

Stem cell-based peripheral vascular regeneration

Chronic critical limb ischemia (CLI) represents an end-stage manifestation of peripheral arterial disease (PAD). CLI patients are at very high risk of amputation and cardiovascular complications, leading to severe morbidity and mortality. Because many patients with CLI are ineligible for conventional revascularization procedures, it is urgently needed to explore alternative strategies to improve blood supply in the ischemic tissue. Although researchers initially focused on gene/protein therapy using proangiogenic growth factors/cytokines, recent discovery of somatic stem/progenitor cells including bone marrow (BM)-derived endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) has drastically developed the field of therapeutic angiogenesis for CLI. Overall, early phase clinical trials demonstrated that stem/progenitor cell therapies may be safe, feasible and potentially effective. However, only few late-phase clinical trials have been conducted. This review provides an overview of the preclinical and clinical reports to demonstrate the usefulness and the current limitations of the cell-based therapies.

Autologous Bone Marrow Mononuclear Cell Implantation and Its Impact on the Outcome of Patients With Critical Limb Ischemia - Results of a Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Cell therapy is a therapeutic option for patients presenting with nonrevascularizable critical limb ischemia (CLI). However there is a lack of firm evidence on its efficacy because of the paucity of randomized controlled trials.Methods and Results:The BALI trial was a multicenter, randomized, controlled, double-blind clinical trial that included 38 patients. For all of them, 500 mL of bone marrow were collected for preparation of a BM-MNC product that was implanted in patients assigned to active treatment. For the placebo group, a placebo cell-free product was implanted. Within 6 months after inclusion, major amputations had to be performed in 5 of the 19 placebo-treated patients and in 3 of the 17 BM-MNC-treated patients. According to a classical logistic regression analysis there was no significant difference. However, when using the jackknife analysis, 6 months after inclusion BM-MNC implantation was associated with a lower risk of major amputation (odds ratio (OR): 0.55; 95% confidence interval (CI): 0.52-0.58; P<0.0001) and of occurrence of any event (major or minor amputation, or revascularization) (OR: 0.30; 95% CI: 0.29-0.31; P<0.0001). The secondary endpoints (i.e., pain, ulcers, TcPO₂, and ankle-brachial index value) were not statistically different between groups.

CONCLUSIONS

Our results suggested that cell therapy reduced the risk of major amputation in patients presenting with nonrevascularizable CLI.

Percutaneous injection of bone marrow mesenchymal stem cells for ankle non-unions decreases complications in patients with diabetes

PURPOSE

Clinical studies in diabetic patients have demonstrated that there is a high incidence of complications in distal tibia and ankle fracture treatments. One strategy to mitigate issues with wound healing and infection in diabetic patients is to use a percutaneous technique in which autologous, bone marrow-derived, concentrated cells are injected at the site of non-unions.

METHODS

Eighty-six ankle non-union in diabetic patients were treated with bone marrow mesenchymal stem cells (BM-MSCs) delivered in an autologous bone marrow concentrate (BMC). Clinical outcomes of the 86 diabetic non-union patients treated with BMC were compared with 86 diabetic matched non-unions treated with a standard bone iliac crest autograft.

RESULTS

Treatment with BMC promoted non-union healing in 70 among 86 diabetic patients (82.1 %) with a low number of complications. Of the 86 diabetic patients treated with iliac bone graft, 53 (62.3 %) had healing; major complications were observed: 5 amputations, 11 osteonecroses of the fracture wound edge and 17 infections.

CONCLUSIONS

In diabetic patients with ankle non-unions, treatment with BM-MSCs from bone marrow concentrate may be preferable in view of the high risks of major complications after open surgery and iliac bone grafting, and improved healing rates compared with standard iliac bone autograft treatment.

Efficacy of autologous bone marrow mononuclear cell therapy in patients with peripheral arterial disease

AIM

Peripheral arterial disease (PAD), particularly critical limb ischemia (CLI), is a severe cause of amputation and mortality. More than 50% of diabetic patients with CLI die within four to five years. The development of novel stem cell therapies may bring new hope to these patients. We aimed to assess the efficacy of autologous bone marrow cell therapy for treating CLI using a meta-analysis.

METHODS

We searched the literature in PubMed, the Cochrane Central Registry of Controlled Trials, the Elsevier database and EBSCO for trials of autologous cell therapy in patients with severe PAD published before October 30, 2013. We chose objective clinical endpoints to assess the efficacy of therapy in the meta-analysis, including changes in the ankle-brachial index (ABI), transcutaneous oxygen tension (TcO2), pain scale (0-10 scale) and amputation-free survival (AFS).

RESULTS

Thirty-one articles reporting clinical trials involving a total of 1,214 patients treated with bone marrow stem cell-based therapy were collected for the meta-analysis, in which the randomized controlled trials (RCTs) and other trials (non-RCTs) were classified into two groups. Regarding the efficacy of stem cell therapy, the ABI showed significant increases (P＜0.05) at 12 , 24 and 48 weeks after therapy in the non-RCT and RCT groups, but not after four to eight weeks in the non-RCT group. The TcO2 values also increased in the RCT group at four to eight weeks after therapy and 24 weeks after therapy (P＜0.001) and in the non-RCT group at four to eight weeks after therapy (P= 0.01), although no significant increases were observed in the RCT group at 12 weeks after therapy or the non-RCT group at 24 weeks after therapy. Meanwhile, pain was significantly reduced (P＜0.05) at four to eight weeks and 24 weeks after therapy in both the non-RCT and RCT groups, but not at four to eight weeks or 12 weeks after therapy in the RCT group. In addition, the long-term clinical trials demonstrated that the AFS rate improved after therapy with bone marrow stem cells (one-year AFS, P＜0.00001; three-year AFS, P=0.0003).

CONCLUSIONS

The present results suggest that autologous bone marrow stem cells have an advantageous therapy effect in PAD patients who are not eligible for revascularization.

Postischemic revascularization: from cellular and molecular mechanisms to clinical applications

After the onset of ischemia, cardiac or skeletal muscle undergoes a continuum of molecular, cellular, and extracellular responses that determine the function and the remodeling of the ischemic tissue. Hypoxia-related pathways, immunoinflammatory balance, circulating or local vascular progenitor cells, as well as changes in hemodynamical forces within vascular wall trigger all the processes regulating vascular homeostasis, including vasculogenesis, angiogenesis, arteriogenesis, and collateral growth, which act in concert to establish a functional vascular network in ischemic zones. In patients with ischemic diseases, most of the cellular (mainly those involving bone marrow-derived cells and local stem/progenitor cells) and molecular mechanisms involved in the activation of vessel growth and vascular remodeling are markedly impaired by the deleterious microenvironment characterized by fibrosis, inflammation, hypoperfusion, and inhibition of endogenous angiogenic and regenerative programs. Furthermore, cardiovascular risk factors, including diabetes, hypercholesterolemia, hypertension, diabetes, and aging, constitute a deleterious macroenvironment that participates to the abrogation of postischemic revascularization and tissue regeneration observed in these patient populations. Thus stimulation of vessel growth and/or remodeling has emerged as a new therapeutic option in patients with ischemic diseases. Many strategies of therapeutic revascularization, based on the administration of growth factors or stem/progenitor cells from diverse sources, have been proposed and are currently tested in patients with peripheral arterial disease or cardiac diseases. This review provides an overview from our current knowledge regarding molecular and cellular mechanisms involved in postischemic revascularization, as well as advances in the clinical application of such strategies of therapeutic revascularization.

Both autologous bone marrow mononuclear cell and peripheral blood progenitor cell therapies similarly improve ischaemia in patients with diabetic foot in comparison with control treatment

BACKGROUND

The aim of our study was to compare the effect of bone marrow mononuclear cell and peripheral blood progenitor cell therapies in patients with diabetic foot disease and critical limb ischaemia unresponsive to revascularization with conservative therapy.

METHODS

Twenty-eight patients with diabetic foot disease (17 treated by bone marrow cells and 11 by peripheral blood cell) were included into an active group and 22 patients into a control group without cell treatment. Transcutaneous oxygen pressure and rate of major amputation, as the main outcome measures, were compared between bone marrow cells, peripheral blood cell and control groups over 6 months; both cell therapy methods were also compared by the characteristics of cell suspensions. Possible adverse events were evaluated by changes of serum levels of angiogenic cytokines and retinal fundoscopic examination.

RESULTS

The transcutaneous oxygen pressure increased significantly (p < 0.05) compared with baseline in both active groups after 6 months, with no significant differences between bone marrow cells and peripheral blood cell groups; however, no change of transcutaneous oxygen pressure in the control group was observed. The rate of major amputation by 6 months was significantly lower in the active cell therapy group compared with that in the control group (11.1% vs. 50%, p = 0.0032), with no difference between bone marrow cells and peripheral blood cell. A number of injected CD34+ cells and serum levels of angiogenic cytokines after treatment did not significantly differ between bone marrow cells and peripheral blood cell.

CONCLUSIONS

Our study showed a superior benefit of bone marrow cells and peripheral blood cell treatments of critical limb ischaemia in patients with diabetic foot disease when compared with conservative therapy. There was no difference between both cell therapy groups, and no patient demonstrated signs of systemic vasculogenesis.

Autologous bone marrow cell therapy for peripheral arterial disease

Inadequate blood supply to tissues caused by obstruction of arterioles and/or capillaries results in ischemic injuries – these injuries can range from mild (eg, leg ischemia) to severe conditions (eg, myocardial infarction, stroke). Surgical and/or endovascular procedures provide cutting-edge treatment for patients with vascular disorders; however, a high percentage of patients are currently not treatable, owing to high operative risk or unfavorable vascular involvement. Therapeutic angiogenesis has recently emerged as a promising new therapy, promoting the formation of new blood vessels by the introduction of bone marrow–derived stem and progenitor cells. These cells participate in the development of new blood vessels, the enlargement of existing blood vessels, and sprouting new capillaries from existing blood vessels, providing evidence of the therapeutic utility of these cells in ischemic tissues. In this review, the authors describe peripheral arterial disease, an ischemic condition affecting the lower extremities, summarizing different aspects of vascular regeneration and discussing which and how stem cells restore the blood flow. The authors also present an overview of encouraging results from early-phase clinical trials using stem cells to treat peripheral arterial disease. The authors believe that additional research initiatives should be undertaken to better identify the nature of stem cells and that an intensive cooperation between laboratory and clinical investigators is needed to optimize the design of cell therapy trials and to maximize their scientific rigor. Only this will allow the results of these investigations to develop best clinical practices. Additionally, although a number of stem cell therapies exist, many treatments are performed outside international and national regulations and many clinical trials have been not registered on databases such as ClinicalTrials.gov or EudraCT. Therefore, more rigorous clinical trials are required to confirm the first hopeful results and to address the challenging issues.

A phase II trial of autologous transplantation of bone marrow stem cells for critical limb ischemia: results of the Naples and Pietra Ligure Evaluation of Stem Cells study

Critical limb ischemia (CLI) is a vascular disease affecting lower limbs, which is going to become a demanding challenge because of the aging of the population. Despite advances in endovascular therapies, CLI is associated with high morbidity and mortality. Patients without direct revascularization options have the worst outcomes. To date, 25%-40% of CLI patients are not candidates for surgical or endovascular approaches, ultimately facing the possibility of a major amputation. This study aimed to assess the safety and efficacy of autologous bone marrow (BM) transplantation performed in "no-option" patients, in terms of restoring blood perfusion by collateral flow and limb salvage. A multicenter, prospective, not-controlled phase II study for no-option CLI patients was performed. Patients were subjected to intra-arterial infusion of autologous bone marrow and followed for 12 months after the treatment. Variation of blood perfusion parameters, evaluated by laser Doppler flowmetry or transcutaneous oximetry, was set as the primary endpoint at 12 months after treatment and amputation-free survival as the secondary endpoint. Sixty patients were enrolled and treated with BM transplantation, showing improvement in objective and subjective measures of perfusion. Furthermore, survival analysis demonstrated improved amputation-free survival rates (75.2%) at 12 months after the treatment. This study provides further evidence that autologous bone marrow transplantation is well tolerated by CLI patients without adverse effects, demonstrating trends toward improvement in perfusion and reduced amputation rate, confirming the feasibility and safety of the procedure.

Safety and efficacy of autologous cell therapy in critical limb ischemia: a systematic review

Researchers have accumulated a decade of experience with autologous cell therapy in the treatment of critical limb ischemia (CLI). We conducted a systematic review of clinical trials in the literature to determine the safety and efficacy of cell therapy in CLI. We searched the literature for clinical trials of autologous cell therapy in CLI, including observational series of five or more patients to accrue a large pool of patients for safety analysis. Safety analysis included evaluation of death, cancer, unregulated angiogenesis, and procedural adverse events such as bleeding. Efficacy analysis included the clinical endpoints amputation and death as well as functional and surrogate endpoints. We identified 45 clinical trials, including seven RCTs, and 1,272 patients who received cell therapy. The overall adverse event rate was low (4.2%). Cell therapy patients did not have a higher mortality rate than control patients and demonstrated no increase in cancer incidence when analyzed against population rates. With regard to efficacy, cell therapy patients had a significantly lower amputation rate than control patients (OR 0.36, p = 0.0004). Cell therapy also demonstrated efficacy in a variety of functional and surrogate outcomes. Clinical trials differed in the proportion of patients with risk factors for clinical outcomes, and these influenced rates of amputation and death. Cell therapy presents a favorable safety profile with a low adverse event rate and no increase in severe events such as mortality and cancer and treatment with cell therapy decreases the risk of amputation. Cell therapy has a positive benefit-to-risk ratio in CLI and may be a valuable treatment option, particularly for those challenging patients who cannot undergo arterial reconstruction.

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.

Three-dimensional culture and bioreactors for cellular therapies

A bioreactor is defined as a specifically designed vessel to facilitate the growth of organisms and cells through application of physical and/or electrical stimulus. When cells with therapeutic potential were first discovered, they were initially cultured and expanded in two-dimensional (2-D) culture vessels such as plates or T-flasks. However, it was soon discovered that bioreactors could be used to expand and maintain cultures more easily and efficiently. Since then, bioreactors have come to be accepted as an indispensable tool to advance cell and tissue culture further. A wide array of bioreactors has been developed to date, and in recent years businesses have started supplying bioreactors commercially. Bioreactors in the research arena range from stirred tank bioreactors for suspension culture to those with various mechanical actuators that can apply different fluidic and mechanical stresses to tissues and three-dimensional (3-D) scaffolds. As regenerative medicine gains more traction in the clinic, bioreactors for use with cellular therapies are being developed and marketed. While many of the simpler bioreactors are fit for purpose, others fail to satisfy the complex requirements of tissues in culture. We have examined the use of different types of bioreactors in regenerative medicine and evaluated the application of bioreactors in the realization of emerging cellular therapies.

Upper extremity ischemia treated with tissue repair cells from adult bone marrow

BACKGROUND

Unreconstructable critical ischemia with gangrene of the upper extremity is rarely due to atherosclerosis alone, and few treatment options exist. We describe a patient with gangrene of both hands as a result of unreconstructable atherosclerotic disease of both upper extremities who was successfully treated with tissue repair cells (TRCs) produced from the patient's bone marrow.

METHODS

A patient with type 1 diabetes was referred with bilateral upper extremity digital gangrene due to unreconstructable forearm and hand atherosclerosis. He was evaluated for therapeutic angiogenesis using TRCs.

RESULTS

Following the intramuscular injection of TRCs produced from autologous bone marrow stem cells, the patient demonstrated improved arterial perfusion and a durable clinical response with healing of all amputation sites and cessation of pain.

CONCLUSIONS

The production of TRCs results in the expansion of stem and early progenitor cells, including CD90+ mesenchymal cells and endothelial progenitor cells. This is the first reported case of end-stage upper extremity ischemia treated with TRCs harvested from adult bone marrow.

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.

Use of autologous bone marrow mononuclear cell implantation therapy as a limb salvage procedure in patients with severe peripheral arterial disease

BACKGROUND

Few options other than amputation exist for some patients with peripheral arterial occlusive disease (PAD) and severe anatomical limitations.

METHODS

This prospective study presents short-term results of dual intramuscular and intra-arterial autologous bone marrow mononuclear cell (BM-MNC) implantation for the treatment of patients with severe PAD in whom amputation was considered the only viable treatment option. Baseline, two-week, and three-month evaluations were conducted. Ankle brachial indices (ABI) were calculated for both the dorsal pedis and the posterior tibial arteries. Rest pain and ulcer healing also were assessed. Success was defined as meeting the following four criteria: improvement in ABI measurements; relief of rest pain; ulcer healing, if applicable; and absence of major limb amputations. Patients not undergoing major limb amputations continued to be monitored for subsequent procedures.

RESULTS

Nine patients for whom limb amputation was recommended underwent this procedure. The study population was comprised of five females and four males, with a mean age of 61.7 years. Eight (88.9%) patients had rest pain. Seven (77.8%) patients also had diabetes. Non-healing ulcers were present in eight (88.9%) cases. After the procedure, non-significant improvements of 0.12 and 0.08 in ABI were observed for the dorsalis pedis and posterior tibial ankle arteries, respectively. Three (33.3%) major amputations subsequently were performed, including a below-knee amputation 4.1 weeks after the BM-MNC implantation and two above-knee amputations at 5.4 and 11.0 weeks after the procedure. The six (66.7%) patients who did not have major amputations demonstrated improvement in symptom severity three months after the procedure, as evidenced by alleviation of rest pain and improvements by at least one level in Rutherford and Fontaine classifications, and have not required amputations at a mean follow-up of 7.8 months. Complete wound healing was achieved within three months in all patients who had ulcers prior to BM-MNC implantation and for whom amputation was not required. This specific BM-MNC implantation technique was fully successful in three (33.3%) patients, as major amputation was avoided and the other applicable criteria were met. Five (55.6%) additional patients demonstrated success in at least one of the four criteria.

CONCLUSIONS

With eight (88.9%) of nine patients showing some level of improvement and amputation avoided in six (66.7%) patients, these short-term results indicate the use of BM-MNC implantation as a means of limb salvage therapy for patients with severe PAD shows promise in postponing or avoiding amputation in a patient population currently presented with few alternatives to amputation.

Emerging hurdles in stem cell therapy for peripheral vascular disease

Peripheral vascular disease (PVD) is a growing medical problem in Western societies and presents itself mainly in two different clinical forms. Intermittent claudication is an early moderate manifestation, while patients with critical limb ischemia suffer from severe muscle tissue loss or ulcers and are at high risk for limb amputation. Unfortunately, many patients cannot be helped with currently available surgical or endovascular revascularization procedures because of the complex anatomy of the vascular occlusion and/or the presence of other risk factors. Noninvasive stem cell therapy has been proposed as an alternative for such patients. Although pioneering clinical experience with stem cell-related therapy seems promising, it is too early for general clinical use of this technique, since many questions remain unanswered. Indeed, while questions about safety, dose, and administration route/timing/frequency are the first ones to be addressed when designing a stem cell-based clinical approach, there is accumulating evidence from recent (pre-)clinical studies that other issues may also be at stake. For instance, the choice of stem cells to be used and its precise mechanism of action, the need/possibility for concurrent tissue regeneration in case of irreversible tissue loss, the differentiation degree and specific vascular identity of the transplanted cells, and the long-term survival of engrafted cells in the absence of a normal supportive tissue environment should be well considered. Here, rather than presenting a comprehensive and extensive overview on the current literature on stem/progenitor cells and revascularization, we highlight some of the outstanding issues emerging from the recent (pre-)clinical literature that may codetermine the successful application of stem cells in a wide range of PVD patients in the future.