Long-term clinical outcomes for patients with lower limb ischemia implanted with G-CSF-mobilized autologous peripheral blood mononuclear cells

Acupoint transplantation versus non-acupoint transplantation using autologous peripheral blood mononuclear cells in treating peripheral arterial disease

Numerous studies have discussed the therapeutic outcomes of using cell therapy or acupuncture to treat peripheral artery disease (PAD). However, there are no long-term studies on the safety and efficacy of transplanting peripheral blood mononuclear cells (PBMNCs) via acupoints to treat PAD. We first reviewed the short-term and long-term clinical results of PAD patients treated with PBMNCs through intramuscular non-acupoint transplantation (control group; n = 45) or intramuscular acupoint transplantation (acupoint group; n = 45) at a single university hospital general medical center between December 2002 and September 2022. Pain intensity (assessed with the verbal rating scale [VRS] score) in the acupoint group was considerably lower than that in the control group at month 1 (mean ± standard deviation [SD]: 1.29 ± 0.96 vs 1.76 ± 0.82; P = 0.016) and month 3 (mean ± SD: 1.27 ± 0.90 vs 1.61 ± 0.86; P = 0.042). We observed significant improvement of VRS score (P < .001 for all) and ankle-brachial index (ABI; P < .001 for all) from baseline in both groups at months 1, 3, 6, 12, 36, and 60. The 10-year cumulative rate of major amputation-free survival (MAFS) was higher in the acupoint group as compared to the control group (81.9%, 95% confidence interval [CI]: 71.3%-94.1% vs 78.5%, 95% CI: 66.7%-92.3%; P = 0.768). Compared with the routine injection method, intramuscular transplantation of PBMNCs via selected acupoints could significantly decrease the short-term pain intensity in patients with PAD, which remains an option for consideration.

Long-Term Outcomes of Peripheral Blood Mononuclear Cells in the Treatment of Angiitis-Induced No-Option Critical Limb-Threatening Ischemia

Background: Peripheral blood mononuclear cells (PBMNCs) showed encouraging short outcomes in the treatment of angiitis-induced no-option critical limb-threatening ischemia (AICLTI) in the pilot study. This study aimed to demonstrate the long-term outcomes of this treatment.

Methods: From May 2014 to December 2018, patients diagnosed with AICLTI and treated by autotransplantation of PBMNCs in our center were enrolled and analyzed. The primary endpoint was major amputation-free survival (MAFS), the secondary endpoints included peak pain-free walking time (PPFWT), Wong-Baker FACES pain rating scale score (WFPRSS), labor recovery, ankle-brachial index (ABI), transcutaneous partial oxygen pressure (TcpO2), and SF-36v2 scores.

Results: A total of 58 patients were enrolled. During a minimal follow-up of 36 months, the MAFS was 93.1% and the labor competence restored rate was 62.1%. The WFPRSS was decreased from 8.7 ± 1.6 to 1.6 ± 3.2, and PPFWT was significantly improved from 2.9 ± 4.2 min to 16.6 ± 6.9 min. The quality of life was also significantly improved at each follow-up point. Perfusion evaluating parameters, such as ABI and TcPO2, were also significantly improved. No critical adverse event was observed during the treatment and follow-up period.

Conclusions: The treatment of AICLTI by autotransplantation of PBMNCs demonstrated encouraging long-term results. It could not only restore labor competence, improve the quality of life, but also significantly reduce the major amputation rate.

Autologous peripheral blood-derived stem cells transplantation for treatment of no-option angiitis-induced critical limb ischemia: 10-year management experience

Background

Previous studies have demonstrated that no-option angiitis-induced critical limb ischemia (NO-AICLI) could be significantly improved by transplantation of peripheral blood-derived stem cells (PBDSCs). Additionally, a randomized controlled trial (RCT) recently conducted by us suggested that peripheral blood-derived purified CD34+ cells (PCCs) were not inferior to non-purified peripheral blood mononuclear cells (PBMNCs) at limb salvage in treatment of NO-AICLI. However, most of these clinical trials whether RCT or single-arm studies were characterized with a small sample size and absence of long-term outcomes.

Methods

To analyze long-term clinical outcomes of PBDSCs transplantation for NO-AICLI, we reviewed clinical data of patients with NO-AICLI receiving PBDSCs transplantation at our center during the past decade. Meanwhile, we first compared the long-term safety and efficacy of intramuscular transplantation of PCCs versus PBMNCs in a sizable number of patients with NO-AICLI.

Results

From May 2009 to December 2019, a total of 160 patients with NO-AICLI patients were treated by PBDSCs transplantation (82 with PCCs, 78 with PBMNCs) at our center. Baseline characteristics between two groups were similar. Up to June 2020, the mean follow-up period was 46.6 ± 35.3 months. No critical adverse events were observed in either group. There was one death during the follow-up period. A total of eight major amputations occurred. The cumulative major amputation-free survival (MAFS) rate at 5 years after PBDSCs transplantation was 94.4%, without difference between two groups (P = .855). Wound healing, rest pain, pain-free walking time, ankle-brachial index, transcutaneous oxygen pressure, and quality of life (QoL) also significantly improved after PBDSCs transplantation.

Conclusions

Autologous PBDSCs intramuscular transplantation could significantly decrease the major amputation rates and improve the QoL in patients with NO-AICLI. Long-term observation of a large sample of patients confirmed that the clinical benefits of PBDSCs transplantation were durable, without difference between the PCCs and PBMNCs groups.

[Problems and prospects of cell therapy for critical ischaemia of lower limbs]

BACKGROUND

Cell therapy was proposed as a procedure of indirect revascularization for patients with critical ischaemia of lower extremities for whom endovascular and surgical revascularization is impossible. We present herein a review of the state of the art of studies in the field of cell therapy of this cohort of patients.

BASIC PROVISIONS

Cell therapy has proved safe, however, the results of studies of efficacy are relatively ambiguous and unconvincing. The number of patients in separately taken clinical trials is minimal. The reviewed studies differed not only by heterogeneity of the cell types used but by the routes of administration of cells (cells were delivered either intramuscularly (predominantly) or intraarterially) and the duration of follow up (time of assessment and duration of follow up varied from 1 month to 2 years). One of the problems became the lack of the routine study of the angiogenic potential of stem cells prior to their clinical application. It is known that the angiogenic activity of multipotent cells of apparently healthy patients may differ from that of patients suffering from atherosclerosis, chronic renal failure, diabetes.

CONCLUSIONS

It is supposed that treatment with stem cells or precursor cells is more efficient as compared to protein or gene therapy not only owing to direct vasculogenic properties but a paracrine action through excretion of proangiogenic biologically active substances. More studies with larger cohorts are necessary to provide stronger safety and efficacy data on cell therapy. Besides, a promising trend in the field of cellular approaches is modulation of regenerative capability of stem cells, which may help overcome difficulties in understanding the place of cell therapy in therapeutic angiogenesis.

Autologous stem cell therapy for peripheral arterial disease: a systematic review and meta-analysis of randomized controlled trials

Background

Peripheral arterial disease (PAD) is a common cause of disability and mortality. The reconstruction of blood circulation presents to be the key to treatment, which can be achieved by surgery and interventional therapy. Since 40% patients have lost the chance for the therapy, a new method is needed to reduce the amputation and mortality rate for “no-option” patients. The objective of our systematic review and meta-analysis was to evaluate the efficacy and safety of autologous implantation of stem cells in patients with PAD critically, compared with active controls and placebo.

Methods

Randomized controlled trials (RCTs) of autologous implantation of stem cells compared with placebo and control for PAD were included. Electronic medical databases including MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), the Chinese Biomedical Literature Database, China National Knowledge Infrastructure (CNKI), and ClinicalTrials.gov were searched from initial period to September 2018. Independently, two reviewers screened citations, extracted data, and assessed the risk of bias according to the criteria of the Cochrane handbook. The quality of evidence was evaluated by GRADE evidence profile. The primary outcomes consisted of amputation rate, major amputation rate, ulcer healing rate, and side effects. The second outcomes included ankle-brachial index (ABI), transcutaneous oxygen tension (TcO2), pain-free walking distance (PFWD), and rest pain score. Statistical analysis was conducted via RevMan 5.3 and Stata 12.0.

Results

According to the twenty-seven RCTs, 1186 patients and 1280 extremities were included and the majority of studies showed a high risk of bias. Meta-analysis indicated that autologous stem cell therapy was more effective than conventional therapy on the healing rate of ulcers [OR = 4.31 (2.94, 6.30)]. There was also significant improvement in ABI [MD = 0.13 (0.10, 0.17)], TcO2 [MD = 0.13 (0.10, 0.17)], and PFWD [MD = 178.25 (128.18, 228.31)] while significant reduction was showed in amputation rate [OR = 0.50 (0.36, 0.69)] and rest pain scores [MD = − 1.61 (− 2.01, − 1.21)]. But the result presented no significant improvement in major limb salvage [0.66 (0.42, 1.03)]. Besides, stem cell therapy could reduce the amputation rate [OR = 0.50 (0.06, 0.45] and improve the ulcer healing rate [OR = 4.34 (2.96, 6.38] in DM subgroup. Eight trials reported the side effects of autologous stem cell therapy, and no serious side effects related to stem cells were reported. GRADE evidence profile showed all the quality evidence of outcomes were low.

Conclusions

Based on the review, autologous stem cell therapy may have a positive effect on “no-option” patients with PAD, but presented no significant improvement in major limb salvage. However, the evidence is insufficient to prove the results due to high risk of bias and low-quality evidence of outcomes. Further researches of larger, randomized, double-blind, placebo-controlled, and multicenter trials are still in demand.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1254-5) contains supplementary material, which is available to authorized users.

Cell therapy of critical limb ischemia-problems and prospects

Cell therapy is proposed for indirect revascularization for the patient's incurable by endovascular or surgical revascularization. The therapy with stem cells (SCs) or progenitor cells is assumed to be more efficient as compared with protein or gene therapy not only because of their direct vasculogenic properties, but also thanks to their paracrine effect via secretion of manifold biologically active substances. This review gives an overview of the potential of SC-based therapy for critical limb ischemia (CLI), putative mechanism underlying cell therapy, and comparison of cell therapy to angiogenesis gene therapy in CLI treatment. Human trial data and meta-analysis, as well as some problems of clinical trials and considerations for future SC-based therapy in CLI are also discussed.

Predictors of responders to mononuclear stem cell-based therapeutic angiogenesis for no-option critical limb ischemia

Background

Although the mononuclear cell (MNC) transplantation could theoretically induce therapeutic angiogenesis in the patients with no-option critical limb ischemia (NO-CLI), the clinical responses to this approach are inconsistent among different clinical trials. The purpose of this study was to identify the prognostic factors of responders and develop a predictive nomogram to guide patient selection.

Methods

We retrospectively reviewed a consecutive NO-CLI cohort who received peripheral blood-derived transplantation in our center. The patients who survived and achieved complete remission of CLI at 6 months post-transplantation were defined as responders. Logistic regression models were used to screen and identify the prognostic factors based on which predictive nomogram was developed. A receiver operating characteristic (ROC) curve and a calibration curve were drawn to determine the discrimination level and predictive accuracy.

Results

The study ultimately enrolled 103 patients, including 58 responders and 45 non-responders. Based on the multivariate regression analysis, age ≥ 50 years (odds ratio [OR] 0.201, P = 0.004), blood fibrinogen > 4 g/L (OR 0.176, P = 0.003), arterial occlusion above the knee/elbow (OR 0.232, P = 0.010), the transcutaneous pressure of oxygen (TcPO₂) (OR 1.062, P = 0.006), and the Log total transplanted CD34⁺ cell count (OR 3.506, P = 0.046) were identified as independent prognostic factors of the responders in the nomogram. An area under the ROC curve of 0.851 indicated good discrimination, and the calibration curve of the predicted probability showed optimal agreement with that of the observed probability.

Conclusions

Age, blood fibrinogen, arterial occlusion level, TcPO₂, and the total transplanted CD34⁺ cell count were independent prognostic factors of the responders. A nomogram with high discrimination and accuracy was developed to provide individualized predictions.

Trail registration

ChiCTR, ChiCTR1800019401. Registered 9 November 2018—Retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1117-5) contains supplementary material, which is available to authorized users.

First-in-Man Clinical Pilot Study Showing the Safety and Efficacy of Intramuscular Injection of Basic Fibroblast Growth Factor With Atelocollagen Solution for Critical Limb Ischemia

BACKGROUND

Therapeutic angiogenesis with basic fibroblast growth factor (bFGF) with atelocollagen was confirmed in a study using a limb ischemia mouse model. Because the number of elderly patients with critical limb ischemia (CLI) is increasing, particularly that caused by arteriosclerosis obliterans (ASO), the development of less invasive angiogenesis therapies desired. Methods and Results: This first-in-man clinical study was designed to assess the safety and efficacy of i.m. injection of bFGF with atelocollagen. Human recombinant bFGF (200 μg), combined with 4.8 mL 3% atelocollagen solution, was prepared and injected into the gastrocnemius muscle of the ischemic leg. The primary endpoint was safety, evaluated on all adverse events over 48 weeks after this treatment. The secondary endpoint was efficacy, evaluated by improvement of ischemic symptoms. No serious procedure-related adverse events were observed during the follow-up period. Visual analogue scale (VAS) score was significantly improved at 4, 24 and 48 weeks compared with baseline (P<0.05), and 7 patients became pain free during the follow-up period. Fontaine classification was improved in 4 of 10 patients at 48 weeks. Cyanotic lesions disappeared in 2 patients at 4 weeks.

CONCLUSIONS

I.m. injection of bFGF with atelocollagen is safe and feasible in patients with CLI. Randomized controlled trials are therefore needed to confirm these results.

Purified CD34+ cells versus peripheral blood mononuclear cells in the treatment of angiitis-induced no-option critical limb ischaemia: 12-Month results of a prospective randomised single-blinded non-inferiority trial

BACKGROUND

Peripheral blood mononuclear cells (PBMNCs) and purified CD34+ cells (PCCs) are increasingly being used at treating no-option critical limb ischaemia (NO-CLI). We aimed to compare the efficacies and uncover the advantages associated with each treatment approach.

METHODS

A randomised single-blinded non-inferiority trial (Number: NCT 02089828) was performed. NO-CLI patients were 1:1 randomised to the PBMNCs and PCCs groups, and compared in relation to safety and efficacy outcomes. The primary efficacy outcomes included major amputation and total amputation over 12 months. The major amputation-free survival (MAFS) and total amputation-free survival (TAFS) rates were calculated.

FINDINGS

Fifty patients (25 per group, 47 with thromboangiitis obliterans and 3 with other angiitis) were enrolled, with a median follow-up period of 24.5 months (interquartile range: 17-34 months). One patient in the PCCs group was lost at 2 months and one major amputation occurred in the PBMNCs group at 3 months post-transplantation. The total amputation rates at 6 months post-transplantation were 28.0% in the PCCs group and 16.0% in the PBMNCs group (p = 0.343), and remained unchanged at 12 months. The groups did not differ regarding the MAFS and TAFS (Breslow-Wilcoxon test: p = 0.3014 and p = 0.3414). The PCCs group had a significantly higher probability of rest pain relief than the PBMNCs group (Breslow-Wilcoxon test: p = 0.0454).

INTERPRETATION

PCCs was not inferior to PBMNCs at limb salvage in the treatment of angiitis-induced NO-CLI and appeared to induce earlier ischaemia relief. Each cell type had specific advantages. These outcomes require verification from longer-term trials involving larger numbers of patients. FUND: Training program for outstanding academic leaders of Shanghai health and family planning system (Hundred Talent Program，Grant No. 2018BR40); China National Natural Science Funds (Grant No. 30801122); The excellent core member training programme at Zhongshan Hospital, Fudan University, China (Grant No. 2015ZSYXGG02); and Zhongshan Funds for the Institute of Vascular Surgery, Fudan University, China.

CLINICAL TRIAL REGISTRATION

This study is registered with ClinicalTrials.gov (NCT 02089828).

Autologous Granulocyte Colony-Stimulating Factor-Mobilized Peripheral Blood CD34 Positive Cell Transplantation for Hemodialysis Patients with Critical Limb Ischemia: A Prospective Phase II Clinical Trial

Critical limb ischemia (CLI) is a devastating disease in patients undergoing hemodialysis (HD). Based on the unsatisfactory results of autologous mononuclear cell transplantation for patients with CLI undergoing HD, we conducted a phase II clinical trial to evaluate the safety and efficacy of granulocyte colony‐stimulating factor (G‐CSF)‐mobilized peripheral blood‐derived autologous purified CD34 positive (CD34+) cell transplantation for CLI in patients undergoing HD. Six patients with CLI (two with Rutherford category 4 and four with Rutherford category 5) were enrolled. As for primary endpoint, there were no major adverse events related to this therapy. As for efficacy, the amputation‐free survival rate was 100% at 1 year after cell therapy. Both rest pain scale and ulcer size were significantly improved as early as 4 weeks after therapy compared with baseline (p < .01), and three out of five ulcers completely healed within 12 weeks after cell transplantation. Clinical severity, including Fontaine scale and Rutherford category, significantly improved at 24 weeks after cell transplantation (p < .05), and further improved at 52 weeks (p < .01) compared with baseline. The improvement rate from CLI stage to non‐CLI stage was 83.3% at 52 weeks. Toe skin perfusion pressure and absolute claudication distance were also significantly improved. In conclusion, G‐CSF‐mobilized peripheral blood CD34+ cell transplantation was safe, feasible, and effective for patients with CLI undergoing HD. stem cells translational medicine2018;7:774–782

Human primary CD34+ cells transplantation for critical limb ischemia

BACKGROUND

The goal of this study was to characterize the properties of human CD34⁺ cells in culture and investigate the feasibility and efficacy of CD34⁺ transplantation in a mouse model of limb ischemia and in patients with no-option critical limb ischemia.

METHODS

Human CD34⁺ cells isolated from peripheral blood and grown in culture for up to four passages stained positively for the surface markers CD34 and CD133 and showed high viability after cryopreservation and recovery. Seven days after surgery to induce limb ischemia, ischemic muscles of nude mice were injected with CD34⁺ cells. Two weeks later, mice were scored for extent of ischemic injury, and muscle tissue was collected for immunohistochemical analysis of vascular endothelial cells and RT-PCR analysis of cytokine expression.

RESULTS

Injury scores of CD34⁺ -treated, but not control, mice were significantly different before and after transplantation. Vascular density and expression of VEGF and bFGF mRNAs were also significantly increased in the treated mice. Patients with severe lower extremity arterial ischemia were injected with their own CD34⁺ cells in the affected calf, foot, or toe. Significant improvements were observed in peak pain-free walking time, ankle-brachial index, and transcutaneous partial oxygen pressure. These findings demonstrate that growth of human CD34⁺ cells in vitro and cryopreservations are feasible.

CONCLUSION

Such cells may provide a renewable source of stem cells for transplantation, which appears to be a feasible, safe, and effective treatment for patients with critical limb ischemia.

Outcome From a Randomized Controlled Clinical Trial - Improvement of Peripheral Arterial Disease by Granulocyte Colony-Stimulating Factor-Mobilized Autologous Peripheral-Blood-Mononuclear Cell Transplantation (IMPACT)

BACKGROUND

The clinical usefulness of peripheral blood (PB) mononuclear cell (MNC) transplantation in patients with peripheral arterial disease (PAD), especially in those with mild-to-moderate severity, has not been fully clarified.Methods and Results:A randomized clinical trial was conducted to evaluate the efficacy and safety of granulocyte colony-stimulating factor (G-CSF)-mobilized PBMNC transplantation in patients with PAD (Fontaine stage II-IV and Rutherford category 1-5) caused by arteriosclerosis obliterans or Buerger's disease. The primary endpoint was progression-free survival (PFS). In total, 107 subjects were enrolled. At baseline, Fontaine stage was II/III in 82 patients and IV in 21, and 54 patients were on hemodialysis. A total of 50 patients had intramuscular transplantation of PBMNC combined with standard of care (SOC) (cell therapy group), and 53 received SOC only (control group). PFS tended to be improved in the cell therapy group than in the control group (P=0.07). PFS in Fontaine stage II/III subgroup was significantly better in the cell therapy group than in the control group. Cell therapy-related adverse events were transient and not serious.

CONCLUSIONS

In this first randomized, large-scale clinical trial of G-CSF-mobilized PBMNC transplantation, the cell therapy was tolerated by a variety of PAD patients. The PBMNC therapy was significantly effective for inhibiting disease progression in mild-to-moderate PAD.

A Five-Year Study of the Efficacy of Purified CD34+ Cell Therapy for Angiitis-Induced No-Option Critical Limb Ischemia

Angiitis‐induced critical limb ischemia (AICLI) patients constitute a remarkable proportion of no‐option critical limb ischemia (CLI) patients. Stem cell therapy has become an innovative and promising option for no‐option CLI patients. As one of these promising stem cell therapies, purified CD34+ cell transplantation (PuCeT) has shown favorable short‐term results. However, the long‐term efficacy of PuCeT has yet to be reported. This study evaluates the long‐term efficacy of PuCeT in AICLI patients. Twenty‐seven AICLI patients were enrolled from May 2009 to December 2011. Granulocyte colony‐stimulating factor (G‐CSF) and enoxaparin sodium were administered for 5 days. On day 5, CD34+ cell isolation was performed, and cells were transplanted by intramuscular injection. The primary endpoint, major‐amputation‐free survival rate (MAFS), as well as secondary endpoints, such as peak pain‐free walking time (PPFWT) and the Wong‐Baker FACES pain rating scale score (WFPRSS), were routinely evaluated during the 5‐year follow‐up period. The endpoints were as follows: the MAFS was 88.89%; PPFWT increased from 3 ± 3 to 17 ± 6 minutes; WFPRSS decreased from 7 ± 2 to 0.3 ± 1.7; the ulcer healing rate was 85.71%; the recurrence rate was 11.11%; and SF‐36v2 scores were significantly improved at 5 years after PuCeT. The rate of labor recovery 5 years after PuCeT was 65.38%, and no severe adverse effect was observed during the treatment. PuCeT demonstrated long‐term efficacy and durability as a treatment of AICLI not only in achieving limb salvage but also in recovering the labor competence and improving the quality of life of patients. Stem Cells Translational Medicine2018;7:583–590

Treatment of Arsenite Intoxication-Induced Peripheral Vasculopathy with Mesenchymal Stem Cells

Arsenite (As), a notorious toxic metal, is ubiquitously distributed in the earth and poses a serious threat to human health. Histopathological lesions of As intoxication are known as thromboangiitis obliterans, which are resistant to current treatment and often lead to lower limb amputation. In this study, we attempt to find that treatment with mesenchymal stem cells (MSCs) may be effective for As-induced vasculopathy. We first conducted an in vitro study with a co-culture system containing human MSCs and human umbilical vein endothelial cells (HUVECs) and treated individual and co-cultured cells with various concentrations of arsenite. We also designed an in vivo study in which Sprague Dawley (SD) rats received periodic intraperitoneal (IP) injections of 16 ppm arsenite for 12 weeks. MSCs were harvested from BALB/c mice that were transplanted via tail vein injection. We found that there was significantly higher cellular viability in human mesenchymal stem cells (hMSCs) than in HUVECs under concentrations of arsenite between 15 and 25 μM. The Annexin V apoptosis assay further confirmed this finding. Cytokine array assay for As-conditioned media revealed an elevated vascular endothelial growth factor (VEGF) level secreted by MSCs, which is crucial for HUVEC survival and was evaluated by an siRNA VEGF knockdown test. In the in vivo study, we demonstrated early apoptotic changes in the anterior tibial vessels of As-injected SD rats with a Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, but these apoptotic changes were less frequently observed upon MSCs transplantation, indicating that the cytoprotective effect of MSCs successfully protected against As-induced peripheral vasculopathy. The feasibility of MSCs to treat and /or prevent the progression of As-induced vasculopathy is justified. Further clinical studies are required to demonstrate the therapeutic efficacy of MSCs in patients suffering from As intoxication with vasculopathy.

Angiogenesis in peripheral arterial disease

Peripheral arterial disease (PAD) refers to narrowing of the peripheral arteries and atherosclerosis is the most important cause. In patients with PAD, revascularization is the preferred therapeutic strategy; nonetheless several patients are not deemed candidates for it due to advanced disease or several comorbidities. The main target of therapeutic angiogenesis is to promote development of new arterial vessels and improve perfusion of ischemic tissue. Angiogenic growth factors such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), hepatocyte growth factor (HGF), administered intramuscularly or intra-arterially, have been shown to promote angiogenesis and development of collateral vasculature in preclinical studies. However, clinical studies failed to confirm their efficacy in ulcer healing and prevention of amputation, among patients with claudication or critical limb ischemia (CLI). Autologous progenitor cell therapy with bone marrow or adipose-derived progenitor cells administered intra-arterially or intra-muscularly, was shown to improve claudication symptoms and ankle-brachial index in small studies. However, subsequent randomized controlled studies did not demonstrate any beneficial effects of stem cell therapy on amputation rates and survival. Although, therapeutic angiogenesis remains an area of interest in PAD with several ongoing studies of investigational therapies, so far the use of these strategies in clinical practice has not been successful.

Therapeutic efficacy of CD34+ cell-involved mononuclear cell therapy for no-option critical limb ischemia: A meta-analysis of randomized controlled clinical trials

Early-phase clinical trials in patients with critical limb ischemia (CLI) have shown positive results of mononuclear cell therapy. The current meta-analysis investigated whether cluster of differentiation (CD) 34+ mononuclear cell therapy (CD34+MCT) is effective for no-option CLI. Ten randomized controlled clinical studies of CD34+MCT for no-option CLI with 479 patients were identified and analyzed for pooled results. Compared to control groups, the CD34+MCT was associated with lower total amputation (odds ratio (OR): 0.45, p=0.01; 95% confidence interval (CI): 0.24–0.85) and a higher complete ulcer healing rate (OR: 2.80, p=0.008; 95% CI: 1.31–6.02), but showed no advantage in major amputation (OR: 0.58, p=0.11; 95% CI: 0.29–1.14) and all-cause mortality (OR: 0.82, p=0.62; 95% CI: 0.36–1.83) . Studies with a high CD34+ cell dosage showed significant results in major amputation (OR: 0.38, p=0.002; 95% CI: 0.21–0.70), total amputation (OR: 0.31, p=0.0002; 95% CI: 0.17–0.57) and complete ulcer healing (OR: 7.58, p=0.0005; 95% CI: 2.40–23.88), which were not observed in the low-dose studies. However, inclusion of placebo-controlled studies showed no improvement of the CD34+MCT in total amputation (OR: 0.67, p=0.42; 95% CI: 0.25–1.79), major amputation (OR: 1.31, p=0.43; 95% CI: 0.67–2.54) or complete ulcer healing (OR: 1.52, p=0.27; 95% CI: 0.72–3.21), which were extremely significant in non-placebo-controlled studies ( p<0.001). In conclusion, the significant results of CD34+MCT might not support its therapeutic benefit due to high placebo-effect risk and considerable heterogeneity caused by distinct cell doses. More sizable double-blinded, randomized, placebo-controlled trials with higher CD34+ cell dosage are needed in the future.

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.

Autologous Cell Therapy for Peripheral Arterial Disease

Rationale:

Critical limb ischemia is a life-threatening complication of peripheral arterial disease. In patients who are ineligible for revascularization procedures, there are few therapeutic alternatives, leading to amputations and death.

Objective:

To provide a systematic review of the literature and a meta-analysis of studies evaluating safety and efficacy of autologous cell therapy for intractable peripheral arterial disease/critical limb ischemia.

Methods and Results:

We retrieved 19 randomized controlled trials (837 patients), 7 nonrandomized trials (338 patients), and 41 noncontrolled studies (1177 patients). The primary outcome was major amputation. Heterogeneity was high, and publication bias could not be excluded. Despite these limitations, the primary analysis (all randomized controlled trials) showed that cell therapy reduced the risk of amputation by 37%, improved amputation-free survival by 18%, and improved wound healing by 59%, without affecting mortality. Cell therapy significantly increased ankle brachial index, increased transcutaneous oxygen tension, and reduced rest pain. The secondary analysis (all controlled trials; n=1175 patients) shows that there may be potential to avoid ≈1 amputation/year for every 2 patients successfully treated. The tertiary analysis (all studies; n=2332 patients) precisely estimated the changes in ankle brachial index, transcutaneous oxygen tension, rest pain, and walking capacity after cell therapy. Intramuscular implantation appeared more effective than intra-arterial infusion, and mobilized peripheral blood mononuclear cells may outperform bone marrow–mononuclear cells and mesenchymal stem cells. Amputation rate was improved more in trials wherein the prevalence of diabetes mellitus was high. Cell therapy was not associated with severe adverse events. Remarkably, efficacy of cell therapy on all end points was no longer significant in placebo-controlled randomized controlled trials and disappeared in randomized controlled trials with a low risk of bias.

Conclusions:

Although this meta-analysis highlights the need for more high-quality placebo-controlled trials, equipoise may no longer be guaranteed because autologous cell therapy has the potential to modify the natural history of intractable critical limb ischemia.

Therapeutic strategies for cell-based neovascularization in critical limb ischemia

Critical limb ischemia (CLI) causes severe ischemic rest pain, ulcer, and gangrene in the lower limbs. In spite of angioplasty and surgery, CLI patients without suitable artery inflow or enough vascular bed in the lesions are often forced to undergo amputation of a major limb. Cell-based therapeutic angiogenesis has the potential to treat ischemic lesions by promoting the formation of collateral vessel networks and the vascular bed. Peripheral blood mononuclear cells and bone marrow-derived mononuclear cells are the most frequently employed cell types in CLI clinical trials. However, the clinical outcomes of cell-based therapeutic angiogenesis using these cells have not provided the promised benefits for CLI patients, reinforcing the need for novel cell-based therapeutic angiogenesis strategies to cure untreatable CLI patients. Recent studies have demonstrated the possible enhancement of therapeutic efficacy in ischemic diseases by preconditioned graft cells. Moreover, judging from past clinical trials, the identification of adequate transplant timing and responders to cell-based therapy is important for improving therapeutic outcomes in CLI patients in clinical settings. Thus, to establish cell-based therapeutic angiogenesis as one of the most promising therapeutic strategies for CLI patients, its advantages and limitations should be taken into account.

The efficacy of a multidisciplinary team approach in critical limb ischemia

The aim of the present study was to clarify the characteristics of Japanese critical limb ischemia (CLI) patients and analyze the rates of real-world mortality and amputation-free survival (AFS) in all patients with Fontaine stage IV CLI who were treated with/without revascularization therapy by an intra-hospital multidisciplinary care team. All consecutive patients who presented with CLI at Showa University Fujigaoka Hospital between April 2008 and March 2014 were prospectively registered. The intra-hospital committee consisted of cardiologists, plastic surgeons, dermatologists, diabetologists, nephrologists, cardiovascular surgeons, and vascular technologists. The primary endpoint of this study was all-cause mortality and AFS during the follow-up period. The present study included 145 patients with Fontaine stage IV CLI. The mean age was 76.5 ± 10.2 years. The all-cause mortality rate during the follow-up period (15.5 ± 16.1 months) was 21.4 %. The AFS rate during the follow-up period (14.1 ± 16.4 months) was 58.6 %. A multivariate Cox proportional hazards regression analysis found that age >75 years and hemodialysis were significantly associated with all-cause mortality; and that age >75 years, Rutherford 6, and wound infection were significantly associated with AFS. A multidisciplinary approach and comprehensive care may improve the outcomes and optimize the collaborative treatment of CLI patients. However, all-cause mortality remained high in patients with Fontaine stage IV CLI and early referral to a hospital that can provide specialized treatment for CLI, before the occurrence of major tissue loss or infection, is necessary to avoid primary amputation.

Combinatorial Treatment with Apelin-13 Enhances the Therapeutic Efficacy of a Preconditioned Cell-Based Therapy for Peripheral Ischemia

Hypoxic pretreatment of peripheral blood mononuclear cells (PBMNCs) enhances therapeutic angiogenesis in ischemic tissues after cell transplantation. However, newly formed vessels generated using this approach are immature and insufficient for promoting functional recovery from severe ischemia. In this study, we examined whether apelin-13, a regulator of vessel maturation, could be an effective promoter of therapeutic angiogenesis, following severe limb ischemia. Combinatorial treatment of hypoxic preconditioned PBMNCs with apelin-13 resulted in increased blood perfusion and vascular reactivity in ischemic mouse hindlimbs compared with a monotherapy comprising each factor. Apelin-13 upregulated expression of PDGF-BB and TGF-β1 in hypoxic PBMNCs, as well as that of PDGFR-β in vascular smooth muscle cells (VSMCs). Proliferation and migration of VSMCs treated with apelin-13 was accelerated in the presence of PDGF-BB. Interestingly, expression of an apelin receptor, APJ, in PBMNC was increased under hypoxia but not under normoxia. In addition, an in vitro angiogenesis assay using a co-culture model comprising mouse thoracic aorta, hypoxic PBMNCs, and apelin-13 demonstrated that combinatorial treatment recruited mural cells to sprouted vessel outgrowths from the aortic ring, thereby promoting neovessel maturation. Thus, combinatorial injection of hypoxic PBMNCs and apelin-13 could be an effective therapeutic strategy for patients with severe ischemic diseases.

Current therapies and investigational drugs for peripheral arterial disease

Peripheral artery disease (PAD) is associated with elevated morbidity and mortality with cardiovascular (CV) disease. The guideline recommends smoking cessation and antiplatelet/antithrombotic drugs for asymptomatic and symptomatic PAD patients. It also recommends that PAD patients with critical limb ischemia (CLI) should be considered to receive endovascular and open surgical treatment for limb salvage. Although PAD patients with CLI receive these treatments, they are sometimes unable to deliver sufficient blood flow to eliminate their symptoms. Thus specific strategies are needed to promote enough blood flow. To establish the effective method, many investigations have been performed using cell-based therapy. Endothelial progenitor cells, mononuclear cells and mesenchymal stem cells have been well investigated in clinical settings. To induce angiogenesis, vascular endothelial growth factor, fibroblast growth factor and hepatocyte growth factor (HGF) have also been transfected in PAD patients. Among them, HGF is the most promising factor because it can induce angiogenesis without the induction of vascular inflammation and increased permeability. In this review article, we summarize current treatments and investigational drugs of PAD.

Limb rescue: a new autologous-peripheral blood mononuclear cells technology in critical limb ischemia and chronic ulcers

INTRODUCTION

Therapeutic angiogenesis by autologous-peripheral blood mononuclear cells (A-PBMNC) implantation has been shown to be a safe and effective treatment for critical limb ischemia (CLI). We herein report our investigation of the long-term efficacy of implantation of A-PBMNC produced by selective filtration to treat patients with CLI, for which surgical bypass and/or percutaneous transluminal angioplasty are not possible.

MATERIALS AND METHODS

This is a prospective, and not a randomized, study based on a treated group who did not respond to conventional therapy (n=43) when implanted with A-PBMNC cells versus a historically matched control group. Patients of both groups were suffering from CLI Fontaine scale IV with chronic ulcers and various accompanying conditions (diabetes, heart disease, kidney failure, etc.). Treated patients were implanted with 12 mL of A-PBMNC, 0.2-0.3 mL for each bolus, collected by selective filtration from 120 mL of peripheral blood in the ischemic area of the limbs. Patients were not mobilized by granulocyte colony-stimulating factor, and the A-PBMNC treatment was repeated for a maximum of three times.

RESULTS

The A-PBMNC-treated group showed a statistically significant improvement of limb rescue of 95.3% versus 52.2% of the control group (p<0.001), and the result had been maintained for 2 years. The A-PBMNC group also showed reduction in pain at rest, increased maximum walking distance, and healing of the wound, which led to an overall improvement in the quality of life. Post-treatment radiological studies showed an improvement of vascularization with the formation of new collateral and by histological findings. Within 2 years of follow-up, none of the patients whom we treated showed any major or systemic adverse effects.

CONCLUSION

The local injection of A-PBMNC showed striking early and long-term effects together with a favorable safety profile, significantly decreasing the risk of amputation. Our results are comparable with published data obtained by injection of bone marrow mononuclear cells, but with a lot less invasive approach. Moreover the intraoperative selective filtration system we used is fast, safe, not operator dependent, and easy to use in a sterile operating theatre. This system aims to produce fresh A-PBMNC as a valuable treatment option, particularly for those difficult patients who cannot undergo revascularization.

Revisiting cardiovascular regeneration with bone marrow-derived angiogenic and vasculogenic cells

Cell-based therapy has emerged as a promising therapy for cardiovascular disease. Particularly, bone marrow (BM)-derived cells have been most extensively investigated and have shown encouraging results in preclinical studies. Clinical trials, however, have demonstrated split results in post-myocardial infarction cardiac repair. Mechanistically, transdifferentiation of BM-derived cells into cardiovascular tissue demonstrated by earlier studies is now known to play a minor role in functional recovery, and humoral and paracrine effects turned out to be main mechanisms responsible for tissue regeneration and functional recovery. With this advancement in the mechanistic insight of BM-derived cells, new efforts have been made to identify cell population, which can be readily isolated and obtained in sufficient quantity without mobilization and have higher therapeutic potential. Recently, haematopoietic CD31(+) cells, which are more prevalent in bone marrow and peripheral blood, have been revealed to have angiogenic and vasculogenic activities and strong potential for therapeutic neovascularization in ischaemic tissues. This article will cover the recent advances in BM-derived cell-based therapy and implication of CD31(+) cells.

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.

Clinical application of vascular regenerative therapy for peripheral artery disease

Prognosis of peripheral artery disease (PAD), especially critical limb ischemia, is very poor despite the development of endovascular therapy and bypass surgery. Many patients result in leg amputation and, therefore, vascular regenerative therapy is expected in this field. Gene therapy using vascular endothelial growth factor is the first step of vascular regenerative therapy, but did not confirm effectiveness in a large-scale randomized comparative study. Based on animal experiments, bone marrow mononuclear cells (MNCs), peripheral blood MNCs were used as the cell source for regenerative therapy. Those cells were confirmed to be effective to decrease rest pain and ulcer size, but its effect was not fully satisfied. Mesenchymal stem cells (MSCs) are expected as an effective cell source for vascular regeneration and clinical studies are ongoing, because the cells are able to differentiate into various cell types and produce a significant amount of vascular growth factors. Of vascular regeneration therapy, peripheral MNCs and bone marrow MNCs were recognized as advanced medical technology but do not attain to the standard therapy. However, clinical use of MSCs have already started, and induced pluripotent stem cells are surely promising tool for vascular regeneration therapy although further basic studies are required for clinical application.

Meta-analysis of contemporary short- and long-term mortality rates in patients diagnosed with critical leg ischaemia

BACKGROUND

Critical leg ischaemia (CLI) has been associated with high mortality rates. There is a lack of contemporary data on both short- and long-term mortality rates in patients diagnosed with CLI.

METHODS

This was a systematic literature search for studies prospectively reporting mortality in patients diagnosed with CLI. Meta-analysis and meta-regression models were developed to determine overall mortality rates and specific patient-related factors that were associated with death.

RESULTS

A total of 50 studies were included in the analysis The estimated probability of all-cause mortality in patients with CLI was 3·7 per cent at 30 days, 17·5 per cent at 1 year, 35·1 per cent at 3 years and 46·2 per cent at 5 years. Men had a statistically significant survival benefit at 30 days and 3 years. The presence of ischaemic heart disease, tissue loss and older age resulted in a higher probability of death at 3 years.

CONCLUSION

Early mortality rates in patients diagnosed with CLI have improved slightly compared with previous historical data, but long-term mortality rates are still high.

Cell therapy of peripheral arterial disease: from experimental findings to clinical trials

The age-adjusted prevalence of peripheral arterial disease in the US population was estimated to approach 12% in 1985, and as the population ages, the overall population having peripheral arterial disease is predicted to rise. The clinical consequences of occlusive peripheral arterial disease include intermittent claudication, that is, pain with walking, and critical limb ischemia (CLI), which includes pain at rest and loss of tissue integrity in the distal limbs, which may ultimately lead to amputation of a portion of the lower extremity. The risk factors for CLI are similar to those linked to coronary artery disease and include advanced age, smoking, diabetes mellitus, hyperlipidemia, and hypertension. The worldwide incidence of CLI was estimated to be 500 to 1000 cases per million people per year in 1991. The prognosis is poor for CLI subjects with advanced limb disease. One study of >400 such subjects in the United Kingdom found that 25% required amputation and 20% (including some subjects who had required amputation) died within 1 year. In the United States, ≈280 lower-limb amputations for ischemic disease are performed per million people each year. The first objective in treating CLI is to increase blood circulation to the affected limb. Theoretically, increased blood flow could be achieved by increasing the number of vessels that supply the ischemic tissue with blood. The use of pharmacological agents to induce new blood vessel growth for the treatment or prevention of pathological clinical conditions has been called therapeutic angiogenesis. Since the identification of the endothelial progenitor cell in 1997 by Asahara and Isner, the field of cell-based therapies for peripheral arterial disease has been in a state of continuous evolution. Here, we review the current state of that field.

Transplantation of purified CD34+ cells in the treatment of critical limb ischemia

BACKGROUND

This study investigated the feasibility, safety, and efficacy of the intramuscular injection of CD34+ cells isolated from peripheral blood mononuclear cells (PB-MNCs) mobilized by granulocyte colony-stimulating factor (G-CSF) for the management of patients with critical limb ischemia (CLI) who were considered unlikely to have successful long-term revascularization with open bypass or endovascular methods. Cell therapy represents a new treatment modality for this subgroup of patients with CLI. To date, bone marrow or PB-MNCs have usually been used for transplantation. The current pilot study investigated whether the transplantation of purified CD34+ cells only would be competent in ischemia relief and limb salvage.

METHODS

From May 2009 to July 2011, 25 patients (mean age, 44 ± 12 years) were enrolled, and 25 lower extremities and three upper extremities were treated. After subcutaneous administration of G-CSF for 5 days at a dose of 5 to 10 μg/kg, apheresis and immunomagnetic separation were performed to acquire the isolated CD34+ cells, which were then intramuscularly injected into the ischemic sites. The patients were divided into three groups: low-dose, 10(5)/kg; medium-dose, 5 × 10(5)/kg; and high-dose, 10(6)/kg. The overall outcomes among all patients and the comparison among the groups were evaluated.

RESULTS

During the follow-up of 6 to 33 months, the overall outcomes showed that the Wong-Baker FACES pain rating scale score (WFPRSS) decreased from 7 ± 2 to 3 ± 3 (P < .001) and 1 ± 2 (P < .001) at 1 and 2 months, respectively; at 3 and 6 months, respectively, the peak pain-free walking time increased from 4 ± 3 to 13 ± 7 (P < .001) and 18 ± 6 minutes (P < .001), the ankle-brachial index increased from 0.46 ± 0.21 to 0.60 ± 0.17 (P = .003) and 0.67 ± 0.15 (P = .001), and the transcutaneous partial oxygen pressure increased from 27 ± 10 to 41 ± 11 (P < .001) and 55 ± 12 mm Hg (P < .001). Ulcers were healed in 10 of the 14 patients; four patients required above-knee or below-knee amputation ≤ 3 months. The Kaplan-Meier estimate of the rate of freedom from major amputation at 6 months was 84% (95% confidence interval, 63%-94%). The comparison among the three groups (low-dose, 5; medium-dose, 11; high-dose, 9) revealed no significant difference, except that the WFPRSS improvement at 1 month from baseline in the high-dose group (6.3 ± 1.7) was significantly superior to that in the low-dose (3.2 ± 3.3; P = .0487) and medium-dose (3.7 ± 2.8; P = .0352) groups.

CONCLUSIONS

Transplantation of CD34+ cells isolated from G-CSF-mobilized PB-MNCs appears to be feasible and safe, showing encouraging outcomes in the treatment of CLI patients who appear to have compromised options for long-term revascularization.

Ephrin-B2-activated peripheral blood mononuclear cells from diabetic patients restore diabetes-induced impairment of postischemic neovascularization

We hypothesized that in vitro treatment of peripheral blood mononuclear cells (PB-MNCs) from diabetic patients with ephrin-B2/Fc (EFNB2) improves their proangiogenic therapeutic potential in diabetic ischemic experimental models. Diabetes was induced in nude athymic mice by streptozotocin injections. At 9 weeks after hyperglycemia, 10(5) PB-MNCs from diabetic patients, pretreated by EFNB2, were intravenously injected in diabetic mice with hindlimb ischemia. Two weeks later, the postischemic neovascularization was evaluated. The mechanisms involved were investigated by flow cytometry analysis and in vitro cell biological assays. Paw skin blood flow, angiographic score, and capillary density were significantly increased in ischemic leg of diabetic mice receiving EFNB2-activated diabetic PB-MNCs versus those receiving nontreated diabetic PB-MNCs. EFNB2 bound to PB-MNCs and increased the adhesion and transmigration of PB-MNCs. Finally, EFNB2-activated PB-MNCs raised the number of circulating vascular progenitor cells in diabetic nude mice and increased the ability of endogenous bone marrow MNCs to differentiate into cells with endothelial phenotype and enhanced their proangiogenic potential. Therefore, EFNB2 treatment of PB-MNCs abrogates the diabetes-induced stem/progenitor cell dysfunction and opens a new avenue for the clinical development of an innovative and accessible strategy in diabetic patients with critical ischemic diseases.

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.

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.

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.

Early and Long-term Effects of the Autologous Peripheral Stem Cell Implantation for Critical Limb Ischemia

OBJECTIVE

Therapeutic angiogenesis by peripheral blood mononuclear cells (PB-MNCs) implantation has been shown to be a safe and effective treating for critical limb ischemia (CLI). We herein report our investigation of the long-term efficacy of implantation of granulocyte-colony stimulating factor (G-CSF)-induced PB-MNCs to treat patients with CLI for which surgical bypass and/or percutaneous transluminal angioplasty are not possible. Methods and Methods : Eleven cases were enrolled in this study. Following an injection of G-CSF (250 ug/day) for 3 days, PB-MNCs (1.1 ± 0.5 × 10(10) including 1.5 ± 0.2 × 10(7) CD34-positive cells) were harvested by apheresis and then injected into 13 ischemic limbs.

RESULTS

Resting pain either diminished or improved in 10 cases (91%) at 4 weeks, and ulcer formation was cured in 6 out of 10 limbs (60%) after treatment. The time required to enhance the arteries at the level of foot-joint by angiography which was performed in the abdominal aorta was shortened by 1 month (10 ± 4 seconds) and 6 months (12 ± 1) compared with the pretreatment time (15 ± 5). Three patients died after treatment, and the actuarial survival rate at 3 years was 73%. Freedom from major amputation at 3 years was 92%.

CONCLUSION

The local injection of G-CSF-induced PB-MNCs showed striking early and long-term effects.

Advances in bone marrow-derived cell therapy: CD31-expressing cells as next generation cardiovascular cell therapy

In the past few years, bone marrow (BM)-derived cells have been used to regenerate damaged cardiovascular tissues post-myocardial infarction. Recent clinical trials have shown controversial results in recovering damaged cardiac tissue. New progress has shown that the underlying mechanisms of cell-based therapy relies more heavily on humoral and paracrine effects rather than on new tissue generation. However, studies have also reported the potential of new endothelial cell generation from BM cells. Thus, efforts have been made to identify cells having higher humoral or therapeutic effects as well as their surface markers. Specifically, BM-derived CD31+ cells were isolated by a surface marker and demonstrated high angio-vasculogenic effects. This article will describe recent advances in the therapeutic use of BM-derived cells and the usefulness of CD31+ cells.

The promise of cell-based therapies for diabetic complications: challenges and solutions

The discovery of endothelial progenitor cells (EPCs) in human peripheral blood advanced the field of cell-based therapeutics for many pathological conditions. Despite the lack of agreement about the existence and characteristics of EPCs, autologous EPC populations represent a novel treatment option for complications requiring therapeutic revascularization and vascular repair. Patients with diabetic complications represent a population of patients that may benefit from cellular therapy yet their broadly dysfunctional cells may limit the feasibility of this approach. Diabetic EPCs have decreased migratory prowess and reduced proliferative capacity and an altered cytokine/growth factor secretory profile that can accelerate deleterious repair mechanisms rather than support proper vascular repair. Furthermore, the diabetic environment poses additional challenges for the autologous transplantation of cells. The present review is focused on correcting diabetic EPC dysfunction and the challenges involved in the application of cell-based therapies for treatment of diabetic vascular complications. In addition, ex vivo and in vivo functional manipulation(s) of EPCs to overcome these hurdles are discussed.