Granulocyte Colony-Stimulating Factor A Noninvasive Regeneration Therapy for Treating Atherosclerotic Peripheral Artery Disease

Granulocyte Colony-Stimulating Factor Ameliorates Endothelial Activation and Thrombotic Diathesis Biomarkers in a Murine Model of Hind Limb Ischemia

Novel therapies in peripheral arterial disease, such as granulocyte colony-stimulating factor (GCSF) administration, might result in anti-atherosclerotic effects. In this study, we used 10-week-old male ApoE^−/− mice, which were fed an atherosclerosis-inducing diet for four weeks. At the end of the four weeks, hind limb ischemia was induced through left femoral artery ligation, the atherosclerosis-inducing diet was discontinued, and a normal diet was initiated. Mice were then randomized into a control group (intramuscular 0.4 mL normal saline 0.9% for 7 days) and a group in which GCSF was administrated intramuscularly in the left hind limb for 7 days (100 mg/kg). In the GCSF group, but not in the control group, we observed significant reductions in the soluble adhesion molecules (vascular cell adhesion molecule-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1)), sE-Selectin, and plasminogen activator inhibitor (PAI)-1 when they were measured through ELISA on the 1st and the 28th days after hind limb ischemia induction. Therefore, GCSF administration in an atherosclerotic mouse model of hind limb ischemia led to decreases in the biomarkers associated with endothelial activation and thrombosis. These findings warrant further validation in future preclinical studies.

Filgrastim, fibrinolysis, and neovascularization

Segmental recanalization of chronically occluded arteries was observed in patients with chronic limb-threatening ischemia (CLTI) treated with Filgrastim, a granulocyte colony stimulating factor, every 72 h for up to a month, and an infra-geniculate programmed compression pump (PCP) for 3 h daily. Molecular evidence for fibrinolysis and neovascularization was sought. CLTI patients were treated with PCP alone (N = 19), or with Filgrastim and PCP (N = 8 and N = 6, at two institutions). Enzyme-Linked Immunosorbent Assay was used to measure the plasma concentration of plasmin and of fibrin degradation products (FDP), and the serum concentration of proteins associated with neovascularization. In the PCP-alone group, blood was sampled on Day 1 (baseline) and after 30 days of daily PCP. In the Filgrastim and PCP group, blood was drawn on Day 1, and 1 day after the 5th and the 10th Filgrastim doses. Each blood draw occurred before and after 2 h of supervised PCP. Significant (p < 0.01) PCP independent increases in the plasma concentration of plasmin (>10-fold) and FDP (>5-fold) were observed 1 day after both the 5th and the 10th Filgrastim doses, compared to Day 1. Significant (p < 0.05) increases in the concentration of pro-angiogenic proteins (e.g., HGF, MMP-9, VEGF A) were also observed. Filgrastim at this novel dosimetry induced fibrinolysis without causing acute hemorrhage, in addition to inducing a pro-angiogenic milieu conducive to NV. Further clinical testing is warranted at this novel dosimetry in CLTI, as well as in other chronically ischemic tissue beds. Trial registration. https://clinicaltrials.gov/ct2/show/NCT02802852.

Autologous Stem Cell Therapy for Chronic Lower Extremity Wounds: A Meta-Analysis of Randomized Controlled Trials

Lower extremity chronic wounds (LECWs) commonly occur in patients with diabetes mellitus (DM) and peripheral arterial disease (PAD). Autologous stem cell therapy (ASCT) has emerged as a promising alternative treatment for those who suffered from LECWs. The purpose of this study was to assess the effects of ASCT on LECWs. Two authors searched three core databases, and independently identified evidence according to predefined criteria. They also individually assessed the quality of the included randomized controlled trials (RCTs), and extracted data on complete healing rate, amputation rate, and outcomes regarding peripheral circulation. The extracted data were pooled using a random-effects model due to clinical heterogeneity among the included RCTs. A subgroup analysis was further performed according to etiology, source of stem cells, follow-up time, and cell markers. A total of 28 RCTs (n = 1096) were eligible for this study. The pooled results showed that patients receiving ASCT had significantly higher complete healing rates (risk ratio (RR) = 1.67, 95% confidence interval (CI) 1.28–2.19) as compared with those without ASCT. In the CD34+ subgroup, ASCT significantly led to a higher complete healing rate (RR = 2.70, 95% CI 1.50–4.86), but there was no significant difference in the CD34− subgroup. ASCT through intramuscular injection can significantly improve wound healing in patients with LECWs caused by either DM or critical limb ischemia. Lastly, CD34+ is an important cell marker for potential wound healing. However, more extensive scale and well-designed studies are necessary to explore the details of ASCT and chronic wound healing.

Personalized Cell Therapy for Patients with Peripheral Arterial Diseases in the Context of Genetic Alterations: Artificial Intelligence-Based Responder and Non-Responder Prediction

Stem/progenitor cell transplantation is a potential novel therapeutic strategy to induce angiogenesis in ischemic tissue, which can prevent major amputation in patients with advanced peripheral artery disease (PAD). Thus, clinicians can use cell therapies worldwide to treat PAD. However, some cell therapy studies did not report beneficial outcomes. Clinical researchers have suggested that classical risk factors and comorbidities may adversely affect the efficacy of cell therapy. Some studies have indicated that the response to stem cell therapy varies among patients, even in those harboring limited risk factors. This suggests the role of undetermined risk factors, including genetic alterations, somatic mutations, and clonal hematopoiesis. Personalized stem cell-based therapy can be developed by analyzing individual risk factors. These approaches must consider several clinical biomarkers and perform studies (such as genome-wide association studies (GWAS)) on disease-related genetic traits and integrate the findings with those of transcriptome-wide association studies (TWAS) and whole-genome sequencing in PAD. Additional unbiased analyses with state-of-the-art computational methods, such as machine learning-based patient stratification, are suited for predictions in clinical investigations. The integration of these complex approaches into a unified analysis procedure for the identification of responders and non-responders before stem cell therapy, which can decrease treatment expenditure, is a major challenge for increasing the efficacy of therapies.

A Meta-Analysis of Randomized Controlled Trials on Therapeutic Efficacy and Safety of Autologous Cell Therapy for Atherosclerosis Obliterans

BACKGROUND

Atherosclerosis obliterans (ASO) is a chronic occlusive arterial disease and the most common type of peripheral arterial disease. Current treatment options like medication and vascularization have limited effects for "no-option" patients, and stem cell therapy is considered a viable option although its application and efficacy have not been standardized. The objective of this review was to assess the safety and efficacy of autologous stem cell therapy in patients with ASO.

METHODS

We performed a literature search of published RCTs for ASO patients receiving stem cell therapy without a revascularization option. PubMed, Embase, and the Cochrane Library were searched. This study was conducted by a pair of authors independently and audited by a third author. Data were synthesized with a random-effect model.

RESULTS

630 patients in 12 RCTs were included. The results showed that cell therapy significantly improved total amputation (RR: 0.64, p = 0.004, 95% CI: [0.47, 0.87]), major amputation (RR: 0.69, p = 0.02, 95% CI: [0.50, 0.94]), ankle-brachial index (ABI) (MD = 0.08, p = 0.004, 95% CI: [0.02, 0.13]), transcutaneous oxygen tension (TcO₂) (MD = 11.52, p = 0.004, 95% CI: [3.60, 19.43]) and rest pain score (MD = -0.64, p = 0.007, 95% CI: [-1.10, -0.17]) compared to placebo or standard care. However, current studies showed cell therapy was not superior to placebo or standard care in all-cause death (RR: 0.75, p = 0.34, 95% CI: [0.41, 1.36]) and ulcer size (MD = -8.85, p = 0.39, CI: [-29.05,11.36]).

LIMITATION

The number of trials included was limited. Moreover, most trials were designed for "no-option" patients and thus the results should be applied with caution to other PAD patients.

CONCLUSION

ASO patients can benefit from autologous cell therapy in limb salvage, limb blood perfusion, and rest pain alleviation.

Sargramostim (rhu GM-CSF) as Cancer Therapy (Systematic Review) and An Immunomodulator. A Drug Before Its Time?

BACKGROUND

Sargramostim [recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF)] was approved by US FDA in 1991 to accelerate bone marrow recovery in diverse settings of bone marrow failure and is designated on the list of FDA Essential Medicines, Medical Countermeasures, and Critical Inputs. Other important biological activities including accelerating tissue repair and modulating host immunity to infection and cancer via the innate and adaptive immune systems are reported in pre-clinical models but incompletely studied in humans.

OBJECTIVE

Assess safety and efficacy of sargramostim in cancer and other diverse experimental and clinical settings.

METHODS AND RESULTS

We systematically reviewed PubMed, Cochrane and TRIP databases for clinical data on sargramostim in cancer. In a variety of settings, sargramostim after exposure to bone marrow-suppressing agents accelerated hematologic recovery resulting in fewer infections, less therapy-related toxicity and sometimes improved survival. As an immune modulator, sargramostim also enhanced anti-cancer responses in solid cancers when combined with conventional therapies, for example with immune checkpoint inhibitors and monoclonal antibodies.

CONCLUSIONS

Sargramostim accelerates hematologic recovery in diverse clinical settings and enhances anti-cancer responses with a favorable safety profile. Uses other than in hematologic recovery are less-well studied; more data are needed on immune-enhancing benefits. We envision significantly expanded use of sargramostim in varied immune settings. Sargramostim has the potential to reverse the immune suppression associated with sepsis, trauma, acute respiratory distress syndrome (ARDS) and COVID-19. Further, sargramostim therapy has been promising in the adjuvant setting with vaccines and for anti-microbial-resistant infections and treating autoimmune pulmonary alveolar proteinosis and gastrointestinal, peripheral arterial and neuro-inflammatory diseases. It also may be useful as an adjuvant in anti-cancer immunotherapy.

Current Status of Angiogenic Cell Therapy and Related Strategies Applied in Critical Limb Ischemia

Critical limb ischemia (CLI) constitutes the most severe form of peripheral arterial disease (PAD), it is characterized by progressive blockade of arterial vessels, commonly correlated to atherosclerosis. Currently, revascularization strategies (bypass grafting, angioplasty) remain the first option for CLI patients, although less than 45% of them are eligible for surgical intervention mainly due to associated comorbidities. Moreover, patients usually require amputation in the short-term. Angiogenic cell therapy has arisen as a promising alternative for these "no-option" patients, with many studies demonstrating the potential of stem cells to enhance revascularization by promoting vessel formation and blood flow recovery in ischemic tissues. Herein, we provide an overview of studies focused on the use of angiogenic cell therapies in CLI in the last years, from approaches testing different cell types in animal/pre-clinical models of CLI, to the clinical trials currently under evaluation. Furthermore, recent alternatives related to stem cell therapies such as the use of secretomes, exosomes, or even microRNA, will be also described.

Stem cell therapy in critical limb ischemia: Current scenario and future trends

Critical limb ischemia (CLI) represents the most severe manifestation of peripheral arterial disease (PAD). It imposes a huge economic burden and is associated with high short-term mortality and adverse cardiovascular outcomes. Prompt recognition and early revascularization, surgical or endovascular, with the aim of improving the inline bloodflow to the ischemic limb, are currently the standard of care. However, this strategy may not always be feasible or effective; hence, evaluation of newer pharmacological or angiogenic therapies for alleviating the symptoms of this alarming condition is of utmost importance. Cell-based therapies have shown promise in smaller studies; however, large-scale studies, demonstrating definite survival benefits, are entailed to ascertain their role in the management of CLI.

Activation of stem cell up-regulation/mobilization: a cardiovascular risk in both mice and humans with implications for liver disease, psoriasis and SLE

Experimentally induced injury triggers up-regulation and mobilization of stem cells in Apoe -/- mice that causes accelerated atherosclerosis. Abca1 -/- Abcg1-/- mice have chronic activation of stem cell up-regulation/mobilization and accelerated atherosclerosis. In addition, the Abca1 -/- Abcg1-/- mice have elevation of serum cytokines G-CSF, IL-17 and IL-23, each necessary for stem cell mobilization. IL-17 and IL-23 are elevated in two human illnesses that have cardiovascular (CV) risk independent of traditional risk factors—SLE and psoriasis. Serum G-CSF, which can be elevated in liver disease, predicts major adverse cardiovascular events in humans. These serum cytokine elevations suggest activation of the stem cell mobilization mechanism in humans that results, as in mice, in accelerated atherosclerosis. Efforts to reduce CV disease in these patient populations should include mitigation of the diseases that trigger stem cell mobilization. Since activation of the stem cell up-regulation/mobilization mechanism appears to accelerate human atherosclerosis, use of stem cells as therapy for arterial occlusive disease should distinguish between direct administration of stem cells and activation of the stem cell up-regulation/mobilization mechanism.

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.

Autologous cells derived from different sources and administered using different regimens for 'no-option' critical lower limb ischaemia patients

BACKGROUND

Revascularisation is the gold standard therapy for patients with critical limb ischaemia (CLI). In over 30% of patients who are not suitable for or have failed previous revascularisation therapy (the 'no-option' CLI patients), limb amputation is eventually unavoidable. Preliminary studies have reported encouraging outcomes with autologous cell-based therapy for the treatment of CLI in these 'no-option' patients. However, studies comparing the angiogenic potency and clinical effects of autologous cells derived from different sources have yielded limited data. Data regarding cell doses and routes of administration are also limited.

OBJECTIVES

To compare the efficacy and safety of autologous cells derived from different sources, prepared using different protocols, administered at different doses, and delivered via different routes for the treatment of 'no-option' CLI patients.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Cochrane Vascular Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE Ovid, Embase Ovid, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Allied and Complementary Medicine Database (AMED), and trials registries (16 May 2018). Review authors searched PubMed until February 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) involving 'no-option' CLI patients comparing a particular source or regimen of autologous cell-based therapy against another source or regimen of autologous cell-based therapy.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the eligibility and methodological quality of the trials. We extracted outcome data from each trial and pooled them for meta-analysis. We calculated effect estimates using a risk ratio (RR) with 95% confidence interval (CI), or a mean difference (MD) with 95% CI.

MAIN RESULTS

We included seven RCTs with a total of 359 participants. These studies compared bone marrow-mononuclear cells (BM-MNCs) versus mobilised peripheral blood stem cells (mPBSCs), BM-MNCs versus bone marrow-mesenchymal stem cells (BM-MSCs), high cell dose versus low cell dose, and intramuscular (IM) versus intra-arterial (IA) routes of cell implantation. We identified no other comparisons in these studies. We considered most studies to be at low risk of bias in random sequence generation, incomplete outcome data, and selective outcome reporting; at high risk of bias in blinding of patients and personnel; and at unclear risk of bias in allocation concealment and blinding of outcome assessors. The quality of evidence was most often low to very low, with risk of bias, imprecision, and indirectness of outcomes the major downgrading factors.Three RCTs (100 participants) reported a total of nine deaths during the study follow-up period. These studies did not report deaths according to treatment group.Results show no clear difference in amputation rates between IM and IA routes (RR 0.80, 95% CI 0.54 to 1.18; three RCTs, 95 participants; low-quality evidence). Single-study data show no clear difference in amputation rates between BM-MNC- and mPBSC-treated groups (RR 1.54, 95% CI 0.45 to 5.24; 150 participants; low-quality evidence) and between high and low cell dose (RR 3.21, 95% CI 0.87 to 11.90; 16 participants; very low-quality evidence). The study comparing BM-MNCs versus BM-MSCs reported no amputations.Single-study data with low-quality evidence show similar numbers of participants with healing ulcers between BM-MNCs and mPBSCs (RR 0.89, 95% CI 0.44 to 1.83; 49 participants) and between IM and IA routes (RR 1.13, 95% CI 0.73 to 1.76; 41 participants). In contrast, more participants appeared to have healing ulcers in the BM-MSC group than in the BM-MNC group (RR 2.00, 95% CI 1.02 to 3.92; one RCT, 22 participants; moderate-quality evidence). Researchers comparing high versus low cell doses did not report ulcer healing.Single-study data show similar numbers of participants with reduction in rest pain between BM-MNCs and mPBSCs (RR 0.99, 95% CI 0.93 to 1.06; 104 participants; moderate-quality evidence) and between IM and IA routes (RR 1.22, 95% CI 0.91 to 1.64; 32 participants; low-quality evidence). One study reported no clear difference in rest pain scores between BM-MNC and BM-MSC (MD 0.00, 95% CI -0.61 to 0.61; 37 participants; moderate-quality evidence). Trials comparing high versus low cell doses did not report rest pain.Single-study data show no clear difference in the number of participants with increased ankle-brachial index (ABI; increase of > 0.1 from pretreatment), between BM-MNCs and mPBSCs (RR 1.00, 95% CI 0.71 to 1.40; 104 participants; moderate-quality evidence), and between IM and IA routes (RR 0.93, 95% CI 0.43 to 2.00; 35 participants; very low-quality evidence). In contrast, ABI scores appeared higher in BM-MSC versus BM-MNC groups (MD 0.05, 95% CI 0.01 to 0.09; one RCT, 37 participants; low-quality evidence). ABI was not reported in the high versus low cell dose comparison.Similar numbers of participants had improved transcutaneous oxygen tension (TcO₂) with IM versus IA routes (RR 1.22, 95% CI 0.86 to 1.72; two RCTs, 62 participants; very low-quality evidence). Single-study data with low-quality evidence show a higher TcO₂ reading in BM-MSC versus BM-MNC groups (MD 8.00, 95% CI 3.46 to 12.54; 37 participants) and in mPBSC- versus BM-MNC-treated groups (MD 1.70, 95% CI 0.41 to 2.99; 150 participants). TcO₂ was not reported in the high versus low cell dose comparison.Study authors reported no significant short-term adverse effects attributed to autologous cell implantation.

AUTHORS' CONCLUSIONS

Mostly low- and very low-quality evidence suggests no clear differences between different stem cell sources and different treatment regimens of autologous cell implantation for outcomes such as all-cause mortality, amputation rate, ulcer healing, and rest pain for 'no-option' CLI patients. Pooled analyses did not show a clear difference in clinical outcomes whether cells were administered via IM or IA routes. High-quality evidence is lacking; therefore the efficacy and long-term safety of autologous cells derived from different sources, prepared using different protocols, administered at different doses, and delivered via different routes for the treatment of 'no-option' CLI patients, remain to be confirmed.Future RCTs with larger numbers of participants are needed to determine the efficacy of cell-based therapy for CLI patients, along with the optimal cell source, phenotype, dose, and route of implantation. Longer follow-up is needed to confirm the durability of angiogenic potential and the long-term safety of cell-based therapy.

Autologous Stem Cell Therapy in Critical Limb Ischemia: A Meta-Analysis of Randomized Controlled Trials

Objective

Critical limb ischemia (CLI) is the most dangerous stage of peripheral artery disease (PAD). Many basic researches and clinical treatment had been focused on stem cell transplantation for CLI. This systematic review was performed to review evidence for safety and efficacy of autologous stem cell therapy in CLI.

Methods

A systematic literature search was performed in the SinoMed, PubMed, Embase, ClinicalTrials.gov, and Cochrane Controlled Trials Register databases from building database to January 2018.

Results

Meta-analysis showed that cell therapy significantly increased the probability of ulcer healing (RR = 1.73, 95% CI = 1.45–2.06), angiogenesis (RR = 5.91, 95% CI = 2.49–14.02), and reduced the amputation rates (RR = 0.59, 95% CI = 0.46–0.76). Ankle-brachial index (ABI) (MD = 0.13, 95% CI = 0.11–0.15), TcO₂ (MD = 12.22, 95% CI = 5.03–19.41), and pain-free walking distance (MD = 144.84, 95% CI = 53.03–236.66) were significantly better in the cell therapy group than in the control group (P < 0.01).

Conclusions

The results of this meta-analysis indicate that autologous stem cell therapy is safe and effective in CLI. However, higher quality and larger RCTs are required for further investigation to support clinical application of stem cell transplantation.

Cell therapy for peripheral artery disease

Patients with severe peripheral artery disease (PAD) who are not candidates for revascularization have poor prognosis. Cell therapy using peripheral blood-derived or bone marrow-derived mononuclear cells, mesenchymal stem cells, or marker-specific subsets of bone marrow cells with angiogenic properties may hold promise for no-option PAD patients. Injected cells may exert beneficial actions by enhancing local angiogenesis (either through maturation of endothelial progenitors, or through secretion of angiogenic mediators), or by transducing cytoprotective signals that preserve tissue structure. Despite extensive research, robust clinical evidence supporting the use of cell therapy in patients with critical limb ischemia is lacking. Larger, well-designed placebo-controlled clinical trials did not support the positive results of smaller less rigorous studies. There is a need for high-quality clinical studies to test the effectiveness of cell therapy in PAD patients. Moreover, fundamental cell biological studies are needed to identify the optimal cell types, and to develop strategies that may enhance homing, survival and effectiveness of the injected cells.

Effect of Granulocyte-Macrophage Colony-Stimulating Factor With or Without Supervised Exercise on Walking Performance in Patients With Peripheral Artery Disease: The PROPEL Randomized Clinical Trial

IMPORTANCE

Benefits of granulocyte-macrophage colony-stimulating factor (GM-CSF) for improving walking ability in people with lower extremity peripheral artery disease (PAD) are unclear. Walking exercise may augment the effects of GM-CSF in PAD, since exercise-induced ischemia enhances progenitor cell release and may promote progenitor cell homing to ischemic calf muscle.

OBJECTIVES

To determine whether GM-CSF combined with supervised treadmill exercise improves 6-minute walk distance, compared with exercise alone and compared with GM-CSF alone; to determine whether GM-CSF alone improves 6-minute walk more than placebo and whether exercise improves 6-minute walk more than an attention control intervention.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial with 2 × 2 factorial design. Participants were identified from the Chicago metropolitan area and randomized between January 6, 2012, and December 22, 2016, to 1 of 4 groups: supervised exercise + GM-CSF (exercise + GM-CSF) (n = 53), supervised exercise + placebo (exercise alone) (n = 53), attention control  + GM-CSF (GM-CSF alone) (n = 53), attention control + placebo (n = 51). The final follow-up visit was on August 15, 2017.

INTERVENTIONS

Supervised exercise consisted of treadmill exercise 3 times weekly for 6 months. The attention control consisted of weekly educational lectures by clinicians for 6 months. GM-CSF (250 μg/m2/d) or placebo were administered subcutaneously (double-blinded) 3 times/wk for the first 2 weeks of the intervention.

MAIN OUTCOMES AND MEASURES

The primary outcome was change in 6-minute walk distance at 12-week follow-up (minimum clinically important difference, 20 m). P values were adjusted based on the Hochberg step-up method.

RESULTS

Of 827 persons evaluated, 210 participants with PAD were randomized (mean age, 67.0 [SD, 8.6] years; 141 [67%] black, 82 [39%] women). One hundred ninety-five (93%) completed 12-week follow-up. At 12-week follow-up, exercise + GM-CSF did not significantly improve 6-minute walk distance more than exercise alone (mean difference, -6.3 m [95% CI, -30.2 to +17.6]; P = .61) or more than GM-CSF alone (mean difference, +28.7 m [95% CI, +5.1 to +52.3]; Hochberg-adjusted P = .052). GM-CSF alone did not improve 6-minute walk more than attention control + placebo (mean difference, -1.4 m [95% CI, -25.2 to +22.4]; P = .91). Exercise alone improved 6-minute walk compared with attention control + placebo (mean difference, +33.6 m [95% CI, +9.4 to +57.7]; Hochberg-adjusted P = .02).

CONCLUSIONS AND RELEVANCE

Among patients with PAD, supervised treadmill exercise significantly improved 6-minute walk distance compared with attention control + placebo, whereas GM-CSF did not significantly improve walking performance, either when used alone or when combined with supervised treadmill exercise. These results confirm the benefits of exercise but do not support using GM-CSF to treat walking impairment in patients with PAD.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01408901.

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.

The Effect of Granulocyte Colony-Stimulating Factor on the Progression of Atherosclerosis in Animal Models: A Meta-Analysis

Background

Atherosclerosis is a common inflammatory disease. Stem cell and endothelial progenitor cell treatments can improve cardiac function after myocardial infarction. Granulocyte colony-stimulating factor (G-CSF) is a mobilisation agent, mobilising stem cells from the bone marrow to circulation in the blood. G-CSF may constitute a treatment of atherosclerosis. We have conducted meta-analysis to evaluate the current evidence for the effect of G-CSF on the progression of atherosclerosis in animal models and to provide reference for preclinical experiments and future human clinical trials of atherosclerosis treatment.

Methods

We searched several databases and conducted a meta-analysis across seven articles using a random-effect model. All statistical analyses were performed using Review Manager Version 5.2 and Stata 12.0.

Results

We found that G-CSF therapy was associated with reduced atherosclerotic lesion area (weighted mean difference (WMD): 7.29%; 95% confidence interval (CI): 2.06-12.52%; P = 0.006). No significant differences in total serum cholesterol (P = 0.54) and triglyceride levels (P = 0.95) were noted in G-CSF treatment groups compared with controls. Multivariable metaregression analysis revealed that the animal type (rabbit, P = 0.022) and frequency of G-CSF administration (>20, P = 0.007) impacted the atherosclerotic lesion area changes.

Conclusion

The meta-analysis suggested that G-CSF treatment might inhibit the progression of atherosclerosis in animal models.

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 genetics of exceptional longevity identifies new druggable targets for vascular protection and repair

Therapeutic angiogenesis is a relatively new medical strategy in the field of cardiovascular diseases. The underpinning concept is that angiogenic growth factors or proangiogenic cells could be exploited therapeutically in cardiovascular patients to enhance native revascularization responses to an ischemic insult, thereby accelerating tissue healing. The initial enthusiasm generated by preclinical studies has been tempered by the modest success of clinical trials assessing therapeutic angiogenesis. Similarly, proangiogenic cell therapy has so far not maintained the original promises. Intriguingly, the current trend is to consider regeneration as a prerogative of the youngest organism. Consequentially, the embryonic and foetal models are attracting much attention for clinical translation into corrective modalities in the adulthood. Scientists seem to undervalue the lesson from Mother Nature, e.g. all humans are born young but very few achieve the goal of an exceptional healthy longevity. Either natural experimentation is driven by a supreme intelligence or stochastic phenomena, one has to accept the evidence that healthy longevity is the fruit of an evolutionary process lasting million years. It is therefore extremely likely that results of this natural experimentation are more reliable and translatable than the intensive, but very short human investigation on mechanisms governing repair and regeneration. With this preamble in mind, here we propose to shift the focus from the very beginning to the very end of human life and thus capture the secret of prolonged health span to improve well-being in the adulthood.

Delivering therapeutics in peripheral artery disease: challenges and future perspectives

Targeted and sustained delivery of biologicals to improve neovascularization has been focused on stimulation angiogenesis. The formation of collaterals however is hemodynamically much more efficient, but as a target of therapy has been under-utilized. Although there is good understanding of the molecular processes involving collateral formation and there are interesting drugable candidates, the need for targeting and sustained delivery is still an obstacle towards safe and effective treatment. Molecular targeting with nanoparticles of liposomes is promising and so are peri-vascularly delivered polymer-based protein reservoirs. These developments will lead to future arteriogenesis strategies that are adjunct to current revascularization.

Safety and efficacy of cell-based therapy on critical limb ischemia: A meta-analysis

BACKGROUND AIMS

Critical limb ischemia (CLI) is a major health problem worldwide, affecting approximately 500-1000 people per million per annum. Cell-based therapy has given new hope for the treatment of limb ischemia. This study assessed the safety and efficacy of cellular therapy CLI treatment.

METHODS

We searched the PubMed, Embase and Cochrane databases through October 20, 2015, and selected the controlled trials with cell-based therapy for CLI treatment compared with cell-free treatment. We assessed the results by meta-analysis using a variety of outcome measures, as well as the association of mononuclear cell dosage with treatment effect by dose-response meta-analysis.

RESULTS

Twenty-five trials were included. For the primary evaluation index, cell-based therapy significantly reduced the rate of major amputation (odds ratio [OR] 0.44, 95% confidence interval [CI] 0.32-0.60, P = 0.000) and significantly increased the rate of amputation-free survival (OR 2.80, 95% CI 1.70-4.61, P = 0.000). Trial sequence analysis indicated that optimal sample size (n = 3374) is needed to detect a plausible treatment effect in all-cause mortality. Cell-based therapy significantly improves ankle brachial index, increases the rate of ulcer healing, increases the transcutaneous pressure of oxygen, reduces limb pain and improves movement ability. Subgroup analysis indicated heterogeneity is caused by type of control, design bias and transplant route. In the dose-response analysis, there was no significant correlation between cell dosage and the therapeutic effect.

CONCLUSIONS

Cell-based therapy has a significant therapeutic effect on CLI, but randomized double-blind placebo-controlled trials are needed to improve the credibility of this conclusion. Assessment of all-cause mortality also requires a larger sample size to arrive at a strong conclusion. In dose-response analysis, increasing the dosage of cell injections does not significantly improve the therapeutic effects of cell-based therapy.

Cell Therapy for Critical Limb Ischemia: A Meta-Analysis of Randomized Controlled Trials

Early-phase trials showed the feasibility and potential efficacy of cell therapy in patients with critical limb ischemia (CLI). For systematic review, randomized controlled trials (RCTs) of cell therapy versus no cell therapy in CLI were searched from PubMed and the Cochrane library databases. Outcome measures included major amputation, complete ulcer healing, ankle-brachial index (ABI), and all-cause mortality. Data were pooled using 16 RCTs, involving 774 patients. Compared with no cell therapy, cell therapy significantly reduced major amputation (odds ratio [OR]: 0.54; 95% CI: 0.34-0.87:P= .01) and improved ulcer healing (OR: 2.90; 95% confidence interval [CI]: 1.44-5.82;P< .01) and ABI (OR: 5.91; 95% CI: 1.85-18.86:P< .01). Peripheral blood-derived mononuclear cells (PB-MNCs; OR: 0.29; 95% CI: 0.12-0.72;P< .01) and bone marrow concentrate (OR: 0.44; 95% CI: 0.21-0.93;P= .03) significantly lowered the risk of major amputation. The PB-MNCs also significantly increased ulcer healing (OR: 5.77; 95% CI: 1.77-18.87;P< .01). All-cause mortality was similar in both groups (OR: 0.78; 95% CI: 0.44-1.40;P= .41). However, all estimates were nonsignificant following reanalysis using placebo-controlled RCTs only. Cell therapy remains a potential therapeutic option in CLI, but further larger placebo-controlled RCTs are needed.

Local intramuscular transplantation of autologous mononuclear cells for critical lower limb ischaemia

BACKGROUND

Peripheral arterial disease is a major health problem, and in about 1% to 2% of patients the disease progresses to critical limb ischaemia (CLI). In a substantial number of patients with CLI, no effective treatment option other than amputation is available and around a quarter of these patients will require a major amputation during the following year. This is an update of the review first published in 2011.

OBJECTIVES

To determine the effectiveness and safety of local intramuscular transplantation of autologous adult bone marrow mononuclear cells (BMMNCs) as a treatment for critical limb ischaemia (CLI).

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched February 2014) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 1).

SELECTION CRITERIA

We included all randomised controlled trials of CLI in which participants were randomly allocated to intramuscular administration of autologous adult BMMNCs or control (either no intervention or conventional conservative therapy). We excluded studies on patients with intermittent claudication.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data. Disagreements were resolved by consensus or by the third author.

MAIN RESULTS

Only two small studies, with a combined total of 57 participants, met our inclusion criteria and were finally included. They were classified as having a moderate risk of bias with unclear issues regarding their methods, and according to the GRADE approach, the overall quality of the evidence would be considered as moderate. In one study the effects of intramuscular injections of BMMNCs in the ischaemic lower limbs of patients with CLI were compared with control (standard conservative treatment). No deaths were reported and no significant difference was observed between the two groups for either pain (P = 0.37) or the ankle brachial index (ABI) parameter. However, the treatment group showed a significantly smaller proportion of participants undergoing amputation compared with the control group (P = 0.026).In the other study, following subcutaneous injections of granulocyte colony-stimulating factor (G-CSF) for five days, peripheral blood derived mononuclear cells were collected and then transplanted by intramuscular injections into ischaemic lower limbs. The effects were compared with daily intravenous prostaglandin E1 injections (control group). No deaths were reported. Pain reduction was greater in the treatment group than in the control group (P < 0.001) as was increase in ABI (mean increase 0.13 versus 0.02, P < 0.01). The treatment group experienced a statistically significant increase in pain-free walking distance (PFWD) compared with the control group (mean increase 306.4 m versus 78.6 m, P = 0.007). A smaller proportion of participants underwent amputation in the treatment group compared with the control group (0% versus 36%, P = 0.007).

AUTHORS' CONCLUSIONS

The data from the published trials suggest that there is insufficient evidence to support this treatment. These results were based on only two trials which had a very small number of participants. Therefore evidence from larger randomised controlled trials is needed in order to provide adequate statistical power to assess the role of intramuscular mononuclear cell implantation in patients with CLI.

Clinical trials of adult stem cell therapy for peripheral artery disease

Peripheral artery disease (PAD) refers to noncoronary vascular disease affecting the peripheral arteries. Most commonly the term is applied to occlusive arterial disease affecting the limb arteries, typically due to atherosclerosis. Preclinical studies indicate that a variety of stem cell therapies provide growth factors and cytokines for therapeutic angiogenesis. Small clinical trials with bone marrow mononuclear cells, as well as other cell types, have shown promise. However, mechanisms of therapeutic effect, if any, are not understood. Definitive clinical trials are needed to determine if there are any beneficial effects on functional capacity or morbidity.

Bilateral administration of autologous CD133+ cells in ambulatory patients with refractory critical limb ischemia: lessons learned from a pilot randomized, double-blind, placebo-controlled trial

BACKGROUND AIMS

CD133+ cells confer angiogenic potential and may be beneficial for the treatment of critical limb ischemia (CLI). However, patient selection, blinding methods and end points for clinical trials are challenging. We hypothesized that bilateral intramuscular administration of cytokine-mobilized CD133+ cells in ambulatory patients with refractory CLI would be feasible and safe.

METHODS

In this double-blind, randomized sham-controlled trial, subjects received subcutaneous injections of granulocyte colony-stimulating factor (10 μg/kg per day) for 5 days, followed by leukapheresis, and intramuscular administration of 50-400 million sorted CD133+ cells delivered into both legs. Control subjects received normal saline injections, sham leukapheresis and intramuscular injection of placebo buffered solution. Subjects were followed for 1 year. An aliquot of CD133+ cells was collected from each subject to test for genes associated with cell senescence.

RESULTS

Seventy subjects were screened, of whom 10 were eligible. Subject enrollment was suspended because of a high rate of mobilization failure in subjects randomly assigned to treatment. Of 10 subjects enrolled (7 randomly assigned to treatment, 3 randomly assigned to control), there were no differences in serious adverse events at 12 months, and blinding was preserved. There were non-significant trends toward improved amputation-free survival, 6-minute walk distance, walking impairment questionnaire and quality of life in subjects randomly assigned to treatment. Successful CD133+ mobilizers expressed fewer senescence-associated genes compared with poor mobilizers.

CONCLUSIONS

Bilateral administration of autologous CD133+ cells in ambulatory CLI subjects was safe, and blinding was preserved. However, poor mobilization efficiency combined with high CD133+ senescence suggests futility in this approach.

Thromoboagiitis Obliterans (TAO)

Thromboangiitis obliterans (TAO) is nonatherosclerotic inflammatory disease of the peripheral blood vessels, and TAO affects the small and medium sized vessels of the extremities. TAO is mainly seen in young males who smoke, and smoking is strongly associated with the disease course and progression. The diagnosis is made on the basis of the history, the physical examination and the clinical diagnostic criteria. As the bedrock for treating patients with TAO, absolute abstinence from tobacco is most important factor, and patients with TAO are usually managed conservatively. Surgical bypass or endovascular therapy is usually not possible for patients with TAO because of the diffuse segmental involvement and the distal nature of the disease. Therefore, stem cell therapy is considered to be a novel therapeutic modality for treating patients with TAO and who are not eligible for conventional revascularization therapies. In this paper, I have summarized the recent knowledge about TAO and I have reviewed the recent studies that have focused on the treatment of TAO.

Gene therapy and cell-based therapies for therapeutic angiogenesis in peripheral artery disease

Gene therapy and cell-based therapy have emerged as novel therapies to promote therapeutic angiogenesis in critical limb ischemia (CLI) caused by peripheral artery disease (PAD). Although researchers initially focused on gene therapy using proangiogenic factors, such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and hepatocyte growth factors (HGF), cell therapy using bone marrow mononuclear cells (BMMNCs), mesenchymal stem cells (BMMSCs), G-CSF-mobilized peripheral blood mononuclear cells (M-PBMNCs), and endothelial progenitor cells (EPCs) have also been extensively studied. Based on the elaborate studies and favorable results of basic research, some clinical phase I/II trials have been performed, and the results demonstrate the safety of these approaches and their potential for symptomatic improvement in CLI. However, the phase 3 clinical trials have thus far been limited to gene therapy using the HGF gene. Further studies using well-designed larger placebo-controlled and long-term randomized control trials (RCTs) will clarify the effectiveness of gene therapy and cell-based therapy for the treatment of CLI. Furthermore, the development of efficient gene transfer systems and effective methods for keeping transplanted cells healthy will make these novel therapies more effective and ease the symptoms of CLI.

Progenitor cell release plus exercise to improve functional performance in peripheral artery disease: the PROPEL Study

Functional impairment, functional decline, and mobility loss are major public health problems in people with lower extremity peripheral artery disease (PAD). Few medical therapies significantly improve walking performance in PAD. We describe methods for the PROgenitor cell release Plus Exercise to improve functionaL performance in PAD (PROPEL) Study, a randomized controlled clinical trial designed to determine whether granulocyte-macrophage colony stimulating factor (GM-CSF) combined with supervised treadmill walking exercise improves six-minute walk distance more than GM-CSF alone, more than supervised treadmill exercise alone, and more than placebo plus attention control in participants with PAD, respectively. PROPEL Study participants are randomized to one of four arms in a 2 by 2 factorial design. The four study arms are GM-CSF plus supervised treadmill exercise, GM-CSF plus attention control, placebo plus supervised exercise therapy, or placebo plus attention control. The primary outcome is change in six-minute walk distance at 12-week follow-up. Secondary outcomes include change in brachial artery flow-mediated dilation (FMD), change in maximal treadmill walking time, and change in circulating CD34+ cells at 12-week follow-up. Outcomes are also measured at six-week and six-month follow-up. Results of the PROPEL Study will have important implications for understanding mechanisms of improving walking performance and preventing mobility loss in the large and growing number of men and women with PAD.

Bone marrow endothelial progenitors augment atherosclerotic plaque regression in a mouse model of plasma lipid lowering

The major event initiating atherosclerosis is hypercholesterolemia-induced disruption of vascular endothelium integrity. In settings of endothelial damage, endothelial progenitor cells (EPCs) are mobilized from bone marrow into circulation and home to sites of vascular injury where they aid endothelial regeneration. Given the beneficial effects of EPCs in vascular repair, we hypothesized that these cells play a pivotal role in atherosclerosis regression. We tested our hypothesis in the atherosclerosis-prone mouse model in which hypercholesterolemia, one of the main factors affecting EPC homeostasis, is reversible (Reversa mice). In these mice, normalization of plasma lipids decreased atherosclerotic burden; however, plaque regression was incomplete. To explore whether endothelial progenitors contribute to atherosclerosis regression, bone marrow EPCs from a transgenic strain expressing green fluorescent protein (GFP) under the control of endothelial cell-specific Tie2 promoter (Tie2-GFP(+)) were isolated. These cells were then adoptively transferred into atheroregressing Reversa recipients where they augmented plaque regression induced by reversal of hypercholesterolemia. Advanced plaque regression correlated with engraftment of Tie2-GFP(+) EPCs into endothelium and resulted in an increase in atheroprotective nitric oxide and improved vascular relaxation. Similarly augmented plaque regression was also detected in regressing Reversa mice treated with the stem cell mobilizer AMD3100 which also mobilizes EPCs to peripheral blood. We conclude that correction of hypercholesterolemia in Reversa mice leads to partial plaque regression that can be augmented by AMD3100 treatment or by adoptive transfer of EPCs. This suggests that direct cell therapy or indirect progenitor cell mobilization therapy may be used in combination with statins to treat atherosclerosis.

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.

Bone marrow endothelial progenitors in atherosclerotic plaque resolution

Atherosclerosis is a major cause of morbidity and mortality in the United States. Persistently elevated circulating low-density lipoprotein, or hypercholesterolemia, and deposition of low-density lipoprotein in the vascular wall are the main inducers of atherosclerosis, which manifests itself as arterial lesions or plaques. Some plaques become thrombosis-prone and rupture, causing acute myocardial infarction or stroke. Lowering plasma cholesterol through the use of statins is the primary intervention against atherosclerosis. Treatment with statins slows progression of atherosclerosis but can only support limited plaque regression. Partially regressed plaques continue to pose a serious threat due to their remaining potential to rupture. Thus, new interventions inducing complete reversal of atherosclerosis are being sought. Implementation of new therapies will require clear understanding of the mechanisms driving plaque resolution. In this Views and Commentary, we highlight the role of bone marrow endothelial progenitors in atherosclerotic plaque regression and discuss how regenerative cell-based interventions could be used in combination with plasma lipid-lowering to induce plaque reversal in order to prevent and/or reduce adverse cardiovascular events.

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.

Granulocyte colony-stimulating factor and interleukin-1β are important cytokines in repair of the cirrhotic liver after bone marrow cell infusion: comparison of humans and model mice

We previously described the effectiveness of autologous bone marrow cell infusion (ABMi) therapy for patients with liver cirrhosis (LC). We analyzed chronological changes in 19 serum cytokines as well as levels of specific cytokines in patients after ABMi therapy and in a mouse model of cirrhosis generated using green fluorescent protein (GFP)/carbon tetrachloride (CCl4). We measured expression profiles of cytokines in serum samples collected from 13 patients before and at 1 day and 1 week after ABMi. Child-Pugh scores significantly improved in all of these patients. To analyze the meaning of early cytokine change, we infused GFP-positive bone marrow cells (BMCs) into mice with CCl4-induced LC and obtained serum and tissue samples at 1 day and as well as at 1, 2, 3, and 4 weeks later. We compared chronological changes in serum cytokine expression in humans and in the model mice at 1 day and 1 week after BMC infusion. Among 19 cytokine, both granulocyte colony-stimulating factor (G-CSF) and interleukin-1β(IL-1β) in serum was found to show the same chronological change pattern between human and mice model. Next, we examined changes in cytokine expression in cirrhosis liver before and at 1, 2, 3, and 4 weeks after BMC infusion. Both G-CSF and IL-1β were undetectable in the liver tissues before and at 1 week after BMC infusion but increased at 2 weeks and continued until 4 weeks after infusion. The infused BMCs induced an early decrease of both G-CSF and IL-1β in serum and an increase in the model mice with LC. These dynamic cytokine changes might be important to repair liver cirrhosis after BMC infusion.

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.

Autologous peripheral blood-derived mononuclear cells induced by erythropoietin improve critical ischemic limbs

PURPOSE

Efficient and secure collection of CD34+ cells are crucial for the angiogenic therapies. We have developed autologous peripheral blood-mononuclear cell (MNC) transplantation induced by erythropoietin (rhEPO) for critical ischemic limbs.

METHODS

Seven patients, including five with arteriosclerosis obliterans, one with Buerger's disease and one with progressive systemic sclerosis, underwent ten cell therapies. The first administration of rhEPO was performed two weeks before apheresis, and the second administration and blood donation were performed one week before apheresis to activate bone marrow. MNCs including CD34+ cells, isolated from peripheral blood by apheresis, were immediately injected intramuscularly into ischemic limbs.

RESULTS

The number of peripheral blood-CD34 + cells had significantly increased from 1.32 ± 0.83/microL, before the rhEPO induction, to 1.86 ± 0.94/microL, before the apheresis. The number of transplanted MNCs ranged between 0.5 × 10(9) and 16.5 × 10(9), and that of CD34+ cells, between 0.1 × 10(6) and 12.7 × 10(6), accounting for 0.02%-0.1% of MNCs. There were no serious complications. Finger ulcers with Buerger's disease were significantly improved one month after the transplantations, but the same or other ulcer(s) appeared 2-6 months later. Three patients had an improvement in rest pain, and one patient extended maximum pain-free walking distance.

CONCLUSIONS

Erythropoietin-induced autologous peripheral blood-MNC transplantation is a useful and safe alternative for ischemic limbs.

Local intramuscular transplantation of autologous mononuclear cells for critical lower limb ischaemia

BACKGROUND

Peripheral arterial disease (PAD) is a major health problem and in about 1% to 2% of patients the disease progresses to critical limb ischaemia (CLI). In a substantial number of patients with CLI, no effective treatment option other than amputation is available and around a quarter of these patients will require a major amputation during the following year.

OBJECTIVES

To determine the effectiveness and safety of autologous adult bone marrow derived mononuclear cells (BMMNCs) as a treatment for CLI.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched November 2010) and CENTRAL (2010, Issue 4). We searched the reference lists of identified articles.

SELECTION CRITERIA

All randomised controlled trials of CLI in which participants were randomly allocated to intramuscular administration of autologous adult BMMNCs or control (either no intervention or conventional conservative therapy) were included. Studies on patients with intermittent claudication were not included.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed trials for eligibility and methodological quality, and extracted data. Disagreements were resolved by consensus or by the third author.

MAIN RESULTS

Thirty-seven potential studies were identified after initial screening of titles and abstracts. Only two small studies, with a combined total of 57 patients, met our inclusion criteria and were finally included. In one study the effects of intramuscular injections of BMMNCs in the ischaemic lower limbs of patients with CLI were compared with control (standard conservative treatment). No deaths were reported and no significant difference was observed between the two groups for either pain (P = 0.37) or the ankle brachial pressure index (ABI) parameter. However, the treatment group showed a significantly smaller proportion of participants undergoing amputation compared with the control group (P = 0.026).In the other study, following subcutaneous injections of granulocyte colony-stimulating factor (G-CSF) for five days peripheral blood derived mononuclear cells were collected and then transplanted by intramuscular injections into ischaemic lower limbs. The effects were compared with daily intravenous prostaglandin E1 injections (control group). No deaths were reported. Pain reduction was greater in the treatment group than in the control group (P < 0.001) as was increase in ABI (mean increase 0.13 versus 0.02, P < 0.01). The treatment group experienced a statistically significant increase in pain-free walking distance compared with the control group (mean increase 306.4 m versus 78.6 m, P = 0.007). A smaller proportion of participants underwent amputation in the treatment group compared with the control group (0% versus 36%, P = 0.007).

AUTHORS' CONCLUSIONS

The data from the published trials suggest that there is insufficient evidence to support this treatment. These results were based on only two trials which had a very small number of participants. Therefore evidence from larger randomised controlled trials is needed in order to provide adequate statistical power to assess the role of intramuscular mononuclear cell implantation in patients with CLI.

Transcriptome analysis in endothelial progenitor cell biology

The use of endothelial progenitor cells (EPCs) is a promising new treatment option for cardiovascular diseases. Many of the underlying mechanisms that result in an improvement of endothelial function in vivo remain poorly elucidated to this date, however. We summarize the current positions and potential applications of gene-expression profiling in the field of EPC biology. Based on our own and published gene-expression data, we demonstrate that gene-expression profiling can efficiently be used to characterize different EPC types. Furthermore, we highlight the potential of gene-expression profiling for the analysis of changes that EPCs undergo during culture and examine changes in gene transcription in diseased patients. Transcriptome profiling is a powerful tool for the characterization and functional analysis of EPCs in health and disease.

The therapeutic potential of G-CSF in pressure overload induced ventricular reconstruction and heart failure in mice

In animal models of clinical entities causative of severe right and left ventricular (LV) pressure overload hypertrophy, increased density of the cellular microtubule network, through viscous loading of active myofilaments, causes contractile dysfunction that is normalized by microtubule depolymerization. In this study, 86 male mice were divided into seven groups. The transverse ascending aorta constriction (TAC) in six groups were performed in order to make heart failure model. Mice in each group were injected with G-CSF or/and telmisartan subcutaneously at different time respectively. Results showed that reduction in left ventricular volume and improved function persisted at 2 week, but recurrent dilatation at 4 weeks was associated with a loss of functional improvement. Compared with PBS group, the expression of VEGF protein and HIF-1 mRNA were significantly higher in mice injected with G-CSF or/and telmisartan (P<0.05). The expression of p53 mRNA, myocardial fibrosis and mortality were significantly lower in mice injected with G-CSF or/and telmisartan (P<0.05). It could be concluded that G-CSF can delay the progression of pressure overload induced ventricular reconstruction and heart failure in mice.

Transplantation of Endothelial Progenitor Cells as Therapeutics for Cardiovascular Diseases

With better understanding of endothelial progenitor cells (EPCs), many therapeutic approaches to cardiovascular diseases have been developed. This article will review novel research of EPCs in promoting angiogenesis, vasculogenesis, and endothelialization, as a design for future clinical treatment. Cell therapy has the potential to supply stem/progenitor cells and multiple angiogenic factors to the region of ischemia. The efficacy of EPC transplantation may be impaired by low survival rate, insufficient cell number, and impaired function in aging and diseases. Combination of EPCs or cells primed with growth factors or genetic modification may improve the therapeutic efficacy. The molecular mechanism involved in EPC repairing processes is essential. Thus, we have also addressed the molecular mechanism of mobilization, homing, and differentiation of EPCs. The potential of therapeutic neovascularization, angiogenic factor therapy, and cell transplantation have been elucidated. Based on past experience and actual knowledge, future strategies for EPC therapy will be proposed in order to fully exploit the potential of EPC transplantation with clinical relevance for cardiovascular disease applications.

Autologous stem cell therapy for peripheral arterial disease meta-analysis and systematic review of the literature

BACKGROUND

Peripheral arterial disease (PAD) is a common cause of disability and mortality. Up to one third of patients are not susceptible to traditional revascularization and may benefit from stem cell therapies.

OBJECTIVE

In this meta-analysis, we sought to determine whether autologous cell therapy is effective in the treatment of PAD.

METHODS

We searched the English literature in Medline, Excerpta Medica and the Cochrane database for trials of autologous cell therapy in patients with PAD published before 31 January 2009. We included controlled and non-controlled, randomized and non-randomized trials using autologous bone marrow or granulocyte colony stimulating factor (G-CSF) mobilized peripheral blood cells to treat PAD. We also collected data from trials of G-CSF monotherapy, as a control treatment.

RESULTS

In a meta-analysis of 37 trials, autologous cell therapy was effective in improving surrogate indexes of ischemia, subjective symptoms and hard endpoints (ulcer healing and amputation). On the contrary, G-CSF monotherapy was not associated with significant improvement in the same endpoints. Patients with thromboangiitis obliterans showed some larger benefits than patients with atherosclerotic PAD. The intramuscular route of administration and the use of bone marrow cells seemed somehow more effective than intrarterial administration and the use of mobilized peripheral blood cells. The procedures were well tolerated and generally safe.

CONCLUSION

This meta-analysis indicates that intramuscular autologous bone marrow cell therapy is a feasible, relatively safe and potentially effective therapeutic strategy for PAD patients, who are not candidate for traditional revascularization. Larger, placebo-controlled, randomized multicenter trials need to be planned and conducted to confirm these findings.

Bone marrow mobilization with granulocyte macrophage colony-stimulating factor improves endothelial dysfunction and exercise capacity in patients with peripheral arterial disease

BACKGROUND

We hypothesized that granulocyte macrophage colony-stimulating factor (GM-CSF) administration will be safe and will improve endothelial dysfunction and exercise capacity by mobilizing progenitor cells in patients with peripheral arterial disease (PAD).

METHODS

Forty-five patients with PAD received thrice-weekly injections for 2 weeks of 3, 6, or 10 microg/kg per day of GM-CSF or placebo in successive cohorts of 15 subjects randomized 2:1 to drug or placebo. CD34+ mononuclear cell subsets and colony formation assay, endothelial function, ankle-brachial index, and walking capacity were measured.

RESULTS

Granulocyte macrophage colony-stimulating factor administration was safe. After pooling data from GM-CSF cohorts, at 2 weeks, there was a significant increase in total leukocytes (43%, P < .0001), CD34+ cells (46%, P = .035), and colony-forming units (31%, P = .026, week 1). At 12 weeks, endothelial function improved with GM-CSF (flow-mediated vasodilation increased by 59%, P < .01) as did pain-free treadmill walking time (38 seconds, P = .008) and total treadmill walking time (55 seconds, P = .016). Corresponding changes were not observed in the placebo group.

CONCLUSIONS

Granulocyte macrophage colony-stimulating factor therapy in patients with PAD was associated with mobilization of progenitor cells, improvement of endothelial dysfunction, and exercise capacity. The efficacy of strategies designed to mobilize bone marrow progenitors warrants further study in patients with PAD.

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

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

Suppression of right ventricular hypertrophy after extensive pulmonary resection in rats by granulocyte colony-stimulating factor

BACKGROUND

The objective of the present study was to investigate the effects of granulocyte colony-stimulating factor (G-CSF) on right ventricular hypertrophy following extensive pulmonary resection in rats.

MATERIALS AND METHODS

Adult rats were divided into four groups: (1) Group S (right thoracotomy only); (2) Group L (right three lobectomy); (3) Group LG10 (Group L+G-CSF [10microg/kg/d]); and (4) Group LG100 (Group L+G-CSF [100microg/kg/d]). At postoperative day 21, weight ratio of the right ventricular to the left ventricle plus septum (RV/LV+S, indicator of right ventricular hypertrophy) were measured, and a histopathological study was conducted to determine percentage wall thickness of peripheral pulmonary arteries and proliferating cell nuclear antigen labeling index (indicator of oxidative DNA damage) of right ventricles.

RESULTS

Mean RV/LV+S for Group S was 0.27+/-0.02, significantly smaller than that for the lobectomy groups (Group L, LG10, LG100; 0.47+/-0.05, 0.35+/-0.02, 0.38+/-0.05). G-CSF significantly suppressed right ventricular hypertrophy. Mean medial wall thickness of peripheral pulmonary arteries for Group S was 13.6% +/- 4.9%, significantly smaller than that for Group L (22.9% +/- 9.6%). Compared with Group L, G-CSF reduced medial wall thickness (LG10, 17.6% +/- 9.5%; LG100, 18.0% +/- 11.2%). Incidence of proliferating cell nuclear antigen positive nuclei for Group S was 1.07% +/- 0.49%, significantly smaller than that for Group L (13.77% +/- 5.87%). G-CSF significantly reduced the incidence of proliferating cell nuclear antigen positive nuclei (LG10, 4.04% +/- 2.14%; LG100, 3.18% +/- 1.66%).

CONCLUSIONS

G-CSF administration not only reduce medial wall thickness of peripheral pulmonary arteries but also directly protect cardiomyocytes of the right ventricle, thus suppressing right ventricular hypertrophy. These results suggest that low-dose G-CSF administration can prevent right heart failure following extensive pulmonary resection.