Characterization and comparison of bone marrow and peripheral blood mononuclear cells used for cellular therapy in critical leg ischaemia: towards a new cellular product

Local intramuscular transplantation of autologous bone marrow 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), also known as critical limb-threatening ischaemia. In a substantial number of individuals with CLI, no effective treatment options other than amputation are available, with around a quarter of these patients requiring a major amputation during the following year. This is the second update of a review first published in 2011.

OBJECTIVES

To evaluate the benefits and harms of local intramuscular transplantation of autologous adult bone marrow mononuclear cells (BMMNCs) as a treatment for CLI.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 8 November 2021.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) of CLI in which participants were randomly allocated to intramuscular administration of autologous adult BMMNCs or control (either no intervention, conventional conservative therapy, or placebo).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes of interest were all-cause mortality, pain, and amputation. Our secondary outcomes were angiographic analysis, ankle-brachial index (ABI), pain-free walking distance, side effects and complications. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included four RCTs involving a total of 176 participants with a clinical diagnosis of CLI. Participants were randomised to receive either intramuscular cell implantation of BMMNCs or control. The control arms varied between studies, and included conventional therapy, diluted autologous peripheral blood, and saline. There was no clear evidence of an effect on mortality related to the administration of BMMNCs compared to control (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.15 to 6.63; 3 studies, 123 participants; very low-certainty evidence). All trials assessed changes in pain severity, but the trials used different forms of pain assessment tools, so we were unable to pool data. Three studies individually reported that no differences in pain reduction were observed between the BMMNC and control groups. One study reported that reduction in rest pain was greater in the BMMNC group compared to the control group (very low-certainty evidence). All four trials reported the rate of amputation at the end of the study period. We are uncertain if amputations were reduced in the BMMNC group compared to the control group, as a possible small effect (RR 0.52, 95% CI 0.27 to 0.99; 4 studies, 176 participants; very low-certainty evidence) was lost after undertaking sensitivity analysis (RR 0.52, 95% CI 0.19 to 1.39; 2 studies, 89 participants). None of the included studies reported any angiographic analysis. Ankle-brachial index was reported differently by each study, so we were not able to pool the data. Three studies reported no changes between groups, and one study reported greater improvement in ABI (as haemodynamic improvement) in the BMMNC group compared to the control group (very low-certainty evidence). One study reported pain-free walking distance, finding no clear difference between BMMNC and control groups (low-certainty evidence). We pooled the data for side effects reported during the follow-up, and this did not show any clear difference between BMMNC and control groups (RR 2.13, 95% CI 0.50 to 8.97; 4 studies, 176 participants; very low-certainty evidence). We downgraded the certainty of the evidence due to the concerns about risk of bias, imprecision, and inconsistency.

AUTHORS' CONCLUSIONS

We identified a small number of studies that met our inclusion criteria, and these differed in the controls they used and how they measured important outcomes. Limited data from these trials provide very low- to low-certainty evidence, and we are unable to draw conclusions to support the use of local intramuscular transplantation of BMMNC for improving clinical outcomes in people with CLI. Evidence from larger RCTs is needed in order to provide adequate statistical power to assess the role of this procedure.

Stem and Somatic Cell Monotherapy for the Treatment of Diabetic Foot Ulcers: Review of Clinical Studies and Mechanisms of Action

Diabetic foot ulcer (DFU) is one of the most severe complications of diabetes mellitus, often resulting in a limb amputation. A cell-based therapy is a highly promising approach for an effective DFU treatment. However, there is no consensus regarding the most effective cell type for DFU treatment. Various cell types contribute to chronic wound healing via different mechanisms. For example, application of keratinocytes can stimulate migration of native keratinocytes from the wound edge, while mesenchymal stem cells can correct limb ischemia. To assess the effectiveness of a certain cell type, it should be administered as a monotherapy without other substances and procedures that have additional therapeutic effects. In the present review, we described therapeutic effects of various cells and provided an overview of clinical studies in which stem and somatic cell-based therapy was administered as a monotherapy. Topical application of somatic cells contributes to DFU healing only, while injection of mesenchymal stem cells and mononuclear cells can break a pathophysiological chain leading from insufficient blood supply to DFU development. At the same time, the systemic use of mesenchymal stem cells carries greater risks. Undoubtedly, cell therapy is a potent tool for the treatment of DFU. However, it is vital to conduct further high-quality clinical research to determine the most effective cell type, dosage and way of administration for DFU treatment. Ischemia, neuropathy and neuro-ischemia are underlying factors of diabetic foot ulcer. Stem and somatic cells monotherapy can improve chronic wound healing via different mechanisms.

Patrolling human SLE haematopoietic progenitors demonstrate enhanced extramedullary colonisation; implications for peripheral tissue injury

Systemic lupus erythematosus (SLE) is an autoimmune disease where bone-marrow-derived haematopoietic cells have a key role in its pathogenesis with accumulating evidence suggesting an aberrant function of haematopoietic stem/progenitor cells (HSPCs). We examined whether patrolling HSPCs differ from bone-marrow HSPCs both in SLE and healthy individuals, and how they participate in peripheral tissue injury. By employing next-generation RNA sequencing, the transcriptomes of CD34⁺ HSPCs deriving from the bone marrow and those patrolling the bloodstream of both healthy and individuals with SLE were compared. Patrolling SLE and Healthy human HSPC kinetics were examined through their inoculation into humanised mice. Patrolling and bone-marrow HSPCs have distinct molecular signatures, while patrolling SLE HSPCs showed an enhanced extramedullary gene expression profile. Non-mobilised, SLE-derived circulating HSPCs demonstrated altered homing capacities. Xenotransplantation of circulating HSPCs in humanised mice showed that human peripheral blood HSPCs possess the ability for extramedullary organ colonisation to the kidneys. Circulating and bone marrow-derived HSPCs are distinct in steady and diseased states. Patrolling SLE CD34⁺ HSPCs are able to home at extramedullary sites such as the spleen and kidneys, potentially participating in peripheral tissue injury.

Prognostic Prediction of Cytogenetically Normal Acute Myeloid Leukemia Based on a Gene Expression Model

Acute myeloid leukemia (AML) refers to a heterogeneous group of hematopoietic malignancies. The well-known European Leukemia Network (ELN) stratifies AML patients into three risk groups, based primarily on the detection of cytogenetic abnormalities. However, the prognosis of cytogenetically normal AML (CN-AML), which is the largest AML subset, can be hard to define. Moreover, the clinical outcomes associated with this subgroup are diverse. In this study, using transcriptome profiles collected from CN-AML patients in the BeatAML cohort, we constructed a robust prognostic Cox model named NEST (Nine-gEne SignaTure). The validity of NEST was confirmed in four external independent cohorts. Moreover, the risk score predicted by the NEST model remained an independent prognostic factor in multivariate analyses. Further analysis revealed that the NEST model was suitable for bone marrow mononuclear cell (BMMC) samples but not peripheral blood mononuclear cell (PBMC) samples, which indirectly indicated subtle differences between BMMCs and PBMCs. Our data demonstrated the robustness and accuracy of the NEST model and implied the importance of the immune dysfunction in the leukemogenesis that occurs in CN-AML, which shed new light on the further exploration of molecular mechanisms and treatment guidance for CN-AML.

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.

Cost-Effective, Safe, and Personalized Cell Therapy for Critical Limb Ischemia in Type 2 Diabetes Mellitus

Cell therapy is a progressively growing field that is rapidly moving from preclinical model development to clinical application. Outcomes obtained from clinical trials reveal the therapeutic potential of stem cell-based therapy to deal with unmet medical treatment needs for several disorders with no therapeutic options. Among adult stem cells, mesenchymal stem cells (MSCs) are the leading cell type used in advanced therapies for the treatment of autoimmune, inflammatory and vascular diseases. To date, the safety and feasibility of autologous MSC-based therapy has been established; however, their indiscriminate use has resulted in mixed outcomes in preclinical and clinical studies. While MSCs derived from diverse tissues share common properties depending on the type of clinical application, they markedly differ within clinical trials in terms of efficacy, resulting in many unanswered questions regarding the application of MSCs. Additionally, our experience in clinical trials related to critical limb ischemia pathology (CLI) shows that the therapeutic efficacy of these cells in different animal models has only been partially reproduced in humans through clinical trials. Therefore, it is crucial to develop new research to identify pitfalls, to optimize procedures and to clarify the repair mechanisms used by these cells, as well as to be able to offer a next generation of stem cell that can be routinely used in a cost-effective and safe manner in stem cell-based therapies targeting CLI.

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.

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.

Multiple therapeutic effect of endothelial progenitor cell regulated by drugs in diabetes and diabetes related disorder

BACKGROUND

Reduced levels of endothelial progenitor cells (EPCs) counts have been reported in diabetic mellitus (DM) patients and other diabetes-related disorder. EPCs are a circulating, bone marrow-derived cell population that appears to participate in vasculogenesis, angiogenesis and damage repair. These EPC may revert the damage caused in diabetic condition. We aim to identify several existing drugs and signaling molecule, which could alleviate or improve the diabetes condition via mobilizing and increasing EPC number as well as function.

MAIN BODY

Accumulated evidence suggests that dysregulation of EPC phenotype and function may be attributed to several signaling molecules and cytokines in DM patients. Hyperglycemia alone, through the overproduction of reactive oxygen species (ROS) via eNOS and NOX, can induce changes in gene expression and cellular behavior in diabetes. Furthermore, reports suggest that EPC telomere shortening via increased oxidative DNA damage may play an important role in the pathogenesis of coronary artery disease in diabetic patients. In this review, different type of EPC derived from different sources has been discussed along with cell-surface marker. The reduced number and immobilized EPC in diabetic condition have been mobilized for the therapeutic purpose via use of existing, and novel drugs have been discussed. Hence, evidence list of all types of drugs that have been reported to target the same pathway which affect EPC number and function in diabetes has been reviewed. Additionally, we highlight that proteins are critical in diabetes via polymorphism and inhibitor studies. Ultimately, a lucid pictorial explanation of diabetic and normal patient signaling pathways of the collected data have been presented in order to understand the complex signaling mystery underlying in the diseased and normal condition.

CONCLUSION

Finally, we conclude on eNOS-metformin-HSp90 signaling and its remedial effect for controlling the EPC to improve the diabetic condition for delaying diabetes-related complication. Altogether, the review gives a holistic overview about the elaborate therapeutic effect of EPC regulated by novel and existing drugs in diabetes and diabetes-related disorder.

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.

Growth factors for angiogenesis in peripheral arterial disease

BACKGROUND

Peripheral artery disease (PAD) is associated with a high clinical and socioeconomic burden. Treatments to alleviate the symptoms of PAD and decrease the risks of amputation and death are a high societal priority. A number of growth factors have shown a potential to stimulate angiogenesis. Growth factors delivered directly (as recombinant proteins), or indirectly (e.g. by viral vectors or DNA plasmids encoding these factors), have emerged as a promising strategy to treat patients with PAD.

OBJECTIVES

To assess the effects of growth factors that promote angiogenesis for treating people with PAD of the lower extremities.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Specialised Register (June 2016) and CENTRAL (2016, Issue 5). We searched trial registries for details of ongoing or unpublished studies. We also checked the reference lists of relevant publications and, if necessary, tried to contact the trialists for details of the studies.

SELECTION CRITERIA

We included randomised controlled trials comparing growth factors (delivered directly or indirectly) with no intervention, placebo or any other intervention not based on the growth factor's action in patients with PAD of the lower extremities. The primary outcomes were limb amputation, death and adverse events. The secondary outcomes comprised walking ability, haemodynamic measures, ulceration and rest pain.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and assessed the risk of bias. We used outcomes of the studies at low risk of bias for the main analysis and of all studies in the sensitivity analyses. We calculated odds ratios (OR) for dichotomous outcomes and mean differences for continuous outcomes with 95% confidence intervals (CI). We evaluated statistical heterogeneity using the I2 statistic and Cochrane's Q test. We conducted meta-analysis for the overall effect and for each growth factor as a subgroup analysis using OR in a fixed-effect model. We evaluated the robustness of the results in a sensitivity analysis using risk ratio (RR) and/or a random-effects model. We also assessed the quality of the evidence for each outcome.

MAIN RESULTS

We included 20 trials in the review and used 14 studies (on approximately 1400 participants) with published results in the analyses. Six published studies compared fibroblast growth factors (FGF), four studies hepatocyte growth factors (HGF) and another four studies vascular endothelial growth factors (VEGF), versus placebo or no therapy. Six of these studies exclusively or mainly investigated participants with intermittent claudication and eight studies exclusively participants with critical limb ischaemia. Follow-up generally ranged from three months to one year. Two small studies provided some data at 2 years and one of them also at 10 years.The direction and size of effects for growth factors on major limb amputations (OR 0.99, 95% CI 0.71 to 1.38; 10 studies, N = 1075) and death (OR 0.99, 95% CI 0.69 to 1.41; 12 studies, N = 1371) at up to two years are uncertain. The quality of the evidence is low due to risk of bias and imprecision (at one year, moderate-quality evidence due to imprecision). However, growth factors may decrease the rate of any limb amputations (OR 0.56, 95% CI 0.31 to 0.99; 6 studies, N = 415). The quality of the evidence is low due to risk of bias and selective reporting.The direction and size of effects for growth factors on serious adverse events (OR 1.09, 95% CI 0.79 to 1.50; 13 studies, N = 1411) and on any adverse events (OR 1.10, 95% CI 0.73 to 1.64; 4 studies, N = 709) at up to two years are also uncertain. The quality of the evidence is low due to risk of bias and imprecision (for serious adverse events at one year, moderate-quality evidence due to imprecision).Growth factors may improve haemodynamic measures (low-quality evidence), ulceration (very low-quality evidence) and rest pain (very low-quality evidence) up to one year, but they have little or no effect on walking ability (low-quality evidence). We did not identify any relevant differences in effects between growth factors (FGF, HGF and VEGF).

AUTHORS' CONCLUSIONS

The results of this review do not support the use of therapy with the growth factors FGF, HGF or VEGF in people with PAD of the lower extremities to prevent death or major limb amputation or to improve walking ability. However, the use of these growth factors may improve haemodynamic measures and decrease the rate of any limb amputations (probably due to preventing minor amputations) with an uncertain effect on adverse events; an improvement of ulceration and rest pain is very uncertain. New trials at low risk of bias are needed to generate evidence with more certainty.

Outgrowing endothelial and smooth muscle cells for tissue engineering approaches

In recent years, circulating progenitors of endothelial cells and smooth muscle cells were identified in the peripheral blood. In our study, we evaluated the utilization of both cell types isolated and differentiated from peripheral porcine blood in terms for their use for tissue engineering purposes. By means of density gradient centrifugation, the monocyte fraction from porcine blood was separated, split, and cultivated with specific culture media with either endothelial cell growth medium-2 or smooth muscle cell growth medium-2 for the differentiation of endothelial cells or smooth muscle cells. Obtained cells were characterized at an early stage of cultivation before the first passage and a late stage (fourth passage) on the basis of the expression of the antigens CD31, CD34, CD45, nitric oxide synthase, and the contractile filaments smooth-muscle alpha-actin (sm-alpha-actin) and smoothelin. Functional characterization was done based on the secretion of nitric oxide, the formation of a coherent monolayer on polytetrafluoroethylene, and capillary sprouting. During cultivation in both endothelial cell growth medium-2 and smooth muscle cell growth medium-2, substantially two types of cells grew out: early outgrown CD45-positive cells, which disappeared during further cultivation, and in 85% (n = 17/20) of cultures cultivated with endothelial cell growth medium-2 colony-forming late outgrowth endothelial cells. During cultivation with smooth muscle cell growth medium-2 in 80% (n = 16/20) of isolations colony-forming late outgrowth smooth muscle cells entered the stage. Cultivation with either endothelial cell growth medium-2 or smooth muscle cell growth medium-2 had selective effect on the late outgrown cells to that effect that the number of CD31-positive cells increased from 34.8% ± 13% to 83.9% ± 8% in cultures cultivated with endothelial cell growth medium-2 and the number of sm-α-actin+ cells increased from 52.6% ± 18% to 88% ± 5% in cultures cultivated with smooth muscle cell growth medium-2, respectively. Functional analyses revealed significantly higher levels of nitric oxide secretion, endothelialization capacity, and capillary formation in not expanded cultures cultivated with endothelial cell growth medium-2 in comparison to later stages of cultivation and mature aortic cells. Blood seems to be a reliable and feasible source for the isolation of both endothelial and smooth muscle cells for application in tissue engineering approaches. Whereas, early co-cultures of early and late outgrowth cells provide functional advantages, the differentiation of cells can be directed selectively by the used culture medium for the expansion of highly proliferative late outgrowth endothelial cells and late outgrowth smooth muscle cells, respectively.

Deconstructing the Tissue Engineered Vascular Graft: Evaluating Scaffold Pre-Wetting, Conditioned Media Incubation, and Determining the Optimal Mononuclear Cell Source

Stenosis limits widespread use of tissue-engineered vascular grafts (TEVGs), and bone marrow mononuclear cell (BM-MNC) seeding attenuates this complication. Yet seeding is a multistep process, and the singular effects of each component are unknown. We investigated which components of the clinical seeding protocol confer graft patency and sought to identify the optimal MNC source. Scaffolds composed of polyglycolic acid and ε-caprolactone/ι-lactic acid underwent conditioned media (CM) incubation (n = 25) and syngeneic BM-MNC (n = 9) or peripheral blood (PB)-MNC (n = 20) seeding. TEVGs were implanted for 2 weeks in the mouse IVC. CM incubation and PB-MNC seeding did not increase graft patency compared to control scaffolds prewet with PBS (n = 10), while BM-MNC seeding reduced stenosis by suppressing inflammation and smooth muscle cell, myofibroblast, and pericyte proliferation. IL-1β, IL-6, and TNFα were elevated in the seeded BM-MNC supernatant. Further, BM-MNC seeding reduced platelet activation in a dose-dependent manner, possibly contributing to TEVG patency.

Characterization of the Pall Celeris system as a point-of-care device for therapeutic angiogenesis

BACKGROUND AIMS

The Pall Celeris system is a filtration-based point-of-care device designed to obtain a high concentrate of peripheral blood total nucleated cells (PB-TNCs). We have characterized the Pall Celeris-derived TNCs for their in vitro and in vivo angiogenic potency.

METHODS

PB-TNCs isolated from healthy donors were characterized through the use of flow cytometry and functional assays, aiming to assess migratory capacity, ability to form capillary-like structures, endothelial trans-differentiation and paracrine factor secretion. In a hind limb ischemia mouse model, we evaluated perfusion immediately and 7 days after surgery, along with capillary, arteriole and regenerative fiber density and local bio-distribution.

RESULTS

Human PB-TNCs isolated by use of the Pall Celeris filtration system were shown to secrete a panel of angiogenic factors and migrate in response to vascular endothelial growth factor and stromal-derived factor-1 stimuli. Moreover, after injection in a mouse model of hind limb ischemia, PB-TNCs induced neovascularization by increasing capillary, arteriole and regenerative fiber numbers, with human cells detected in murine tissue up to 7 days after ischemia.

CONCLUSIONS

The Pall Celeris system may represent a novel, effective and reliable point-of-care device to obtain a PB-derived cell product with adequate potency for therapeutic angiogenesis.

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.

The unfolded protein response in retinal vascular diseases: implications and therapeutic potential beyond protein folding

Angiogenesis is a complex, step-wise process of new vessel formation that is involved in both normal embryonic development as well as postnatal pathological processes, such as cancer, cardiovascular disease, and diabetes. Aberrant blood vessel growth, also known as neovascularization, in the retina and the choroid is a major cause of vision loss in severe eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinopathy of prematurity, and central and branch retinal vein occlusion. Yet, retinal neovascularization is causally and dynamically associated with vasodegeneration, ischemia, and vascular remodeling in retinal tissues. Understanding the mechanisms of retinal neovascularization is an urgent unmet need for developing new treatments for these devastating diseases. Accumulating evidence suggests a vital role for the unfolded protein response (UPR) in regulation of angiogenesis, in part through coordinating the secretion of pro-angiogenic growth factors, such as VEGF, and modulating endothelial cell survival and activity. Herein, we summarize current research in the context of endoplasmic reticulum (ER) stress and UPR signaling in retinal angiogenesis and vascular remodeling, highlighting potential implications of targeting these stress response pathways in the prevention and treatment of retinal vascular diseases that result in visual deficits and blindness.

Imaging techniques to evaluate cell therapy in peripheral artery disease: state of the art and clinical trials

Cell-based therapies, as potential approach to cure peripheral artery disease (PAD), have been clinically investigated after promising results in preclinical models. The so far published studies are very heterogeneous, as different cell sources, cell types, amounts of administered cells and delivering strategies have been used. Overall, cell therapies for PAD bring about a general improvement of patient's clinical condition, even though conclusions cannot be established due to the small size and non-randomized design of these trials. In this context, non-invasive imaging techniques, aimed to monitor angiogenesis and neovascularization after cell therapy, will help the follow-up of clinical studies. However, still much work is needed to establish advanced imaging procedure to overcome the limitation of the current techniques and to accumulate more data in large populations of patients. Here, we report the main imaging techniques employed to evaluate the outcome of the different cell-based therapies in PAD. Moreover, we focus on both published and ongoing clinical trials utilizing cell therapy in PAD.

Cell-based interventions for therapeutic angiogenesis: review of potential cell sources

Alternative therapies are currently being developed to treat patients with chronic limb ischemia who are unable to be revascularized in order to avoid amputation. Cell-based therapy using mononuclear cells is gaining attention as many clinical trials are currently underway. We review cell differentiation along with the different potential cell sources for use in therapeutic angiogenesis.

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.

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.

Feasibility of combination allogeneic stem cell therapy for spinal cord injury: a case report

Cellular therapy for spinal cord injury (SCI) is overviewed focusing on bone marrow mononuclear cells, olfactory ensheathing cells, and mesenchymal stem cells. A case is made for the possibility of combining cell types, as well as for allogeneic use. We report the case of 29 year old male who suffered a crush fracture of the L1 vertebral body, lacking lower sensorimotor function, being a score A on the ASIA scale. Stem cell therapy comprised of intrathecal administration of allogeneic umbilical cord blood ex-vivo expanded CD34 and umbilical cord matrix MSC was performed 5 months, 8 months, and 14 months after injury. Cell administration was well tolerated with no adverse effects observed. Neuropathic pain subsided from intermittent 10/10 to once a week 3/10 VAS. Recovery of muscle, bowel and sexual function was noted, along with a decrease in ASIA score to "D". This case supports further investigation into allogeneic-based stem cell therapies for SCI.

CD34(+) cell selection using small-volume marrow aspirates: a platform for novel cell therapies and regenerative medicine

BACKGROUND AIMS

This study was initiated to determine whether CD34(+) cell selection of small-volume bone marrow (BM) samples could be performed effectively on the Isolex(R) 300i Magnetic Cell Selection System device and whether the results obtained from these samples were comparable with results from large standard-volume samples. The impact on CD34(+) recovery using a full versus half vial of Isolex(R) CD34 reagent and the effects of shipping a post-selection product were evaluated.

METHODS

A protocol to evaluate CD34(+) cell selection with two ranges of smaller volume BM samples (c. 50 mL and c. 100 mL) was developed and instituted at three Production Assistance for Cellular Therapies (PACT) facilities. The study was performed in two phases.

RESULTS

In phase I, the mean post-selection CD34(+) recoveries from the two sizes of samples were 104.1% and 103.3% (smallest and largest volumes, respectively), and mean CD34(+) recoveries were 115.6% and 88.7%, with full and half vials of reagent, respectively. Mean CD34(+) recoveries for post-shipment smaller volume samples were 106.8% and for larger volume samples 116.4%; mean CD34(+) recoveries were 99.9% and 127.4% for post-shipment samples processed with full and half vials of reagent, respectively. In phase II, mean CD34(+) recovery was 76.8% for post-selection samples and 74.0% for post-shipment samples.

CONCLUSIONS

The results suggest that smaller volume BM sample processing on the Isolex(R) system is as efficient or more efficient compared with standard-volume sample processing. Post-processing mean CD34(+) recovery results obtained using a full or half vial of CD34 reagent were not significantly different.