Stem cell therapy for critical limb ischaemia - a review

Hyaluronic Acid Facilitates Angiogenesis of Endothelial Colony Forming Cell Combining With Mesenchymal Stem Cell via CD44/ MicroRNA-139-5p Pathway

Stem cells and progenitor cells have been identified as potential new therapeutic options for severe limb ischemia to induce angiogenesis, and hyaluronic acid (HA) is commonly applied as a biomaterial in tissue engineering. However, the efficiency of HA combined with human umbilical cord blood-derived endothelial colony forming cells (ECFCs) and human umbilical-derived mesenchymal stem cells (MSCs) on angiogenesis is unclear. In the present study, we showed that HA promoted angiogenesis induced by MSCs-ECFCs in Matrigel plugs and promoted blood perfusion of murine ischemic muscles. Laser confocal microscopy revealed that human-derived cells grew into the host vasculature and formed connections, as shown by mouse-specific CD31⁺/human-specific CD31⁺ double staining. In vitro assays revealed that HA supported cell proliferation and migration, enhanced CD44 expression and reduced microRNA (miR)-139-5p expression. Further analysis revealed that miR-139-5p expression was negatively regulated by CD44 in ECFCs. Flow cytometry assays showed that HA increased CD31 positive cells proportion in MSC-ECFC and could be reversed by miR-139-5p mimics transfection. Moreover, the improvement of MSC-ECFC proliferation and migration induced by HA could be blocked by upregulation of miR-139-5p expression. In conclusion, HA facilitates angiogenesis of MSCs-ECFCs, and this positive effect be associated with activation of the CD44/miR-139-5p pathway, providing a promising strategy for improving severe limb ischemia.

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.

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.

Efficacy, safety and influencing factors of intra-calf muscular injection of bone marrow mononuclear cells in the treatment of type 2 diabetes mellitus-induced lower extremity vascular disease

The efficacy, safety and impact of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) associated with the intra-calf muscular injection of bone marrow mononuclear cells (BMMCs) in the treatment of type 2 diabetes mellitus (T2DM)-induced lower extremity vascular disease (LEVD) were evaluated. Patients with T2DM-LEVD were randomly divided into a control group and BMMCs group to assess the efficacy and safety of the treatment; serum VEGF and bFGF levels were detected. The BMMCs group was divided into superior genicular artery (SGA) and inferior genicular artery (IGA) subgroups as well as low-dose and high-dose subgroups for the comparison of efficacy indices. The BMMCs group exhibited significantly improved indices (P<0.05) compared with the control group and no fatalities or cancer occurred. There were no significant changes in serum VEGF and bFGF levels (P>0.05). The claudication distance in the IGA subgroup was significantly greater that in the SGA subgroup (P<0.05); the low-dose subgroup and the high-dose subgroup did not demonstrate any significant differences in each index (P>0.05). BMMC treatment for T2DM-LEVD was found to be safe and effective and had no significant impact on serum VEGF and bFGF levels in the short term; However, the degree of LEVD may affect its efficacy.

Development of a surrogate potency assay to determine the angiogenic activity of Stempeucel®, a pooled, ex-vivo expanded, allogeneic human bone marrow mesenchymal stromal cell product

BACKGROUND

Mesenchymal stromal cells (MSCs) have emerged as a more beneficial alternative to conventional therapy and may offer a potential cure for unmet medical needs. MSCs are known to possess strong immunomodulatory and anti-inflammatory properties. Moreover, they promote angiogenesis and tissue regeneration through the secretion of trophic factors. For these reasons, the past decade witnessed a sharp increase in the number of clinical trials conducted with stem cells for various vascular diseases requiring angiogenesis. In this study, we evaluated the in vitro angiogenic potency of Stempeucel®, which is an allogeneic pooled human bone marrow-derived mesenchymal stromal cell (phBMMSC) product. We previously established the safety of Stempeucel® in our pre-clinical studies, and clinical trials conducted for critical limb ischaemia and acute myocardial infarction.

METHODS

Because the proposed mechanism of action of phBMMSCs is mainly through the secretion of pro-angiogenic cytokines, we developed a surrogate potency assay by screening various batches of large-scale expanded phBMMSCs for the expression of angiogenic factors and cytokines through gene expression and growth factor analyses, followed by in vitro functional assays.

RESULTS

The well characterized angiogenic vascular endothelial growth factor (VEGF) was selected and quantified in twenty six manufactured batches of phBMMSCs to establish consistency following the United States Food and Drug Administration recommendations. According to recommendations 21 CFR 211.165(e) and 211.194(a)(2), we also established and documented the specificity and reproducibility of the test methods employed through validation. Moreover, we also attempted to elucidate the mechanism of action of the cell population to ensure appropriate biological activity. The functional role of VEGF has been established through in vitro angiogenic assays and a dose-dependent correlation was observed with in vitro functional results.

CONCLUSIONS

The data generated from this study suggest the selection of VEGF as a single surrogate marker to test the angiogenic potency of phBMMSCs. Our study reports the quantification of VEGF in twenty six batches of large-scale manufactured phBMMSCs, and a concentration-dependent correlation of secreted VEGF to endothelial cell functions of migration, proliferation and tube formation, in the conditioned medium obtained from nine phBMMSC batches. To our cognizance, this is the first study in which a single angiogenic factor (VEGF) has been qualified as a surrogate potency marker through all three in vitro functional assays to determine the angiogenic potency of the phBMMSC population.

Improvement in Blood Supply After "Heparin-Dextran" Therapy in Patients of Buerger's Disease with Critical Limb Ischemia

Alleviating the agonizing pain of critical limb ischemia (CLI) in patients of Buerger's disease (BD) has been challenging, due to lack of definitive treatment; "Heparin-Dextran" infusion has been tried in this study. Assessment of clinical improvement and vascular changes following therapy. Patients with CLI admitted to emergency surgical ward were studied prospectively. BD was diagnosed by Shionoya's criteria, and confirmed by digital subtraction angiography (DSA). Heparin and Dextran intravenous infusion was administered for 10 days. Severity of rest pain, ischemic changes in the feet, claudication distance and ankle brachial index (ABI) were estimated prior to therapy, at completion and 3 weeks after therapy. Vascular changes were assessed by CT angiography (CTA) performed prior to and 3 weeks after therapy. Twenty consecutive patients were studied. Successful hemodilution reflected by decreased hematocrit (37.4 % to 32.6 %, p < 0.05) and increased mean ABI (0.46 to 0.83, p < 0.01), improved rest pain in 75 % patients (p < 0.001), increased claudication distance in 94 % (p < 0.05) and ulcers healing in 70 % patients. CTA revealed recanalised vessels (decreased length of occluded segments) in 10 (50 %, p = 0.005), increased collaterals in 12 (60 %, p < 0.01) and improved distal run-off in 13 (65 %, p < 0.01) patients. "Heparin-Dextran" therapy in patients of CLI from BD improves tissue perfusion by increasing collaterals and recanalisation of vessels, resulting in significant relief from rest pain and clinical improvements. CTA is as efficacious as DSA for evaluation of BD.