Stem-cell Therapy for Peripheral Arterial Occlusive Disease

Effect of hypoxia on the expression of microRNA in extracellular vesicles of human umbilical cord stem cells in vitro

Mesenchymal stem cells (MSCs) derived extracellular vesicles, which have been shown to possess therapeutic effects for many diseases. However, how hypoxic conditions would affect exosomal microRNA expression in human umbilical cord MSCs (hUC-MSCs) is currently not investigated. This study aims to investigate the potential function of in vitro microRNAs of hUC-MSC cultured under normoxic and hypoxic conditions. Extracellular vesicles secreted from hUC-MSCs cultured in normoxic (21% O2) and hypoxic (5% O2) conditions were collected for microRNA identification. Zeta View Laser Scattering and transmission electron microscopy were used to observe the size and morphology of extracellular vesicles. qRT-PCR was performed to measure the expression of related microRNAs. The Gene Ontology and KEGG pathway were used to predict the function of microRNAs. Finally, the effects of hypoxia on the expression of related mRNAs and cellular activity were examined. This study identified 35 upregulated and 8 downregulated microRNAs in the hypoxia group. We performed target genes analysis to explore the potential function of these microRNA upregulated in the hypoxia group. Significant enrichment of the cell proliferation, pluripotency of stem cells, MAPK, Wnt, and adherens junction pathways were observed in the GO and KEGG pathways. Under hypoxic conditions, the expression levels of 7 target genes were lower than that of the normal environment. In conclusion, this study demonstrated for the first time that microRNA expression in extracellular vesicles of human umbilical vein stem cells cultured under hypoxia is different from that under normal conditions, and these microRNAs may be markers for detecting hypoxia.

Risk Factors, Mechanisms and Treatments of Thromboangiitis Obliterans: An Overview of Recent Research

BACKGROUND

Thromboangiitis obliterans (TAO) is a nonatherosclerotic thromboticocclusive vasculitis that affects the vessels of the small and medium-sized extremities. No explicit etiology or pathogenesis of TAO has been proven, and more effective treatments are needed.

OBJECTIVE

The study aimed to summarize and present an overview of recent advances regarding the risk factors, mechanisms and treatments of TAO and to organize the related information in figures to provide a comparatively complete reference.

METHODS

We searched PubMed for English-language literature about TAO without article type limits, including articles about the risk factors, pathological mechanisms and treatments of TAO in the last 10 years with essential supplements (references over ranges and English abstracts of Russian literature).

RESULTS

After screening content of works of literature, 99 references were evaluated. We found that risk factors of TAO include smoking, gene factors and periodontal diseases. The underlying mechanism of TAO involves oxidative stress, immunity, hemodynamic changes, inflammation and so on. Moreover, similarities in genetic factors and cigarette relevance existed between periodontal diseases and TAO, so further study of relationship was required. For TAO treatment, medicine, endovascular intervention and revascularization surgery, autologous cell therapy and novel therapies were also mentioned. Besides, a hypothesis that infection triggers autoimmunity in TAO could be speculated, in which TLR4 plays a key role.

CONCLUSION

1. A hypothesis is put forward that infections can trigger autoimmunity in TAO development, in which TLR4, as a key agent, can activate immune signaling pathways and induce autoimmune cytokines expression. 2. It is suggested to reconsider the association between periodontal diseases and TAO, as they share the same high-risk population. Controlling periodontal disease severity in TAO studies may provide new clues. 3. For TAO treatment, endovascular intervention and autologous cell therapy both showed promising long-term therapeutic effectiveness, in which autologous cell therapy is becoming more popular, although more clinical comparisons are needed.

Protein profiling and angiogenic effect of hypoxia-cultured human umbilical cord blood-derived mesenchymal stem cells in hindlimb ischemia

The aim of the present study was to investigate protein profiles of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) cultured in normoxic (21% O₂) and hypoxic (1% O₂) conditions, and evaluate oxygenation effects on angiogenesis in an ischemic hindlimb mouse model using a modified ischemic scoring system. Hypoxic conditions did not change the expression of phenotypic markers and increased adipogenesis and chondrogenesis. Epidermal growth factor (EGF), transforming growth factor alpha (TGF-α), TGF-β RII, and vascular endothelial growth factor (VEGF) were upregulated in the conditioned medium of hypoxic hUCB-MSCs, which are commonly related to angiogenesis and proliferation of biological processes by Gene Ontology. In the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, significant enrichment of the phosphorylation of abelson murine leukemia viral oncogene homolog 1 (ABL1) (Phospho-Tyr204) and B-cell lymphoma-extra large (BCL-XL) (Phospho-Thr47) as anti-apoptotic pathways was observed in hypoxic hUCB-MSCs. Furthermore, hypoxic conditions induced proliferation and migration, and reduced apoptosis of hUCB-MSCs in vitro. Based on the results of protein antibody array, we evaluated the angiogenic effects of injecting normoxic or hypoxic hUCB-MSCs (1×10⁶) into the ischemic hindlimb muscles of mice. Ischemic scores and capillary generation were significantly greater in the hypoxic hUCB-MSC injection group than in the normoxic hUCB-MSC group. Our findings demonstrate that culturing hUCB-MSCs in hypoxic conditions not only significantly enriches phosphorylation in the anti-apoptosis pathway and enhances the secretion of several angiogenic proteins from cells, but also alleviates ischemic injury of hindlimb of mice.

Stem Cell Smart Technology, where are we now and how far we have to go?

Approximately eight million people in the United States have peripheral arterial disease, which increases exponentially with age. There have been a plethora of available treatments including surgery, angioplasty, atherectomy, laser technology, and cell-based therapies. Cell-based therapies were developed in the hope of translating laboratory-based technology into clinical successes. However, clinical results have been disappointing. Infusion or injection for stem cell therapy is still considered experimental and investigational, and major questions on safety and durability have arisen. In no option patients, how can they be treated safely and successfully? In this article, we review contemporary practice for cell therapy, its pitfalls and breakthroughs, and look at the future ahead. We introduce a novel smart system for minimally invasive delivery of cell therapies, which exemplifies the next generation of endovascular solutions to stem cell technology and promises safety, efficacy, and reliability.

Early Results of Clinical Application of Autologous Whole Bone Marrow Stem Cell Transplantation for Critical Limb Ischemia with Buerger's Disease

Our goal was to evaluate early results of the clinical application of autologous whole bone marrow stem cell transplantation (AWBMSCT) for critical limb ischemia (CLI) in patients with Buerger's disease. We retrospectively analyzed the data of 58 limbs of 37 patients (mean age, 43.0 years; range, 28-63 years; male, 91.9%) with Buerger's disease with CLI who were treated with AWBMSCT from March 2013 to December 2014. We analyzed Rutherford category, pain score, pain-free walking time (PFWT), total walking time (TWT), ankle brachial pressure index (ABPI), and toe brachial pressure index (TBPI), and investigated wound healing and occurrence of unplanned amputations. The mean follow-up duration was 11.9 ± 7.2 months (range, 0.9-23.9 months) and 100%, 72.4%, and 74.1% of patients were available to follow-up 1, 3 and 6 months after AWBMST, respectively. At 6 months, patients demonstrated significant improvements in Rutherford category (P < 0.0001), pain score (P < 0.0001), PFWT (P < 0.0001) and TBPI (P < 0.0001). ABPI was increased compared to baseline, but the difference was not significant. A total of 76.5% ischemic wounds achieved complete or improved healing. AWBMSCT is a safe and effective alternative or adjunctive treatment modality to achieve clinical improvement in patients with CLI.

Evaluation of the clinical relevance and limitations of current pre-clinical models of peripheral artery disease

Peripheral artery disease (PAD) has recognized treatment deficiencies requiring the discovery of novel interventions. This article describes current animal models of PAD and discusses their advantages and disadvantages. There is a need for models which more directly simulate the characteristics of human PAD, such as acute-on-chronic presentation, presence of established risk factors and impairment of physical activity.

Therapeutic Effects of Umbilical Cord Blood Derived Mesenchymal Stem Cell-Conditioned Medium on Pulmonary Arterial Hypertension in Rats

Background:

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) may have multiple therapeutic applications for cell based therapy including the treatment of pulmonary artery hypertension (PAH). As low survival rates and potential tumorigenicity of implanted cells could undermine the mesenchymal stem cell (MSC) cell-based therapy, we chose to investigate the use of conditioned medium (CM) from a culture of MSC cells as a feasible alternative.

Methods:

CM was prepared by culturing hUCB-MSCs in three-dimensional spheroids. In a rat model of PAH induced by monocrotaline, we infused CM or the control unconditioned culture media via the tail-vein of 6-week-old Sprague-Dawley rats.

Results:

Compared with the control unconditioned media, CM infusion reduced the ventricular pressure, the right ventricle/(left ventricle+interventricular septum) ratio, and maintained respiratory function in the treated animals. Also, the number of interleukin 1α (IL-1α), chemokine (C-C motif) ligand 5 (CCL5), and tissue inhibitor of metalloproteinase 1 (TIMP-1)–positive cells increased in lung samples and the number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling technique (TUNEL)–positive cells decreased significantly in the CM treated animals.

Conclusions:

From our in vivo data in the rat model, the observed decreases in the TUNEL staining suggest a potential therapeutic benefit of the CM in ameliorating PAH-mediated lung tissue damage. Increased IL-1α, CCL5, and TIMP-1 levels may play important roles in this regard.

The relevance of epigenetics to occlusive cerebral and peripheral arterial disease

Athero-thrombosis of the arteries supplying the brain and lower limb are the main causes of stroke and limb loss. New therapies are needed to improve the outcomes of athero-thrombosis. Recent evidence suggests a role for epigenetic changes in the development and progression of ischaemic injury due to atherosclerotic occlusion of peripheral arteries. DNA hypermethylation have been associated with cardiovascular diseases. Histone post-translational modifications have also been implicated in atherosclerosis. Oxidized low-density lipoprotein regulated pro-inflammatory gene expression within endothelial cells is controlled by phosphorylation/acetylation of histone H3 and acetylation of histone H4 for example. There are a number of challenges in translating the growing evidence implicating epigenetics in atherosclerosis to improved therapies for patients. These include the small therapeutic window in conditions such as acute stroke and critical limb ischaemia, since interventions introduced in such patients need to act rapidly and be safe in elderly patients with many co-morbidities. Pre-clinical animal experiments have also reported conflicting effects of some novel epigenetic drugs, which suggest that further in-depth studies are required to better understand their efficacy in resolving ischaemic injury. Effective ways of dealing with these challenges are needed before epigenetic approaches to therapy can be introduced into practice.

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.

Endothelial progenitor cells regenerate infracted myocardium with neovascularisation development

We achieved possibility of isolation, characterization human umbilical cord blood endothelial progenitor cells (EPCs), examination potency of EPCs to form new blood vessels and differentiation into cardiomyoctes in canines with acute myocardial infarction (AMI). EPCs were separated and cultured from umbilical cord blood. Their phenotypes were confirmed by uptake of double stains dioctadecyl tetramethylindocarbocyanine-labeled acetylated LDL and FITC-labeled Ulex europaeus agglutinin 1 (DILDL-UEA-1). EPCs of cord blood were counted. Human VEGFR-2 and eNOS from the cultured EPCs were assessed by qPCR. Human EPCs was transplanted intramyocardially in canines with AMI. ECG and cardiac enzymes (CK-MB and Troponin I) were measured to assess severity of cellular damage. Histopathology was done to assess neovascularisation. Immunostaining was done to detect EPCs transdifferentiation into cardiomyocytes in peri-infarct cardiac tissue. qPCR for human genes (hVEGFR-2, and eNOS) was done to assess homing and angiogenic function of transplanted EPCs. Cultured human cord blood exhibited an increased number of EPCs and significant high expression of hVEGFR-2 and eNOS genes in the culture cells. Histopathology showed increased neovascularization and immunostaining showed presence of EPCs newly differentiated into cardiomyocyte-like cells. Our findings suggested that hEPCs can mediate angiogenesis and differentiate into cardiomyoctes in canines with AMI.

A phase I study of human cord blood-derived mesenchymal stem cell therapy in patients with peripheral arterial occlusive disease

BACKGROUND AND OBJECTIVES

Half of patients with critical limb ischemia (CLI) are ineligible for revascularization at diagnosis. The aim of this study was to assess the safety and feasibility of intramuscular human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) therapy in patients with CLI due to atherosclerosis obliterans (ASO) or thromboangiitis obliterans (TAO).

METHODS AND RESULTS

A total of eight patients (all male, median age 52 years, range 31∼77) with CLI were enrolled in this phase I trial. All patients were considered ineligible for further revascularization to improve CLI. We injected 1×10(7) hUCB-MSCs per single dose intramuscularly into the affected limb. The primary end points of safety were occurrence of adverse events (procedure-related complication, allergic reaction to hUCB-MSCs, graft-versus-host disease, cardiovascular and cerebrovascular events) and improvement of symptoms/clinical parameters (healing of foot ulcer, ankle-brachial index, and pain-free walking distance). Angiogenesis was measured with conventional angiography and scored by an independent reviewer. There were four adverse events in three patients. One patient, developed whole body urticaria after injection on treatment day, which disappeared after one day of antihistamine treatment. The other adverse events included diarrhea, oral ulceration, and elevation of serum creatinine level; all conditions improved without treatment. Abnormal results of laboratory parameters were not detected in any patients. Three of four ulcerations (75%) healed completely. Angiographic scores increased in three of eight patients.

CONCLUSIONS

This phase I study demonstrates that intramuscular hUCB-MSC injection is a safe and well tolerated treatment for patients with end-stage CLI due to ASO and TAO.

Transplantation of umbilical cord blood-derived cells for novel indications in regenerative therapy or immune modulation: a scoping review of clinical studies

Although used mainly for transplantation of hematopoietic stem cells in the treatment of blood disorders, umbilical cord blood (UCB)-based therapies are now being used increasingly for novel applications in nonhematopoietic diseases and as a form of cellular regenerative therapy or immune modulation. We performed a systematic scoping review by searching Medline, EMBASE, and the Cochrane Library for published articles, and we searched www.clinicaltrials.com and the World Health Organization International Clinical Trials Registry Platform to describe the breadth of published studies and ongoing clinical activity in umbilical cord-based cellular therapy for regenerative therapy and immune modulation. The most commonly published area of expertise in the use of UCB-derived cellular transplantation for novel indications is for neurological disorders and this remains the most active area of study in ongoing registered trials. An increasingly broad range of disorders, however, are reflected in ongoing registered trials, which suggests greater activity, interest, and investment in UCB-derived cellular therapy. Interestingly, adult patients compose the majority of patients reported in published reports and registered ongoing clinical studies continue to enroll predominantly adult subjects. Geographically, Asian countries appear most active in UCB-derived cellular therapy and our analysis of ongoing studies suggests this trend will likely continue. Regular assessment of published and ongoing activity in UCB transplantation for emerging novel indications will be critical for informing UCB banking establishments and funding agencies to guide changes in banking practices related to emerging trends in cell therapy.

Allogeneic lethally irradiated cord blood mononuclear cells in no-option critical limb ischemia: a "box of rain"

Critical limb ischemia (CLI) is burdened by a 40% major amputation rate, and a 5-year life expectancy <50%. We report the first in-human injection of lethally γ-irradiated non-human leukocyte antigen (HLA)-matched cord blood (CB)-derived mononuclear cells in a no-option CLI patient, to induce therapeutic neo-angiogenesis, with evidence of successful outcome supported by clinical findings (ulcer healing and pain relief), instrumental assessment (transcutaneous O2 pressure, ankle/brachial index, and contrast-enhanced ultrasonography), and histological demonstration of muscular tissue repair and capillary network expansion. If our approach will be confirmed, the huge number of CB units currently discarded might be redirected toward regenerative medicine purposes, leading to cutting-edge solutions for important unmet clinical needs, such as ischemic diseases, which remain the main cause of disability and mortality in western countries.