CD34 + Cells Home, Proliferate, and Participate in Capillary Formation, and in Combination With CD34 − Cells Enhance Tube Formation in a 3-Dimensional Matrix

CD34+ synovial fibroblasts exhibit high osteogenic potential in synovial chondromatosis

Synovial chondromatosis (SC) is a disorder of the synovium characterized by the formation of osteochondral nodules within the synovium. This study aimed to identify the abnormally differentiated progenitor cells and possible pathogenic signaling pathways. Loose bodies and synovium were obtained from patients with SC during knee arthroplasty. Single-cell RNA sequencing was used to identify cell subsets and their gene signatures in SC synovium. Cells derived from osteoarthritis (OA) synovium were used as controls. Multi-differentiation and colony-forming assays were used to identify progenitor cells. The roles of transcription factors and signaling pathways were investigated through computational analysis and experimental verification. We identified an increased proportion of CD34+ sublining fibroblasts in SC synovium. CD34+CD31- cells and CD34-CD31- cells were sorted from SC synovium. Compared with CD34- cells, CD34+ cells had larger alkaline phosphatase (ALP)-stained area and calcified area after osteogenic induction. In addition, CD34+ cells exhibited a stronger tube formation ability than CD34- cells. Our bioinformatic analysis suggested the expression of TWIST1, a negative regulator of osteogenesis, in CD34- sublining fibroblasts and was regulated by the TGF-β signaling pathway. The experiment showed that CD34+ cells acquired the TWIST1 expression during culture and the combination of TGF-β1 and harmine, an inhibitor of Twist1, could further stimulate the osteogenesis of CD34+ cells. Overall, CD34+ synovial fibroblasts in SC synovium have multiple differentiation potentials, especially osteogenic differentiation potential, and might be responsible for the pathogenesis of SC.

Neuroprotective Effect of Angiopoietin2 Is Associated with Angiogenesis in Mouse Brain Following Ischemic Stroke

Angiogenic factors play an important role in protecting, repairing, and reconstructing vessels after ischemic stroke. In the brains of transient focal cerebral ischemic mice, we observed a reduction in infarct volume after the administration of Angiopoietin 2 (Angpt2), but whether this process is promoted by Angpt2-induced angiogenesis has not been fully elaborated. Therefore, this study explored the angiogenic activities, in reference to CD34 which is a marker of activated ECs and blood vessels, of cultured ECs in vitro and in ischemic damaged cerebral area in mice following Angpt2 administration. Our results demonstrate that Angpt2 administration (100 ng/mL) is neuroprotective by significantly increasing the CD34 expression in in vitro-cultured ECs, reducing the infarct volume and mitigating neuronal loss, as well as enhancing CD34⁺ vascular length and area. In conclusion, these results indicate that Angpt2 promotes repair and attenuates ischemic injury, and that the mechanism of this is closely associated with angiogenesis in the brain after stroke.

Potential biomarkers in the fibrosis progression of nonalcoholic steatohepatitis (NASH)

PURPOSE

Fibrosis is the only histological feature reflecting the severity and prognosis of nonalcoholic steatohepatitis (NASH). We aim to explore novel genes associated with fibrosis progression in NASH.

METHODS

Two human RNA-seq datasets were downloaded from the public database. Weighted gene co-expression network analysis (WGCNA) was used to identify their co-expressed modules and further bioinformatics analysis was performed to identify hub genes within the modules. Finally, based on two single-cell RNA-seq datasets from mice and one microarray dataset from human, we further observed the expression of hub genes in different cell clusters and liver tissues.

RESULTS

7 hub genes (SPP1, PROM1, SOX9, EPCAM, THY1, CD34 and MCAM) associated with fibrosis progression were identified. Single-cell RNA-seq analysis revealed that those hub genes were expressed by different cell clusters such as cholangiocytes, natural killer (NK) cells, and hepatic stellate cells (HSCs). We also found that SPP1 and CD34 serve as markers of different HSCs clusters, which are associated with inflammatory response and fibrogenesis, respectively. Further study suggested that SPP1, SOX9, MCAM and THY1 might be related to NASH-associated hepatocellular carcinoma (HCC). Receiver operating characteristic (ROC) analysis showed that the high expression of these genes could well predict the occurrence of HCC. At the same time, there were significant differences in metabolism-related pathway changes between different HCC subtypes, and SOX9 may be involved in these changes.

CONCLUSIONS

The present study identified novel genes associated with NASH fibrosis and explored their effects on fibrosis from a single-cell perspective that might provide new ideas for the early diagnosis, monitoring, evaluation, and prediction of fibrosis progression in NASH.

Autologous cell therapy in diabetes‑associated critical limb ischemia: From basic studies to clinical outcomes (Review)

Cell therapy is becoming an attractive alternative for the treatment of patients with no‑option critical limb ischemia (CLI). The main benefits of cell therapy are the induction of therapeutic angiogenesis and neovascularization that lead to an increase in blood flow in the ischemic limb and tissue regeneration in non‑healing cutaneous trophic lesions. In the present review, the current state of the art of strategies in the cell therapy field are summarized, focusing on intra‑operative autologous cell concentrates in diabetic patients with CLI, examining different sources of cell concentrates and their mechanisms of action. The present study underlined the detrimental effects of the diabetic condition on different sources of autologous cells used in cell therapy, and also in delaying wound healing capacity. Moreover, relevant clinical trials and critical issues arising from cell therapy trials are discussed. Finally, the new concept of cell therapy as an adjuvant therapy to increase wound healing in revascularized diabetic patients is introduced.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

Therapeutic Efficacy of Autologous Non-Mobilized Enriched Circulating Endothelial Progenitors in Patients With Critical Limb Ischemia - The SCELTA Trial

BACKGROUND

The therapeutic efficacy of bone marrow mononuclear cells (BM-MNC) autotransplantation in critical limb ischemia (CLI) has been reported. Variable proportions of circulating monocytes express low levels of CD34 (CD14⁺CD34^lowcells) and behave in vitro as endothelial progenitor cells (EPCs). The aim of the present randomized clinical trial was to compare the safety and therapeutic effects of enriched circulating EPCs (ECEPCs) with BM-MNC administration.Methods and Results:ECEPCs (obtained from non-mobilized peripheral blood by immunomagnetic selection of CD14⁺and CD34⁺cells) or BM-MNC were injected into the gastrocnemius of the affected limb in 23 and 17 patients, respectively. After a mean of 25.2±18.6-month follow-up, both groups showed significant and progressive improvement in muscle perfusion (primary endpoint), rest pain, consumption of analgesics, pain-free walking distance, wound healing, quality of life, ankle-brachial index, toe-brachial index, and transcutaneous PO₂. In ECEPC-treated patients, there was a positive correlation between injected CD14⁺CD34^lowcell counts and the increase in muscle perfusion. The safety profile was comparable between the ECEPC and BM-MNC treatment arms. In both groups, the number of deaths and major amputations was lower compared with eligible untreated patients and historical reference patients.

CONCLUSIONS

This study supports previous trials showing the efficacy of BM-MNC autotransplantation in CLI patients and demonstrates comparable therapeutic efficacy between BM-MNC and EPEPCs.

Shear stress: An essential driver of endothelial progenitor cells

The blood flow through vessels produces a tangential, or shear, stress sensed by their innermost layer (i.e., endothelium) and representing a major hemodynamic force. In humans, endothelial repair and blood vessel formation are mainly performed by circulating endothelial progenitor cells (EPCs) characterized by a considerable expression of vascular endothelial growth factor receptor 2 (VEGFR2), CD34, and CD133, pronounced tube formation activity in vitro, and strong reendothelialization or neovascularization capacity in vivo. EPCs have been proposed as a promising agent to induce reendothelialization of injured arteries, neovascularization of ischemic tissues, and endothelialization or vascularization of bioartificial constructs. A number of preconditioning approaches have been suggested to improve the regenerative potential of EPCs, including the use of biophysical stimuli such as shear stress. However, in spite of well-defined influence of shear stress on mature endothelial cells (ECs), articles summarizing how it affects EPCs are lacking. Here we discuss the impact of shear stress on homing, paracrine effects, and differentiation of EPCs. Unidirectional laminar shear stress significantly promotes homing of circulating EPCs to endothelial injury sites, induces anti-thrombotic and anti-atherosclerotic phenotype of EPCs, increases their capability to form capillary-like tubes in vitro, and enhances differentiation of EPCs into mature ECs in a dose-dependent manner. These effects are mediated by VEGFR2, Tie2, Notch, and β1/3 integrin signaling and can be abrogated by means of complementary siRNA/shRNA or selective pharmacological inhibitors of the respective proteins. Although the testing of sheared EPCs for vascular tissue engineering or regenerative medicine applications is still an unaccomplished task, favorable effects of unidirectional laminar shear stress on EPCs suggest its usefulness for their preconditioning.

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.

Downregulation of transgelin blocks interleukin-8 utilization and suppresses vasculogenic mimicry in breast cancer cells

Vasculogenic mimicry (VM) is a non-classical mechanism recently described in many tumors, whereby cancer cells, rather than endothelial cells, form blood vessels. Transgelin is an actin-binding protein that has been implicated in multiple stages of cancer development. In this study, we investigated the role of transgelin in VM and assessed its effect on the expression of endothelial and angiogenesis-related genes during VM in MDA-MB-231 breast cancer cells. We confirmed the ability of MDA-MB-231 cells to undergo VM through a tube formation assay. Flow cytometry analysis revealed an increase in the expression of the endothelial-related markers VE-cadherin and CD34 in cells that underwent VM, compared with those growing in a monolayer, which was confirmed by immunocytochemistry. We employed siRNA to silence transgelin, and knockdown efficiency was determined by western blot analyses. Downregulation of transgelin suppressed cell proliferation and tube formation, but increased IL-8 levels in Matrigel cultures. RT-PCR analyses revealed that the expression of IL-8, VE-cadherin, and CD34 was unaffected by transgelin knockdown, indicating that increased IL-8 expression was not due to enhanced transcriptional activity. More importantly, the inhibition of IL-8/CXCR2 signaling also resulted in suppression of VM with increased IL-8 levels, confirming that increased IL-8 levels after transgelin knockdown was due to inhibition of IL-8 uptake. Our findings indicate that transgelin regulates VM by enhancing IL uptake. These observations are relevant to the future development of efficient antivascular agents. Impact statement Vasculogenic mimicry (VM) is an angiogenic-independent mechanism of blood vessel formation whereby aggressive tumor cells undergo formation of capillary-like structures. Thus, interventions aimed at angiogenesis might not target the entire tumor vasculature. A more holistic approach is therefore needed in the development of improved antivascular agents. Transgelin, an actin-binding protein, has been associated with multiple stages of cancer development such as proliferation, migration and invasion, but little is known about its role in vasculogenic mimicry. We present here, an additional mechanism by which transgelin promotes malignancy by way of its association with the occurrence of VM. Although transgelin knockdown did not affect the transcript levels of most of the angiogenesis-related genes in this study, it was associated with the inhibition of the uptake of IL-8, accompanied by suppressed VM, indicating that transgelin is required for VM. These observations are relevant to the future development of efficient antivascular agents.

Characteristics of responders to autologous bone marrow cell therapy for no-option critical limb ischemia

BACKGROUND

The present study investigated factors associated with therapeutic benefits after autologous bone marrow cell (BMC) therapy in patients with "no-option" critical limb ischemia (CLI).

METHODS AND RESULTS

Sixty-two patients with advanced CLI (Rutherford category 5 or 6) not eligible for revascularization were randomized to treatment with 40 ml of autologous BMCs (SmartPreP2) by local intramuscular (n = 32) or intra-arterial (n = 30) application. The primary endpoint was limb salvage and wound healing at 12 months. Seven patients (11 %) died during the follow-up from reasons unrelated to stem cell therapy. The BMC product of patients with limb salvage and wound healing (33/55) was characterized by a higher CD34(+) cell count (p = 0.001), as well as a higher number of total bone marrow mononuclear cells (BM-MNCs) (p = 0.032), than that of nonresponders (22/55). Patients with limb salvage and wound healing were younger (p = 0.028), had lower C-reactive protein levels (p = 0.038), and had higher transcutaneous oxygen pressure (tcpO2) (p = 0.003) before cell application than nonresponders. All patients with major tissue loss at baseline (Rutherford 6 stage of CLI, n = 5) showed progression of limb ischemia and required major limb amputation. In the multiple binary logistic regression model, the number of applied CD34(+) cells (p = 0.046) and baseline tcpO2 (p = 0.031) were independent predictors of limb salvage and wound healing. The number of administrated BM-MNCs strongly correlated with decreased peripheral leukocyte count after 6 months in surviving patients with limb salvage (p = 0.0008).

CONCLUSION

Patients who benefited from autologous BMC therapy for "no-option" CLI were treated with high doses of CD34(+) cells. The absolute number of applied BM-MNCs correlated with the improvement of inflammation. We hypothesize that the therapeutic benefit of cell therapy for peripheral artery disease is the result of synergistic effects mediated by a mixture of active cells with regenerative potential. Patients at the most advanced stage of CLI do not appear to be suitable candidates for cell therapy.

TRIAL REGISTRATION

The study was approved and registered by the ISRCTN registry.

TRIAL REGISTRATION

ISRCTN16096154 . Registered: 26 July 2016.

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

INTRODUCTION

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Neovascularization and hematopoietic stem cells

Vasculogenesis and angiogenesis are the major forms of blood vessel formation. Angiogenesis is the process where new vessels grow from pre-existing blood vessels, and is very important in the functional recovery of pathological conditions, such as wound healing and ischemic heart diseases. The development of better animal model and imaging technologies in past decades has greatly enriched our understanding on vasculogenesis and angiogenesis processes. Hypoxia turned out to be an important driving force for angiogenesis in various ischemic conditions. It stimulates expression of many growth factors like vascular endothelial growth factor, platelet-derived growth factor, insulin-like growth factor, and fibroblast growth factor, which play critical role in induction of angiogenesis. Other cellular components like monocytes, T cells, neutrophils, and platelets also play significant role in induction and regulation of angiogenesis. Various stem/progenitor cells also being recruited to the ischemic sites play crucial role in the angiogenesis process. Pre-clinical studies showed that stem/progenitor cells with/without combination of growth factors induce neovascularization in the ischemic tissues in various animal models. In this review, we will discuss about the fundamental factors that regulate the angiogenesis process and the use of stem cells as therapeutic regime for the treatment of ischemic diseases.

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.

Prognostic relevance of circulating endothelial progenitor cells for severe traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) promotes the recruitment of endothelial progenitor cells (EPCs) into the injured tissue where EPCs play an important role in repairing injured vasculature. However, the repair mechanism and prognostic significance of EPCs after TBI remain poorly understood.

METHODS

Blood samples were collected from 21 patients with severe TBI and 20 healthy subjects. EPCs were quantified by flow cytometry and serum VEGF and MMP-9 level measured by ELISA on days 1, 4, 7, 14 and 21 after TBI.

RESULTS

EPCs in the patients decreased originally, then increased to the peak level at 7 days and was significantly correlated with GOS scores 6 months after TBI. VEGF and MMP-9 were significantly increased during the follow-up period after TBI. EPCs was also positively correlated with GCS score 1 day after TBI and with MMP-9 and VEGF 7 days and 14 days after TBI.

CONCLUSION

The data demonstrate that TBI led to an increase of EPCs, VEGF and MMP-9, suggesting that increased VEGF and MMP-9 may mediate the recruitment of bone marrow-derived EPCs into the circulation. The association of EPCs with nerve functional recovery in patients provides evidence that EPCs may be a potential biomarker to monitor TBI angiogenesis and prognosis.

Correlation of CD34+ cells with tissue angiogenesis after traumatic brain injury in a rat model

Increasing evidence suggests that circulating endothelial progenitor cells, which are a subpopulation of hematopoietic progenitor CD34(+) cells, play a critical role in neovascularization and tissue repair. We have tested the hypothesis that traumatic brain injury (TBI) could mobilize CD34(+) cells to peripheral blood and brain tissue, a process critical for vascular repair, in a rat model of TBI. Male Wistar rats were subjected to controlled fluid percussion. Blood and brain tissue were collected before and after TBI to measure the levels of CD34(+) cells in peripheral blood and to detect their accumulation in the damaged cerebral tissue. Compared with surgery controls, CD34(+) cells significantly increased in the peripheral blood and accumulated in the brain tissue of TBI rats. Immunohistochemistry detected new vessels with incomplete CD34(+) endothelial-like cell lining and an increased number of microvessels in the injured and surrounding tissue. The results demonstrate a close correlation between an increase in circulating CD34(+) cells in response to traumatic injury and angiogenesis in TBI rat brain. They also suggest that transplantation of CD34(+) cells or augmentation of endogenous CD34(+) cells may be a novel therapeutic approach for patients with TBI.

Endothelial activation and circulating markers of endothelial activation in kidney disease

The recognition of a central role for the endothelium in the development of kidney disease or the development of vascular lesions in patients with established renal dysfunction has led to the emergence of methods to test different aspects of endothelium function, including in endothelium injury and repair. Endothelial-cell activation is associated with the shedding of components of the glycocalyx, adhesion molecules and endothelial microparticles into the circulation. This process may eventually result in the detachment of endothelial cells and recruitment of circulating myeloid and progenitor cells that are involved in vascular remodeling and repair. Circulating markers of endothelium activation may therefore represent novel markers of vessel wall injury. This Review describes the biology of these circulating markers of vessel wall injury, the methodologies used to measure them, and their possible relevance to patients with kidney disease.

Endothelial progenitor cell transplantation improves long-term stroke outcome in mice

OBJECTIVE

Endothelial progenitor cells (EPCs) play an important role in tissue repairing and regeneration in ischemic organs, including the brain. However, the cause of EPC migration and the function of EPCs after ischemia are unclear. In this study, we demonstrated the effects of EPCs on ischemic brain injury in a mouse model of transient middle cerebral artery occlusion (tMCAO).

METHODS

Circulating human EPCs were characterized with immunofluorescent staining and flow cytometry. EPCs (1 x 10(6)) were injected into nude mice after 1 hour of tMCAO. Histological analysis and behavioral tests were performed from day 0 to 28 days after tMCAO.

RESULTS

EPCs were detected in ischemic brain regions 24 hours after tMCAO. EPC transplantation significantly reduced ischemic infarct volume at 3 days after tMCAO compared with control animals (p < 0.05). CXCR4 was expressed in the majority of EPCs, and stromal-derived factor-1 (SDF-1) induced EPC migration, which was blocked by pretreated EPCs with AMD3100 in vitro. SDF-1 was upregulated in ischemic brain. Compared with control animals, injecting AMD3100-pretreated EPCs resulted in a larger infarct volume 3 days after tMCAO, suggesting that SDF-1-mediated signaling was involved in EPC-mediated neuroprotection. In addition, EPC transplantation reduced mouse cortex atrophy 4 weeks after tMCAO and improved neurobehavioral outcomes (p < 0.05). EPC injection potently increased angiogenesis in the peri-infarction area (p < 0.05).

INTERPRETATION

We conclude that systemic delivery of EPCs protects the brain against ischemic injury, promotes neurovascular repair, and improves long-term neurobehavioral outcomes. Our data suggest that SDF-1-mediated signaling plays a critical role in EPC-mediated neuroprotection.

Effects of intracoronary autologous bone marrow cells on left ventricular function in acute myocardial infarction: a systematic review and meta-analysis for randomized controlled trials

BACKGROUND

Experimental and clinical studies have suggested that intracoronary infusion of bone marrow-derived stem/progenitor cells (BMC) may improve left ventricular function after acute myocardial infarction (AMI). We conducted a systematic review and meta-analysis to investigate the efficacy and safety of BMC therapy on global left ventricular function in AMI.

METHODS

A systematic literature search of MEDLINE, Cochrane Controlled Trials Register, EMBASE, Science Citation Index, and PUBMED from their inception to March 2007 was conducted using specific search terms. Reference lists of papers and reviews on the topic were further searched. Finally, six randomized controlled trials that comprised 517 patients were eligible for further meta-analysis. We used a standardized protocol to extract information on the included studies.

RESULTS

Compared with the control groups, BMC therapy produced a slight improvement of the follow-up left ventricular ejection fraction (LVEF) [2.53%, 95% confidence interval (CI): 0.67-4.39, P=0.008] between 3 and 6 months. Similarly, BMC therapy also significantly improved the LVEF change from baseline to follow-up [2.88%, 95%CI: 1.69-4.08, P=0.000] compared to control groups, and the heterogeneity across the studies with regards to the follow-up LVEF (P=0.696) and the LVEF change (P=0.179). Major adverse cardiovascular events, including ventricular arrhythmia, rehospitalization for heart failure, and the composite of other cardiovascular events (cardiac death, recurrent myocardial infarction, infarct-vessel revascularization procedure, and stroke), were not significantly different between BMC therapy and control groups [relative risk (RR): 1.19, 95%CI: 0.68-2.06; RR: 1.79, 95%CI: 0.62-5.17; and RR: 1.05, 95%CI: 0.81-1.35, respectively].

CONCLUSION

On the basis of present evidence, intracoronary BMC infusion in patients with AMI seems to be safe and associated with slight improvement of the left ventricular ejection fraction at 3-6 months' follow-up.

Stem cell therapy: a promising and prospective approach in the treatment of patients with severe Buerger's disease

No effective blood-flow enhancement therapies are available for patients with severe peripheral arterial disease (SPAD), thus amputation remains the only option for relief of rest pain or gangrene. Autologous bone marrow-derived stem cell therapy (ABMSCT) is an emerging modality to induce angiogenesis from endothelial progenitors. A total of 5 patients with SPAD were treated by ABMSCT using isolated CD34+ cells with characterized phenotype administered by intramuscular injections. The follow-up before and 1, 3, 6, 9, and 12 months after ABMSCT was based on clinical (rest pain, walking distance without pain, nonhealing ulcers, ankle-brachial index [ABI]) and laboratory (angiography, duplex and laser ultrasonography, TcPO(2)) parameters. Significant improvement of pain and walking distance was observed in all patients. Nonhealing ulcers disappeared in 3 patients and became smaller and thinner in 1 patient. The average of ABI improved significantly on the treated limb but did not change on the contralateral limb. New collaterals were detected by angiography in 3 patients, but duplex ultrasonography detected improvement in one patient only. Laser ultrasonography showed a mild significant change, TcPO(2) values improved mainly on the foot. Severe adverse events were not observed. We conclude that ABMSCT with isolated CD34+ cells is safe, effective, and results in sustained clinical benefit for patients with SPAD.

Endothelial progenitor cell research in stroke: a potential shift in pathophysiological and therapeutical concepts

BACKGROUND AND PURPOSE

Stroke is the leading cause of disability in the Western world; however, few therapies are at hand to decrease this burden.

SUMMARY OF REVIEW

Endothelial progenitor cells (EPCs) have been introduced in cardiovascular medicine as factotums. EPCs can repair damaged endothelium and attenuate the development and progression of atherosclerosis. Also, EPCs can form new vessels in ischemic areas and thus promote recovery after ischemic events. In stroke, however, EPC research is limited. In our overview, we provide background information on EPC use as a risk marker and as a potential therapeutic agent.

CONCLUSIONS

In our opinion, the lack of EPC studies in stroke should instigate vascular neurologists to participate in EPC research, as EPCs could also change pathophysiological concepts and improve clinical treatments in vascular neurology.

Met-RANTES reduces endothelial progenitor cell homing to activated (glomerular) endothelium in vitro and in vivo

The chemokine RANTES (regulated upon activation normal T-cell expressed and secreted) is involved in the formation of an inflammatory infiltrate during glomerulonephritis. However, RANTES receptor inhibition, although reducing glomerular leukocyte infiltration, can also increase damage. We hypothesized that RANTES does not only promote the influx and activation of inflammatory leukocytes but also mediates glomerular microvascular repair by stimulating the homing of bone marrow (BM)-derived endothelial progenitor cells. To investigate the role of RANTES in the participation of BM-derived cells in glomerular vascular repair, we used a rat BM transplantation model in combination with reversible anti-Thy-1.1 glomerulonephritis. Twenty-four hours after the induction of glomerulonephritis, BM-transplanted rats were treated for 7 days with either the RANTES receptor antagonist Met-RANTES or saline. The participation of BM-derived endothelial cells in glomerular repair, glomerular monocyte infiltration, and proteinuria was evaluated at days 7 and 28. Furthermore, we used an in vitro perfusion chamber assay to study the role of RANTES receptors in shear-resistant adhesion of the CD34+ stem cells to activated endothelium under flow. In our reversible glomerulonephritis model, RANTES receptor inhibition specifically reduced the participation of BM-derived cells in glomerular vascular repair by more than 40% at day 7 without impairing monocyte influx. However, no obvious change in recovery from proteinuria or morphological damage was observed. Blockade of RANTES receptors on CD34+ cells in vitro partially inhibited platelet-enhanced, shear-resistant firm adhesion of the CD34+ cells to activated endothelium. In conclusion, our data suggest that RANTES is involved in the homing and participation of BM-derived endothelial cells in glomerular repair.

Quality of Life Improvement and Long-Term Effects of Peripheral Blood Mononuclear Cell Transplantation for Severe Arteriosclerosis Obliterans in Diabetic Patients on Dialysis

BACKGROUND

Severe arteriosclerosis obliterans (ASO) can be intractable, especially in diabetic patients on hemodialysis (HD). Recently, the transplantation of autologous peripheral blood mononuclear cells (PBMNCs) has been reported to have beneficial effects, but the long-term effects and impact on quality of life (QOL) have not been studied.

METHODS AND RESULTS

Autologous PBMNCs were transplanted into 7 diabetic patients on HD who had severe ASO (5 cases with Fontaine IV and 2 with Fontaine III) after administration of 5 microg/kg granulocyte colony stimulating factor; QOL and degree of ischemia was assessed by measuring skin temperature, skin perfusion pressure (SPP), ankle-brachial index (ABI), and ulcer size, and from angiographic findings. At 4 weeks after the procedure, skin temperature was significantly improved, and SPP and ABI also were increased. These beneficial effects persisted for up to 24 weeks. Angiographic findings and ulcer size improved in 3 of 7 and 3 of 4 patients, respectively. SF-36v2 analysis revealed significant improvements in pain scores. No serious complications were detected.

CONCLUSION

Transplantation of PBMNCs resulted in improvement in pain and leg ischemia for over 6 months without serious complications. This therapy is safe and effective for severe ASO in diabetic patients on HD.

Different ways to antiangiogenesis by angiostatin and suramin, and quantitation of angiostatin-induced antiangiogenesis

Angiogenesis, i.e. sprouting of new vessels, their remodelling and regression, is a prerequisite for growth and differentiation of organs and tissues. It is involved in many pathological processes, particularly growth and metastasis of tumours. Angiostatic therapy is a promising new strategy in the treatment of cancer. Angiogenesis inhibitors could intervene in the different phases of the angiogenic cascade, i.e. migration, proliferation, differentiation and three-dimensional organisation of endothelial cells, to inhibit the generation of tumour vessels. The aim of this study was to explore whether in a previously validated in vitro model for quantitation of angiogenesis the effects of the angiostatic factors angiostatin and suramin can be investigated and quantified. Examination of angiostatin and suramin showed that angiostatin-induced antiangiogenesis resulted in inverse angiogenesis. The addition of suramin initially resulted in increased angiogenesis. However, long-term incubation ultimately led to disintegration of endothelial structures, thus establishing the angiostatic effects of suramin. Antiangiogenesis was not only quantified using the previously validated method. It also lent itself to assessment of the extent of antiangiogenesis within the various phases of the angiogenic cascade. This method may therefore be employed in trial studies of potential angiostatic substances and related cellular mechanisms.

Endothelial progenitor cells: biology and therapeutic potential in hypertension

PURPOSE OF REVIEW

In this review, we summarize some of the recent advances in our understanding of the biology of endothelial progenitor cells, and discuss the potential relevance of these progenitor cells for endothelial function and associated microvascular abnormalities that can form the structural basis of essential hypertension.

RECENT FINDINGS

Both in experimental models of hypertension and in patients with hypertension, the function of endothelial progenitor cells is impaired. Also, some antihypertensive drugs that have been associated with reversal of endothelial function and microvascular rarefaction appear to correct endothelial progenitor cell dysfunction.

SUMMARY

While information on endothelial progenitor biology is still limited in patients with hypertension in comparison with, for example, patients with coronary artery disease, it is a topic that warrants the attention of researchers in the hypertension field, as it may have important implications for the development of organ damage, and potentially could be linked to the pathogenesis of hypertension itself.

Stem cells for the ischaemic heart

The discovery of adult progenitor cells capable of generating new vascular and myocardial tissue offers the promise of salvage of ischaemically threatened or irreversibly damaged cardiac tissue. Not surprisingly, great interest has focused on the use of a variety of cell types to treat both acute myocardial infarction and chronic ischaemic heart disease. This review focuses on the treatment of these two categories of disease, the cell types being considered, our understanding of timing and methods of cellular administration, and possible mechanisms of myocardial salvage.