Statin and Stromal Cell-Derived Factor-1 Additively Promote Angiogenesis by Enhancement of Progenitor Cells Incorporation into New Vessels

Liraglutide Improves the Angiogenic Capability of EPC and Promotes Ischemic Angiogenesis in Mice under Diabetic Conditions through an Nrf2-Dependent Mechanism

The impairment in endothelial progenitor cell (EPC) functions results in dysregulation of vascular homeostasis and dysfunction of the endothelium under diabetic conditions. Improving EPC function has been considered as a promising strategy for ameliorating diabetic vascular complications. Liraglutide has been widely used as a therapeutic agent for diabetes. However, the effects and mechanisms of liraglutide on EPC dysfunction remain unclear. The capability of liraglutide in promoting blood perfusion and angiogenesis under diabetic conditions was evaluated in the hind limb ischemia model of diabetic mice. The effect of liraglutide on the angiogenic function of EPC was evaluated by cell scratch recovery assay, tube formation assay, and nitric oxide production. RNA sequencing was performed to assess the underlying mechanisms. Liraglutide enhanced blood perfusion and angiogenesis in the ischemic hindlimb of db/db mice and streptozotocin-induced type 1 diabetic mice. Additionally, liraglutide improved tube formation, cell migration, and nitric oxide production of high glucose (HG)-treated EPC. Assessment of liraglutide target pathways revealed a network of genes involved in antioxidant activity. Further mechanism study showed that liraglutide decreased the production of reactive oxygen species and increased the activity of nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2 deficiency attenuated the beneficial effects of liraglutide on improving EPC function and promoting ischemic angiogenesis under diabetic conditions. Moreover, liraglutide activates Nrf2 through an AKT/GSK3β/Fyn pathway, and inhibiting this pathway abolished liraglutide-induced Nrf2 activation and EPC function improvement. Overall, these results suggest that Liraglutide represents therapeutic potential in promoting EPC function and ameliorating ischemic angiogenesis under diabetic conditions, and these beneficial effects relied on Nrf2 activation.

Pleiotropic properties of statins via angiogenesis modulation in cardiovascular disease

Inhibition of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase by statins is affected by inhibiting the active site of the enzyme in a competitive manner. Statins reduce plasma cholesterol by inhibiting its de novo synthesis. In addition, statins impart 'pleiotropic' activities that do not directly relate to their ability to decrease cholesterol. The proangiogenic and antiangiogenic characteristics of statins are among these pleiotropic effects. These angiogenic-modifying properties could offer new therapeutic applications. Statins stimulate or suppress angiogenesis in a biphasic manner. Whereas low doses of statin stimulate angiogenesis, high doses reduce protein prenylation and limit cell development and angiogenesis. In this review, we discuss how statins impact angiogenesis, with a particular focus on angiogenesis in stroke and cardiovascular disease (CVD).

Regulation of Endothelial Progenitor Cell Functions in Ischemic Heart Disease: New Therapeutic Targets for Cardiac Remodeling and Repair

Ischemic heart disease (IHD) is the leading cause of morbidity and mortality worldwide. Ischemia and hypoxia following myocardial infarction (MI) cause subsequent cardiomyocyte (CM) loss, cardiac remodeling, and heart failure. Endothelial progenitor cells (EPCs) are involved in vasculogenesis, angiogenesis and paracrine effects and thus have important clinical value in alternative processes for repairing damaged hearts. In fact, this study showed that the endogenous repair of EPCs may not be limited to a single cell type. EPC interactions with cardiac cell populations and mesenchymal stem cells (MSCs) in ischemic heart disease can attenuate cardiac inflammation and oxidative stress in a microenvironment, regulate cell survival and apoptosis, nourish CMs, enhance mature neovascularization, alleviate adverse ventricular remodeling after infarction and enhance ventricular function. In this review, we introduce the definition and discuss the origin and biological characteristics of EPCs and summarize the mechanisms of EPC recruitment in ischemic heart disease. We focus on the crosstalk between EPCs and endothelial cells (ECs), smooth muscle cells (SMCs), CMs, cardiac fibroblasts (CFs), cardiac progenitor cells (CPCs), and MSCs during cardiac remodeling and repair. Finally, we discuss the translation of EPC therapy to the clinic and treatment strategies.

Role of Stromal Cell-Derived Factor-1 in Endothelial Progenitor Cell-Mediated Vascular Repair and Regeneration

Endothelial progenitor cells (EPCs) are immature endothelial cells that participate in vascular repair and postnatal neovascularization and provide a novel and promising therapy for the treatment of vascular disease. Studies in different animal models have shown that EPC mobilization through pharmacological agents and autologous EPC transplantation contribute to restoring blood supply and tissue regeneration after ischemic injury. However, these effects of the progenitor cells in clinical studies exhibit mixed results. The therapeutic efficacy of EPCs is closely associated with the number of the progenitor cells recruited into ischemic regions and their functional abilities and survival in injury tissues. In this review, we discussed the regulating role of stromal cell-derived factor-1 (also known CXCL12, SDF-1) in EPC mobilization, recruitment, homing, vascular repair and neovascularization, and analyzed the underlying machemisms of these functions. Application of SDF-1 to improve the regenerative function of EPCs following vascular injury was also discussed. SDF-1 plays a crucial role in mobilizing EPC from bone marrow into peripheral circulation, recruiting the progenitor cells to target tissue and protecting against cell death under pathological conditions; thus improve EPC regenerative capacity. SDF-1 are crucial for regulating EPC regenerative function, and provide a potential target for improve therapeutic efficacy of the progenitor cells in treatment of vascular disease.

FGF21 promotes ischaemic angiogenesis and endothelial progenitor cells function under diabetic conditions in an AMPK/NAD+-dependent manner

Diabetic vascular complications are closely associated with long‐term vascular dysfunction and poor neovascularization. Endothelial progenitor cells (EPCs) play pivotal roles in maintaining vascular homeostasis and triggering angiogenesis, and EPC dysfunction contributes to defective angiogenesis and resultant diabetic vascular complications. Fibroblast growth factor 21 (FGF21) has received substantial attention as a potential therapeutic agent for diabetes via regulating glucose and lipid metabolism. However, the effects of FGF21 on diabetic vascular complications remain unclear. In the present study, the in vivo results showed that FGF21 efficiently improved blood perfusion and ischaemic angiogenesis in both type 1 and type 2 diabetic mice, and these effects were accompanied by enhanced EPC mobilization and infiltration into ischaemic muscle tissues and increases in plasma stromal cell–derived factor‐1 concentration. The in vitro results revealed that FGF21 directly prevented EPC damage induced by high glucose, and the mechanistic studies demonstrated that nicotinamide adenine dinucleotide (NAD⁺) was dramatically decreased in EPCs challenged with high glucose, whereas FGF21 treatment significantly increased NAD⁺ content in an AMPK‐dependent manner, resulting in improved angiogenic capability of EPCs. These results indicate that FGF21 promotes ischaemic angiogenesis and the angiogenic ability of EPCs under diabetic conditions by activating the AMPK/NAD⁺ pathway.

MicroRNAs As Master Regulators of Atherosclerosis: From Pathogenesis to Novel Therapeutic Options

Significance: Cardiovascular disease (CVD) remains the major cause of morbidity and mortality worldwide. Accumulating evidence indicates that atherosclerosis and its sequelae, coronary artery disease, contribute to the majority of cardiovascular deaths. Atherosclerosis is a chronic inflammatory disease of the arteries in which atherosclerotic plaques form within the vessel wall. Epidemiological studies have identified various risk factors for atherosclerosis, such as diabetes, hyperlipidemia, smoking, genetic predisposition, and sedentary lifestyle. Recent Advances: Through the advancement of genetic manipulation techniques and their use in cardiovascular biology, it was shown that small RNAs, especially microRNAs (miRNAs), are dynamic regulators of disease pathogenesis. They are considered to be central during the regulation of gene expression through numerous mechanisms and provide a means to develop biomarkers and therapeutic tools for the diagnosis and therapy of atherosclerosis. Circulating miRNAs encapsulated within membrane-surrounded vesicles, which originate from diverse subcellular compartments, are now emerging as novel regulators of intercellular communication. The miRNAs, in both freely circulating and vesicle-bound forms, represent a valuable tool for diagnosing and monitoring CVD, recently termed as "liquid biopsy." Critical Issues: However, despite the recent advancements in miRNA-based diagnostics and therapeutics, understanding how miRNAs can regulate atherosclerosis is still crucial to achieving an effective intervention and reducing the disease burden. Future Directions: We provide a landscape of the current developmental progression of RNA therapeutics as a holistic approach for treating CVD in different animal models and clinical trials. Future interrogations are warranted for the development of miRNA-based therapeutics to overcome challenges for the treatment of the disease.

Surface Engineering of Cardiovascular Devices for Improved Hemocompatibility and Rapid Endothelialization

Cardiovascular devices have been widely applied in the clinical treatment of cardiovascular diseases. However, poor hemocompatibility and slow endothelialization on their surface still exist. Numerous surface engineering strategies have mainly sought to modify the device surface through physical, chemical, and biological approaches to improve surface hemocompatibility and endothelialization. The alteration of physical characteristics and pattern topographies brings some hopeful outcomes and plays a notable role in this respect. The chemical and biological approaches can provide potential signs of success in the endothelialization of vascular device surfaces. They usually involve therapeutic drugs, specific peptides, adhesive proteins, antibodies, growth factors and nitric oxide (NO) donors. The gene engineering can enhance the proliferation, growth, and migration of vascular cells, thus boosting the endothelialization. In this review, the surface engineering strategies are highlighted and summarized to improve hemocompatibility and rapid endothelialization on the cardiovascular devices. The potential outlook is also briefly discussed to help guide endothelialization strategies and inspire further innovations. It is hoped that this review can assist with the surface engineering of cardiovascular devices and promote future advancements in this emerging research field.

Humoral factors secreted from adipose tissue-derived mesenchymal stem cells ameliorate atherosclerosis in Ldlr-/- mice

AIMS

Atherosclerosis is a chronic inflammatory disease of the vasculature. Mesenchymal stem cells (MSCs) exert immunomodulatory and immunosuppressive effects by secreting humoral factors; however, the intravascular MSC administration presents a risk of vascular occlusion. Here, we investigated both the effect of conditioned medium from cultured MSCs (MSC-CM) on atherosclerosis and the underlying mechanism.

METHODS AND RESULTS

Low-density lipoprotein receptor-deficient (Ldlr-/-) mice were fed a high-fat diet and received intravenous injections of either MSC-CM from adipose tissue-derived MSCs or control medium 2×/week for 13 weeks. MSC-CM treatment decreased the atherosclerotic plaque area in the aorta and aortic root of Ldlr-/- mice by 41% and 30%, respectively, with no change in serum lipoprotein levels. Histopathologically, the MSC-CM treatment decreased the expression of cell adhesion molecules (CAMs) and the accumulation of macrophages on the vascular walls. Extracellular vesicles (EVs) and supernatant (MSC-CM supernatant) were separated from the MSC-CM by ultracentrifugation. In tumour necrosis factor-α stimulated human aortic endothelial cells (HAOECs), both the MSC EVs and MSC-CM supernatant decreased CAM expression by inhibiting the mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NFκB) pathways. In macrophages, the MSC-CM supernatant decreased the lipopolysaccharide-induced increases in M1 marker expression by inhibiting both the MAPK and NFκB pathways and increased the expression of M2 markers by activating the signal transducer and activator of transcription 3 pathway. In co-culture, inflamed HAOECs pretreated with MSC-CM supernatant and MSC EVs exhibited decreased monocyte adhesion to HAOECs. In addition, the neutralization of hepatocyte growth factor (HGF) in MSC-CM or MSC-CM supernatant attenuated their abilities to suppress monocyte adhesion to HAOECs in co-culture.

CONCLUSION

MSC-CM ameliorated atherosclerosis in Ldlr-/- mice and suppressed CAM expression and macrophage accumulation in the vascular walls. Humoral factors, including HGF and EVs from MSCs, hold promise as therapeutic agents to reduce the residual risk of coronary artery diseases.

Vascular Regeneration for Ischemic Retinopathies: Hope from Cell Therapies

Retinal vascular diseases, such as diabetic retinopathy, retinopathy of prematurity, retinal vein occlusion, ocular ischemic syndrome and ischemic optic neuropathy, are leading causes of vision impairment and blindness. Whilst drug, laser or surgery-based treatments for the late stage complications of many of these diseases are available, interventions that target the early vasodegenerative stages are lacking. Progressive vasculopathy and ensuing ischemia is an underpinning pathology in many of these diseases, leading to hypoperfusion, hypoxia, and ultimately pathological neovascularization and/or edema in the retina and other ocular tissues, such as the optic nerve and iris. Therefore, repairing the retinal vasculature may prevent progression of ischemic retinopathies into late stage vascular complications. Various cell types have been explored for their vascular repair potential. Endothelial progenitor cells, mesenchymal stem cells and induced pluripotent stem cells are studied for their potential to integrate with the damaged retinal vasculature and limit ischemic injury. Clinical trials for some of these cell types have confirmed safety and feasibility in the treatment of ischemic diseases, including some retinopathies. Another promising avenue is mobilization of endogenous endothelial progenitors, whereby reparative cells are moved from their niche to circulating blood to target and home into ischemic tissues. Several aspects and properties of these cell types have yet to be elucidated. Nevertheless, we foresee that cell therapy, whether through delivery of exogenous or enhancement of endogenous reparative cells, will become a valuable and beneficial treatment for ischemic retinopathies.

Endothelial progenitor cells, potential biomarkers for diagnosis and prognosis of ischemic stroke: protocol for an observational case-control study

Ischemic stroke is a devastating, life altering event which can severely reduce patient quality of life. Despite years of research there have been minimal therapeutic advances. Endothelial progenitor cells (EPCs), stem cells involved in both vasculogenesis and angiogenesis, may be a potential therapeutic target. After a stroke, EPCs migrate to the site of ischemic injury to repair cerebrovascular damage, and their numbers and functional capacity may determine patients’ outcome. This study aims to determine whether the number of circulating EPCs and their functional aspects may be used as biomarkers to identify the type (cortical or lacunar) and/or severity of ischemic stroke. The study will also investigate if there are any differences in these characteristics between healthy volunteers over and under 65 years of age. 100 stroke patients (50 lacunar and 50 cortical strokes) will be recruited in this prospective, observational case-controlled study. Blood samples will be taken from stroke patients at baseline (within 48 hours of stroke) and days 7, 30 and 90. EPCs will be counted with flow cytometry. The plasma levels of pro- and anti-angiogenic factors and inflammatory cytokines will also be determined. Outgrowth endothelial cells will be cultured to be used in tube formation, migration and proliferation functional assays. Primary outcome is disability or dependence on day 90 after stroke, assessed by the modified Rankin Scale. Secondary outcomes are changes in circulating EPC numbers and/or functional capacity between patient and healthy volunteers, between patient subgroups and between elderly and young healthy volunteers. Recruitment started in February 2017, 167 participants have been recruited. Recruitment will end in November 2019. West Midlands - Coventry & Warwickshire Research Ethics Committee approved this study (REC number: 16/WM/0304) on September 8, 2016. Protocol version: 2.0. The Bayraktutan Dunhill Medical Trust EPC Study was registered in ClinicalTrials.gov (NCT02980354) on November 15, 2016. This study will determine whether the number of EPCs can be used as a prognostic or diagnostic marker for ischemic strokes and is a step towards discovering if transplantation of EPCs may aid patient recovery.

Endothelialization of cardiovascular devices

Blood-contacting surfaces of cardiovascular devices are not biocompatible for creating an endothelial layer on them. Numerous research studies have mainly sought to modify these surfaces through physical, chemical and biological means to ease early endothelial cell (EC) adhesion, migration and proliferation, and eventually to build an endothelial layer on the surfaces. The first priority for surface modification is inhibition of protein adsorption that leads to inhibition of platelet adhesion to the device surfaces, which may favor EC adhesion. Surface modification through surface texturing, if applicable, can bring some hopeful outcomes in this regard. Surface modifications through chemical and/or biological means may play a significant role in easy endothelialization of cardiovascular devices and inhibit smooth muscle cell proliferation. Cellular engineering of cells relevant to endothelialization can boost the positive outcomes obtained through surface engineering. This review briefly summarizes recent developments and research in early endothelialization of cardiovascular devices. STATEMENT OF SIGNIFICANCE: Endothelialization of cardiovascular implants, including heart valves, vascular stents and vascular grafts is crucial to solve many problems in our health care system. Numerous research efforts have been made to improve endothelialization on the surfaces of cardiovascular implants, mainly through surface modifications in three ways - physically, chemically and biologically. This review is intended to highlight comprehensive research studies to date on surface modifications aiming for early endothelialization on the blood-contacting surfaces of cardiovascular implants. It also discusses future perspectives to help guide endothelialization strategies and inspire further innovations.

Critical limb ischemia: Current and novel therapeutic strategies

Critical limb ischemia (CLI) is the advanced stage of peripheral artery disease spectrum and is defined by limb pain or impending limb loss because of compromised blood flow to the affected extremity. Current conventional therapies for CLI include amputation, bypass surgery, endovascular therapy, and pharmacological approaches. Although these conventional therapeutic strategies still remain as the mainstay of treatments for CLI, novel and promising therapeutic approaches such as proangiogenic gene/protein therapies and stem cell-based therapies have emerged to overcome, at least partially, the limitations and disadvantages of current conventional therapeutic approaches. Such novel CLI treatment options may become even more effective when other complementary approaches such as utilizing proper bioscaffolds are used to increase the survival and engraftment of delivered genes and stem cells. Therefore, herein, we address the benefits and disadvantages of current therapeutic strategies for CLI treatment and summarize the novel and promising therapeutic approaches for CLI treatment. Our analyses also suggest that these novel CLI therapeutic strategies show considerable advantages to be used when current conventional methods have failed for CLI treatment.

SDF-1 plasmid treatment for patients with peripheral artery disease (STOP-PAD): Randomized, double-blind, placebo-controlled clinical trial

The efficacy of biologic therapies in critical limb ischemia (CLI) remains elusive, in part, due to limitations in trial design and patient selection. Using a novel design, we examined the impact of complementing revascularization therapy with intramuscular JVS-100 – a non-viral gene therapy that activates endogenous regenerative repair pathways. In this double-blind, placebo-controlled, Phase 2B trial, we randomized 109 patients with CLI (Rutherford class V or VI) to 8 mg or 16 mg intramuscular injections of placebo versus JVS-100. Patients were eligible if they persistently had reduced forefoot perfusion, by toe–brachial index (TBI) or skin perfusion pressure (SPP), following successful revascularization with angiographic demonstration of tibial arterial flow to the ankle. The primary efficacy end point was a 3-month wound healing score assessed by an independent wound core laboratory. The primary safety end point was major adverse limb events (MALE). Patients’ mean age was 71 years, 33% were women, 79% had diabetes, and 8% had end-stage renal disease. TBI after revascularization was 0.26, 0.27, and 0.26 among the three groups (placebo, 8 mg, and 16 mg injections, respectively). Only 26% of wounds completely healed at 3 months, without any differences between the three groups (26.5%, 26.5%, and 25%, respectively). Similarly, there were no significant changes in TBI at 3 months. Three (2.8%) patients died and two (1.8%) had major amputations. Rates of MALE at 3 months were 8.8%, 20%, and 8.3%, respectively. While safe, JVS-100 failed to improve wound healing or hemodynamic measures at 3 months. Only one-quarter of CLI wounds healed at 3 months despite successful revascularization, highlighting the need for additional research in therapies that can improve microcirculation in these patients. ClinicalTrials.gov Identifier: NCT02544204

Approaches to therapeutic angiogenesis for ischemic heart disease

Ischemic heart disease (IHD) is caused by the narrowing of arteries that work to provide blood, nutrients, and oxygen to the myocardial tissue. The worldwide epidemic of IHD urgently requires innovative treatments despite the significant advances in medical, interventional, and surgical therapies for this disease. Angiogenesis is a physiological and pathophysiological process that initiates vascular growth from pre-existing blood vessels in response to a lack of oxygen. This process occurs naturally over time and has encouraged researchers and clinicians to investigate the outcomes of accelerating or enhancing this angiogenic response as an alternative IHD therapy. Therapeutic angiogenesis has been shown to revascularize ischemic heart tissue, reduce the progression of tissue infarction, and evade the need for invasive surgical procedures or tissue/organ transplants. Several approaches, including the use of proteins, genes, stem/progenitor cells, and various combinations, have been employed to promote angiogenesis. While clinical trials for these approaches are ongoing, microvesicles and exosomes have recently been investigated as a cell-free approach to stimulate angiogenesis and may circumvent limitations of using viable cells. This review summarizes the approaches to accomplish therapeutic angiogenesis for IHD by highlighting the advances and challenges that addresses the applicability of a potential pro-angiogenic medicine.

Regulation of plasticity and biological features of endothelial progenitor cells by MSC-derived SDF-1

Bone marrow (BM) is a source of mesenchymal stromal cells (MSCs) and endothelial progenitor cells (EPCs). MSCs provide a specific niche in the BM and biological features of EPCs may be changed with this niche. Stromal cell-derived factor 1 (SDF-1) secreted from primary BM-MSCs and biological features of this niche on EPC development are still yet to be understood. The aim of this study was to evaluate the role of SDF-1 produced by MSCs on EPC development. We applied the CRISPR/Cas9 system for the knock-out of the SDF-1 gene in BM-derived MSCs. BM-derived EPCs were then cocultured with MSCs^SDF-1-/- or MSCs^SDF-1+/+ to identify the role of MSC-derived SDF-1α on proliferation, migration and angiogenic activity of EPCs. Next, pre-expanded EPCs were harvested and co-transplanted with MSCs^SDF-1-/- or MSCs^SDF-1+/+ into sublethally irradiated mice to analyze the potency of these cells for marrow reconstitution. Our results revealed that proliferation, colony formation, migration and angiogenic activity of EPCs was significantly increased after coculture with MSCs^SDF-1+/+. We also found that co-transplantation of EPCs with MSCs^SDF-1+/+, in contrast to MSCs^SDF-1-/-, into irradiated mice resulted in marrow repopulation and hematologic recovery, leading to improved survival of transplanted mice. In conclusions, MSC-derived SDF-1 niche plays an important role in the development of EPCs and this niche is essential for bone marrow repopulation by these cells and can enhance the efficiency of EPC therapy for ischemic diseases.

Bone marrow stromal cells from low-turnover osteoporotic mouse model are less sensitive to the osteogenic effects of fluvastatin

This study aimed to investigate the effects of fluvastatin on the differentiation of bone marrow stromal cells (BMSCs) into osteoblasts in senescence-accelerated mouse prone 6 (SAMP6) compared with that in the normal senescence-accelerated-resistant mouse (SAMR1) model. SAMP strains arose spontaneously from the AKR/J background and display shortened life span and an array of signs of accelerated aging, compared with control SAMR strains. The dose effects of fluvastatin were also evaluated. BMSCs were cultured with/without fluvastatin (0 μM, 0.1 μM, 0.5 μM, and 1.0 μM). WST-1-based colorimetry was performed to evaluate cell proliferation. To evaluate cell differentiation, gene expression levels of bmp2 and runx2 were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR), and protein expression levels were determined using enzyme-linked immunosorbent assay (BMP2) and immunofluorescence staining (BMP2 and Runx2). Alkaline phosphatase (ALP) activity assay and histochemical detection were determined; the effect of noggin, a BMP-specific antagonist, was examined using ALP histochemical detection. To assess for mature osteogenic marker, gene expression levels of bglap2 were determined by qRT-PCR and mineralization was determined by alizarin red staining. RhoA activity was also examined by Western blotting. In SAMP6, BMP2, Runx2 and Bglap2 mRNA and protein expressions were significantly increased by fluvastatin, and ALP activity was increased by BMP2 action. RhoA activity was also inhibited by fluvastatin. The concentration of fluvastatin sufficient to increase BMP2 and Runx2 expression and ALP activity was 0.5 μM in SAMP6 and 0.1 μM in SAMR1. In conclusion, the present study revealed that fluvastatin promoted BMSC differentiation into osteoblasts by RhoA-BMP2 pathway in SAMP6. BMSCs of SAMP6 are less sensitive to the osteogenic effects of fluvastatin than SAMR1.

Danhong Injection Enhances the Therapeutic Efficacy of Mesenchymal Stem Cells in Myocardial Infarction by Promoting Angiogenesis

Stem cell-based therapies have the potential to dramatically transform the treatment and prognosis of myocardial infarction (MI), and mesenchymal stem cells (MSCs) have been suggested as a promising cell population to ameliorate the heart remodeling in post-MI. However, poor implantation and survival in ischemic myocardium restrict its efficacy and application. In this study, we sought to use the unique mode of action of Chinese medicine to improve this situation. Surrounding the myocardial infarct area, we performed a multi-point MSC transplantation and administered in conjunction with Danhong injection, which is mainly used for the treatment of MI. Our results showed that the MSC survival rate and cardiac function were improved significantly through the small animal imaging system and echocardiography, respectively. Moreover, histological analysis showed that MSC combined with DHI intervention significantly reduced myocardial infarct size in myocardial infarcted mice and significantly increased MSC resident. To investigate the mechanism of DHI promoting MSC survival and cell migration, PCR and WB experiments were performed. Our results showed that DHI could promote the expression of CXC chemokine receptor 4 in MSC and enhance the expression of stromal cell–derived factor-1 in myocardium, and this effect can be inhibited by AMD3100 (an SDF1/CXCR4 antagonist). Additionally, MSC in combination with DHI interfered with MI in mice and this signifies that when combined, the duo could the expression of vascular endothelial growth factor (VEGF) in the marginal zone of infarction compared with when either MSC or DHI are used individually. Based on these results, we conclude that DHI enhances the residence of MSCs in cardiac tissue by modulating the SDF1/CXCR4 signaling pathway. These findings have important therapeutic implications for Chinese medicine-assisted cell-based therapy strategies.

Statins in conditions other than hypocholesterolemic effects for chronic subdural hematoma therapy, old drug, new tricks?

Chronic subdural hematoma (CSDH) is one of the most common intracranial hematomas worldwide with a high incidence in the general population. However, the optimum treatment for CSDH is Burr-hole drainage with or without rinse Considering the poor outcomes of CSDH in aged patients, and ambiguous prediction of recurrence in many sides of recurrent CSDHs who have been analyzed, new effective therapies are needed for those CSDHs who are predicated to have poor prognosis for surgery and/or have a higher risk of recurrence. Statins, which is the first-line treatment for patients with high cholesterol and coronary heart disease. However, statins are still not solely limited in the treatment of these diseases. It has been demonstrated that statins could improve CSDH due to its effect of regulation of angiogenesis and inflammation. In this review, in order to provide potential new treatment for CSDH we summarize the recent findings of statins in CSDH in order to try to clarify the mechanisms of this effect.

The Role of SDF-1/CXCR4/CXCR7 in Neuronal Regeneration after Cerebral Ischemia

Stromal cell-derived factor-1 is a chemoattractant produced by bone marrow stromal cell lines. It is recognized as a critical factor in the immune and central nervous systems (CNSs) as well as exerting a role in cancer. SDF-1 activates two G protein-coupled receptors, CXCR4 and CXCR7; these are expressed in both developing and mature CNSs and participate in multiple physiological and pathological events, e.g., inflammatory response, neurogenesis, angiogenesis, hematopoiesis, cancer metastasis, and HIV infection. After an ischemic stroke, SDF-1 levels robustly increase in the penumbra regions and participate in adult neural functional repair. Here we will review recent findings about SDF-1 and its receptor, analyse their functions in neurogeneration after brain ischemic injury: i.e., how the system promotes the proliferation, differentiation and migration of neural precursor cells and mediates axonal elongation and branching.

Endothelial Progenitor Cells for Ischemic Stroke: Update on Basic Research and Application

Ischemic stroke is one of the leading causes of human death and disability worldwide. So far, ultra-early thrombolytic therapy is the most effective treatment. However, most patients still live with varying degrees of neurological dysfunction due to its narrow therapeutic time window. It has been confirmed in many studies that endothelial progenitor cells (EPCs), as a kind of adult stem cells, can protect the neurovascular unit by repairing the vascular endothelium and its secretory function, which contribute to the recovery of neurological function after an ischemic stroke. This paper reviews the basic researches and clinical trials of EPCs especially in the field of ischemic stroke and addresses the combination of EPC application with new technologies, including neurovascular intervention, synthetic particles, cytokines, and EPC modification, with the aim of shedding some light on the application of EPCs in treating ischemic stroke in the future.

Preconditioning-induced CXCL12 upregulation minimizes leukocyte infiltration after stroke in ischemia-tolerant mice

Repetitive hypoxic preconditioning creates long-lasting, endogenous protection in a mouse model of stroke, characterized by reductions in leukocyte-endothelial adherence, inflammation, and infarct volumes. The constitutively expressed chemokine CXCL12 can be upregulated by hypoxia and limits leukocyte entry into brain parenchyma during central nervous system inflammatory autoimmune disease. We therefore hypothesized that the sustained tolerance to stroke induced by repetitive hypoxic preconditioning is mediated, in part, by long-term CXCL12 upregulation at the blood-brain barrier (BBB). In male Swiss Webster mice, repetitive hypoxic preconditioning elevated cortical CXCL12 protein levels, and the number of cortical CXCL12+ microvessels, for at least two weeks after the last hypoxic exposure. Repetitive hypoxic preconditioning-treated mice maintained more CXCL12-positive vessels than untreated controls following transient focal stroke, despite cortical decreases in CXCL12 mRNA and protein. Continuous administration of the CXCL12 receptor (CXCR4) antagonist AMD3100 for two weeks following repetitive hypoxic preconditioning countered the increase in CXCL12-positive microvessels, both prior to and following stroke. AMD3100 blocked the protective post-stroke reductions in leukocyte diapedesis, including macrophages and NK cells, and blocked the protective effect of repetitive hypoxic preconditioning on lesion volume, but had no effect on blood-brain barrier dysfunction. These data suggest that CXCL12 upregulation prior to stroke onset, and its actions following stroke, contribute to the endogenous, anti-inflammatory phenotype induced by repetitive hypoxic preconditioning.

Electroacupuncture modulates stromal cell-derived factor-1α expression and mobilization of bone marrow endothelial progenitor cells in focal cerebral ischemia/reperfusion model rats

Stromal cell-derived factor-1α(SDF-1α) plays a crucial role in regulating the mobilization, migration and homing of endothelial progenitor cells(EPCs). Electroacupuncture(EA), a modern version of Traditional Chinese Medicine, can improve neurological recovery and angiogenesis in cerebral ischemic area. This study aimed to investigate the effects of electroacupuncture(EA) on the mobilization and migration of bone marrow EPCs and neurological functional recovery in rats model after focal cerebral ischemia/reperfusion and the potentially involved mechanisms. Sprague-Dawley rats received filament occlusion of the right middle cerebral artery for 2h followed by reperfusion for 12h, 1d, 2d, 3d, 7d respectively. Rats were randomly divided into sham group, model group and EA group. After 2h of the reperfusion, EA was given at the "Baihui" (GV 20)/Siguan ("Hegu" (LI 4)/"Taichong" (LR 3)) acupoints in the EA group. Modified neurological severity score (mNSS) was used to assess the neurological functional recovery. EPCs number and SDF-1α level in bone marrow(BM) and peripheral blood(PB) were detected by using fluorescence-activated cell sorting (FACS) analysis and quantitative real time polymerase chain reaction (qRT-PCR) respectively. An mNSS test showed that EA treatment significantly improved the neurological functional outcome. EPCs number in PB and BM were obviously increased in the EA group. After cerebral ischemia, the SDF-1α level was decreased in BM while it was increased in PB, which implied a gradient of SDF-1α among BM and PB after ischemia. It suggested that the forming of SDF-1α concentration gradient can induce the mobilization and homing of EPCs. Eletroacupuncture as a treatment can accelerate and increase the forming of SDF-1α concentration gradient to further induce the mobilization of EPCs and angiogenesis in ischemic brain and improve the neurological function recovery.

Heat shock protein 90 stimulates rat mesenchymal stem cell migration via PI3K/Akt and ERK1/2 pathways

The objective of this study was to determine the role of Hsp90α in regulating the migration of mesenchymal stem cells (MSCs) and to investigate the underlying mechanisms of this effect. MSCs migration was assessed by wound healing assay and transwell migration assay. Hsp90α expression was silenced in MSC by siRNA (sirHsp90α). The activity of secreted metalloproteases MMP-2 and MMP-9, and their expression levels in MSC were evaluated using gelatin zymography, Western blot analysis and real-time PCR. Gene expression of VCAM-1 and CXCR4 cytokines was evaluated by real-time PCR. Akt and ERK activity were analyzed by Western blotting using antibodies against phosphorylated forms of these proteins. Treatment with Hsp90α significantly enhanced MSC migration, and this effect was blocked by transfecting MSC with sirHsp90α. Treating the cells with recombinant human Hsp90α (rhHsp90α) enhanced gene expression and protein levels of MMP-2 and MMP-9, as well as their secretion and activity. MSC incubated with rhHsp90α exhibited increased gene expression of CXCR4 and VCAM-1. Finally, the levels of phosphorylated Akt and Erk were markedly increased by rhHsp90α treatment. These findings indicate that Hsp90α promotes MSCs migration via PI3K/Akt and ERK signaling pathways, and that this effect is possibly mediated by MMPs, SDF-1/CXCR4 pathway, and VCAM-1.

Profound Actions of an Agonist of Growth Hormone-Releasing Hormone on Angiogenic Therapy by Mesenchymal Stem Cells

OBJECTIVE

The efficiency of cell therapy is limited by poor cell survival and engraftment. Here, we studied the effect of the growth hormone-releasing hormone agonist, JI-34, on mesenchymal stem cell (MSC) survival and angiogenic therapy in a mouse model of critical limb ischemia.

APPROACH AND RESULTS

Mouse bone marrow-derived MSCs were incubated with or without 10(-8) mol/L JI-34 for 24 hours. MSCs were then exposed to hypoxia and serum deprivation to detect the effect of preconditioning on cell apoptosis, migration, and tube formation. For in vivo tests, critical limb ischemia was induced by femoral artery ligation. After surgery, mice received 50 μL phosphate-buffered saline or with 1×10(6) MSCs or with 1×10(6) JI-34-reconditioned MSCs. Treatment of MSCs with JI-34 improved MSC viability and mobility and markedly enhanced their capability to promote endothelial tube formation in vitro. These effects were paralleled by an increased phosphorylation and nuclear translocation of signal transducer and activator of transcription 3. In vivo, JI-34 pretreatment enhanced the engraftment of MSCs into ischemic hindlimb muscles and augmented reperfusion and limb salvage compared with untreated MSCs. Significantly more vasculature and proliferating CD31(+) and CD34(+) cells were detected in ischemic muscles that received MSCs treated with JI-34.

CONCLUSIONS

Our studies demonstrate a novel role for JI-34 to markedly improve therapeutic angiogenesis in hindlimb ischemia by increasing the viability and mobility of MSCs. These findings support additional studies to explore the full potential of growth hormone-releasing hormone agonists to augment cell therapy in the management of ischemia.

Hematopoietic stem/progenitor cells directly contribute to arteriosclerotic progression via integrin β2

Recent studies described the association between hematopoietic stem/progenitor cell (HSPC) expansion in the bone marrow (BM), leukocytosis in the peripheral blood, and accelerated atherosclerosis. We hypothesized that circulating HSPC may home to inflamed vessels, where they might contribute to inflammation and neointima formation. We demonstrated that Lin⁻ Sca-1⁺ cKit⁺ (LSK cells) in BM and peripheral blood of LDLr^−/− mice on high fat diet expressed significantly more integrin β₂, which was responsible for LSK cell adhesion and migration toward ICAM-1 in vitro, and homing to injured arteries in vivo, all of which were blocked with an anti-CD18 blocking antibody. When homed LSK cells were isolated from ligated artery and injected to irradiated recipients, they resulted in BM reconstitution. Injection of CD18^+/+ LSK cells to immunodeficient Balb/C Rag2⁻ γC^−/− recipients resulted in more severe inflammation and reinforced neointima formation in the ligated carotid artery, compared to mice injected with PBS and CD18^−/− LSK cells. Hypercholesterolemia stimulated ERK phosphorylation (pERK) in LSK cells of LDLr^−/− mice in vivo. Blockade of pERK reduced ARF1 expression, leading to decreased integrin β₂ function on HSPC. In addition, integrin β₂ function could be regulated via ERK-independent LRP1 pathway. Integrin β₂ expression on HSPC is regulated by hypercholesterolemia, specifically LDL, in pERK-dependent and -independent manners, leading to increased homing and localization of HSPC to injured arteries, which is highly correlated with arteriosclerosis. Stem Cells2015;33:1230–1240

Infusion of endothelial progenitor cells ameliorates liver injury in mice after haematopoietic stem cell transplantation

BACKGROUND & AIMS

Injury to liver sinusoidal endothelial cells (LSECs) is thought to be the initial factor for Hepatic veno-occlusive disease, a severe complication after haematopoietic stem cell transplantation (HSCT). Endothelial progenitor cells (EPCs) have the capacity to differentiate into endothelial cells and play a critical role in vasculogenesis, tissue regeneration and repair. Whether EPCs infusion ameliorates LSECs injury remains unclear. The aim of this study was to evaluate the effects of EPCs on liver injury in mice after HSCT.

METHODS

Mice received HSCT without or with EPCs infusion (HSCT + EPCs). Untreated mice were used as control. Liver and whole blood were collected post HSCT and used for the analysis of pathology of liver sinusoidal endothelial cells (LSECs) and hepatocytes, liver ultrastructure, function, level of IL-6, TNF-α and platelet activation.

RESULTS

Severe LSECs injury, hepatocyte damage, abnormal liver function was observed in HSCT group. In addition, increased P-selectin expression and secretion of IL-6, TNF-α was also found. However, all the above changes were alleviated in HSCT + EPCs at all the time points and normalized at the endpoint. Meanwhile, EPCs-induced repair of LSECs and hepatocytes was totally inhibited by the addition of anti-VE-cadherin antibody.

CONCLUSIONS

EPCs infusion ameliorated the damage to LSECs and hepatocytes as well as reduced secretion of IL-6, TNF-α and inhibited platelet activation after HSCT, leading to improved liver function, suggesting EPCs might be a new therapeutic strategy in the prophylaxis of liver injury after HSCT.

Vascular Ageing and Exercise: Focus on Cellular Reparative Processes

Ageing is associated with an increased risk of developing noncommunicable diseases (NCDs), such as diabetes and cardiovascular disease (CVD). The increased risk can be attributable to increased prolonged exposure to oxidative stress. Often, CVD is preceded by endothelial dysfunction, which carries with it a proatherothrombotic phenotype. Endothelial senescence and reduced production and release of nitric oxide (NO) are associated with “vascular ageing” and are often accompanied by a reduced ability for the body to repair vascular damage, termed “reendothelialization.” Exercise has been repeatedly shown to confer protection against CVD and diabetes risk and incidence. Regular exercise promotes endothelial function and can prevent endothelial senescence, often through a reduction in oxidative stress. Recently, endothelial precursors, endothelial progenitor cells (EPC), have been shown to repair damaged endothelium, and reduced circulating number and/or function of these cells is associated with ageing. Exercise can modulate both number and function of these cells to promote endothelial homeostasis. In this review we look at the effects of advancing age on the endothelium and these endothelial precursors and how exercise appears to offset this “vascular ageing” process.

Dipeptidyl Peptidase-4 Regulation of SDF-1/CXCR4 Axis: Implications for Cardiovascular Disease

Dipeptidyl peptidase-4 (DPP4) is a ubiquitously expressed protease that regulates diverse number of physiological functions. As a dipeptidase, it exerts its catalytic effects on proteins/peptides with proline, alanine, or serine in the penultimate (P1) amino acid residue from the amino terminus. The evidence to date supports an important effect of DPP4 in catalytic cleavage of incretin peptides and this perhaps represents the main mechanism by which DPP4 inhibition improves glycemic control. DPP4 also plays an important role in the degradation of multiple chemokines of which stromal cell-derived factor-1 (SDF-1, also known as CXCL12) is perhaps an increasingly recognized target, given its importance in processes, such as hematopoiesis, angiogenesis, and stem cell homing. In the current review, we will summarize the importance of DPP4-mediated enzymatic processing of cytokines/chemokines with an emphasis on SDF-1 and resultant implications for cardiovascular physiology and disease.

A vascular patch prepared from Thai silk fibroin and gelatin hydrogel incorporating simvastatin-micelles to recruit endothelial progenitor cells

Delayed re-endothelialization is one of the major disadvantages in synthetic vascular grafts, especially in small-diameter grafts (inner diameter <6 mm), leading to thrombosis and stenosis of the grafts. Simvastatin, a serum cholesterol-lowering drug, has promotional effects on endothelial progenitor cell (EPC) mobilization from bone marrow and recruitment to sites of vascular injury exhibiting acceleration of re-endothelialization. In this study, we prepared double-layer vascular patches from Thai silk fibroin/gelatin with gelatin hydrogel incorporating simvastatin-micelles (SM) for sustained release of simvastatin to recruit circulation EPCs. To enhance simvastatin solubility, simvastatin was entrapped in micelles of l-lactic acid oligomer-grafted gelatin. The drug loading efficiency was at 4.1 ± 0.5 μg/mg micelles. SM had a chemoattractive effect on EPCs comparable to nonmodified simvastatin. Gelatin hydrogel incorporating SM at 100 μM of simvastatin (GSM100) could enhance in vitro EPC activities of adhesion and proliferation. In vitro results showed the initial cell adhesion of 86%, specific growth rate of 15.33×10(-3) h(-1), and population doubling time of 46.21 h. In vivo implantation of the patches incorporating SM significantly increased the recruitment of circulating EPCs. From the results of immunofluorescence staining, they demonstrated the complete re-endothelialization on the implanted patches containing SM at 2 weeks after implantation in rat carotid arteries. The gelatin hydrogel incorporating SM could be an effective inner layer of multifunctional vascular grafts to accelerate re-endothelialization in vascular tissue engineering.

The role of eNOS in the migration and proliferation of bone-marrow derived endothelial progenitor cells and in vitro angiogenesis

The role of endothelial nitric oxide synthase (eNOS) in the activities of endothelial progenitor cells (EPCs) including migration, proliferation, and tube formation in vitro was investigated. EPCs were obtained from rat bone mononuclear cells by culturing for 7-10 days in EGM-2MV and identified by their capacity for FITC-UEA-1 binding and acetylated low-density lipoprotein (Dil-ac-LDL) intake using fluorescence microscopy. Migration, proliferation and tube formation activities were assessed in the presence or absence of N(ω)-nitro-L-argininemethylester (L-NAME), an eNOS inhibitor. mRNA and protein expression of CXCR4, CXCR7, VEGFR2, and eNOS were detected by real-time PCR and western blotting in the presence or absence of L-NAME. Nitric oxide production was detected by nitrate reductase in the presence or absence of L-NAME. Typical spindle-shaped cells appeared on the 7(th)-10(th) day and confluence reached about 80%. The percentage of FITC-UEA-1 and Dil-ac-LDL double-stained cells was about 85%. Cell migration, proliferation, and tube formation were significantly weakened after eNOS was inhibited (P < 0.05), and the expressions of CXCR4 and eNOS were significantly reduced (P < 0.05, respectively), but there was little change in CXCR7 and VEGFR2. NO production was dramatically decreased after eNOS was inhibited (P < 0.05). In summary, L-NAME significantly reduced the expression of eNOS and NO production by EPCs and inhibited migration, proliferation and tube formation by these cells, suggesting that eNOS affects EPC activities; CXCR4 may be implicated in the action of eNOS.

Statins impair survival of primary human mesenchymal progenitor cells via mevalonate depletion, NF-κB signaling, and Bnip3

Circulating progenitor cells of bone marrow origin have been implicated in transplant cardiac allograft vasculopathy (CAV) and cardiac fibrosis. HMG-CoA reductase inhibitors, called "statins," have been shown to impair the progression of CAV and improve patient survival. We examined the in vitro effects of three HMG-CoA reductase inhibitors atorvastatin, simvastatin, and pravastatin on the viability of MSCs and expression of nuclear factor kappa B (NF-κB). Mesenchymal stem cells (MSCs) isolated from human patients were treated with atorvastatin, simvastatin, and pravastatin at 0.1, 1.0, or 10 μM ± mevalonate. Human MSC treatment with 1 and 10 μM simvastatin or atorvastatin resulted in progressively reduced cell viability, which was associated with a decline in NF-κB p65. Viability was rescued by co-incubation with mevalonate or by pretreatment with Inhibitor of nuclear factor kappa-B kinase subunit beta (Iκκ-β). Pravastatin did not affect MSC viability or NF-κB expression. Mevalonate depletion through HMG-CoA reductase inhibition impairs the viability of primary human MSC through down-regulating NF-κB.

A novel molecule Me6TREN promotes angiogenesis via enhancing endothelial progenitor cell mobilization and recruitment

Critical limb ischaemia is the most severe clinical manifestation of peripheral arterial disease. The circulating endothelial progenitor cells (EPCs) play important roles in angiogenesis and ischemic tissue repair. The increase of circulating EPC numbers by using mobilization agents is critical for obtaining a better therapeutic outcome in patients with ischemic disease. Here, we firstly report a novel small molecule, Me6TREN (Me6), can efficiently mobilize EPCs into the blood circulation. Single injection of Me6 induced a long-lasting increase in circulating Flk-1⁺ Sca-1⁺ EPC numbers. In a mouse hind limb ischemia (HLI) model, local intramuscular transplantation of these Me6-mobilized cells accelerated the blood flow restoration in the ischemic muscles. More importantly, systemic administration of Me6 notably increased the capillary density, arteriole density and regenerative muscle weight in the ischemic tissue of HLI. Mechanistically, we found Me6 reduced stromal cell-derived factor-1α level in bone marrow by up-regulation of matrix metallopeptidase-9 expression, which allowed the dissemination of EPCs into peripheral blood. These data indicate that Me6 may represent a potentially useful therapy for ischemic disease via enhancing autologous EPC recruitment and promote angiogenesis.

Systemic influences contribute to prolonged microvascular rarefaction after brain irradiation: a role for endothelial progenitor cells

Whole brain radiation therapy (WBRT) induces profound cerebral microvascular rarefaction throughout the hippocampus. Despite the vascular loss and localized cerebral hypoxia, angiogenesis fails to occur, which subsequently induces long-term deficits in learning and memory. The mechanisms underlying the absence of vessel recovery after WBRT are unknown. We tested the hypotheses that vascular recovery fails to occur under control conditions as a result of loss of angiogenic drive in the circulation, chronic tissue inflammation, and/or impaired endothelial cell production/recruitment. We also tested whether systemic hypoxia, which is known to promote vascular recovery, reverses these chronic changes in inflammation and endothelial cell production/recruitment. Ten-week-old C57BL/6 mice were subjected to a clinical series of fractionated WBRT: 4.5-Gy fractions 2 times/wk for 4 wk. Plasma from radiated mice increased in vitro endothelial cell proliferation and adhesion compared with plasma from control mice, indicating that WBRT did not suppress the proangiogenic drive. Analysis of cytokine levels within the hippocampus revealed that IL-10 and IL-12(p40) were significantly increased 1 mo after WBRT; however, systemic hypoxia did not reduce these inflammatory markers. Enumeration of endothelial progenitor cells (EPCs) in the bone marrow and circulation indicated that WBRT reduced EPC production, which was restored with systemic hypoxia. Furthermore, using a bone marrow transplantation model, we determined that bone marrow-derived endothelial-like cells home to the hippocampus after systemic hypoxia. Thus, the loss of production and homing of EPCs have an important role in the prolonged vascular rarefaction after WBRT.

Effects of pitavastatin versus atorvastatin on the peripheral endothelial progenitor cells and vascular endothelial growth factor in high-risk patients: a pilot prospective, double-blind, randomized study

BACKGROUND

Circulating endothelial progenitor cells (EPCs) reflect endothelial repair capacity and may be a significant marker for the clinical outcomes of cardiovascular disease. While some high-dose statin treatments may improve endothelial function, it is not known whether different statins may have similar effects on EPCs.This study aimed to investigate the potential class effects of different statin treatment including pitavastatin and atorvastatin on circulating EPCs in clinical setting.

METHODS

A pilot prospective, double-blind, randomized study was conducted to evaluate the ordinary dose of pitavastatin (2 mg daily) or atorvastatin (10 mg daily) treatment for 12 weeks on circulating EPCs in patients with cardiovascular risk such as hypercholesterolemia and type 2 diabetes mellitus (T2DM). Additional in vitro study was conducted to clarify the direct effects of both statins on EPCs from the patients.

RESULTS

A total of 26 patients (19 with T2DM) completed the study. While the lipid-lowering effects were similar in both treatments, the counts of circulating CD34+KDR+EPCs were significantly increased (from 0.021 ± 0.015 to 0.054 ± 0.044% of gated mononuclear cells, P < 0.05) only by pitavastatin treatment. Besides, plasma asymmetric dimethylarginine level was reduced (from 0.68 ± 0.10 to 0.53 ± 0.12 μmol/L, P < 0.05) by atorvastatin, and plasma vascular endothelial growth factor (VEGF) level was increased (from 74.33 ± 32.26 to 98.65 ± 46.64 pg/mL, P < 0.05) by pitavastatin. In the in vitro study, while both statins increased endothelial nitric oxide synthase (eNOS) expression, only pitavastatin increased the phosphorylation of eNOS in EPCs. Pitavastatin but not atorvastatin ameliorated the adhesion ability of early EPCs and the migration and tube formation capacities of late EPCs.

CONCLUSIONS

While both statins similarly reduced plasma lipids, only pitavastatin increased plasma VEGF level and circulating EPCs in high-risk patients, which is probably related to the differential pleiotropic effects of different statins.

TRIAL REGISTRATION

This trial is registered at ClinicalTrials.gov, NCT01386853.

Vasculogenic conditioning of peripheral blood mononuclear cells promotes endothelial progenitor cell expansion and phenotype transition of anti-inflammatory macrophage and T lymphocyte to cells with regenerative potential

Background

Cell‐based therapies involving mononuclear cells (MNCs) have been developed for vascular regeneration to treat ischemic diseases; however, quality control of therapeutic MNCs has not been evaluated. We investigated the therapeutic potential of peripheral blood (PB) MNCs, operated by recently developed quality and quantity (QQ) culture of endothelial progenitor cells (EPCs).

Methods and Results

PBs were collected from healthy volunteers; peripheral blood mononuclear cells (PBMNCs) isolated from these PBs were subjected to QQ culture for 7 days with medium containing stem cell factor, thrombopoietin, Flt‐3 ligand, vascular endothelial growth factor, and interleukin‐6. The resulting cells (QQMNCs) in EPC colony‐forming assay generated significantly more definitive EPC colonies than PBMNCs. In flow cytometry, macrophages and helper T lymphocytes of QQMNCs became phenotypically polarized into angiogenic, anti‐inflammatory, and regenerative subsets: classical M1 to alternative M2; T helper (Th)1 to Th2; angiogenic or regulatory T‐cell expansion. Quantitative real‐time polymerase chain reaction (qRT‐PCR) assay revealed the predominant proangiogenic gene expressions in QQMNCs versus PBMNCs. Using murine ischemic hindlimb models, the efficacy of QQMNC intramuscular transplantation (Tx) was compared to that of PBMNCTx, cultured “early EPC” Tx (eEPCTx), and granulocyte colony‐stimulating factor mobilized CD34⁺ cell Tx (GmCD34Tx). Laser Doppler imaging revealed the blood perfusion recovery in ischemic hindlimbs after QQMNCTx superior to after PBMNCTx and eEPCTx, but also earlier than after GmCD34Tx. Histological evaluations and qRT‐PCR assays in ischemic hindlimbs demonstrated that QQMNCTx, similarly to GmCD34Tx, enhanced angiovasculogenesis and myogenesis, whereas it preponderantly inhibited inflammation and fibrosis versus PBMNCTx and eEPCTx.

Conclusions

QQ culture potentiates the ability of PBMNCs to promote regeneration of injured tissue; considering the feasible cell preparation, QQ culture‐treated PBMNCs may provide a promising therapeutic option for ischemic diseases.

Clinical Trial Registration

URL: irb.med.u-tokai.ac.jp/d/2/monthly/2010.html; IRB No.: 10R‐020.

URL: irb.med.u-tokai.ac.jp/d/2/monthly/201312.html; IRB No.: 13R228.

Myocardial transfection of hypoxia-inducible factor-1α and co-transplantation of mesenchymal stem cells enhance cardiac repair in rats with experimental myocardial infarction

Introduction

Mesenchymal stem cells (MSCs) have potential for the treatment of myocardial infarction. However, several meta-analyses revealed that the outcome of stem cell transplantation is dissatisfactory. A series of studies demonstrated that the combination of cell and gene therapy was a promising strategy to enhance therapeutic efficiency. The aim of this research is to investigate whether and how the combination of overexpression of hypoxia-inducible factor-1α (HIF-1α) and co-transplantation of mesenchymal stem cells can enhance cardiac repair in myocardial infarction.

Methods

We investigated the therapeutic effects of myocardial transfection of HIF-1α and co-transplantation of MSCs on cardiac repair in myocardial infarction by using myocardial transfection of HIF-1α via an adenoviral vector. Myocardial infarction was produced by coronary ligation in Sprague-Dawley (SD) rats. Animals were divided randomly into six groups: (1) HIF-1α + MSCs group: Ad-HIF-1α (6 × 10⁹ plate forming unit) and MSCs (1 × 10⁶) were intramyocardially injected into the border zone simultaneously; (2) HIF-1α group: Ad-HIF-1α (6 × 10⁹ plate forming unit) was injected into the border zone; (3) HIF-1α-MSCs group: Ad-HIF-1α transfected MSCs (1 × 10⁶) were injected into the border zone; (4) MSCs group: MSCs (1 × 10⁶) were injected into the border zone; (5) Control group: same volume of DMEM was injected; (6) SHAM group. Cardiac performance was then quantified by echocardiography as well as molecular and pathologic analysis of heart samples in the peri-infarcted region and the infarcted region at serial time points. The survival and engraftment of transplanted MSCs were also assessed.

Results

Myocardial transfection of HIF-1α combined with MSC transplantation in the peri-infarcted region improved cardiac function four weeks after myocardial infarction. Significant increases in vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1α (SDF-1α) expression, angiogenesis and MSC engraftment, as well as decreased cardiomyocyte apoptosis in peri-infarcted regions in the hearts of the HIF-1α + MSCs group were detected compared to the MSCs group and Control group.

Conclusions

These findings suggest that myocardial transfection of HIF-1α and co-transplantation of mesenchymal stem cells enhance cardiac repair in myocardial infarction, indicating the feasibility and preliminary safety of a combination of myocardial transfection of HIF-1α and MSC transplantation to treat myocardial infarction.

Effect and mechanism of thrombospondin-1 on the angiogenesis potential in human endothelial progenitor cells: an in vitro study

Objective

Coronary collateral circulation plays a protective role in patients with coronary artery disease (CAD). We investigated whether thrombospondin-1(TSP-1) has an inhibitory effect on angiogenesis potential in endothelial progenitor cells(EPCs) and tested whether TSP-1 are altered in plasma of patients who had chronic total occlusion (CTO) in at least one coronary artery and with different collateral stages(according to Rentrop grading system).

Methods and Results

We isolated early and late EPCs from human cord blood and investigated a dose-dependent effect of TSP-1 on their angiogenesis potential by Matrigel angiogenesis assay. We found that TSP-1 (5 µg/ml) inhibited early EPCs incorporation into tubules after pretreatment for 1, 6 and 12 hours, respectively (83.3±11.9 versus 50.0±10.1 per field for 1 hour,161.7±12.6 versus 124.0±14.4 for 6 hours, 118.3±12.6 versus 68.0±20.1 for 12 hours, p<0.05). TSP-1 also inhibited late EPCs tubule formation at 1 µg/ml (6653.4±422.0 µm/HPFversus 5552.8±136.0 µm/HPF, p<0.05), and the inhibition was further enhanced at 5 µg/ml (6653.4±422.0 µm/HPF versus 2118.6±915.0 µm/HPF p<0.01). To explore the mechanism involved, a small interfering RNA was used. In vitro, CD47 siRNA significantly attenuated TSP-1's inhibition of angiogenesis on late EPCs and similar results were obtained after functional blocking by anti-CD47 antibody. Then we investigated pathways downstream of CD47 and found TSP-1 regulated VEGF-induced VEGFR2 phosphorylation via CD47. Furthermore, we examined plasma TSP-1 levels in patients with CTO who developed different stages of collaterals and found a paradoxical higher level of TSP-1 in patients with good collaterals compared with bad ones (612.9±554.0 ng/ml versus 224.4±132.4 ng/ml, p<0.05).

Conclusion

TSP-1 inhibited angiogenesis potential of early and late EPCs in vitro. This inhibition may be regulated by TSP-1's interaction with CD47, resulting in down regulation of VEGFR2 phosphorylation. In patients with CTO, there may be a self-adjustment mechanism in bad collaterals which is shown as low level of angiogenesis inhibitor TSP-1, and thus favoring collateral formation.

Old World hantaviruses: aspects of pathogenesis and clinical course of acute renal failure

Hantavirus-associated diseases represent emerging infections that are ranked in the highest priority group of communicable diseases for surveillance and epidemiological research. In the last years, several novel hantavirus species were described and the number of host reservoir species harboring hantaviruses is also increasing. Reports of cases with severe or atypical clinical courses become also more frequent. These facts raise more and more questions concerning host reservoir specificity, pathogenicity and molecular mechanism of pathogenesis. Hantavirus disease is characterized by vascular leakage due to increased capillary permeability. The infection manifests often in the lung (hantaviral cardiopulmonary syndrome; HCPS) or in the kidney (hemorrhagic fever with renal syndrome, HFRS). The underlying mechanisms of both syndromes are probably similar despite the difference in organ tropism. Characterization of hantaviral replication cycle and of patient-specific determinants will help to identify factors responsible for the clinical symptoms and course.

Stromal cell-derived factor-1 promoted angiogenesis and inflammatory cell infiltration in aneurysm walls

OBJECT

A small percentage of cerebral aneurysms rupture, but when they do, the effects are devastating. Current management of unruptured aneurysms consists of surgery, endovascular treatment, or watchful waiting. If the biology of how aneurysms grow and rupture were better known, a novel drug could be developed to prevent unruptured aneurysms from rupturing. Ruptured cerebral aneurysms are characterized by inflammation-mediated wall remodeling. The authors studied the role of stromal cell-derived factor-1 (SDF-1) in inflammation-mediated wall remodeling in cerebral aneurysms.

METHODS

Human aneurysms, murine carotid artery aneurysms, and murine intracranial aneurysms were studied using immunohistochemistry. Flow cytometry analysis was performed on blood from mice developing carotid or intracranial aneurysms. The effect of SDF-1 on endothelial cells and macrophages was studied by chemotaxis cell migration assay and capillary tube formation assay. Anti-SDF-1 blocking antibody was given to mice and compared with control (vehicle)-administered mice for its effects on the walls of carotid aneurysms and the development of intracranial aneurysms.

RESULTS

Human aneurysms, murine carotid aneurysms, and murine intracranial aneurysms all expressed SDF-1, and mice with developing carotid or intracranial aneurysms had increased progenitor cells expressing CXCR4, the receptor for SDF-1 (p < 0.01 and p < 0.001, respectively). Human aneurysms and murine carotid aneurysms had endothelial cells, macrophages, and capillaries in the walls of the aneurysms, and the presence of capillaries in the walls of human aneurysms was associated with the presence of macrophages (p = 0.01). Stromal cell-derived factor-1 promoted endothelial cell and macrophage migration (p < 0.01 for each), and promoted capillary tube formation (p < 0.001). When mice were given anti-SDF-1 blocking antibody, there was a significant reduction in endothelial cells (p < 0.05), capillaries (p < 0.05), and cell proliferation (p < 0.05) in the aneurysm wall. Mice given anti-SDF-1 blocking antibody developed significantly fewer intracranial aneurysms (33% vs 89% in mice given control immunoglobulin G, respectively; p < 0.05).

CONCLUSIONS

These data suggest SDF-1 is associated with angiogenesis and inflammatory cell migration and proliferation in the walls of aneurysms, and may have a role in the development of intracranial aneurysms.

Mobilization of circulating endothelial progenitor cells correlates with the clinical course of hantavirus disease

Infections with hemorrhagic fever viruses are characterized by increased permeability leading to capillary leakage. Hantavirus infection is associated with endothelial dysfunction, and the clinical course is related to the degree of vascular injury. Circulating endothelial progenitor cells (cEPCs) play a pivotal role in the repair of the damaged endothelium. Therefore, we analyzed the number of cEPCs and their mobilizing growth factors in patients suffering from hantavirus disease induced by infection with Puumala virus. The numbers of EPCs of 36 hantavirus-infected patients and age- and gender-matched healthy controls were analyzed by flow cytometry. Concentrations of cEPC-mobilizing growth factors in plasma were determined by enzyme-linked immunosorbent assay. Laboratory parameters were correlated with the number of cEPCs. In patients infected with hantavirus, the number of cEPCs was significantly higher than that in healthy controls. Levels of mobilizing cytokines were upregulated in patients, and the mobilization of cEPCs is paralleled with the normalization of clinical parameters. Moreover, higher levels of cEPCs correlated with higher serum albumin levels and platelet concentrations. Our data indicate that cEPCs may play a role in the repair of hantavirus-induced endothelial damage, thereby influencing the clinical course and the severity of symptoms.

Whole brain radiation-induced vascular cognitive impairment: mechanisms and implications

Mild cognitive impairment is a well-documented consequence of whole brain radiation therapy (WBRT) that affects 40-50% of long-term brain tumor survivors. The exact mechanisms for the decline in cognitive function after WBRT remain elusive and no treatment or preventative measures are available for use in the clinic. Here, we review recent findings indicating how changes in the neurovascular unit may contribute to the impairments in learning and memory. In addition to affecting neuronal development, WBRT induces profound capillary rarefaction within the hippocampus - a region of the brain important for learning and memory. Therapeutic strategies such as hypoxia, which restore the capillary density, result in the rescue of cognitive function. In addition to decreasing vascular density, WBRT impairs vasculogenesis and/or angiogenesis, which may also contribute to radiation-induced cognitive decline. Further studies aimed at uncovering the specific mechanisms underlying these WBRT-induced changes in the cerebrovasculature are essential for developing therapies to mitigate the deleterious effects of WBRT on cognitive function.

Lysine acetyltransferase PCAF is a key regulator of arteriogenesis

OBJECTIVE

Therapeutic arteriogenesis, that is, expansive remodeling of preexisting collaterals, using single-action factor therapies has not been as successful as anticipated. Modulation of factors that act as a master switch for relevant gene programs may prove more effective. Transcriptional coactivator p300-CBP-associated factor (PCAF) has histone acetylating activity and promotes transcription of multiple inflammatory genes. Because arteriogenesis is an inflammation-driven process, we hypothesized that PCAF acts as multifactorial regulator of arteriogenesis.

APPROACH AND RESULTS

After induction of hindlimb ischemia, blood flow recovery was impaired in both PCAF(-/-) mice and healthy wild-type mice treated with the pharmacological PCAF inhibitor Garcinol, demonstrating an important role for PCAF in arteriogenesis. PCAF deficiency reduced the in vitro inflammatory response in leukocytes and vascular cells involved in arteriogenesis. In vivo gene expression profiling revealed that PCAF deficiency results in differential expression of 3505 genes during arteriogenesis and, more specifically, in impaired induction of multiple proinflammatory genes. Additionally, recruitment from the bone marrow of inflammatory cells, in particular proinflammatory Ly6C(hi) monocytes, was severely impaired in PCAF(-/-) mice.

CONCLUSIONS

These findings indicate that PCAF acts as master switch in the inflammatory processes required for effective arteriogenesis.

Intracavernous administration of bone marrow mononuclear cells: a new method of treating erectile dysfunction?

While PDE5 inhibitors have revolutionized treatment of ED, approximately 30% of patients are non-responsive. A significant cause of this is vascular and smooth muscle dysfunction, as well as nerve atrophy. Autologous administration of bone marrow mononuclear cells (BMMC) has been performed in over 2000 cardiac patients without adverse effects, for stimulation of angiogenesis/regeneration. Despite its ease of access, and dependence on effective vasculature for function, comparatively little has been perform in terms of BMMC therapy for ED. Here we outline the rationale for use of autologous BMMC in patients with ED, as well as provide early safety data on the first use of this procedure clinically.