Therapeutic Angiogenesis

Differentiation and characterization of rat adipose tissue mesenchymal stem cells into endothelial-like cells

In this study, mesenchymal stem cells were isolated from rat adipose tissue (AD-MSCs) to characterize and differentiate them into endothelial-like cells. AD-MSCs were isolated by mechanical and enzymatic treatments, and their identity was verified by colony-forming units (CFU) test and by differentiation into cells of mesodermal lineages. The endothelial differentiation was induced by plating another aliquot of cells in EGM-2 medium, enriched with specific endothelial growth factors. Five subcultures were performed. The expression of stemness genes (OCT4, SOX2 and NANOG) was investigated. The presence of CD90 and the absence of the CD45 were evaluated by flow cytometry. The endothelial-like cells were characterized by the evaluation of morphological changes and gene expression analysis for endothelial markers (CD31, CD144, CD146). Characterization of AD-MSCs showed their ability to form clones, to differentiate in vitro and the OCT-4, SOX-2, NANOG genes expression. Immunophenotypic characterization showed the CD90 presence and the CD45 absence. The endothelial-like cells showed morphological changes, the expression of CD31, CD144, CD146 genes and the presence of CD31 membrane receptor. Matrigel assay showed their ability to form network and vessels-like structures. This study lays the foundations for future evaluation of the potential AD-MSCs pro-angiogenic and therapeutic role.

The evolving concept of physiological ischemia training vs. ischemia preconditioning

Ischemic heart diseases are the leading cause of death with increasing numbers of patients worldwide. Despite advances in revascularization techniques, angiogenic therapies remain highly attractive. Physiological ischemia training, which is first proposed in our laboratory, refers to reversible ischemia training of normal skeletal muscles by using a tourniquet or isometric contraction to cause physiologic ischemia for about 4 weeks for the sake of triggering molecular and cellular mechanisms to promote angiogenesis and formation of collateral vessels and protect remote ischemia areas. Physiological ischemia training therapy augments angiogenesis in the ischemic myocardium by inducing differential expression of proteins involved in energy metabolism, cell migration, protein folding, and generation. It upregulates the expressions of vascular endothelial growth factor, and induces angiogenesis, protects the myocardium when infarction occurs by increasing circulating endothelial progenitor cells and enhancing their migration, which is in accordance with physical training in heart disease rehabilitation. These findings may lead to a new approach of therapeutic angiogenesis for patients with ischemic heart diseases. On the basis of the promising results in animal studies, studies were also conducted in patients with coronary artery disease without any adverse effect in vivo, indicating that physiological ischemia training therapy is a safe, effective and non-invasive angiogenic approach for cardiovascular rehabilitation. Preconditioning is considered to be the most protective intervention against myocardial ischemia-reperfusion injury to date. Physiological ischemia training is different from preconditioning. This review summarizes the preclinical and clinical data of physiological ischemia training and its difference from preconditioning.

Hinokitiol increases the angiogenic potential of dental pulp cells through ERK and p38MAPK activation and hypoxia-inducible factor-1α (HIF-1α) upregulation

Hinokitiol, a natural iron-chelating agent, is known to have diverse biological and pharmacological activities in various cell types. However, the effect of hinokitiol on dental pulp cells has not yet been reported. In this study, hinokitiol increases hypoxia-inducible factor-1α (HIF-1α) protein levels and vascular endothelial growth factor (VEGF) secretion in human dental pulp cells. The extracellular-signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways are involved in hinokitiol-induced HIF-1α protein expression in dental pulp cells. Conditioned media from hinokitiol-treated pulp cells enhances angiogenesis in vitro and in vivo. Overall, these results show that hinokitiol promotes ERK and p38MAPK activation and HIF-1α-induced VEGF production, thus increasing the angiogenic potential of dental pulp cells.

Therapeutic angiogenesis with VEGF164 for facilitation of guidewire crossing in experimental arterial chronic total occlusions

AIMS

Percutaneous revascularisation of chronic total occlusions (CTO) is limited by failure of guidewire crossing. Neovascularisation within the proximal CTO segment may be important for guidewire crossing and dramatically declines in CTO beyond six weeks of age. The aims of the current study were to determine whether local delivery of a pro-angiogenic growth factor increases neovascularisation in mature CTO and facilitates guidewire crossings.

METHODS AND RESULTS

CTO (n=51) were created in the femoral arteries of 44 New Zealand white rabbits using the thrombin injection model. At 12 weeks, CTO were treated with poly-lactic-glycolic-acid (PLGA) microspheres containing either bovine serum albumin (BSA) (n=15) or recombinant mouse VEGF164 (n=14), or received no intervention (controls, n=12). Contrast-enhanced magnetic resonance angiography (CEMRA) was performed prior to treatment and at three weeks post treatment. Animals were sacrificed at three weeks post treatment and arterial samples were excised for micro-computed tomography imaging (µCT) and histologic morphometric analysis. Guidewire crossing was assessed at three weeks post treatment in an additional 10 VEGF164-treated CTO. In comparison to BSA-treated and control non-intervened CTO, VEGF164-treated CTO showed a significant increase in relative blood volume index in the proximal segment of the CTO lesion as determined by CEMRA and by µCT. Histologic measurements of microvessel area were also higher in VEGF164-treated CTO. Guidewire crossing across the proximal fibrous cap was successful in eight out of 10 VEGF164-treated CTO.

CONCLUSIONS

Angiogenic therapy appears to be a promising strategy to improve neovascularisation and guidewire crossing rates in CTO.

Adipose-derived mesenchymal stem cells and regenerative medicine

Adipose tissue-derived mesenchymal stem cells (ADSCs) are multipotent and can differentiate into various cell types, including osteocytes, adipocytes, neural cells, vascular endothelial cells, cardiomyocytes, pancreatic β-cells, and hepatocytes. Compared with the extraction of other stem cells such as bone marrow-derived mesenchymal stem cells (BMSCs), that of ADSCs requires minimally invasive techniques. In the field of regenerative medicine, the use of autologous cells is preferable to embryonic stem cells or induced pluripotent stem cells. Therefore, ADSCs are a useful resource for drug screening and regenerative medicine. Here we present the methods and mechanisms underlying the induction of multilineage cells from ADSCs.

Spatial and temporal coordination of bone marrow-derived cell activity during arteriogenesis: regulation of the endogenous response and therapeutic implications

Arterial occlusive disease is the leading cause of morbidity and mortality throughout the developed world, which creates a significant need for effective therapies to halt disease progression. Despite success of animal and small-scale human therapeutic arteriogenesis studies, this promising concept for treating arterial occlusive disease has yielded largely disappointing results in large-scale clinical trials. One reason for this lack of successful translation is that endogenous arteriogenesis is highly dependent on a poorly understood sequence of events and interactions between bone marrow derived cells (BMCs) and vascular cells, which makes designing effective therapies difficult. We contend that the process follows a complex, ordered sequence of events with multiple, specific BMC populations recruited at specific times and locations. Here, we present the evidence suggesting roles for multiple BMC populations-from neutrophils and mast cells to progenitor cells-and propose how and where these cell populations fit within the sequence of events during arteriogenesis. Disruptions in these various BMC populations can impair the arteriogenesis process in patterns that characterize specific patient populations. We propose that an improved understanding of how arteriogenesis functions as a system can reveal individual BMC populations and functions that can be targeted for overcoming particular impairments in collateral vessel development.

ICAM-1 cytoplasmic tail regulates endothelial glutathione synthesis through a NOX4/PI3-kinase-dependent pathway

We previously reported that ICAM-1 expression modulates endothelial intracellular glutathione (GSH) metabolism through unknown mechanisms. Here we report that the cytoplasmic tail of ICAM-1 is critically involved in governing intracellular GSH production. Peptides containing the antennapedia cell-permeative sequence (AP) or an AP peptide linked to the transmembrane and cytosolic tail of ICAM-1 (AP-ICAM) were synthesized and used to measure alterations in redox status in cultured endothelial cells and determine their biological effect. Treatment with AP-ICAM significantly increased GSH concentrations and glutamate-cysteine ligase (GCL) activity over time. Measuring reactive oxygen species (ROS) production with DCF revealed a rapid increase in ROS generation after AP-ICAM treatment. Measurement of superoxide production with hydroethidium revealed biphasic production at 30 min and 6h after treatment with AP-ICAM. Apocynin, DPI, catalase, or SOD attenuated AP-ICAM-dependent ROS production, GCL activity, and GSH production, implicating superoxide production and dismutation to peroxide. Consistent with these findings, NOX4 siRNA knockdown blocked AP-ICAM peptide increases in GSH or GCL activity, demonstrating the importance of NADPH oxidase. Last, inhibition of PI3-kinase activity with LY 294002 or wortmannin blocked AP-ICAM GSH induction and ROS production. These data reveal that the ICAM-1 cytoplasmic tail regulates production of endothelial GSH through a NOX4/PI3-kinase-dependent redox-sensitive pathway.

Mango extracts and the mango component mangiferin promote endothelial cell migration

This study tested the hypothesis that mango extracts contain bioactive molecules capable of modulating endothelial cell migration, an essential step in the formation of new blood vessels or angiogenesis. The formation of new blood vessels is an important therapeutic target for diseases such as limb ischemia, coronary infarction or stroke. We examined the effect of mango peel and flesh extracts as well as the individual polyphenolic molecules, mangiferin and quercetin, on bovine aortic cell migration using a modified Boyden chamber assay. Our results show that mangiferin, and extracts rich in mangiferin, increase endothelial cell migration. The dose-effect relationship for various extracts further suggests that this action of mangiferin is modulated by other components present in the extracts. The promigratory effect of mango extracts or mangiferin was unrelated to an effect on cell proliferation, and did not involve a change in the production of matrix metalloprotease-2 or -9 by the endothelial cells. Taken together, these results suggest that mangiferin present in mango extracts may have health promoting effects in diseases related to the impaired formation of new blood vessels.

Pharmacologic therapy for intermittent claudication

Peripheral artery disease, defined as atherosclerosis in the lower extremities, affects nearly 8.5 million people in the United States. Due to the frequent asymptomatic manifestation of peripheral artery disease, diagnosis may be delayed and its true incidence underestimated. However, some patients may experience aching pain, numbness, weakness, or fatigue, a condition termed intermittent claudication. Peripheral atherosclerosis is associated with cardiovascular risk and physical impairment; therefore, treatment goals are aimed at decreasing cardiovascular risk, as well as improving quality of life. Little debate exists regarding the management of cardiovascular risk reduction, which consists of both antiplatelet therapy and risk factor modification. Despite recently published guidelines, the treatment of intermittent claudication is less well established and the management remains controversial and uncertain. Exercise remains the first-line therapy for intermittent claudication; however, pharmacologic treatment is often necessary. Although only two prescription drugs have been approved by the U.S. Food and Drug Administration for the treatment of intermittent claudication, several supplements and investigational agents have been evaluated. Therapeutic optimization should balance the anticipated improvements in quality of life with the potential safety risks.

Fibroblast growth factor 2 promotes endothelial differentiation of adipose tissue-derived stem cells

INTRODUCTION

Adipose tissue-derived stem cells (ADSC) could potentially restore endothelial function in vasculogenic erectile dysfunction (ED). The mechanism for ADSC endothelial differentiation remained unidentified.

AIM

To test whether ADSC could differentiate into endothelial cells in the penis and to identify the underlying mechanism of ADSC endothelial differentiation.

METHODS

For in vivo endothelial differentiation, ADSC were labeled with bromodeoxyuridine (BrdU), injected into rat corpora cavernosa, and localized by immunofluorescence and phase-contrast microscopy. For in vitro endothelial differentiation, ADSC were grown in endothelial growth medium 2 (EGM2), stained for endothelial markers CD31, von Willebrand Factor (vWF), and endothelial nitric oxide synthase (eNOS), and assessed for the ability to form tube-like structures in Matrigel and to endocytose acetylated low-density lipoprotein (Ac-LDL). To identify factors that promote ADSC endothelial differentiation, ADSC were grown in various media, each of which contained a specific combination of supplemental factors and assessed for LDL-uptake. PD173074, a selective inhibitor of fibroblast growth factor 2 (FGF2) receptor, was used to confirm the importance of FGF2 signaling for ADSC endothelial differentiation.

MAIN OUTCOME MEASURES

In vivo endothelial differentiation was assessed by immunofluorescence microscopy. In vitro endothelial differentiation was assessed by immunofluorescence, Matrigel tube formation, and Ac-LDL uptake.

RESULTS

Injected ADSC were localized to the sinusoid endothelium, some of which stained positive for both BrdU and endothelial antigen rat endothelial cell antigen. ADSC proliferated at a faster rate in EGM2 than in standard DMEM, expressed endothelial markers CD31, vWF, and eNOS, formed tube-like structures in Matrigel, and endocytosed Ac-LDL. These properties were greatly diminished when ADSC were grown in the absence of FGF2 but were unaffected when grown in the absence of vascular endothelial growth factor, insulin-like growth factor, or epidermal growth factor. Furthermore, ADSC displayed similar endothelial properties when grown in FGF2-supplemented basic medium as in EGM2. Finally, blockade of FGF2 signaling with PD173074 abrogated ADSC endothelial differentiation.

CONCLUSIONS

ADSC could differentiate into endothelial cells in the penis. FGF2 signaling mediates ADSC endothelial differentiation.