Endothelial Progenitor Cells Treatment Research Articles

Erythropoietin promotes the protective properties of transplanted endothelial progenitor cells against acute lung injury via PI3K/Akt pathway.

Accumulating evidences have indicted the participation and repairing effects of endothelial progenitor cells (EPCs) on acute lung injury (ALI). Researchers have also revealed that erythropoietin (EPO) may exert multiple effects on EPCs including proliferative and adhesive properties. The present study was designed to investigate whether EPO can promote the healing efficiency of transplanted EPCs against ALI and the potential mechanism. Endothelial progenitor cells were derived from bone marrow mononuclear cells of BALB/c mice. In our in vitro studies, we tested the proproliferative and antiapoptotic effects of EPO on cultured EPCs. In our in vivo studies, we induced BALB/c mice ALI model by intratracheal instillation of lipopolysaccharide and treated with/without intravenous injection of enhanced green fluorescent protein-EPCs harvested from enhanced green fluorescent protein-BALB/c mice. Mice that received EPC transplantation either underwent EPO administration or not. The effects of EPO and EPC treatment on promoting pulmonary endothelial repair, decreasing pulmonary capillary permeability, alleviating pulmonary inflammation, improving gas exchange, and promoting pulmonary vessel angiogenesis were tested. The potential mechanisms that mediate EPO functions on EPC were also investigated. Our studies revealed a significant antiapoptotic property of EPO on cultured EPCs as well as its promotion on EPC proliferation. We also found the severity of ALI was reduced by EPC therapy, and the protective effects of EPCs were highly enhanced when combined with EPO administration. However, all these stimulating effects of EPO on EPCs were consisted with the expression of phospho-Akt and were abrogated by PI3K inhibitors. Transplanted EPCs directly incorporated into the injured pulmonary vessels and maintain the integrity of pulmonary endothelium. Erythropoietin improved the survival and proliferation of transplanted EPCs and recruited them to the injured sites to exert their repairing functions. PI3K/Akt pathway mediated EPO's functions on EPCs. The combination of EPO and EPC treatment may be a promising cell-based therapy for ALI patients.

Angiogenesis effect of Astragalus polysaccharide combined with endothelial progenitor cells therapy in diabetic male rat following experimental hind limb ischemia

Background Diabetes mellitus (DM) is a common disease accompanied with a high incidence of hind limb ischemia (HLI). In recent years, numerous studies demonstrated that endothelial progenitor cells (EPCs) are involved in angiogenesis and maintenance of vascular integrity following HLI. On the other side, it has been proved that Astragalus polysaccharide (APS) could promote angiogenesis. In the present study, we aimed to evaluate the effect of APS and EPCs on enhancing angiogenesis after experimental HLI caused by femoral artery ligation in rats with streptozotocin (STZ)-induced diabetes. Methods Rats (n=110) were randomly assigned to the following groups: sham group, ischemia group, APS group, EPCs group and APS+EPCs group. APS, EPCs or an equal volume of vehicle was administered intramuscularly after HLI induction, and 6 rats were assessed by angiography at 28 days after induction of HLI, 6 rats were sacrificed at the same time point to take histological studies, biochemical tests were also performed at that point in the rest rats. Results APS or EPCs treatment induced an increase, respectively, in the protein expression of vascular endothelial growth factor (VEGF) (36.61%, 61.59%), VEGF receptor-1 (VEGFR-1) (35.50%, 57.33%), VEGFR-2 (31.75%, 41.89%), Angiopoietin-1 (Ang-1) (37.57%, 64.66%) and Tie-2 (42.55%, 76.94%) (P <0.05), after HLI injury. And combined therapy of APS and EPCs enhanced the effort of angiogenesis after HLI induction in diabetic rats, through elevating protein expression of VEGF (99.67%), VEGFR-1 (105.33%), VEGFR2 (72.05%), Ang-1 (114.30%) and Tie-2 (111.87%) (P<0.05). Similarly, mRNA expression of VEGF, VEGFR-1, VEGFR2, Ang-1, Tie-2 also show similar trends as well as protein expression (P<0.05). Conclusion APS or EPCs could enhance angiogenesis, and the combined treatment leads to better effort, at least, partially via VEGF/VEGFR and Ang-1/Tie-2 signaling pathway.

Image-guided pro-angiogenic therapy in diabetic stroke mouse models using a multi-modal nanoprobe.

Purpose: The efficacy of pro-angiogenic therapy is difficult to evaluate with current diagnostic modalities. The objectives were to develop a non-invasive imaging strategy to define the temporal characteristics of angiogenesis and to evaluate the response to pro-angiogenic therapy in diabetic stroke mouse models.Methods: A home-made ανβ3 integrin-targeted multi-modal nanoprobe was intravenously injected into mouse models at set time points after photothrombotic stroke. Magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging were carried out at 24 h post-injection. Bone marrow-derived endothelial progenitor cells (EPCs) were infused into the mouse models of ischemic stroke to stimulate angiogenesis.Results: The peak signal intensity in the ischemic-angiogenic area of diabetic and wild-type mouse models was achieved on day 10, with significantly lower signal enhancement observed in the diabetic models. Although the signal intensity was significantly higher after EPC treatment in both models, the enhancement was less pronounced in the diabetic animals compared with the wild-type controls. Histological analysis revealed that the microvessel density and expression of β3 integrin were correlated with the signal intensity assessed with MRI and NIRF imaging.Conclusions: The non-invasive imaging method could be used for early and accurate evaluation of the response to pro-angiogenic therapy in diabetic stroke models.

EFFECTS OF ERYTHROPOIETIN ON ENDOTHELIAL PROGENITOR CELL TRANSPLANTATION AFTER MYOCARDIAL INFARCTION IN MICE

ObjectivesPrevious studies suggested that transplantation of endothelial progenitor cells (EPC) could improve cardiac function after myocardial infarction (MI). However, survival of transplanted EPC seems unsatisfactory. The purpose of the present...

Hydrogel-embedded endothelial progenitor cells evade LPS and mitigate endotoxemia.

Sepsis and its complications are associated with poor clinical outcomes. The circulatory system is a well-known target of lipopolysaccharide (LPS). Recently, several clinical studies documented mobilization of endothelial progenitor cells (EPCs) during endotoxemia, with the probability of patients' survival correlating with the rise in circulating EPCs. This fact combined with endotoxemia-induced vascular injury led us to hypothesize that the developing functional EPC incompetence could impede vascular repair and that adoptive transfer of EPCs could improve hemodynamics in endotoxemia. We used LPS injection to model endotoxemia. EPCs isolated from endotoxemic mice exhibited impaired clonogenic potential and LPS exerted Toll-like receptor 4-mediated cytotoxic effects toward EPCs, which was mitigated by embedding them in hyaluronic acid (HA) hydrogels. Therefore, intact EPCs were either delivered intravenously or embedded within pronectin-coated HA hydrogels. Adoptive transfer of EPCs in LPS-injected mice improved control of blood pressure and reduced hepatocellular and renal dysfunction. Specifically, EPC treatment was associated with the restoration of renal microcirculation and improved renal function. EPC therapy was most efficient when cells were delivered embedded in HA hydrogel. These findings establish major therapeutic benefits of adoptive transfer of EPCs, especially when embedded in HA hydrogels, in mice with LPS-induced endotoxemia, and they argue that hemodynamic and renal abnormalities of endotoxemia are in significant part due to developing incompetence of endogenous EPCs.

Cell-based therapies in pulmonary hypertension: who, what, and when?

pulmonary hypertension (PH), diagnosed when mean pulmonary arterial pressure exceeds the upper limits of normal (i.e., >25 mmHg) at rest (2), occurs in a variety of clinical situations and is associated with a broad spectrum of histological patterns and abnormalities. PH is currently classified into five distinct World Health Organization (WHO) groups, based on common clinical parameters, potential etiological mechanisms, and responses to treatment (22). Although any form of PH can contribute to increased patient morbidity and mortality, pulmonary arterial hypertension (PAH) (WHO group 1) is a particularly severe and progressive form associated with right heart failure and premature death (1). At present, therapeutic approaches to stabilize or reverse this debilitating condition involve treatment with one or a combination of up to three specific classes of agents, including prostacyclin analogs, endothelin-1 receptor antagonists, and/or phosphodiesterase-5 inhibitors. Retrospective (meta)analyses of these therapeutic strategies have demonstrated a reduction in mortality with their use (7, 12); however, many experts believe that current PAH treatment is inadequate given the persistently high mortality rate and functional hemodynamic impairment in many patients. These observations have led to continued intensive investigation into pathogenetic mechanisms and many proposals for additional alternative new therapies (20, 24). Among the potential new therapies, increasing interest in the role of endothelial progenitor cells (EPCs) as a cell-based therapy has emerged. However, issues remain regarding what group of PH patients are most likely to benefit from treatment, at what point in the disease is treatment most likely to be successful, and what types of cells should be utilized for therapy.

INTRAVENOUS DELIVERY OF BONE MARROW-DERIVED ENDOTHELIAL PROGENITOR CELLS IMPROVES SURVIVAL AND ATTENUATES LIPOPOLYSACCHARIDE-INDUCED LUNG INJURY IN RATS

Acute lung injury (ALI) is a devastating disease, which is characterized by diffuse endothelium, epithelial damage, and increased pulmonary capillary permeability. Recent data have suggested that the circulating endothelial progenitor cells (EPCs) play an important role in endothelial repair after vascular injury. This study was undertaken to investigate possible endothelial-repairing effects of EPC transplantation after LPS-induced ALI in rats. Using Y-chromosome in situ hybridization and reverse transcription polymerase chain reaction assay, we detected the expression of sex-determining region y in the injured lungs of female model rats, suggesting that allogenic EPCs can migrate to the injured lung tissues. Rats that have received the EPC treatment had a reduced pulmonary edema level, inflammation, hemorrhage, and hyaline membrane formation, as well as an increased survival rate from 44% to 81%. Furthermore, anti-inflammatory cytokine IL-10 levels were dramatically increased in the EPC-treated rats compared with the phosphate buffered saline-treated rats. On the contrary, endothelin-1 and iNOS were downregulated in the EPC-treated group. These findings provide evidence that i.v. EPC treatment results in engraftment of EPCs to the injured lung tissue, which can significantly attenuate lung injury and improve survival in ALI rats. The beneficial effects of EPC engraftment is likely to come from maintaining the integrity of pulmonary alveolar-capillary barrier, reestablishing the endothelial function in vessels and ameliorating the inflammatory state.

Abstract 3751: Selective Improvement of Renal Function in Renovascular Disease by Intra-Renal Infusion of Endothelial Progenitor Cells Restores Myocardial Microvascular Integrity

Background : Renovascular disease (RVD) and impaired renal function are important risk factors for cardiac disease, but it remained unclear whether selective recovery of renal function can reverse cardiac dysfunction. Aims: This study tested the hypothesis that improvement in renal function using selective intra-renal administration of endothelial progenitor cells (EPC) in swine renovascular hypertension would improve myocardial microvascular (MV) integrity. Methods: The functions of the myocardial MV (response to IV adenosine) and the stenotic kidney of 7 pigs were assessed in-vivo using multi-detector CT after 6 weeks of RVD and hypertension. Autologous EPC expanded in culture were then infused (10x10 6 cells) intra-renally, and in vivo studies repeated 4 wks later. Six normal pigs served as controls. Results : Glomerular filtration rate was lower in RVD compared to normal (47.9±10.1 vs. 70.8±4.3 mL/min, p<0.05) and improved after EPC (to 62.7±1.5 mL/min, p=NS vs. normal), as did renal blood flow. Mean arterial pressure remained elevated after EPC (120.7±11 and 129.4±6 vs. 99.9±4.7 mmHg in normal, p<0.05), and plasma renin activity was unchanged. Myocardial MV permeability-surface area increased in RVD in response to adenosine (0.009±0.001 to 0.011±0.002 AU, p=0.01), while MV volume fraction decreased (4.3±0.8 to 2.7±0.6%, p=0.01), indicating impaired MV barrier function and integrity. Contrarily, both remained unchanged in response to adenosine 4 wks after EPC (0.01±0.002 to 0.01±0.002 AU, p=0.24, and 3.5±0.8 to 3.4±0.5%, p=0.46, respectively), as did normal MV. Conclusion : A single intra-renal infusion of EPC that improved renal function in experimental RVD also preserved remote myocardial MV function, despite sustained systemic hypertension. These findings underscore the cross talk between renal and cardiac function, and the potential of selective renal EPC intervention to preserve both the kidney and heart in RVD. Renal and myocardial microvascular function change in normal and RVD before and after EPC treatment

Vascular endothelial growth factor promoted endothelial progenitor cell mobilization into the peripheral blood of a patient with POEMS syndrome

We assessed the percentage of endothelial progenitor cells (EPCs) in the peripheral blood of a patient with POEMS with elevated VEGF plasma levels. High VEGF plasma levels were associated with increased EPC concentration and treatment with an anti-VEGF antibody induced a consensual decrease of both parameters. In vitro cultures of the patient BM cells suggested that the stromal compartment could be responsible for VEGF overproduction.

Angiogenesis by transplantation of HIF‐1α modified EPCs into ischemic limbs

Hypoxia inducible factor-1 alpha (HIF-1 alpha) is a key determinant of oxygen-dependent gene regulation in angiogenesis. HIF-1 alpha overexpression may be beneficial in cell therapy of hypoxia-induced pathophysiological processes, such as ischemic heart disease. To address this issue, human peripheral blood mononuclear cells (PBMNCs) were induced to differentiate into endothelial progenitor cells (EPCs), and then were transfected with either an HIF-1 alpha-expressing or a control vector and cultured under normoxia or hypoxia. Hypoxia-induced HIF-1 alpha mRNA and protein expression was increased after HIF-1 alpha transfection. This was accompanied by VEGF mRNA induction and increased VEGF secretion. Hypoxia-stimulated VEGF mRNA induction was significantly abrogated by HIF-1 alpha-specific siRNA. Functional studies showed that HIF-1 alpha overexpression further promoted hypoxia-induced EPC differentiation, proliferation and migration. The expressions of endothelial cell markers CD31, VEGFR2 (Flk-1) and eNOS as well as VEGF and NO secretions were also increased. Furthermore, in an in vivo model of hindlimb ischemia, HIF-1 alpha-transfected EPCs homed to the site of ischemia. A higher revascularization potential was also demonstrated by increased capillary density at the injury site. Our results revealed that endothelial progenitor cells ex vivo modification by hypoxia inducible factor-1 alpha gene transfection is feasible and may offer significant advantages in terms of EPC expansion and treatment efficacy.

Low-Energy Shock Wave for Enhancing Recruitment of Endothelial Progenitor Cells

Stem and progenitor cell therapy is a novel approach to improve neovascularization and function of ischemic tissue. Enhanced tissue expression of chemoattractant factors such as stromal cell-derived factor 1 and vascular endothelial growth factor is crucial for the recruitment of circulating endothelial progenitor cells (EPCs) during acute ischemia. In chronic ischemia, however, expression of these chemoattractants is less pronounced, which results in insufficient EPC recruitment into the target tissue. Therefore, we investigated the effect of targeted extracorporeal shock wave (SW) application in order to facilitate EPC recruitment into nonischemic and chronic ischemic tissue. Hind limb adductor muscles of nude rats were treated with 500, 1000, and 2000 impulses of focused low-energy SW (flux density level: 0.05 mJ/mm2). Twenty-four hours later, mRNA expression of the chemoattractant stromal cell-derived factor 1 was significantly increased with 1000 impulses (stromal cell-derived factor 1/GAPDH: 0.95+/-0.09) and 2000 impulses (stromal cell-derived factor 1/GAPDH: 1.17+/-0.24; both P<0.05 versus untreated). Histologically, the number of vascular endothelial growth factor-positive endothelial cells per myocyte was significantly increased with 2000 impulses (0.24+/-0.05 versus 0.09+/-0.02; P<0.01). This preconditioning effect resulted in significantly enhanced recruitment and homing of EPCs that were intravenously infused 24 hours after SW treatment (P<0.05). In a rat model of chronic hind limb ischemia, SW-facilitated EPC treatment resulted in a significant increase in relative blood flow recovery as assessed by laser Doppler imaging (P<0.05). Preconditioning of both nonischemic and chronic ischemic tissue with low-energy SW improves recruitment of circulating EPCs via enhanced expression of chemoattractant factors. Thus, SW-facilitated cell therapy may improve the efficacy of EPC treatment in patients with chronic ischemia.