Topical Erythropoietin Accelerates Wound Closure in Patients with Diabetic Foot Ulcers: A Prospective, Multicenter, Single-Blind, Randomized, Controlled Trial.

The diabetic foot ulcer (DFU) is a major disabling complication of diabetes mellitus. Growing evidence suggests that topical erythropoietin (EPO) can promote wound healing. The aim of this study is to clinically assess the efficacy of a proprietary topical EPO-containing hydrogel for treating DFUs. We conducted a randomized, controlled trial in 20 patients with DFUs. After a 14-day screening period, the DFUs of 20 eligible participants who fulfilled the inclusion criteria were randomly assigned (1:1) to either a 12-week of daily treatment with topical EPO and standard-of-care (SOC) or SOC treatment alone. The DFUs were assessed weekly until week 12. The primary outcome was 75% ulcer closure or higher. After 12 weeks of treatment, 75% ulcer closure was achieved in 6 of the 10 patients whose DFUs were treated with topical EPO and in one of the 8 patients whose DFUs were treated with SOC alone. The mean area of the DFUs that were treated with topical EPO and SOC was significantly smaller than those treated with SOC alone (1.2 ± 1.4 cm2 vs. 4.2 ± 3.4 cm2; p = 0.023). Re-epithelialization was faster in the topically EPO-treated DFUs than in the SOC-treated DFUs. There were no treatment-related adverse events. We conclude that topical EPO is a promising treatment for promoting the healing of DFUs. Clinical Trial Registration number: NCT02361931.

Interim Results of the Remede d'Or Study: A Multicenter, Single-Blind, Randomized, Controlled Trial to Assess the Safety and Efficacy of an Innovative Topical Formulation of Erythropoietin for Treating Diabetic Foot Ulcers.

Objective: To inform on the interim results of the Remede d'Or study, which is a prospective, multicenter, single-blind, randomized, controlled clinical study on the safety and efficacy of RMD-G1, a topical carbopol-based hydrogel with a fibronectin matrix whose active pharmaceutical ingredient is erythropoietin (EPO), for treating diabetic foot ulcers (DFU). Approach: The trial will comprise 20 patients with type 2 diabetes mellitus with neuroischemic DFUs who will be randomized into two groups: (1) a control group in which standard-of-care (SOC) will be used to treat the DFUs, and (2) a test group in which SOC and RMD-G1 will be used to treat the DFUs. On day 0, all participants will be randomized to receive either RMD-G1 and SOC treatment or SOC alone. The primary endpoint of the study is complete closure of the DFU within the 12-week study period following daily treatments and dressing changes. Results: Interim results reveal that those DFUs which were treated with RMD-G1 responded positively: there was a significant reduction in the wound areas. In contrast, the condition of those DFUs which were treated with only SOC deteriorated. Innovation: To date, no topical therapies with proven efficacy for treating DFUs exist. Topical application of EPO-based RMD-G1 in conjunction with SOC to a DFU accelerates their healing and closure. Conclusions: The interim results of this trial indicate that topical RMD-G1 is a safe adjunctive therapy to SOC, which accelerates the closure of a DFU. RMD-G1 is safe pharmaceutical because EPO has a proven safety profile.

Topical Erythropoietin Treatment Accelerates the Healing of Cutaneous Burn Wounds in Diabetic Pigs Through an Aquaporin-3-Dependent Mechanism.

We have previously reported that the topical application of erythropoietin (EPO) to cutaneous wounds in rats and mice with experimentally induced diabetes accelerates their healing by stimulating angiogenesis, reepithelialization, and collagen deposition, and by suppressing the inflammatory response and apoptosis. Aquaporins (AQPs) are integral membrane proteins whose function is to regulate intracellular fluid hemostasis by enabling the transport of water and glycerol. AQP3 is the AQP that is expressed in the skin where it facilitates cell migration and proliferation and re-epithelialization during wound healing. In this report, we provide the results of an investigation that examined the contribution of AQP3 to the mechanism of EPO action on the healing of burn wounds in the skin of pigs with experimentally induced type 1 diabetes. We found that topical EPO treatment of the burns accelerated their healing through an AQP3-dependent mechanism that activates angiogenesis, triggers collagen and hyaluronic acid synthesis and the formation of the extracellular matrix (ECM), and stimulates reepithelialization by keratinocytes. We also found that incorporating fibronectin, a crucial constituent of the ECM, into the topical EPO-containing gel, can potentiate the accelerating action of EPO on the healing of the burn injury.

Erythropoietin, a novel repurposed drug: an innovative treatment for wound healing in patients with diabetes mellitus.

Developing a new drug is expensive: the cost of going from bench to bedside is about $US1 billion. Therefore, the repurposing of an approved drug is potentially rewarding because it expands the drug's existing therapeutic profile and preempts additional development costs. As the safety profile of a repurposed drug is already well known, any new investigations could then focus on its efficacy and other therapeutic benefits. Recombinant erythropoietin (EPO) is a potential candidate for repurposing because the results of numerous studies have shown that systemic and topical EPO is therapeutically beneficial when it is administered to healthy and diabetic animals with acute and chronic skin wounds and burns. Moreover, the molecular mechanisms of EPO's actions have been elucidated: EPO acts on those nonhematopoietic cells which are involved in the innate immune response where it promotes cellular proliferation and differentiation, exerts its cytoprotective actions, and inhibits apoptosis. In this review, the mechanism of EPO's action in skin wound healing is reviewed, and its potential for treating acute and chronic skin wounds and stimulating tissue regeneration in diabetic patients is discussed.

The chemokine stromal cell-derived factor-1α promotes endothelial progenitor cell-mediated neovascularization of human transplanted fat tissue in diabetic immunocompromised mice.

BACKGROUND: Stromal cell-derived factor-1α is a chemokine and mediates endothelial progenitor cell-induced neovascularization. Because vascularization of a graft is crucial for its survival, the authors investigated whether stromal cell-derived factor-1α could improve fat graft survival by inducing endothelial progenitor cell-mediated neovascularization and preventing its resorption. METHODS: The authors injected 1 ml of human fat tissue into the scalps of 30 diabetic and 10 nondiabetic immunocompromised mice. The fat grafts were treated with phosphate-buffered saline or stromal cell-derived factor-1α. Determination of graft phenotype included measurements of their weights and volumes, vascular endothelial growth factor (VEGF) levels, the stromal cell-derived factor-1α receptor CXCR4, VEGF receptor 2, endothelial nitric oxide synthase, serine/threonine-specific protein kinase (protein kinase B), caspase 3, and cytochrome c expression levels, and the extent of vascularization. RESULTS: Eighteen days after transplantation, stromal cell-derived factor-1α treatment of the grafts in the diabetic mice (1) increased plasma VEGF levels; (2) raised VEGF receptor 2, CXCR4, endothelial nitric oxide synthase, and protein kinase B expression levels; and (3) reduced caspase 3 and cytochrome c expression levels in the fat grafts. Fifteen weeks after transplantation, stromal cell-derived factor-1α treatment of the grafts prevented their resorption and increased the extent of their vascularization. CONCLUSION: Locally delivered stromal cell-derived factor-1α increases fat graft survival by stimulating neovascularization and reducing fat cell apoptosis through an endothelial progenitor cell-mediated mechanism.

Treating fat grafts with human endothelial progenitor cells promotes their vascularization and improves their survival in diabetes mellitus.

BACKGROUND: Bone marrow-derived endothelial progenitor cells are required for vascularization of a fat graft to form a functional microvasculature within the graft and to facilitate its integration into the surrounding tissues. Organ transplantation carries a high risk of graft loss and rejection in patients with diabetes mellitus because endothelial progenitor cell function is impaired. The authors investigated the influence of endothelial progenitor cell treatment on the phenotype and survival of human fat grafts in immunocompromised mice with experimentally induced diabetes mellitus. METHODS: The authors injected 1 ml of human fat tissue into the scalps of 14 nondiabetic and 28 diabetic immunocompromised mice, and then treated some of the grafts with endothelial progenitor cells that was isolated from the blood of a human donor. The phenotype of the endothelial progenitor cell-treated fat grafts from the 14 diabetic mice was compared with that of the untreated fat grafts from 14 nondiabetic and 14 diabetic mice, 18 days and 15 weeks after fat transplantation. Determination of graft phenotype included measurements of weight and volume, vascular endothelial growth factor levels, vascular endothelial growth factor receptor-2, endothelial nitric oxide synthase, and caspase 3 expression levels, and histologic analysis of the extent of vascularization. RESULTS: The untreated grafts from the diabetic mice were fully resorbed 15 weeks after fat transplantation. The phenotype of endothelial progenitor cell-treated fat grafts from the diabetic mice was similar to that of the untreated fat grafts from the nondiabetic mice. CONCLUSION: Endothelial progenitor cell treatment of transplanted fat can increase the survival of a fat graft by inducing its vascularization and decreasing the extent of apoptosis.

Fibronectin potentiates topical erythropoietin-induced wound repair in diabetic mice.

Diabetes mellitus disrupts all phases of the wound repair cascade and leads to development of chronic wounds. We previously showed that topical erythropoietin (EPO) can promote wound repair in diabetic rats. Fibronectin (FN) has a critical role throughout the process of wound healing, yet it is deficient in wound tissues of diabetic patients. Therefore, we investigated the effect of topical treatment of both EPO and FN (EPO/FN) on wound repair in diabetic mice. Full-thickness excisional skin wounds in diabetic and nondiabetic mice were treated with a cream containing vehicle, EPO, FN, or EPO/FN. We assessed the rate of wound closure, angiogenesis, apoptosis, and expression of inflammatory cytokines, endothelial nitric oxide synthase (eNOS) and ß1-integrin, in the wound tissues. We also investigated the effect of EPO, FN, and EPO/FN on human dermal microvascular endothelial cells and fibroblasts cultured on fibrin-coated plates, or in high glucose concentrations. EPO/FN treatment significantly increased the rate of wound closure and this effect was associated with increased angiogenesis, increased eNOS and ß1-integrin expression, and reduced expression of inflammatory cytokines and apoptosis. Our findings show that EPO and FN have an additive effect on wound repair in diabetic mice.

Nitric oxide: a key factor behind the dysfunctionality of endothelial progenitor cells in diabetes mellitus type-2.

Diabetes mellitus type-2 (DM-2) contributes to atherogenesis by inducing endothelial cell injury and dysfunction. Endothelial progenitor cells (EPCs) are essential to blood vessel formation, can differentiate into mature endothelial cells, and promote the repair of damaged endothelium. In DM-2, the circulating EPC count is low and their functionality is impaired. The mechanisms that underlie this reduced count and impaired functionality are poorly understood. Nitric oxide (NO) is a short-lived signalling molecule that is produced by vascular endothelial cells and participates in the maintenance of vascular tone. NO is also known to participate in other physiological processes, such as cell survival, proliferation, and migration. The bioavailability of NO is reduced in EPCs from DM-2 patients. Interestingly, an inverse relationship exists between the reduction in NO bioavailability in EPCs and the patient's plasma glucose and glycated haemoglobin levels. In addition, NO bioavailability in EPCs correlates with plasma oxidized low-density lipoprotein levels in DM-2. Although this reduction in NO bioavailability could be attributed to oxidative stress in DM-2 patients, it also may be due to impairment of one or more members of the protein signalling cascades that are responsible for NO production. The stimulation of NO production or its signalling cascades in EPCs may increase their numbers and improve their function, thus attenuating endothelium damage, independent of the vasodilatory effects of NO. This review summarizes the metabolic alterations that underlie the molecular mechanisms that may be responsible for EPC decrease and dysfunction in DM-2 with emphasis on the involvement of the NO system.

Erythropoietin improves the survival of fat tissue after its transplantation in nude mice.

BACKGROUND: Autologous transplanted fat has a high resorption rate, providing a clinical challenge for the means to reduce it. Erythropoietin (EPO) has non-hematopoietic targets, and we hypothesized that EPO may improve long-term fat graft survival because it has both pro-angiogenic and anti-apoptotic properties. We aimed to determine the effect of EPO on the survival of human fat tissue after its transplantation in nude mice. METHODOLOGY/PRINCIPAL FINDINGS: Human fat tissue was injected subcutaneously into immunologically-compromised nude mice, and the grafts were then treated with either 20 IU or 100 IU EPO. At the end of the 15-week study period, the extent of angiogenesis, apoptosis, and histology were assessed in the fat grafts. The results were compared to vascular endothelial growth factor (VEGF)-treated and phosphate-buffered saline (PBS)-treated fat grafts. The weight and volume of the EPO-treated grafts were higher than those of the PBS-treated grafts, whose weights and volumes were not different from those of the VEGF-treated grafts. EPO treatment also increased the expression of angiogenic factors and microvascular density, and reduced inflammation and apoptosis in a dose-dependent manner in the fat grafts. CONCLUSIONS/SIGNIFICANCE: Our data suggest that stimulation of angiogenesis by a cluster of angiogenic factors and decreased fat cell apoptosis account for potential mechanisms that underlie the improved long-term survival of fat transplants following EPO treatment.

Red wine consumption improves in vitro migration of endothelial progenitor cells in young, healthy individuals.

BACKGROUND: Endothelial progenitor cells (EPCs) contribute to the maintenance of vascular endothelial function. The moderate consumption of red wine provides cardiovascular protection. OBJECTIVE: We investigated the underlying molecular mechanism of EPC migration in young, healthy individuals who drank red wine. DESIGN: Fourteen healthy volunteers consumed 250 mL red wine daily for 21 consecutive days. Vascular endothelial function, plasma stromal cell-derived factor 1alpha (SDF1alpha) concentrations, and the number, migration, and nitric oxide production of EPCs were determined before and after the daily consumption of red wine. EPCs were glucose stressed to study the effect of red wine on EPC migration, proliferation, and senescence and to study the expressions of CXC chemokine receptor 4 (CXCR4) and members of the Pi3K/Akt/eNOS (phosphatidylinositol 3-kinase/protein kinase B/endothelial nitric oxide synthase) signaling pathway by Western blotting. RESULTS: Daily red wine consumption for 21 consecutive days significantly enhanced vascular endothelial function. Although plasma SDF1alpha concentrations were unchanged, EPC count and migration were significantly increased after this 21-d consumption period. Red wine increased the migration, proliferation, CXCR4 expression, and activity of the Pi3K/Akt/eNOS signaling pathway and decreased the extent of apoptosis in glucose-stressed EPCs. CONCLUSIONS: The results of the present study indicate that red wine exerts its effect through the up-regulation of CXCR4 expression and activation of the SDF1alpha/CXCR4/Pi3K/Akt/eNOS signaling pathway, which results in increased EPC migration and proliferation and decreased extent of apoptosis. Our findings suggest that these effects could be linked to the mechanism of cardiovascular protection that is associated with the regular consumption of red wine.

Hyperglycemia and oxidized-LDL exert a deleterious effect on endothelial progenitor cell migration in type 2 diabetes mellitus.

INTRODUCTION: Type 2 diabetes mellitus (DM) patients with coronary artery disease (CAD) have elevated plasma oxidized-LDL (OxLDL) levels and impaired neovascularization. Hyperglycemia and hyperlipidemia impair endothelial progenitor cell (EPC) migration, and endothelial nitric oxide (NO) bioavailability and NO synthase (NOS) activity are essential for EPC migration. Stromal-derived factor-1alpha (SDF1alpha) contributes to EPC mobilization and homing by stimulating the CXC receptor-4 (CXCR4) on the EPC plasmalemma to activate the Pi3K/Akt/eNOS signaling pathway. Therefore, we investigated the effect of high glucose (HG) and OxLDL on the migration and NO bioavailability of EPCs from healthy individuals, and then correlated the findings with those of EPCs from type 2 DM patients with and without CAD. MATERIALS AND METHODS: EPCs from 15 healthy and 55 patients were exposed to HG, OxLDL, or both before evaluating EPC count, migration and NO production, and expression of CXCR4 and members of Pi3K/Akt/eNOS signaling cascade. RESULTS: Counts, migration, CXCR4 expression, and NO production were significantly reduced in EPCs from DM and CAD patients compared with that obtained in EPCs from healthy, and were further reduced in DM patients with CAD. The expression of CXCR4 and activation of Pi3K/Akt/eNOS signaling cascade were suppressed in OxLDL- and HG-treated EPCs, and this suppression was exacerbated when EPCs were treated simultaneously with HG and OxLDL. CONCLUSIONS: Hyperglycemia and elevated circulating OxLDL in DM patients with CAD severely impair EPC migration. These results suggest that the underlying mechanism for this impaired EPC migration is linked to the CXCR4/Pi3K/Akt/eNOS signaling pathway.

Topical erythropoietin promotes wound repair in diabetic rats.

Wound healing in diabetic patients is slower than in healthy individuals. Erythropoietin (EPO) has non-hemopoietic targets in the skin, and systemically administered EPO promotes wound healing in experimental animals. This study investigated the effect of topical EPO treatment on defective wound repair in the skin of diabetic rats. Full-thickness excisional skin wounds were made in 38 rats, of which 30 had diabetes. The wounds were then treated topically with a cream that contained either vehicle, 600 IU ml(-1) EPO (low dose), or 3,000 IU ml(-1) (high dose) EPO. We assessed the rate of wound closure during the 12-day treatment period, and microvascular density (MVD), vascular endothelial growth factor (VEGF), and hydroxyproline (HP) contents, and the extent of apoptosis in wound tissues at the end of the 12-day treatment period. Topical EPO treatment significantly reduced the time to final wound closure. This increased rate of closure of the two EPO-treated wounds in diabetic rats was associated with increased MVD, VEGF, and HP contents, and a reduced extent of apoptosis. In light of our finding that topical EPO treatment promotes skin wound repair in diabetic rats, we propose that topical EPO treatment is a therapeutically beneficial method of treating chronic diabetic wounds.

Nitric oxide and superoxide dismutase modulate endothelial progenitor cell function in type 2 diabetes mellitus.

BACKGROUND: The function of endothelial progenitor cells (EPCs), which are key cells in vascular repair, is impaired in diabetes mellitus. Nitric oxide (NO) and reactive oxygen species can regulate EPC functions. EPCs tolerate oxidative stress by upregulating superoxide dismutase (SOD), the enzyme that neutralizes superoxide anion (O2-). Therefore, we investigated the roles of NO and SOD in glucose-stressed EPCs. METHODS: The functions of circulating EPCs from patients with type 2 diabetes were compared to those from healthy individuals. Healthy EPCs were glucose-stressed, and then treated with insulin and/or SOD. We assessed O2- generation, NO production, SOD activity, and their ability to form colonies. RESULTS: EPCs from diabetic patients generated more O2-, had higher NAD(P)H oxidase and SOD activity, but lower NO bioavailability, and expressed higher mRNA and protein levels of p22-phox, and manganese SOD and copper/zinc SOD than those from the healthy individuals. Plasma glucose and HbA1c levels in the diabetic patients were correlated negatively with the NO production from their EPCs. SOD treatment of glucose-stressed EPCs attenuated O2- generation, restored NO production, and partially restored their ability to form colonies. Insulin treatment of glucose-stressed EPCs increased NO production, but did not change O2- generation and their ability to form colonies. However, their ability to produce NO and to form colonies was fully restored after combined SOD and insulin treatment. CONCLUSION: Our data provide evidence that SOD may play an essential role in EPCs, and emphasize the important role of antioxidant therapy in type 2 diabetic patients.

Role of protein kinase C in the expression of endothelin converting enzyme-1.

Increased expression of endothelin converting enzyme-1 (ECE-1) is associated with diabetic nephropathy. The molecular mechanisms underlying this association, as yet unknown, possibly involve protein kinase C (PKC) pathways. In the present study, we examined the effects of high glucose and PKC activation on ECE-1 expression in primary human umbilical vein endothelial cells (HUVECs) and in HUVEC line (EA.hy926). Increasing glucose concentration, but not mannitol, from 5.5-22.2 mmol/liter for 3 d, enhanced prepro endothelin-1 (ET-1) mRNA expression, ET-1 levels, ECE-1 protein, and mRNA expressions by 7, 4, 20, and 2.6-fold, respectively. High glucose increased ECE-1 protein expression dose and time dependently. By Western blot analysis, PKC-beta1, -beta2, and -delta isoform levels were significantly increased relative to other isoforms when glucose level was increased. Treatment with Rottlerin, a PKC-delta isoform inhibitor, reduced significantly the glucose-induced ET-1 secretion, and ECE-1 protein expression, but (S)-13-[(dimethylamino)methyl]-10,11,14,15-tetrahydro-4,9:16,21-dimetheno 1H,1(3)H-dibenzo[e,k]pyrrolo[3,4-h] (1, 4, 3) oxadiaza-cyclohexadecene-1,3(2H)-dione or Gö6976, specific PKC-beta and -alpha inhibitors, respectively, did not. Overexpression of PKC-delta but not PKC-alpha or -beta1 isoforms by adenovirus vector containing the respective cDNA in HUVECs incubated with 5.5 mmol/liter glucose, increased in parallel PKC proteins, and glucose-induced endothein-1 and ECE-1 protein expression by 4- to 6-fold. These results show that enhanced ECE-1 expression induced by hyperglycemia is partly due to activation of the PKC-delta isoform. Thus, inhibition of this PKC isoform may prevent diabetes-related increase in ET-1.

[Endothelial progenitor cells and atherosclerosis].

The integrity and functional activity of the endothelial monolayer play a crucial role in the prevention of atherosclerosis. Extended endothelial cell damage by cardiovascular risk factors can result in endothelial cell apoptosis with loss of the integrity of the endothelium. Endothelial progenitor cells (EPCs) originating from the bone marrow play a significant role in neovascularization of ischemic tissues and in re-endothelialization of injured blood vessels. This may potentially limit atherosclerotic lesion formation. However, risk factors for coronary artery disease such as age and smoking, hypertension, hyperlipidemia and diabetes reduce the number and functional activity of these circulating endothelial progenitor cells, potentially restricting the therapeutic prospective of progenitor cells and limiting the regenerative capacity. The impairment of EPCs by risk factors may contribute to atherogenesis and atherosclerotic disease progression. The article reviews the role of EPCs as markers for atherosclerosis and cardiovascular outcomes and highlights possible novel strategies to interfere with the balance of injury and repair mechanisms.

Erythropoietin improves myocardial performance in doxorubicin-induced cardiomyopathy.

AIMS: Doxorubicin (Dox) is a potent chemotherapeutic agent associated with severe cardiotoxicity. Erythropoietin (Epo) has recently been shown to exhibit proangiogenic properties related to endothelial progenitor cell (EPC) mobilization. We tested the hypothesis that EPC are compromised in rats with Dox-induced cardiotoxicity and correction of this functional impairment by treatment with Epo could result in attenuation of myocardial dysfunction. METHODS AND RESULTS: Wistar rats were either treated with two different doses of Epo (20U or 200U) or PBS (n = 40 in each group) for four consecutive weeks, followed by Dox administration. In a second study, EPC obtained from healthy rats were transfused intravenously (n = 20/group) prior to induction of Dox cardiomyopathy. EPC from healthy subjects were evaluated for their proliferative and migratory properties in the presence or absence of Dox and Epo pre-treatment. Echocardiography demonstrated an improvement in fractional shortening (FS) in Epo-treated rats. Epo treatment was associated with a reduced mortality in both Epo-treated groups. Circulating EPC numbers were three times higher in Epo-treated compared with non-treated animals. Adhesive properties, migration, and tube formation capacity in matrigel of EPCs from both Epo-treated groups as compared with controls were significantly enhanced. EPC transfer to Dox-treated rats led to functional myocardial improvement equivalent to the protection afforded by treatment with Epo. In EPC obtained from humans, pre-incubation with Epo significantly attenuated the anti-proliferative and anti-migratory effects of treatment with Dox. CONCLUSION: Epo treatment is potentially protective against myocardial dysfunction induced by Dox. These effects are partially mediated by enhancement in the number of EPC and their functional properties.

Erythropoietin promotes endothelial progenitor cell proliferative and adhesive properties in a PI 3-kinase-dependent manner.

OBJECTIVES: Patients with congestive heart failure (CHF) suffer considerable morbidity and mortality despite advances in therapy. Treatment with erythropoietin (Epo) has shown promise in CHF patients, yet its mechanisms of action remain elusive. Endothelial progenitor cells (EPC) contribute to postnatal angiogenesis and vasculogenesis, and Epo was shown to promote EPC mobilization. We explored the effect of chronic treatment with Epo on the numbers and functional properties of EPC in CHF patients. METHODS AND RESULTS: Twenty-eight patients with CHF treated with Epo for a mean period of 28 months were compared to a matched group (n = 28) with regard to the number of circulating hematopoietic and endothelial stem cells (either CD34+, CD34+/CD45+, CD34+/CD133+, CD34+/VEGF-R2+ or CD34+/CD133+/VEGF-R2+) as well as their proliferative and adhesive capacity. In vitro, Epo was added to cultured EPC from healthy subjects to test proliferation and adhesion. No differences were observed in circulating numbers of hematopoietic and endothelial stem cells between CHF patients chronically treated with Epo or untreated. EPC from Epo-treated patients exhibited enhanced proliferation as well as a trend towards adhesion to cultured endothelial cells prior to and following stimulation with TNF-alpha. Addition of Epo to EPC from healthy subjects dose-dependently increased their proliferation and adhesion to fibronectin, cultured endothelial cells, and cardiomyocytes. These effects were significantly reduced in the presence of phosphatidylinositol (PI) 3-kinase inhibitors. CONCLUSIONS: Chronic Epo treatment is associated with an increase in the adhesive and proliferative properties of circulating EPC in patients with CHF.