Erythropoietin attenuates hypertrophy of neonatal rat cardiac myocytes induced by angiotensin-II in vitro

EPO modified MSCs can inhibit asthmatic airway remodeling in an animal model

There was no effective measures can be obtained at present to reverse or prevent airway remodeling. We investigated the therapeutic effect of Erythropoietin (EPO) gene modified mesenchymal stem cells (MSCs) on asthmatic airway remodeling and the possible underlied molecular mechanisms. EPO gene was transfected into MSCs via lentivirus vector. The transfected cells (EPO-MSCs) were identified by flow cytometry and the EPO secreting function was detected by PCR and Western blot. MSCs or EPO-MSCs were administrated to albumin (OVA)-induced chronic asthmatic mouse model via tail veins. The asthmatic phenotype was analyzed. Number of cells in bronchoalveolar lavage fluid (BALF) was counted using a hemocytometer. Histological findings of airways were evaluated by microscopic examination. The concentrations of interleukin 4(IL-4), interleukin 5(IL-5), and interleukin 13(IL-13) in lung homogenate were determined by ELISA. The activation state of transforming growth factor-β 1 (TGF-β1), Transforming growth factor beta-activated kinase 1 (TAK1), and p38 Mitogen Activated Protein Kinase (p38MAPK) signaling was detected by Real-Time PCR and Western blotting. EPO-MSCs were successfully constructed. EPO-MSCs showed a more potently suppressive effect on local asthmatic airway inflammation and the level of IL-4, IL-5, and IL-13 in lung tissue than MSCs. Moreover, the numbers of goblet cells, the thicknesses of smooth muscle layer, collagen density, percentage of proliferating cell nuclear antigen positive (PCNA⁺ ) mesenchymal cells, and von Willebrand factor positive(vWF⁺ ) vessels were also significantly inhibited by EPO-MSCs. Furthermore, EPO-MSCs could downregulate the expression of TGF-β1, TAK1, and p38MAPK in lung tissue both in mRNA level and in protein level. EPO gene modified MSCs may more efficiently attenuate asthmatic airway remodeling, which maybe related with the downregulation of TGF-β1-TAK1-p38MAPK pathway activity.

Effect of Erythropoietin in patients with acute myocardial infarction: five-year results of the REVIVAL-3 trial

BACKGROUND

Erythropoietin (EPO) has been suggested to promote cardiac repair after MI. However, the randomized, double-blind, placebo controlled REVIVAL-3 trial showed that short term high dose EPO in timely reperfused myocardium does not improve left ventricular ejection fraction after 6 months. Moreover, the study raised safety concerns due to a trend towards a higher incidence of adverse clinical events as well as a increase in neointima formation after treatment with EPO. The present study therefore aimed to assess the 5-year clinical outcomes.

METHODS

After successful reperfusion 138 patients with STEMI were randomly assigned to receive epoetin beta (3.33×10⁴ U, n = 68) or placebo (n = 70) immediately, 24 and 48 h after percutaneous coronary intervention. The primary outcome of the present study- the combined incidence of MACE 5 years after randomization - occurred in 25% of the patients assigned to epoetin beta and 17% of the patients assigned to placebo (RR 1.5; 95% CI 0.8-3.5; p = 0.26). Target lesion revascularization was required in 15 patients (22.1%) treated with epoetin-ß and 9 patients (12.9%) treated with placebo (p = 0.15). Analysis of patients in the upper and lower quartile of baseline hemoglobin as an indirect estimate of endogenous erythropoietin levels revealed no significant impact of endogenous erythropoietin on efficiency of exogen administered epoetin-ß in terms of death and MACE.

CONCLUSION

These long-term follow-up data show that epoetin beta does not improve clinical outcomes of patients with acute myocardial infarction.

TRIAL REGISTRATION

URL www.clinicaltrials.gov ; Unique identifier NCT00390832; trial registration date October 19th 2006.

Fibronectin and transforming growth factor beta contribute to erythropoietin resistance and maladaptive cardiac hypertrophy

The use of recombinant human erythropoietin (rhEPO) to promote repair and minimize cardiac hypertrophy after myocardial infarction has had disappointing outcomes in clinical trials. We hypothesized that the beneficial non-hematopoietic effects of rhEPO against cardiac hypertrophy could be offset by the molecular changes initiated by rhEPO itself, leading to rhEPO resistance or maladaptive hypertrophy. This hypothesis was investigated using an isoproterenol-induced model of myocardial infarct and cardiac remodelling with emphasis on hypertrophy. In h9c2 cardiomyocytes, rhEPO decreased isoproterenol-induced hypertrophy, and the expression of the pro-fibrotic factors fibronectin, alpha smooth muscle actin and transforming growth factor beta-1 (TGF-β1). In contrast, by itself, rhEPO increased the expression of fibronectin and TGF-β1. Exogenous TGF-β1 induced a significant increase in hypertrophy, which was further potentiated by rhEPO. Exogenous fibronectin not only induced hypertrophy of cardiomyocytes, but also conferred resistance to rhEPO treatment. Based on these findings we propose that the outcome of rhEPO treatment for myocardial infarction is determined by the baseline concentrations of fibronectin and TGF-β1. If endogenous fibronectin or TGF-β levels are above a certain threshold, they could cause resistance to rhEPO therapy and enhancement of cardiac hypertrophy, respectively, leading to maladaptive hypertrophy.

EPC-derived microvesicles protect cardiomyocytes from Ang II-induced hypertrophy and apoptosis

Cell-released microvesicles (MVs) represent a novel way of cell-to-cell communication. Previous evidence indicates that endothelial progenitor cells (EPCs)-derived MVs can modulate endothelial cell survival and proliferation. In this study, we evaluated whether EPC-MVs protect cardiomyocytes (CMs) against angiotensin II (Ang II)-induced hypertrophy and apoptosis. The H9c2 CMs were exposed to Ang II in the presence or absence of EPC-MVs. Cell viability, apoptosis, surface area and β-myosin heavy chain (β-MHC) expression were analyzed. Meanwhile, reactive oxygen species (ROS), serine/threonine kinase (Akt), endothelial nitric oxide synthase (eNOS), and their phosphorylated proteins (p-Akt, p-eNOS) were measured. Phosphatidylinositol-3-kinase (PI3K) and NOS inhibitors were used for pathway verification. The role of MV-carried RNAs in mediating these effects was also explored. Results showed 1) EPC-MVs were able to protect CMs against Ang II-induced changes in cell viability, apoptosis, surface area, β-MHC expression and ROS over-production; 2) The effects were accompanied with the up-regulation of Akt/p-Akt and its downstream eNOS/p-eNOS, and were abolished by PI3K inhibition or partially blocked by NOS inhibition; 3) Depletion of RNAs from EPC-MVs partially or totally eliminated the effects of EPC-MVs. Our data indicate that EPC-MVs protect CMs from hypertrophy and apoptosis through activating the PI3K/Akt/eNOS pathway via the RNAs carried by EPC-MVs.

Erythropoietin and the heart: physiological effects and the therapeutic perspective

Erythropoietin (Epo) has been thought to act exclusively on erythroid progenitor cells. The identification of Epo receptor (EpoR) in non-haematopoietic cells and tissues including neurons, astrocytes, microglia, immune cells, cancer cell lines, endothelial cells, bone marrow stromal cells, as well as cells of myocardium, reproductive system, gastrointestinal tract, kidney, pancreas and skeletal muscle indicates that Epo has pleiotropic actions. Epo shows signals through protein kinases, anti-apoptotic proteins and transcription factors. In light of interest of administering recombinant human erythropoietin (rhEpo) and its analogues for limiting infarct size and left ventricular (LV) remodelling after acute myocardial infarction (AMI) in humans, the foremost studies utilising rhEpo are reviewed. The putative mechanisms involved in Epo-induced cardioprotection are related to the antiapoptotic, anti-inflammatory and angiogenic effects of Epo. Thus, cardioprotective potentials of rhEpo are reviewed in this article by focusing on clinical applicability. An overview of non-haematopoietic Epo analogues, which are a reliable alternative to the classic EpoR agonists and may prevent undesired side effects, is also provided.