Erythropoietin (EPO) increases myelin gene expression in CG4 oligodendrocyte cells through the classical EPO receptor

Erythropoietin regulates developmental myelination in the brain stimulating postnatal oligodendrocyte maturation

Myelination is a process tightly regulated by a variety of neurotrophic factors. Here, we show-by analyzing two transgenic mouse lines, one overexpressing EPO selectively in the brain Tg21(PDGFB-rhEPO) and another with targeted removal of EPO receptors (EPORs) from oligodendrocyte progenitor cells (OPC)s (Sox10-cre;EpoRfx/fx mice)-a key function for EPO in regulating developmental brain myelination. Overexpression of EPO resulted in faster postnatal brain growth and myelination, an increased number of myelinating oligodendrocytes, faster axonal myelin ensheathment, and improved motor coordination. Conversely, targeted ablation of EPORs from OPCs reduced the number of mature oligodendrocytes and impaired motor coordination during the second postnatal week. Furthermore, we found that EPORs are transiently expressed in the subventricular zone (SVZ) during the second postnatal week and EPO increases the postnatal expression of essential oligodendrocyte pro-differentiation and pro-maturation (Nkx6.2 and Myrf) transcripts, and the Nfatc2/calcineurin pathway. In contrast, ablation of EPORs from OPCs inactivated the Erk1/2 pathway and reduced the postnatal expression of the transcripts. Our results reveal developmental time windows in which EPO therapies could be highly effective for stimulating oligodendrocyte maturation and myelination.

Can Erythropoietin Reduce Hypoxemic Neurological Damages in Neonates With Congenital Heart Defects?

Congenital heart defects (CHD), the most common cause of birth defects with increasing birth prevalence, affect nearly 1% of live births worldwide. Cyanotic CHD are characterized by hypoxemia, with subsequent reduced oxygen delivery to the brain, especially critical during brain development, beginning in the fetus and continuing through the neonatal period. Therefore, neonates with CHD carry a high risk for neurological comorbidities, even more frequently when there are associated underlying genetic disorders. We review the currently available knowledge on potential prevention strategies to reduce brain damage induced by hypoxemia during fetal development and immediately after birth, and the role of erythropoietin (EPO) as a potential adjunctive treatment. Maternal hyper-oxygenation had been studied as a potential therapeutic to improve fetal oxygenation. Despite demonstrating some effectiveness, maternal hyper-oxygenation has proven to be impractical for extensive clinical application, thus prompting the investigation of specific pathways for pharmacological intervention. Among those, the role of antioxidant pathways and Hypoxia Inducible Factors (HIF) have been studied for their involvement in the protective response to hypoxic injury. One of the proteins induced by HIF, EPO, has properties of being anti-apoptotic, antioxidant, and protective for neurons, astrocytes, and oligodendrocytes. In human trials, EPO administration in neonates with hypoxic ischemic encephalopathy (HIE) significantly reduced the neurological hypoxemic damages in several reported studies. Currently, it is unknown if the mechanisms of pathophysiology of cyanotic CHD are like HIE. Neonates with cyanotic CHD are exposed to both chronic hypoxemia and episodes of acute ischemia-reperfusion injury when undergo cardiopulmonary bypass surgery requiring aortic cross-clamp and general anesthesia. Our review supports future trials to evaluate the potential efficiency of EPO in reducing the hypoxemic neurologic damages in neonates with CHD. Furthermore, it suggests the need to identify early biomarkers of hypoxia-induced neurological damage, which must be sensitive to the neuroprotective effects of EPO.

Functional recovery with histomorphometric analysis of nerves and muscles after combination treatment with erythropoietin and dexamethasone in acute peripheral nerve injury

Introduction

Peripheral nerve injury (PNI) often leads to significant functional loss in patients and poses a challenge to physicians since treatment options for improving functional outcomes are limited. Recent studies suggest that erythropoietin and glucocoticoids have beneficial effects as mediators of neuro-regenerative processes. We hypothesized that combination treatment with erythropoietin and glucocoticoids would have a synergistic effect on functional outcome after PNI.

Materials and methods

Sciatic nerve crush injury was simulated in ten-week-old male C57BL/6 mice. The mice were divided into four groups according to the type of drugs administered (control, erythropoietin, dexamethasone, and erythropoietin with dexamethasone). Motor functional recovery was monitored by walking track analysis at serial time points up to 28 days after injury. Morphological analysis of the nerve was performed by immunofluorescent staining for neurofilament (NF) heavy chain and myelin protein zero (P0) in cross-sectional and whole-mount nerve preparations. Additionally, morphological analysis of the muscle was performed by Hematoxylin and eosin staining.

Results

Combination treatment with erythropoietin and dexamethasone significantly improved the sciatic functional index at 3, 7, 14, and 28 days after injury. Fluorescence microscopy of cross sectional nerve revealed that the combination treatment increased the ratio of P0/NF-expressing axons. Furthermore, confocal microscopy of the whole-mount nerve revealed that the combination treatment increased the fluorescence intensity of P0 expression. The cross-sectional area and minimum Feret’s diameter of the muscle fibers were significantly larger in the mice which received combination treatment than those in the controls.

Conclusion

Our results demonstrated that combination treatment with erythropoietin and dexamethasone accelerates functional recovery and reduces neurogenic muscle atrophy caused by PNI in mice, which may be attributed to the preservation of myelin and Schwann cell re-myelination. These findings may provide practical therapeutic options for patients with acute PNI.

Vitamins D3 and D2 have marked but different global effects on gene expression in a rat oligodendrocyte precursor cell line

Background

Vitamin D deficiency increases the risk of developing multiple sclerosis (MS) but it is unclear whether vitamin D supplementation improves the clinical course of MS, and there is uncertainty about the dose and form of vitamin D (D2 or D3) to be used. The mechanisms underlying the effects of vitamin D in MS are not clear. Vitamin D3 increases the rate of differentiation of primary oligodendrocyte precursor cells (OPCs), suggesting that it might help remyelination in addition to modulating the immune response. Here we analyzed the transcriptome of differentiating rat CG4 OPCs treated with vitamin D2 or with vitamin D3 at 24 h and 72 h following onset of differentiation.

Methods

Gene expression in differentiating CG4 cells in response to vitamin D2 or D3 was quantified using Agilent DNA microarrays (n = 4 replicates), and the transcriptome data were processed and analysed using the R software environment. Differential expression between the experimental conditions was determined using LIMMA, applying the Benjamini and Hochberg multiple testing correction to p-values, and significant genes were grouped into co-expression clusters by hierarchical clustering. The functional significance of gene groups was explored by pathway enrichment analysis using the clusterProfiler package.

Results

Differentiation alone changed the expression of about 10% of the genes at 72 h compared to 24 h. Vitamin D2 and D3 exerted different effects on gene expression, with D3 influencing 1272 genes and D2 574 at 24 h. The expression of the vast majority of these genes was either not changed in differentiating cells not exposed to vitamin D or followed the same trajectory as the latter. D3-repressed genes were enriched for Gene Ontology (GO) categories including transcription factors and the Notch pathway, while D3-induced genes were enriched for the Ras pathway.

Conclusions

This study shows that vitamin D3, compared with D2, changes the expression of a larger number of genes in OLs. Identification of genes affected by D3 in OLs should help to identify mechanisms mediating its action in MS.

3D Bioprinting of Novel Biocompatible Scaffolds for Endothelial Cell Repair

The aim of this study was to develop and evaluate an optimized 3D bioprinting technology in order to fabricate novel scaffolds for the application of endothelial cell repair. Various biocompatible and biodegradable macroporous scaffolds (D = 10 mm) with interconnected pores (D = ~500 µm) were fabricated using a commercially available 3D bioprinter (r3bEL mini, SE3D, USA). The resolution of the printing layers was set at ~100 µm for all scaffolds. Various compositions of polylactic acid (PLA), polyethylene glycol (PEG) and pluronic F127 (F127) formulations were prepared and optimized to develop semi-solid viscous bioinks. Either dimethyloxalylglycine (DMOG) or erythroprotein (EPO) was used as a model drug and loaded in the viscous biocompatible ink formulations with a final concentration of 30% (w/w). The surface analysis of the bioinks via a spectroscopic analysis revealed a homogenous distribution of the forming materials throughout the surface, whereas SEM imaging of the scaffolds showed a smooth surface with homogenous macro-porous texture and precise pore size. The rheological and mechanical analyses showed optimum rheological and mechanical properties of each scaffold. As the drug, DMOG, is a HIF-1 inducer, its release from the scaffolds into PBS solution was measured indirectly using a bioassay for HIF-1α. This showed that the release of DMOG was sustained over 48 h. The release of DMOG was enough to cause a significant increase in HIF-1α levels in the bioassay, and when incubated with rat aortic endothelial cells (RAECs) for 2 h resulted in transcriptional activation of a HIF-1α target gene (VEGF). The optimum time for the increased expression of VEGF gene was approximately 30 min and was a 3-4-fold increase above baseline. This study provides a proof of concept, that a novel bioprinting platform can be exploited to develop biodegradable composite scaffolds for potential clinical applications in endothelial cell repair in cardiovascular disease (CVD), or in other conditions in which endothelial damage occurs.

Peripheral nerve injury and myelination: Potential therapeutic strategies

Traumatic peripheral nerve injury represents a major clinical and public health problem that often leads to significant functional impairment and permanent disability. Despite modern diagnostic procedures and advanced microsurgical techniques, functional recovery after peripheral nerve repair is often unsatisfactory. Therefore, there is an unmet need for new therapeutic or adjunctive strategies to promote the functional recovery in nerve injury patients. In contrast to the central nervous system, Schwann cells in the peripheral nervous system play a pivotal role in several aspects of nerve repair such as degeneration, remyelination, and axonal growth. Several non-surgical approaches, including pharmacological, electrical, cell-based, and laser therapies, have been employed to promote myelination and enhance functional recovery after peripheral nerve injury. This review will succinctly discuss the potential therapeutic strategies in the context of myelination following peripheral neurotrauma.

Leukemia inhibitory factor inhibits erythropoietin-induced myelin gene expression in oligodendrocytes

Background

The pro-myelinating effects of leukemia inhibitory factor (LIF) and other cytokines of the gp130 family, including oncostatin M (OSM) and ciliary neurotrophic factor (CNTF), have long been known, but controversial results have also been reported. We recently overexpressed erythropoietin receptor (EPOR) in rat central glia-4 (CG4) oligodendrocyte progenitor cells (OPCs) to study the mechanisms mediating the pro-myelinating effects of erythropoietin (EPO). In this study, we investigated the effect of co-treatment with EPO and LIF.

Methods

Gene expression in undifferentiated and differentiating CG4 cells in response to EPO and LIF was analysed by DNA microarrays and by RT-qPCR. Experiments were performed in biological replicates of N ≥ 4. Functional annotation and biological term enrichment was performed using DAVID (Database for Annotation, Visualization and Integrated Discovery). The gene-gene interaction network was visualised using STRING (Search Tool for the Retrieval of Interacting Genes).

Results

In CG4 cells treated with 10 ng/ml of EPO and 10 ng/ml of LIF, EPO-induced myelin oligodendrocyte glycoprotein (MOG) expression, measured at day 3 of differentiation, was inhibited ≥4-fold (N = 5, P < 0.001). Inhibition of EPO-induced MOG was also observed with OSM and CNTF. Analysis of the gene expression profile of CG4 differentiating cells treated for 20 h with EPO and LIF revealed LIF inhibition of EPO-induced genes involved in lipid transport and metabolism, previously identified as positive regulators of myelination in this system. In addition, among the genes induced by LIF, and not by differentiation or by EPO, the role of suppressor of cytokine signaling 3 (SOCS3) and toll like receptor 2 (TLR2) as negative regulators of myelination was further explored. LIF-induced SOCS3 was associated with MOG inhibition; Pam3, an agonist of TLR2, inhibited EPO-induced MOG expression, suggesting that TLR2 is functional and its activation decreases myelination.

Conclusions

Cytokines of the gp130 family may have negative effects on myelination, depending on the cytokine environment.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0052-3) contains supplementary material, which is available to authorized users.

Erythropoietin Increases Myelination in Oligodendrocytes: Gene Expression Profiling Reveals Early Induction of Genes Involved in Lipid Transport and Metabolism

Several studies have shown that erythropoietin (EPO) has neuroprotective or neuroreparative actions on diseases of the nervous system and that improves oligodendrocyte (OL) differentiation and myelination in vivo and in vitro. This study aims at investigating the early molecular mechanisms for the pro-myelinating action of EPO at the gene expression level. For this purpose, we used a differentiating OL precursor cell line, rat central glia-4 cells. Cells were differentiated or not, and then treated with EPO for 1 or 20 h. RNA was extracted and changes in the gene expression profile were assessed using microarray analysis. Experiments were performed in biological replicates of n = 4. Differentiation alone changed the expression of 11% of transcripts (2,663 out of 24,272), representing 2,436 genes, half of which were upregulated and half downregulated. At 20 h of treatment, EPO significantly affected the expression of 99 genes that were already regulated by differentiation and of 150 genes that were not influenced by differentiation alone. Analysis of the transcripts most upregulated by EPO identified several genes involved in lipid transport (e.g., Cd36) and lipid metabolism (Ppargc1a/Pgc1alpha, Lpin1, Pnlip, Lpin2, Ppard, Plin2) along with Igf1 and Igf2, growth factors known for their pro-myelinating action. All these genes were only induced by EPO and not by differentiation alone, except for Pnlip which was highly induced by differentiation and augmented by EPO. Results were validated by quantitative PCR. These findings suggest that EPO might increase remyelination by inducing insulin-like growth factors and increasing lipid metabolism.

Erythropoietin reduces experimental autoimmune encephalomyelitis severity via neuroprotective mechanisms

BACKGROUND

Treatment with erythropoietin (Epo) in experimental autoimmune encephalomyelitis (EAE), the rodent model of multiple sclerosis (MS), has consistently been shown to ameliorate disease progression and improve overall outcome. The effect has been attributed to modulation of the immune response and/or preservation of the central nervous system (CNS) tissue integrity. It remains unclear, however, if (a) Epo acts primarily in the CNS or the periphery and if (b) Epo's beneficial effect in EAE is mainly due to maintaining CNS tissue integrity or to modulation of the immune response. If Epo acts primarily by modulating the immune system, where is this modulation required? In the periphery, the CNS or both?

METHODS

To address these questions, we used two well-characterized transgenic mouse strains that constitutively overexpress recombinant human Epo (rhEpo) either systemically (tg6) or in CNS only (tg21) in a MOG-induced EAE model. We assessed clinical severity, disease progression, immunomodulation, and CNS tissue integrity, including neuronal survival.

RESULTS

Although disease onset remained unaffected, EAE progression was alleviated in transgenic animals compared to controls with both lines performing equally well showing that expression of Epo in the periphery is not required; Epo expression in the CNS is sufficient. Immunomodulation was observed in both strains but surprisingly the profile of modulation differed substantially between strains. Modulation in the tg21 strain was limited to a reduction in macrophages in the CNS, with no peripheral immunomodulatory effects observed. In contrast, in the tg6 strain, macrophages were upregulated in the CNS, and, in the periphery of this strain, T cells and macrophages were downregulated. The lack of a consistent immunomodulatory profile across both transgenic species suggests that immunomodulation by Epo is unlikely to be the primary mechanism driving amelioration of EAE. Finally, CNS tissue integrity was affected in all strains. Although myelin appeared equally damaged in all strains, neuronal survival was significantly improved in the spinal cord of tg21 mice, indicating that Epo may ameliorate EAE predominantly by protecting neurons.

CONCLUSIONS

Our data suggests that moderate elevated brain Epo levels provide clinically significant neuroprotection in EAE without modulation of the immune response making a significant contribution.

Erythropoietin accelerates functional recovery after moderate sciatic nerve crush injury

INTRODUCTION

Erythropoietin (EPO) has been identified as a neuroregenerative agent. We hypothesize that it may accelerate recovery after crush injury and may vary with crush severity.

METHODS

Mice were randomized to mild, moderate, or severe crush of the sciatic nerve and were treated with EPO or vehicle control after injury. The sciatic function index (SFI) was monitored over the first week. Microstructural changes were analyzed by immunofluorescence for neurofilament (NF) and myelin (P₀ ), and electron microscopy was used to assess ultrastructural changes.

RESULTS

In moderate crush injuries, EPO significantly improved SFI at 7 days post-injury, an effect not observed with other severity levels. Increases in the ratio of P₀ to NF were observed after EPO treatment in moderate crush injuries. Electron microscopy demonstrated endothelial cell hypertrophy in the EPO group.

CONCLUSIONS

EPO accelerates recovery in moderately crushed nerves, which may be through effects on myelination and vascularization. Injury severity may influence the efficacy of EPO. Muscle Nerve 56: 143-151, 2017.

Hemoglobins as new players in multiple sclerosis: metabolic and immune aspects

Basic science investigations and clinical observations in recent years indicate that hemoglobins (Hbs) may have important roles in the pathogenesis of multiple sclerosis (MS). These findings can be summarized as follows: 1- Erythrocyte fragility is higher in MS patients, the released free Hb damages blood-brain barrier, myelin basic protein and also triggers iron overload and inflammation. 2- Free Hb may further activate the inflammatory responses through Toll-like receptor 4 (TLR4), present on microglia and other innate immunocytes. 3- Hbs are expressed in neural cells including dopaminergic neurons. Also, several studies have demonstrated that Hbs are expressed in astrocytes and oligodendroglia. 4- Hb overexpression in neural cells upregulate mitochondrial complex I-V subunits. The comparison of the mitochondrial proteome between healthy and patients with MS revealed only four differentially expressed proteins including Hb β-chain. 5- Microarray analysis of 8300 genes in monocytes of twins with and without MS showed a difference in 25 genes that include genes encoding α- and β-globins as well. 6- β- and α-globin gene clusters reside at chromosomal regions 11p15.5 and 16p13.3, respectively. Whole genome screen (WGS) in Sardinian MS families using 327 markers revealed linkage in 3 regions including 11p15.5 loci. Further, 11p15.5 and 16p13.3 were part of the 17 regions identified in the WGS study of 136 sibling-pairs in Nordic countries analyzing 399 microsatellite markers. In the light of these findings, we propose that free Hb released from dying erythrocytes is detrimental. On the contrary, intracellular Hbs in neural cells are protective in MS. The genomic linkage findings can be explained by common haematologically-silent Hb variants that may lower the protective function of intracellular Hbs, and therefore, enhance the risk for MS. In the absence of such variants, aberrations in the translational and post-translational mechanisms controlling synthesis of neural Hbs may also enhance the vulnerability to MS. Alternatively, such genetic variants may perturb the metabolism of anti-inflammatory hemorphins produced via cleavage of Hbs.

Erythropoietin and a nonerythropoietic peptide analog promote aortic endothelial cell repair under hypoxic conditions: role of nitric oxide

The cytoprotective effects of erythropoietin (EPO) and an EPO-related nonerythropoietic analog, pyroglutamate helix B surface peptide (pHBSP), were investigated in an in vitro model of bovine aortic endothelial cell injury under normoxic (21% O₂) and hypoxic (1% O₂) conditions. The potential molecular mechanisms of these effects were also explored. Using a model of endothelial injury (the scratch assay), we found that, under hypoxic conditions, EPO and pHBSP enhanced scratch closure by promoting cell migration and proliferation, but did not show any effect under normoxic conditions. Furthermore, EPO protected bovine aortic endothelial cells from staurosporine-induced apoptosis under hypoxic conditions. The priming effect of hypoxia was associated with stabilization of hypoxia inducible factor-1α, EPO receptor upregulation, and decreased Ser-1177 phosphorylation of endothelial nitric oxide synthase (NOS); the effect of hypoxia on the latter was rescued by EPO. Hypoxia was associated with a reduction in nitric oxide (NO) production as assessed by its oxidation products, nitrite and nitrate, consistent with the oxygen requirement for endogenous production of NO by endothelial NOS. However, while EPO did not affect NO formation in normoxia, it markedly increased NO production, in a manner sensitive to NOS inhibition, under hypoxic conditions. These data are consistent with the notion that the tissue-protective actions of EPO-related cytokines in pathophysiological settings associated with poor oxygenation are mediated by NO. These findings may be particularly relevant to atherogenesis and postangioplasty restenosis.

Unwrapping Neurotrophic Cytokines and Histone Modification

The conventional view that neuroinflammatory lesions contain strictly pro- and anti-inflammatory cytokines is being challenged. Some proinflammatory products e.g. TNF-α are crucial intermediates in axon regeneration, oligodendroglial renewal and remyelination. A more functional system of nomenclature classifies cytokines by their neuro 'protective' or 'suppressive' properties. Beyond the balance of these 'environmental' or 'extrinsic' signals, specific 'intrinsic' determinants of cytokine signalling appear to influence the outcome of axoglial regeneration. In this commentary, we examine the potential importance of cytokine-induced histone modification on oligodendrocyte differentiation. Neuroinflammation mediates the release of astrocytic leukaemia inhibitory factor (LIF) and erythropoietin (EPO) which potentiates oligodendrocyte differentiation and myelin production. Meanwhile, histone deacetylation strongly suppresses important inhibitors of oligodendrocyte differentiation. Given that LIF and EPO induce histone deacetylases in other systems, future studies should examine whether this mechanism significantly influences the outcome of cytokine-induced remyelination, and whether epigenetic drug targets could potentiate the effects of exogenous cytokine therapy.

Low Oxygen Tension Primes Aortic Endothelial Cells to the Reparative Effect of Tissue-Protective Cytokines

Erythropoietin (EPO) has both erythropoietic and tissue-protective properties. The EPO analogues carbamylated EPO (CEPO) and pyroglutamate helix B surface peptide (pHBSP) lack the erythropoietic activity of EPO but retain the tissue-protective properties that are mediated by a heterocomplex of EPO receptor (EPOR) and the β common receptor (βCR). We studied the action of EPO and its analogues in a model of wound healing where a bovine aortic endothelial cells (BAECs) monolayer was scratched and the scratch closure was assessed over 24 h under different oxygen concentrations. We related the effects of EPO and its analogues on repair to their effect on BAECs proliferation and migration (evaluated using a micro-Boyden chamber). EPO, CEPO and pHBSP enhanced scratch closure only at lower oxygen (5%), while their effect at atmospheric oxygen (21%) was not significant. The mRNA expression of EPOR was doubled in 5% compared with 21% oxygen, and this was associated with increased EPOR assessed by immunofluorescence and Western blot. By contrast, βCR mRNA levels were similar in 5% and 21% oxygen. EPO and its analogues increased both BAECs proliferation and migration, suggesting that both may be involved in the reparative process. The priming effect of low oxygen tension on the action of tissue-protective cytokines may be of relevance to vascular disease, including atherogenesis and restenosis.

Definition of a Family of Tissue-Protective Cytokines Using Functional Cluster Analysis: A Proof-of-Concept Study

The discovery of the tissue-protective activities of erythropoietin (EPO) has underlined the importance of some cytokines in tissue-protection, repair, and remodeling. As such activities have been reported for other cytokines, we asked whether we could define a class of tissue-protective cytokines. We therefore explored a novel approach based on functional clustering. In this pilot study, we started by analyzing a small number of cytokines (30). We functionally classified the 30 cytokines according to their interactions by using the bioinformatics tool STRING (Search Tool for the Retrieval of Interacting Genes), followed by hierarchical cluster analysis. The results of this functional clustering were different from those obtained by clustering cytokines simply according to their sequence. We previously reported that the protective activity of EPO in a model of cerebral ischemia was paralleled by an upregulation of synaptic plasticity genes, particularly early growth response 2 (EGR2). To assess the predictivity of functional clustering, we tested some of the cytokines clustering close to EPO (interleukin-11, IL-11; kit ligand, KITLG; leukemia inhibitory factor, LIF; thrombopoietin, THPO) in an in vitro model of human neuronal cells for their ability to induce EGR2. Two of these, LIF and IL-11, induced EGR2 expression. Although these data would need to be extended to a larger number of cytokines and the biological validation should be done using more robust in vivo models, rather then just one cell line, this study shows the feasibility of this approach. This type of functional cluster analysis could be extended to other fields of cytokine research and help design biological experiments.

Effects of erythropoietin in murine-induced pluripotent cell-derived panneural progenitor cells

Induced cell fate changes by reprogramming of somatic cells offers an efficient strategy to generate autologous pluripotent stem (iPS) cells from any adult cell type. The potential of iPS cells to differentiate into various cell types is well established, however the efficiency to produce functional neurons from iPS cells remains modest. Here, we generated panneural progenitor cells (pNPCs) from mouse iPS cells and investigated the effect of the neurotrophic growth factor erythropoietin (EPO) on their survival, proliferation and neurodifferentiation. Under neural differentiation conditions, iPS-derived pNPCs gave rise to microtubule-associated protein-2 positive neuronlike cells (34% to 43%) and platelet-derived growth factor receptor positive oligodendrocytelike cells (21% to 25%) while less than 1% of the cells expressed the astrocytic marker glial fibrillary acidic protein. Neuronlike cells generated action potentials and developed active presynaptic terminals. The pNPCs expressed EPO receptor (EPOR) mRNA and displayed functional EPOR signaling. In proliferating cultures, EPO (0.1-3 U/mL) slightly improved pNPC survival but reduced cell proliferation and neurosphere formation in a concentration-dependent manner. In differentiating cultures EPO facilitated neurodifferentiation as assessed by the increased number of β-III-tubulin positive neurons. Our results show that EPO inhibits iPS pNPC self-renewal and promotes neurogenesis.