411 STEM CELLS AND DEVELOPMENT Volume 18, Number 3, 2009 © Mary Ann Liebert, Inc. DOI: 10.1089/scd.2008.0040 Erythropoietin Increases the Motility of Human Bone Marrow-Multipotent Stromal Cells (hBM-MSCs) and Enhances the Production of Neurotrophic Factors From hBM-MSCs Seong-Ho Koh, 1 Min Young Noh, 1 Goang Won Cho, 1 Kyung Suk Kim, 2 and Seung Hyun Kim 1 Cell therapy has been extensively studied as an approach to repair damage in nervous system diseases. Multipotent stromal cells [MSCs] are well known to have neuroprotective effects and neural differentiation potential. The ability to induce migration of MSCs near nervous system damage via direct transplantation or via intravenous injections and increase the secretion of neurotrophic factors from MSCs might improve our abil- ity to repair damage to the nervous system through cell therapy. In the present study, we investigated whether recombinant human erythropoietin [rhEPO], known to have a hematopoietic effect, could increase the motil- ity of human bone marrow [hBM]-MSCs and enhance production of neurotrophic factors from hBM-MSCs. Based on the results of our MTT assay, trypan blue staining, and bromodeoxyuridine ELISA, rhEPO treatment increases the viability of MSCs but not their proliferation. With a migration assay kit, we demonstrated that the motility of hBM-MSCs was enhanced in rhEPO-treated cells. Immunoblotting assays revealed increased expression of phospho-Akt, phospho-GSK-3β, phospho-extracellular signal-regulated kinase (ERK), β PAK- interacting exchange factor (PIX), CXCR4, phospho tyrosine kinase B (TrkB), and vascular endothelial growth factor receptor-2 [VEGFR-2] in rhEPO-treated cells. Reverse transcription-polymerase chain reaction and gelatin zymography demonstrated that rhEPO treatment induces MMP-2 mRNA level and activity. In the studies using ELISAs, we found that rhEPO could increase levels of stromal cell–derived factor-1 α, VEGF, and brain-derived neurotrophic factors. These fndings suggest that rhEPO can increase the viability and motility of hBM-MSCs by affecting various intracellular signals including Akt, ERK, β-PIX, CXCR4, TrkB, VEGFR-2, and MMP-2 and can enhance the production of neurotrophic factors from hBM-MSCs. Introduction M ultipotent stromal cells [MSCs] have been exten- sively studied for use in cell-based therapies for vari- ous diseases of the nervous system. In repairing damage of the nervous system, the motility of MSCs might be important because stem cells migrate to the sites of pathological insult in various types of brain injury [1–6]. Therefore, the mechanisms of stem cell migration are being investigated [7–9]. It is possi- ble that increasing the motility of MSCs may be useful for the treatment of nervous system diseases. However, a method to induce an increase in MSC motility has not yet been reported. Recent studies have also shown that the neuroprotective effects of neurotrophic factors produced by MSCs, as well as the potential of MSCs to differentiate into neural cells, might be useful for the treatment or modifcation of nervous system diseases [10–14]. Neurotrophic factors produced by MSCs include brain-derived neurotrophic factors (BDNF) [15], nerve growth factor (NGF) [15], stromal cell–derived factor-1 (SDF-1) [16], and vascular endothelial growth factor (VEGF) [17]. Therefore, fnding a way to enhance the pro- duction of neurotrophic factors by MSCs may increase the usefulness of stem cell therapy for nervous system diseases. Recently, it has been reported that erythropoietin (EPO), a hematopoietic factor, can affect angiogenic potency and regulate the production of neuronal progenitor cells from neural stem cells [18–20]. EPO modulates various cellular signal transduction pathways in pluripotent stem cells to perform multiple functions other than erythropoiesis, and EPO inhibits the induction of apoptosis via activation of diverse signaling kinases [21–23]. 1 Department of Neurology, College of Medicine, Hanyang University, Seoul, Korea. 2 Bioengineering Institute, CoreStem Inc., Seoul, Korea.