J Neurosurg / Volume 111 / July 2009 J Neurosurg 111:155–163, 2009 155 G ranulocyte-macrophaGe colony-stimulating fac- tor is a member of the hematopoietic cytokine family. The main functions of GM-CSF are to stimulate bone marrow stem cell proliferation and de- crease hematopoietic cell apoptosis, the latter of which Reduction in programmed cell death and improvement in functional outcome of transient focal cerebral ischemia after administration of granulocyte-macrophage colony-stimulating factor in rats Laboratory investigation TaeHo Kong, M.Sc., 1,2 Jung-Kyoung cHoi, M.Sc., 1,2 HyeonSeon P arK, M.D., PH.D., 1,3 Byung Hyune cHoi, PH.D., 1,2 Brian Jeffrey SnyDer, M.D., 4 SHefqaT BuKHari, M.D., 4 na-Kyeong KiM M.Sc., 1,2 Xian Huang, M.D., PH.D., 1,3 So ra P arK, M.D., PH.D., 1,2 Hyung cHun P arK, M.D., PH.D., 1,3 anD y oon Ha, M.D., PH.D. 5 1 Cell Therapy Research Center, 2 Departments of Physiology and Neurosurgery, and 3 School of Medicine, Inha University, Incheon; 5 Department of Neurosurgery, School of Medicine, Yonsei University, Seoul, Korea; and 4 Division of Neurosurgery, Toronto Western Hospital, University Health Network and University of Toronto, Ontario, Canada Object. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent hematopoietic growth fac- tor that both enhances the survival and drives the differentiation and proliferation of myeloid lineage cells. Recent studies have suggested that GM-CSF has a neuroprotective effect against CNS injury. In this paper, the authors in- vestigated the neuroprotective effect of GM-CSF on neuron survival and locomotor behavior in a rat model of focal cerebral ischemic injury. Materials. To understand its neuroprotective effect in vitro, GM-CSF was administered to a glutamate-induced excitotoxicity neuronal injury cell culture model that mimics the pathophysiology of focal hypoxic cerebral injury. In the animal study, the authors prepared a rat focal cerebral ischemia model by occluding the unilateral middle cerebral artery. They then examined the effects of GM-CSF administration on changes in infarct volume, apoptosis-related gene expression, and improvement in locomotor behavior. Results. Treatment with GM-CSF signifcantly increased cell viability in a cell culture model of glutamate- induced neuronal injury. Furthermore, in vivo administration of GM-CSF at 60 μg/kg body weight daily for 5 con- secutive days beginning immediately after injury decreased infarction volume, altered the expression of several apoptosis-related genes (Bcl-2, Bax, caspase 3, and p53), and improved locomotor behavior in the focal cerebral ischemia model. Conclusions. The GM-CSF had neuroprotective effects in in vitro and in vivo experiments and resulted in de- creased infarction volume and improved locomotor behavior. Although the specifc mechanism involved in stroke recovery was not fully elucidated as it was not the primary focus of this study, administration of GM-CSF appeared to decrease the extent of neuronal apoptosis by modulating the expression of several apoptosis-related genes such as Bcl-2, Bax, caspase 3, and p53. Further investigations are necessary to better understand the role of GM-CSF on neural regeneration during the recovery phase of a stroke, as well as the intracellular signal transduction pathways that mediate neuroprotection. (DOI: 10.3171/2008.12.JNS08172) Key WorDS • cerebral ischemia • neuroprotection • granulocyte-macrophage colony-stimulating factor 155 Abbreviations used in this paper: BMC = blood mononuclear cell; G-CSF = granulocyte colony-stimulating factor; GM-CSF = granulocyte-macrophage colony-stimulating factor; GM-CSFR = GM-CSF receptor; PBS = phosphate-buffered saline; RT-PCR = reverse transcription-polymerase chain reaction; SEM = standard error of the mean; TUNEL = terminal deoxynucleotidyl transferase– mediated deoxyuridine triphosphate nick-end labeling. This article contains some figures that are displayed in color online but in black and white in the print edition.