Granulocyte Colony-Stimulating Factor

Cerebrovascular events (stroke) are a significant cause of morbidity and mortality worldwide. Ischemic stroke accounts for ~85% of all strokes and is caused by the blockade of blood flow to a certain area of the brain, resulting in oxygen and nutrient deprivation and ultimately cell death. Cerebral ischemia induces a strong neuroinflammatory response that contributes to tissue damage and is driven by changes in the gene expression profile and phenotype of brain cells including neurons, astrocytes, and microglia. Microglia are the resident immune and phagocytic cells of the central nervous system. They rapidly respond to ischemia by migrating to the site of injury and modulating the inflammatory response there. Although microglia may play a deleterious role in the acute phase of stroke, evidence suggests that they play an important role in the reduction of excitotoxic injury as well as in neurogenesis during the tissue regeneration phase. Granulocyte-colony stimulating factor (G-CSF) is a hematopoietic growth factor that has shown beneficial effects in models of ischemic stroke. G-CSF exerts its neuroprotective effects through different mechanisms including mobilization of haemopoietic stem cells, angiogenesis, neurogenesis, anti-inflammation, and anti-apoptosis. However, its effect on microglia is not well understood yet. The main objective of this project was to evaluate the protective and anti-inflammatory effect of G-CSF gene therapy against glutamate cytotoxicity in the human microglial clone 3 cell line (HMC3). Our results show that although G-CSF gene therapy did not significantly protect HMC3 cells against glutamate induced cell death, it reduced the expression levels of pro-inflammatory proteins NF-κB p65, IL-1β and IL-6, while increasing the phosphorylation of Akt, a regulator of cell survival and proliferation.

Ischemic stroke is defined as a blockage or reduced flow of blood to select areas of brain tissue due to either plaque formation or buildup of blood clots in the small blood vessels. A characteristic of sickle cell anemic patients is the potential for them to experience a similar type of blockage due to the sticky nature of the sickled red blood cells as well as defective oxygen delivery to the brain. Because of this similarity, sickle cell anemia may represent a good animal research model for therapeutic intervention based on stroke models. In recent studies, Granulocyte-Colony Stimulating Factor (GCSF), has been shown to exhibit a robust range of neuroprotective properties against neurological disorders including ischemic stroke through preservation of the endoplasmic reticulum (ER) by modulating various ER stress pathways. Through cognitive deficit analysis in the form of behavioral and locomotor experiments in addition to in situ biomarker analysis by way of western blotting and immunohistochemistry, we found that G-CSF gene therapy exhibited neurogenic and neuroprotective effects in ischemic mouse models and could possibly serve as a good therapy for other diseases that share similar pathology to stroke.