Transplantation of hypoxia induced GM-CSF expressing mouse neural stem cell in spinal cord injury model
Dept. of Medical Science/박사
Granulocyte-macrophage colony stimulating factor (GM-CSF) is a hematopoietic cytokine and identified to stimulate the differentiation and function of hematopoietic cells. GM-CSF is recently being suggested to play important roles in the nervous system. Present study intended to understand hypoxia induced GM-CSF effects on neural stem cells (NSCs) in a model of spinal cord injury (SCI). GM-CSF over-expressing NSCs were engineered utilizing a hypoxia-inducible gene expression plasmid, which included the Epo enhancer ahead of the SV promoter (EpoSV-GM-CSF). The resulting cells were then subjected either to hypoxia (pO2, 1%) or a hypoxia-mimicking reagent (CoCl2) in vitro. The expression of GM-CSF was tested in time dependent manner in hypoxia by Real-Time PCR and ELISA assay. Using hydrogen peroxide(H2O2), the viability of EpoSV-GM-CSF transfected NSCs were compared with SV-GM-CSF transfected NSCs. After retinoic acid(RA) treatment for 7 days, β-Ⅲ tubulin expression increased in EpoSV-GM-CSF transfected NSCs. EpoSV-GM-CSF transfected NSCs or SV-GM-CSF transfected NSCs were transplanted into rat spinal cord injury model to assess its effect on NSC survival and restoration of function. Over-expression of GM-CSF in both undifferentiated and differentiated NSCs created resistance to H2O2-induced apoptosis in hypoxia. Moreover, after transplantation, a significantly higher amount of surviving NSCs, neuronal differentiation, as well as a significant improvement in locomotor function was observed in the EpoSV-GM-CSF treated group. These results show GM-CSF over-expression by the Epo enhancer in hypoxia was beneficial for transplanted NSC survival, neuronal differentiation, and behavioral improvement, pointing toward a possible role for GM-CSF in spinal cord injury treatment.