Restoration of microglial function by granulocyte-colony stimulating factor in ALS model mice.

We studied the effects of G-CSF on microglial reactions in mutant SOD1 (mSOD1)-Tg (G93A) ALS model mice. Following hypoglossal axotomy, the numbers of neurons and microglia expressing GDNF were significantly lower in mSOD1-Tg mice than in non-transgenic (NTG) littermates. This decrease in the number of neurons after axotomy and a decrease in the number of large myelinated axons in mSOD1-Tg mice over the disease course were improved by G-CSF, which also increased microglial recruitment. Impaired migration of cultured mSOD1-Tg microglia to MCP-1 was recovered following G-CSF treatment. Restoration of microglial responses by G-CSF may contribute to its neuroprotective effects.