Background and Purpose—Recent reports have described the efficacy of the hematopoietic growth factor granulocyte-colony stimulating factor (G-CSF) in animal stroke models. Early clinical multicenter trials evaluating the effect of G-CSF in acute stroke and pilot clinical trials for the subacute phase are ongoing. To guide further development, a meta-analysis was performed to assess the effects of G-CSF on infarct size and sensorimotor deficits.

Methods—Using electronic and manual searches of the literature, we identified studies describing the efficacy of G-CSF in animal models of focal cerebral ischemia. Two reviewers independently selected studies and extracted data on study quality, G-CSF doses, time of administration, and outcome measured as infarct volume and/or sensorimotor deficit. Data from all studies were pooled by meta-regression analyses.

Results—Thirteen studies including 277 animals for infarct size calculation and 258 animals for assessment of sensorimotor deficit met the criteria for inclusion. Overall efficacy of G-CSF regarding infarct size reduction was 42%. Meta-regression analysis revealed a 0.8% (P<0.0001) decrease in infarct size per 1-µg/kg increase in G-CSF dose when applied within the first 6 hours and a 2.1% (P<0.0001) decrease when applied later than 6 hours after induction of ischemia with a significant (P=0.0004) greater infarct size reduction after delayed treatment. Sensorimotor deficits categorized into 3 subgroups improved between 24% and 40%.

Conclusions—Our findings consolidate G-CSF as a drug that both reduces infarct size and enhances functional recovery. These effects are presumably dose dependent. In contrast to most other neuroprotectants, a beneficial outcome may also be achieved when treatment is delayed.