Granulocyte Colony-Stimulating Factor Significantly Decreases Density Of Hippocampal Caspase 3-Positive Nuclei, Thus Ameliorating Apoptosis-Mediated Damage, In A Model Of Ischaemic Neonatal Brain Injury

OBJECTIVES: Ischaemic brain injury is a major complication in patients undergoing surgery for congenital heart disease, with the hippocampus being a particularly vulnerable region. We hypothesized that neuronal injury resulting from cardiopulmonary bypass and associated circulatory arrest is ameliorated by pretreatment with granulocyte colony-stimulating factor (G-CSF), a cytokine and an antiapoptotic neurotrophic factor.METHODS: In a model of ischaemic brain injury, 4 male newborn piglets were anaesthetized and subjected to deep hypothermic circulatory arrest (DHCA) (cooled to 18 degrees C, DHCA maintained for 60 min, rewarmed and recovered for 8-9 h), while 4 animals received G-CSF (34 mg/kg, intravenously) 2 h prior to the DHCA procedure. At the end of each experiment, the animals were perfused with a fixative, the hippocampus was extracted, cryoprotected, cut and the brain sections were immunoprocessed for activated caspase 3, a pro-apoptotic factor. Immunopositive neuronal nuclei were counted in multiple counting boxes (440 x 330 mm) centred on the CA1 or CA3 hippocampal regions and their mean numbers compared between the different treatment groups and regions.RESULTS: G-CSF pretreatment resulted in significantly lower counts of caspase 3-positive nuclei per counting box in both the CA1 [ 52.2 +/- 9.3 (SD) vs 61.6 +/- 8.4, P < 0.001] and CA3 (41.2 +/- 6.9 vs 60.4 +/- 16.4, P < 0.00002) regions of the hippocampus as compared to DHCA groups. The effects of G-CSF were significant for pyramidal cells of both regions and for interneurons in the CA3 region.CONCLUSIONS: In an animal model of ischaemic brain injury, G-CSF reduces neuronal injury in the hippocampus, thus potentially having beneficial effect on neurologic outcomes.