Effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor on glial scar formation after spinal cord injury in rats

Object. This study investigated the effects of granulocyte colony stimulating factor (G-CSF) on glial scar formation after spinal cord injury (SCI) in rats and compared the therapeutic effects between G-CSF and granulocytemacrophage colony stimulating factor (GM-CSF) to evaluate G-CSF as a potential substitute for GM-CSF in clinical application. Methods. Rats were randomly assigned to 1 of 4 groups: a sham-operated group (Group 1), an SCI group without treatment (Group 2), an SCI group treated with G-CSF (Group 3), and an SCI group treated with GM-CSF (Group 4). G-CSF and GM-CSF were administered via intraperitoneal injection immediately after SCI. The effects of G-CSF and GM-CSF on functional recovery, glial scar formation, and axonal regeneration were evaluated and compared. Results. The rats in Groups 3 and 4 showed better functional recovery and more decreased cavity sizes than those in Group 2 (p < 0.05). Both G-CSF, and GM-CSF suppressed intensive expression of glial fibrillary acidic protein around the cavity at 4 weeks and reduced the expression of chondroitin sulfate proteoglycans (p < 0.05). Also, early administration of G-CSF and GM-CSF protected axon fibers from destructive injury and facilitated axonal regeneration. There were no significant differences in comparisons of functional recovery, glial scar formation, and axonal regeneration between G-CSF and GM-CSF. Conclusions. G-CSF suppressed glial scar formation after SCI in rats, possibly by restricting the expression of glial fibrillary acidic protein and chondroitin sulfate proteoglycans, which might facilitate functional recovery from SCI. GM-CSF and G-CSF had similar effects on glial scar formation and functional recovery after SCI, suggesting that G-CSF can potentially be substituted for GM-CSF in the treatment of SCI.