Granulocyte-colony stimulating factor protects memory impairment in the senescence-accelerated mouse (SAM)-P10

Early applications of granulocyte colony-stimulating factor (G-CSF) can stabilize the blood-optic-nerve barrier and ameliorate inflammation in a rat model of anterior ischemic optic neuropathy (rAION)

Granulocyte colony-stimulating factor (G-CSF) was reported to have a neuroprotective effect in a rat model of anterior ischemic optic neuropathy (rAION model). However, the therapeutic window and anti-inflammatory effects of G-CSF in a rAION model have yet to be elucidated. Thus, this study aimed to determine the therapeutic window of G-CSF and investigate the mechanisms of G-CSF via regulation of optic nerve (ON) inflammation in a rAION model. Rats were treated with G-CSF on day 0, 1, 2 or 7 post-rAION induction for 5 consecutive days, and a control group were treated with phosphate-buffered saline (PBS). Visual function was assessed by flash visual evoked potentials at 4 weeks post-rAION induction. The survival rate and apoptosis of retinal ganglion cells were determined by FluoroGold labeling and TUNEL assay, respectively. ON inflammation was evaluated by staining of ED1 and Iba1, and ON vascular permeability was determined by Evans Blue extravasation. The type of macrophage polarization was evaluated using quantitative real-time PCR (qRT-PCR). The protein levels of TNF-α and IL-1β were analyzed by western blotting. A therapeutic window during which G-CSF could rescue visual function and retinal ganglion cell survival was demonstrated at day 0 and day 1 post-infarct. Macrophage infiltration was reduced by 3.1- and 1.6-fold by G-CSF treatment starting on day 0 and 1 post-rAION induction, respectively, compared with the PBS-treated group (P<0.05). This was compatible with 3.3- and 1.7-fold reductions in ON vascular permeability after G-CSF treatment compared with PBS treatment (P<0.05). Microglial activation was increased by 3.8- and 3.2-fold in the early (beginning treatment at day 0 or 1) G-CSF-treated group compared with the PBS-treated group (P<0.05). Immediate (within 30 mins of infarct) treatment with G-CSF also induced M2 microglia/macrophage activation. The cytokine levels were lower in the group that received immediate G-CSF treatment compared to those in the later G-CSF treatment group (P<0.05). Early treatment with G-CSF stabilized the blood-ON barrier to reduce macrophage infiltration and induced M2 microglia/macrophage polarization to decrease the expressions of pro-inflammatory cytokines in this rAION model.

G-CSF attenuates noise-induced hearing loss

In this study, we investigated the effects of granulocyte colony-stimulating factor (G-CSF) for the treatment of noise-induced hearing loss (NIHL) in a guinea pig model. Forty guinea pigs were randomly divided into four groups: control, noise (white noise, 3 h/d for 2 days at 115 dB), noise+G-CSF (350 μg/kg/d for 5 days), and noise+saline. Auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) were used to determine the hearing threshold and outer hair cell function, respectively, in each group. Cochlear morphology was examined to evaluate hair cell injury induced by intense noise exposure. Fourteen days after noise exposure, the noise+G-CSF group had a lower ABR value than the noise group (P<0.05) or the noise+saline group (P<0.01). At most frequencies, the DPOAE value of the noise+G-CSF group showed a significant rise (P<0.05) compared to the noise group or the noise+saline group. Neither the ABR value nor the DPOAE value differed between the noise group and the noise+saline group. The morphology of the phalloidin-stained organ of Corti was consistent with the functional measurements. In conclusion, G-CSF can preserve hearing in an experimental model of NIHL in guinea pigs, by preserving hair cells after intense noise exposure.