Abstract
Purpose:
A subpopulation of microglia/macrophage (Iba-1+ cells) expressing NG2 (a proteoglycan core protein) has been shown neuroprotective in ischemic brain and spinal cord injury. Lycium barbarum polysaccharide (LBP) has been proven protective to the retinal ganglion cells (RGCs) and retinal vasculature in the ischemic retina. Here we want to know whether Iba1+/NG2+ cells exist in ischemic retina, also whether LBP exert its protection partly via Iba1+/NG2+ cells. M,,,M'FR;[P\
Methods:
Mice aged at 6-10 weeks were used. Acute ocular hypertension (AOH) was introduced in one eye by increasing ocular pressure to 80~90mmHg for 1 hour followed by reperfusion, while the other eye was left as control. As for the LBP treatment, mice were fed orally with LBP solution (1mg/kg) or PBS vehicle once daily from 7 days before the AOH insult till sacrifice. Immunostaining on whole-mounted retinas or retinal sections are performed for analysis.
Results:
First, we found only in AOH retinas Iba-1+/NG2+ cells show up with either ramified or ameboid morphology. Secondly, we checked the time course of Iba-1+/NG2+ cells in AOH retinas and found similar pattern like leukocyte infiltration.Thirdly, we examined the associations between those cells and their surroundings to know whether they might communicate. Those cells indeed showed close association with RGCs and blood vessels but not with astrocytes and Müller cells. Fourthly, we test whether LBP treatment has any effects on the Iba1+/NG2+ cells and found LBP treatment significantly increases the number of Iba1+/NG2+ cells in AOH retina 4 days after ischemia, while decreased the overall number of Iba-1+ cells compared to PBS vehicle.
Conclusions:
Here we report for the first time the existence of Iba1+/NG2+ cells in ischemic mouse retina. And those Iba1+/NG2+ cells contact with RGCs and blood vessel after the ischemia-reperfusion injury.LBP, a possible neuroprotectant, increases the Iba1+/NG2+ cell number while decreases the overall Iba-1+ cells, highlighting possible distinct functions between Iba1+/NG2+ cells and other Iba-1+ cells, which might be due to the different origins. The functional profiles including neurotrophic factors and cytokines expressions of Iba1+/NG2+ cells as well as their origins are now under investigations.