Abstract
Purpose :
While the Oxygen Induced Retinopathy (OIR) model is the most widely studied animal model used to mimic Retinopathy of Prematurity (ROP), the more recent Limited Hyperoxia Induced Retinopathy (LHIPR) model reflects more advanced pathological phenotypes seen in ROP. In this study, we expand upon the findings of the LHIPR model to show vascular changes that mimic other retinopathies.
Methods :
Wild type C57Bl/6J mouse pups were exposed to 65% oxygen from P0 until P7 to model LHIPR. After P7, pups were returned to room air oxygen levels and allowed to recover until endpoints of P21 or P30. LHIPR pups were euthanized along with their age-matched control room air (RA) pups and eyes were harvested. For each mouse, one eye was fixed and prepared for flatmount immunolabeling of retinas and RNA was collected from the other for qPCR analysis. For the flatmounts, endothelial cells were labeled with CD31 antibody and pericytes were labeled with NG2 antibody. NG2 positive pericyte counts were scored by two masked readers. For qPCR experiments, a CD31 antibody/magnetic bead complex was used to isolate endothelial cells from dissociated retinas to purify RNA and perform first strand cDNA synthesis. Relative fold gene expression of endothelial PDGFB, an endothelial-derived pericyte growth factor, was quantified in the endothelial fraction.
Results :
We found that LHIPR retina displayed a decrease of vessel density in P21 and P30 flatmounts (P21 p<0.05, P30 p<0.001). The P21 LHIPR flatmounts showed no relative difference in the number of pericytes. In contrast, P30 LHIPR flatmounts had a 34% pericyte loss relative to RA (P30 RA:1.00±0.05, P30 LHIPR:0.66±0.07, p<0.001).The qPCR data showed a decrease (P21 p>0.05, P30 p<0.001) in PDGFB in P30 LHIPR endothelial samples, and not in P21.
Conclusions :
Our study expands on the LHIPR model where we observe decreased vessel density, pericyte loss, and changes in gene expression involving endothelial-derived pericyte growth factors. These retinal vascular alterations mimic a spectrum of clinical retinopathies, including diabetic retinopathy.
This is a 2021 ARVO Annual Meeting abstract.