Abstract
Purpose:
The purpose of this study was to evaluate the impact of intravitreal bevacizumab (IVB) on 3 cellular components (vascular endothelial cells, pericytes, and myofibroblasts) of the vascular microenvironment in fibrovascular membranes (FVMs) of proliferative diabetic retinopathy (PDR) patients.
Methods:
Immunohistological studies with Abs of CD34, α-SMA, and TGF-β were performed on 20 surgical specimens obtained during a pars plana vitrectomy from 8 IVB-treated eyes, while 12 remained untreated. Four different indexes of vascular phenotype (vascular area, vascular major axis, CD34(+) endothelial area, and blood vessel density), and α-SMA expression in vascular and stromal components were quantitatively-analyzed.
Results:
The intraluminal area of blood vessels, CD34(+) endothelial area, and the blood vessel density in IVB-treated FVMs were significantly less than in untreated FVMs. The number of CD34(+) blood vessels in IVB-treated FVMs was similar to in untreated FVMs. IVB could not affect vascular as well as stromal αSMA(+) area significantly. However, the ratio of vascular αSMA(+) area/CD34(+) area was significantly higher in IVB-treated FVMs than in untreated FVMs. TGF-β expression could be observed in the IVB-treated FVM.
Conclusions:
IVB might primarily affect blood vessels, and the effects on pericytes and myofibroblasts might be secondary. IVB treatment regulates vascular microenvironment by the contraction of blood vessels, the increasing pericyte ratio, and TGF-β expression in FVMs of PDR patients.
Keywords: 499 diabetic retinopathy •
748 vascular endothelial growth factor