In vitro effects of bevacizumab treatment on newborn rat retinal cell proliferation, death, and differentiation.

PURPOSE: Vascular endothelial growth factor (VEGF) is an important signal protein in vertebrate nervous development, promoting neurogenesis, neuronal patterning, and glial cell growth. Bevacizumab, an anti-VEGF agent, has been extensively used for controlling pathological retinal neovascularization in adult and newborn patients, although its effect on the developing retina remains largely unknown. The purpose of this study was to investigate the effect of bevacizumab on cell death, proliferation, and differentiation in newborn rat retina. METHODS: Retinal explants of sixty 2-day-old Lister hooded rats were obtained after eye enucleation and maintained in culture media with or without bevacizumab for 2 days. Immunohistochemical staining was assessed against proliferating cell nuclear antigen (PCNA, to detect cell proliferation); caspase-3 and beclin-1 (to investigate cell death); and vimentin and glial fibrillary acidic protein (GFAP, markers of glial cells). Gene expressions were quantified by real-time reverse-transcription polymerase chain reaction. Results from treatment and control groups were compared. RESULTS: No significant difference in the staining intensity (on immunohistochemistry) of PCNA, caspase-3, beclin-1, and GFAP, or in the levels of PCNA, caspase-3, beclin-1, and vimentin mRNA was observed between the groups. However, a significant increase in vimentin levels and a significant decrease in GFAP mRNA expression were observed in bevacizumab-treated retinal explants compared with controls. CONCLUSIONS: Bevacizumab did not affect cell death or proliferation in early developing rat retina but appeared to interfere with glial cell maturation by increasing vimentin levels and downregulating GFAP gene expression. Thus, we suggest anti-VEGF agents be used with caution in developing retinal tissue.

Trypan blue staining for capsulorhexis: ultrastructural effect on lens epithelial cells and capsules.

PURPOSE: To evaluate the ultrastructural effect of trypan blue 0.1% staining for capsulorhexis on lens epithelial cells (LECs) and capsules. SETTING: Division of Ophthalmology, University of São Paulo, São Paulo, Brazil. METHODS: Before capsulorhexis, patients were randomly assigned to 1 of 2 groups. Trypan blue 0.1% staining was performed in the treatment group. No trypan blue was used in the control group. Samples of capsules with LECs were fixed and analyzed with routine optical microscopy techniques, immunohistochemistry for beclin-1 expression (a marker of autophagy), terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling to detect apoptosis, and transmission electron microscopy (TEM). Morphometric analyses were performed, and the 2 sets of data were compared. RESULTS: Each group comprised 15 patients. Cell death by autophagy and apoptosis was observed in the treatment group but not in the control group. The TEM images of subcapsular epithelium cells showed mitochondrial rupture, dilation of the cisterns of the endoplasmic reticulum, increased cytoplasmic and nuclear electron density, and abnormalities in the nuclear profile of trypan blue-stained cells. Morphometric analysis showed statistically significant differences between the 2 groups in the longest nuclear axes and the ratio between the total nuclear perimeter and the cell area (P = .03). The difference in capsule thickness between groups was not significant. CONCLUSION: Trypan blue caused LEC death, which supports the hypothesis that staining with trypan blue 0.1% can help reduce the incidence of posterior capsule opacification after cataract surgery. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.