Experimental Research On Replication-defective Adenovirus Mediated Expression Of PEDF Gene Against Retinal Neovascularization

Purpose: To investigate if intravitreous injection of recombinationadenovirus-mediated human PEDF (AV-hPEDF) expression can result in increasedlevels of PEDF and reduce proliferating retinal vessels in the eyes of oxygen-inducedretinopathy (OIR) rat model. On the molecular level, to discuss the possibletherapeutic mechanism of AV-hPEDF in retinal neovascularization (RNV).Methods: Postnatal day 7 (PT) Sprague-Dawley (SD) rat litters were randomlyassigned to the experimental and control groups. RNV was induced in both groupsP7 SD rat litters exposed to 80％±2％oxygen for 5 days, followed by room air foranother 5 days. P12 SD rats were given intravitreous injection of 1μl containing1×10~9pfu of AV-hPEDF/AV-Blank (n=10)。RNV was quantified by the number ofendothelial cell nuclei above the inner limiting membrane in P17 eye cross-sections.Levels for PEDFmRNA were measured by RT-PCR. Protein levels for PEDFexpression were measured by immunohistochemistry analysis.Results: Dilation and Proliferation of blood vessel s were found in retinas of P 17 SDrats under the relatively hypoxia status. The mean number of endothelial cell nucleiabove the inner limiting membrane in per P17 eye cross-section was 98.68±10.13 inhyperoxia group, while less than 1 nucleus per cross-section in normoxia control(P＜0.001). 5 days after intravitreous injection, AV-PEDF caused a significant increaseof vitreous PEDFmRNA levels (0.8413±0.07919) and retinal PEDF protein levels(IOD 418921.90±30407.96) compared to eyes treated with AV-Blank (0.3135±0.1795,IOD 56145.63±6319.08) respectively (P＜0.001). The number of endothelial cellnuclei above the inner limiting membrane in eyes treated with AV-PEDF was reducedto a significant level (44.09±9.61) compared to control eyes treated with AV-Blank(102.89±13.45) (P＜0.001).Conclusion: The reproducible and quantifiable rat model of oxygen-induced retinalneovascularization may prove to be useful for the study of medical intervention ofretinal neovascularization. Expression of PEDF from AV vectors reduces the level of RNV in this OIR rat model. The increased PEDFmRNA and protein levels detectedby RT-PCR and immunohistochemistry analysis correlate well with the reduction inRNV and confirm that short-term expression from recombination AV-PEDF may betherapeutically useful in the treatment of retinal neovascular disease, such as diabeticretinopathy and ROP.