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Objective: To investigate the effect of pigment epithelial-derived factor (PEDF) gene-modified human umbilical cord mesenchymal stem cells (MSC) on rats with diabetic retinopathy (DR). Methods: Experimental study. Human umbilical cord MSC were transfected by lentivirus packaging PEDF-MSC-green fluorescent protein (GFP) and GFP-MSC plasmid vectors, and the expression of PEDF and vascular endothelial growth factor (VEGF) was measured in the cell culture medium. Fifty adult male Sprague-Dawley rats were randomly divided into five groups: normal control group (group A), DR control group (group B), phosphate-buffered saline (PBS) treated group (group C), GFP-MSC treated group (group D) and PEDF-MSC-GFP treated group (group E), with 10 rats in each group. Streptozotocin was intraperitoneally injected to make early DR models. After four-month intervention, groups D and E were given intravitreal injection of GFP-MSC and PEDF-MSC-GFP; group C was given intravitreal injection of phosphate-buffered saline; groups A and B did not receive special treatment. The changes of retina in different groups were detected by hematoxylin and eosin staining, and the thickness of inner plexiform layer, inner nuclear layer and outer nuclear layer was measured by computer-based image analytical system. Immunohistochemistry was applied to observe PEDF and VEGF. Real-time quantitative polymerase chain reaction was used to detect the expression of PEDF and VEGF mRNA. Results: The expression of CD105, CD73 and CD90 was positive, while the expression of CD34, CD45, CD11b, CD19 and HLA-DR was negative. ELISA results showed that after transfection PEDF protein expression in the supernatant of PEDF-MSC (84.09±7.07) μg/L was higher than the control group (9.03±0.14) μg/L ( P< 0.05). At 2 weeks after intravitreal injection, green fluorescence was observed in the rat vitreous of groups D and E under a fluorescence microscope; no obvious green fluorescence was found in the retina. After 2 months of intravitreal injection, the thickness of inner plexiform layer in group E was significantly decreased; the thickness of inner nuclear layer and outer nuclear layer was higher ( P< 0.05). Immunohistochemical staining showed that 2 months after intravitreal treatment, the average optical density values of PEDF were improved, but the average optical density values of VEGF were decreased in group E ( P< 0.05). Real-time polymerase chain reaction showed that 2 months after treatment, the expression level of PEDF mRNA in group E was improved, but the expression level of VEGF mRNA was decreased ( P< 0.05). Conclusions: Intravitreal injection of PEDF-MSC could up-regulate the expression of PEDF and down-regulate the expression of VEGF in diabetic rats and may represent a novel candidate resource for cell therapy of DR nerve damage. (Chin J Ophthalmol, 2017, 53, 540-547) .

Age-related macular degeneration (AMD) is a common cause of blindness in elderly population. Exploration of effective treatment of AMD has important significance. Pigment epithelial-derived factor (PEDF) is the most powerful endogenous inhibitor of angiogenesis. Increasing evidences, including results of phase I clinical trial, indicated that PEDF could significantly inhibit the development of choroidal neovascularization, which is the characteristic of wet AMD. Therefore, PEDF is one of the most potential therapeutic agents for AMD treatment.

Objective: To study the effect of adenoviral vectored pigment epithelium-derived factor (AdPEDF) gene transfer on established neovascularization in a rat model of choroidal neovascularization (CNV)., Methods: It was a experimental study. Sixty-eight female BN rats (136 eyes) with 6 to 8 weeks were used in this study. After the CNV model founded, 68 rats were divided into 5 groups with simple random sampling method. Four of them (8 eyes) were randomly selected as normal control group and 64 rats (128 eyes) were as experimental group. The experimental group included intravitreal injection with AdPEDF 1 microliter (group A), intravitreal injection with control vector (AdNull) 1 microliter (group B), periocular injection with AdPEDF 1 microliter (group C), and periocular injection with AdNull 1 microliter (group D). Histopathology, TUNEL staining, fundus fluorescein angiography (FFA), and thickness of CNV were tested 3, 7, 14, and 28 days after injection., Results: (1) The leakages appeared decrease after treatment in group A (54.7%) and C (56.3%) (t = 2.75, t = 3.15; P < 0.01). (2) CNV decreased in group A (57.3%) and C (57.8%) 7 days after injection, and kept fibrovascular proliferation in group B and D. (3) The thickness of CNV in group A [(44.51 +/- 0. 53) micrometers] and C [(44.37 +/- 0.48) micrometers] was significantly less than that in normal control group [(46.35 +/- 0.93) micrometers] after the treatment (F = 7.57, 8.85; P < 0.01), and it diminished with the time prolong (F = 4.31, 5.25; P < 0.05). The thickness of CNV in group A [(46.35 +/- 0.62) micrometers] was greater than that in group C [(44.90 +/- 0.44) micrometers] 3 days after treatment (F = 3.55, P < 0.05), and it was less in group A than that in group C 14 and 28 days after treatment (F = 6.54, P < 0.01; F = 4.41, P < 0.05). (4) There were positive TUNEL stainings in choroidal neovascular endothelium in group A and C. (5) Postoperative complication included cataract (5 eyes) after intravitreal injection., Conclusions: AdPEDF is effective in inhibiting CNV in an animal model. The effect appears 7 days after treatment, reaches the peak on day 14, and keeps stable on day 28. The inhibition effect on CNV appears slowly in eyes with intravitreal injection than that with periocular injection, and it is stronger in eyes with intravitreal injection.

Retinal neovascularization (RNV) is one of the most important causes of blindness. No efficient treatment for RNV is available. Pigment epithelium-derived factor (PEDF) is a natural inhibitor of angiogenesis. It plays an important role in the modulation of ocular neovascularization. It has been demonstrated recently that the ischemia-induced retinal neovascularization can be dramatically inhibited by the recombinant PEDF protein or local viral vector-mediated delivery of PEDF cDNA, which predicts PEDF to be an optional strategy for intractable retinal angiogenic diseases like diabetic retinopathy, retinopathy of prematurity, and central retinal vein occlusion. Therefore, it is necessary to review the biological aspects of PEDF, its effect on the inhibition of angiogenesis and the prospect of using PEDF for the treatment of retinal neovascularization.