Construction of corneal neovascularization rabbit model by suture / 解剖学报

Objective To compare the effect of different sutures and suture method on corneal neovascularization ( CNV) in rabbit models. Methods NV was induced by placing sutures at the corneal periphery of rabbits (n = 45). To observe the NV status, 45 rabbits were randomly divided into 5 equal groups. Group A applied 8-0 absorbable suture (A1 single loop parallel suture, A2 single loop vertical suture). In group B, 10-0 nylon suture was used (B1 double loop parallel suture, B2 double loop vertical suture, B3 three loop radial suture). The development of CNV was observed with slit lamp microscope and photographed. Therefore the effective model for neovascularization induction was selected. Histological examination, immunofluorescent staining and ELISA analysis for the vascular endothelial growth factor( VEGF) were performed before suture, 7 and 14 days after suture. Results Sutures fell off and CNV gradually atrophied in group Al and A2; At the 14th day after suture, Sparse or short cluster CNV grew into the corneal margin in group B1 and B2, while CNV was vigorous and grew in bundles in group B3. The expression of VEGF in aqueous humor increased in B3 group after suturing, and increased in 14 days as compared with 7 days after suture. Corneal edema, neovascularization and little immunofluorescence staining for VEGF were detected in group B3 after 7 days suture. More neovascularization and immunofluorescence staining for VEGF were detected in group B3 after 14 days suture. Conclusion Corneal NV can be induced successfully in rabbit model by suturing. The method of 10-0 thread with three sets of circular seams (B3) is stable and effective.

Effect of poly(DL-lactide-co-glycolide) on scar formation after glaucoma filtration surgery / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Glaucoma filtering surgery (GFS) is the most common procedure performed in the treatment of glaucoma. Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes, they may be associated with an increased incidence of severe and potentially blinding complications. Poly(DL-lactide-co-glycolide) (PDLLA/GA) is a bioresorbable polymer, which can be prepared with a large range of physical, mechanical, and biological properties and has been widely used in medicine, including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering. This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery (GFS).</p><p><b>METHODS</b>Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each. PDLLA/GA membranes were put under the sclera flap for evaluation. GFS with no membrane inserted served as control. Clinical evaluations of intraocular pressure (IOP) and the presence of a filtration bleb were performed at intervals (3 days, 1, 2, 4, 8, 12, 20, and 24 weeks) postoperatively. At each time point, three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type IV, proliferating cell nuclear antigen (PCNA), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1). The expression of connective tissue growth factor (CTGF) mRNA was determined by reverse transcription-polymerase chain reaction.</p><p><b>RESULTS</b>The lower IOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group. The histological analysis showed less inflammation and scar formation, weaker expression of collagen type IV and PCNA, more intense MMP-9 and TIMP-1, slightly elevated ratio of MMP-9 and TIMP-1, and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group (P < 0.05).</p><p><b>CONCLUSION</b>PDLLA/GA membranes may be promising for preventing fibrosis after GFS.</p>

In vivo biological stability of chemically pretreated silicone gel inserts intended for use in keratoprostheses / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Pretreatment with chemical agents could alter the surface chemistry of the silicone gel, which makes it suitable for epithelial migration onto its surface and thus enhances the cytobiocompatibility. This study aimed to evaluate the biological response of the corneal stroma to porous silicone gel pretreated with different chemical agents in vivo.</p><p><b>METHODS</b>The porous silicone gels were treated with a mixed acid solution containing 23.2% H2SO4 and 0.8% K2Cr2O7 for 10 or 15 minutes or with 30% H2O2 for 15 minutes. Discs (4 mm in diameter) were inserted into interlamellar stromal pockets of New Zealand white rabbits and followed up for a period of 3 months. Clinical evaluations such as corneal infiltration, edema and neovascularization were performed daily. At 3 months, the fibroplasias and collagen deposition were examined under light and scanning electron microscopy (SEM) and by immunohistochemical analysis.</p><p><b>RESULTS</b>Pretreatment of the discs obviously decreased conjunctival congestion, discharge, cornea edema, and the extent of neovascularization. More fibroblasts migrated into the pretreated discs than into the control, and collagen was deposited, indicating that the biocompatibility of the corneal replacements was enhanced by the chemical pretreatments. From immunohistochemical analysis, Type I collagen deposition in the pretreated silicone discs was greater than in the control.</p><p><b>CONCLUSIONS</b>Chemical treatment of silicone gel is effective in decreasing rabbit corneal inflammation, encouraging fibroblast in-growth, and enhancing tissue compatibility. Pretreated gels show good biological stability when used as a skirt material in Keratoprosthesis (Kpros).</p>

Effect of chemical treatment of silicon gel on tissue compatibility / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Silicon gel is unfavourable for cell attachment and growth. This study was to study if pretreating the surface of silicon gel with chemical agents affects the proliferation of epithelial cells.</p><p><b>METHODS</b>Silicon gel was made and treated with either mixed acid solution (containing 232 g/dm(3) of H(2)SO(4) and 8 g/dm(3) of K(2)Cr(2)O(7)) or 300 cm(3)/dm(3) peroxide for 5, 10, and 15 minutes or 10, 15, and 20 minutes, respectively. The cultured corneal epithelial cells were seeded onto those silicon gels and kept for 13 days. Immunohistochemical investigations were then carried out for integrin (alpha 6 or beta 4) and actin.</p><p><b>RESULTS</b>Growth of the epithelial cells in silicon gels treated with mixed acid solution for 10 minutes and 15 minutes was much significant than that in the untreated gels. After a 12-hour culture, a small number of corneal epithelial cells were proliferated on the surface of the silicon gels that had been treated with peroxide for 15 minutes. After a 3-day culture, those cells were further proliferated and fused together. The corneal epithelial cells did not grow well in the silicon gels treated with peroxide for 10 or 20 minutes. Immunostaining revealed the expression of actin and integrin alpha 6 or beta 4 on the silicon gels that were treated with mixed acid solution for 10 minutes or peroxide for 15 minutes.</p><p><b>CONCLUSION</b>Silicon gels treated either with mixed acid solution for 10 or 15 minutes or with peroxide for 15 minutes improves cell proliferation.</p>