Poly(lactic acid) (PLA) was modified using collagen through a grafting method to improve its biocompatibility and degradability. The carboxylic group at the open end of PLA was transferred into the reactive acylchlorided group by a reaction with phosphorus pentachloride. Then, collagen-modified PLA (collagen-PLA) was prepared by the reaction between the reactive acylchlorided group and amino/hydroxyl groups on collagen. Subsequently, the structure of collagen-PLA was confirmed by Fourier transform infrared spectroscopy, fluorescein isothiocyanate-labeled fluorescence spectroscopy, X-ray photoelectron spectroscopy, and DSC analyses. Finally, some properties of collagen-PLA, such as hydrophilicity, cell compatibility and degradability were characterized. Results showed that collagen had been grafted onto the PLA with 5% graft ratio. Water contact angle and water absorption behavior tests indicated that the hydrophilicity of collagen-PLA was significantly higher than that of PLA. The cell compatibility of collagen-PLA with mouse embryonic fibroblasts (3T3) was also significantly better than PLA in terms of cell morphology and cell proliferation, and the degradability of PLA was also improved after introducing collagen. Results suggested that collagen-PLA was a promising candidate for biomedical applications.

Preparation, Cell Compatibility and Degradability of Collagen-Modified Poly(lactic acid)

BACKGROUND 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). METHODS 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. RESULTS 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). CONCLUSION PDLLA/GA membranes may be promising for preventing fibrosis after GFS.

Effect of poly(DL-lactide-co-glycolide) on scar formation after glaucoma filtration surgery.

Objective: To find an ideal kind of PLAs membrane to prevent the of-scar formation after the trabeculectomy surgery.Method: 12 rabbits(24 eyes),were divided into PLA group(6 eyes),ploy DL lacticcaid(PLLDA)(6 eyes),PLLDA/GA(6 eyes)and the control group(6 eyes) randomly.All rabbits accepted the trabeculectomy.A piece of4mm×4mm membrane were puted between the sclera flaps in the experimental groups.After the surgery,the filterable bleb and inflammatory reaction,and histological changes were observed in 2weeks and 8 weeks later.Result: Of the 4 groups,the filterable bleb were most obvious in the first week after the surgery,there were no difference among them;Later the blebs of control group were smaller than those of the experimental groups.8 weeks after the surgery,the blebs of PLLDA/GA group was best.Histological study showed that the number of the fibroblast cells and inflammatory cells in the experimental groups were less than those in the control group.Conclusion: The PLAs have effect in the trabeculectomy surgery to prevent the formation of scar,of those groups,PLLDA/GA was best.

Qiao Zhi

Papers

Experimental research of prevention of scar formation after trabeculectomy by several kinds of PLA