Effect of poly(ethylene glycol) graft polymerization of poly(methyl methacrylate) on cell adhesion - In vitro and in vivo study

Purpose: To investigate the effect of surface modification of poly(methyl m ethacrylate) (PMMA) by poly(ethylene glycol) (PEG) grafting on cell adhesio n. Setting: Department of Ophthalmology, Seoul National University Hospital, S eoul, Korea. Methods: The PMMA surface was oxidized with ozone, and PEG acrylate was the n graft polymerized. To verify the PEG grafting on the surface, the oxygen content was measured by electron spectroscopy for chemical analysis. The co ntact angle was measured using the Wilhelmy plate method. The adhesion of k eratocytes on modified PMMA was investigated in vitro. Cultured rabbit kera tocytes (4 x 10(5) cells/mL) were layered on each PMMA disk, cultured in a carbon dioxide incubator for 24 hours, harvested by trypsinization, and cou nted. A commercially available intraocular lens was modified as described a nd then inserted in the anterior chamber of a white rabbit. The cell adhere nce pattern on the modified IOL was examined by scanning electron microscop y. Results: The PEG-grafted PMMA revealed a higher oxygen content and lower dy namic receding contact angles than the untreated PMMA. The mean number of a dhered cells was 72.5 +/- 22 x 10(4)/mL for untreated PMMA. After PEG graft ing of 1 hour and ozone oxidation of 2 hours, the adherent cell counts sign ificantly decreased to 6.5 +/- 1.7 x 10(4)/mL and 7.6 +/- 1.6 x 10(4)/mL, r espectively (P = .002). Scanning electron microscopy showed small round cel ls sparsely scattered on the modified PMMA in contrast to the untreated PMM A. Conclusion: Surface modification of PMMA using PEG grafting reduced cell ad hesion. This may decrease the incidence of retroprosthetic membrane formati on after keratoprosthesis surgery.