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Mercedes Salvador-Silva, Ling C. Huang, Charles H. Powell, Lisa Hoong, Rosanne M. Yetemian; Evaluation of In Vitro Cytotoxicity Assays for Contact Lens Multi-Purpose Solutions. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6117.
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© ARVO (1962-2015); The Authors (2016-present)
Previous methods assessing in vitro cytotoxicity of Contact Lens Multi-Purpose Solutions (MPS) show a lack of correlation in relative responses. This study evaluates correlations among MPS effects on cell cytotoxicity, metabolic activity, membrane integrity, and biocompatibility.
Six MPS were used: - MPS-1: polyquaternium (PQ-1) + alexidine (ALX), MPS-2: PQ-1 + 5 ppm myristamidopropyl dimethylamine (MAPD) + nonanoyl-EDTA, MPS-3: PQ-1 + 5 ppm MAPD, MPS-4: PQ-1 + 6 ppm MAPD, MPS-5: PQ-1 + polyhexamethylene biguanide (PHMB), and MPS-6: PHMB + poloxamer 237 (PLX). Five soft contact lens types (CLs) were used in this study: balafilcon A, senofilcon A, galyfilcon A, lotrafilcon B, and comfilcon A. In vitro biocompatibility was assessed according to ISO 10993. MPS-treated CLs (100mL, 4 days, n=3) were placed onto confluent HCEC SV40 cells for 24hrs. Cells were scored for reactivity according to USP Direct Contact Test criteria and quantitative analysis. MPS were evaluated at 100%, 50%, and 25% as diluted in cultured medium. Cytotoxicity and metabolic activity were determined using alamarBlue® dye. Corneal epithelial barrier function was assessed by ZO-1 IHC and lens preservative uptake-release by HPLC.
Results indicate that effects of MPS on HCEC are dependent on concentration, time of exposure, and the specific assay used. Lens preservative uptake-release data support the observed correlation between relative in vitro cytotoxicity of MPS and previously published clinical results. MPS-1, MPS-5, and MPS-6 demonstrated better ocular biocompatibility than MPS-2, 3 and 4 as measured by direct contact cytotoxicity score (0-2 vs. 2-4, respectively) and percent cell viability (>80% vs.< 45%, respectively, n=3). MPS did not alter integrity of corneal epithelial tight junctions under simulating in-use conditions when diluted at 50% with 5 minutes exposure.
MPS effects on in vitro cell cytotoxicity are best demonstrated by correlation through multiple assays: cell metabolic activity, membrane integrity, and biocompatibility. These in vitro results showed that MPS-1 (PQ-1 + ALX) is highly compatible with all soft hydrogel lenses examined and provided evidence of similar performance to MPS-5 (PQ-1 + PHMB) or MPS-6 (PHMB + PLX), and better than MPS 2-4 (PQ-1 + MAPD combinations).
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