(73f) In-Vitro Assessment of the Biological Effects of Polymethyl Methacrylate in 2D and 3D Cellular Models

Wearable devices (WD) are widely used in direct contact with human skin to monitor important physiological parameters in real-time. Polymethylmethacrylate (PMMA) is a very attractive material for the manufacturing of WDs due to its physicochemical properties and low cost. The assessment of the biological effects of PMMA is needed to avoid unwanted effects such as skin irritation. Currently, in vivo tests with animals are the best way to assess these effects. These tests have been heavily criticized, not only for the pain and discomfort that it creates in animals but also because their results are not necessarily consistent and vary significantly from results obtained from human testing. A more current alternative to these is the use of a 3D reconstructed human epidermis (RhE). These have been validated in Europe by the Organization for Economic Co-operation and Development (OECD) as a full replacement for the Draize test of skin irritation. However, to the best of our knowledge, RhE and cytotoxicity-cell metabolism relationship studies have not been performed with PMMA. In this study, cytotoxicity, metabolic, and irritation effects of PMMA were assessed using the NIH3T3 2D cell cultures and compared to RhE. Two different Molecular weights (Mw~15000 and 5000g/mol) and concentrations (0.003-0.077g/cm²) were used. NIH3T3 cytotoxicity data were statistically analyzed using a multiple linear regression model for viability prediction as a function of the two variables, Mw and concentrations. Cell viability results in NIH3T3 cells indicated moderate cytotoxicity of PMMA for both Mw. Using the RhE model, PMMA showed low toxicity at the highest Mw and moderate toxicity for the lowest Mw at the highest concentration. On the other hand, NIH3T3 cell metabolism results proposed that the surviving cells after treatment with PMMA decreased their maximal respiration compared to the negative control, denoting mitochondrial dysfunction. In conclusion, the 2D and RhE models exhibited different results suggesting that the use of a single test and platform may not always be sufficient to predict the possible biological effect of material on humans. In addition, the results of cell metabolism suggest its relationship with cytotoxicity. Although there are viabilities higher than 70% considering the material as non-cytotoxic, metabolic problems are observed that could possibly cause inflammatory effects.