J Pharm Pharmacogn Res 2(Suppl. 1): S15, 2014
Special supplement with the abstract book of LATINFARMA 2013
CO 028: BASIC ASPECTS OF THE TOXICOLOGICAL EVALUATION OF NANOMATERIALS
Vinardell MP, Nogueira DR, Mitjans M.Departament de Fisiologia, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII s/n, 08028, Barcelona, Spain. E-mail: email@example.com
Nowadays there are no established protocols to evaluate the safety of nanomaterials, but this is an important concern due to the progressive used of this kind of substances in many areas. Because of public and governmental urging to develop alternatives to in vivo testing, in vitro cell-based models may be of great relevance for testing of nanomaterials. We especially aimed to create predictive in vitro toxicological approaches for testing nanotechnology-based products designed for topical applications.
The physicochemical and morphological characterization of nanomaterials is crucial for a correct evaluation together with the study of a potential size change of the nanomaterial in contact with the cell culture medium, as has been described in some papers.
In this context, we have studied novel formulations based on mixed cationic vesicles composed by the phosphocholine DMPC, cholesterol and three different cationic lysine-based surfactants that differ in the cationic charge position and in the alkyl chain length.
The physicochemical properties (particle size, polydispersity index, morphology and zeta potential) and the amount of surfactant incorporated in each cationic nanovesicle formulation were assessed. The cytotoxicity of these nanomaterials was evaluated by means of three in vitro endpoints (MTT, NRU and LDH) using skin representative cell lines (HaCaT keratinocytes and 3T3 fibroblasts). Moreover, the phototoxic effect of the formulations (UVA light, 2.5 J/cm2) and the modulation of the IL-1α cytokine production as inflammatory indicator were also studied.
The cationic nanovesicles were roughly spherical shape with average diameter ranging from 110 to 170 nm, as determined by DLS. The nanovesicles size showed by TEM images was in general smaller. It was observed vesicles with diameter of ~ 150 nm (corroborating the DLS measurements), together with a population of vesicles with diameter ranging from 20 to 50 nm. The amount of surfactant incorporated into the nanovesicles ranged from 75 to 99%. After 24-h of cell exposure to the formulations, different cytotoxic responses were observed, depending on the surfactant, cell line and endpoint assayed. MTT was the most sensitive assay to detect the cytotoxicity, while NRU and LDH assays showed higher IC50 values. Formulations containing the surfactant with the longest alkyl chain showed the most significant cytotoxic effects. Moreover, no significant phototoxic activity was observed in HaCaT cells, while only minimal inflammatory response was induced in HaCaT as demonstrated by the IL-1α production. Taken together, our results demonstrated that the nanomaterials composition play a key role in the resulting toxicity, and also showed that the combination of different assays and skin cell models offers an in depth and comprehensive evaluation of the potential toxic effects of nanomaterials designed for topical delivery of biologically active substances.