Klimeck. W. T., A. H. Borchers, R. E. Egbert, R. B. Nagle, D. E. Carter, and G. T. Bowden. Effects of Acute and Chronic Arsenic Exposure of Human-Derived Keratinocytes in an In Vitro Human Skin Equivalent System: A Novel Model of Human Arsenicism. Toxic. in Vitro 1997. 11: 89-98. [Reprinted with permission from Elsevier Science].

arsenate - 16518-47-1; monomethylarsonic acid - 00124-58-3; dimethylarsinic acid - 00075-60-5

An organotypic culture (OTC) of a human keratinocyte cell line (HaCaT) over a human fibroblast-embedded collagen gel was used to model human epidermis in arsenicism, a syndrome that currently lacks valid experimental models. Keratinocytes were exposed acutely or chronically to a mixture of arsenate (0.5 uM), monomethylarsonic acid (MMA; 0.5 uM) and dimethylarsinic acid (DMA; 1.5 uM), or to the individual components of the mixture. OTCs were assayed for microscopic morphology, the proliferating cell marker, Ki-67, labelling and cytokeratin expression. Acute exposures resulted in an epidermal phenotype that accurately modelled early human lesions, including hyperkeratosis, acanthosis and keratin 16 induction. Chronic exposures resulted in a de-differentiated epidermal phenotype with focal nests of keratinocytes growing into the collagen gel. The keratin 8/18 pair was induced by either acute or chronic arsenic exposure, as was the proliferating cell marker, Ki-67. Exposure of keratinocytes to individual arsenic compounds demonstrated that all arsenic mixture-induced changes could be duplicated by exposure to arsenate alone. In contrast, MMA and DMA were inactive. This study establishes OTC as a useful model of arsenicism, and implicates inorganic arsenic as the ultimate carcinogen.