Construction of a pumpless gravity-driven vascularized Skin-on-a-Chip for the study of hepatocytotoxicity in percutaneous exposure to exogenous chemicals

The utilization of existing Skin-on-a-Chip (SoC) is constrained by the complex structures, the multiplicity of auxiliary devices, and the inability to evaluate exogenous chemicals that are hepatotoxic after percutaneous metabolism. In this study, a gravity-driven SoC without any auxiliary devices was constructed for the hepatocytotoxicity study of exogenous chemicals. The SoC possesses 3 layers of culture chambers, from top to bottom, for human skin equivalent (HSE), Human Umbilical Vein Endothelial Cells (HUVEC) and hepatocytes (HepG2), and the maintenance and expression capacity of the corresponding cells on the SoC were verified by specificity parameters. The reactivity of the SoC to exogenous chemicals was verified by 2-aminofluorene (2-AF). The SoC can realistically simulate the in vivo exposure process of exogenous chemicals that are percutaneously exposed and metabolized into the bloodstream and then to the liver to produce toxicity, and it can achieve the same effects on transcriptome as those of animal tests at lower exposure levels while examining multiple toxicological targets of the skin, vascular endothelial cells, and hepatocytes. Both in terms of species similarity, the principles of reduction, replacement and refinement (3R), or the level of exposure suggest that the present SoC has a degree of replacement for animal models in assessing exogenous chemicals, especially those that are hepatotoxic after percutaneous metabolism.