Non-animal models of epithelial barriers (skin, intestine and lung) in research, industrial applications and regulatory toxicology

TLDR

Non‑animal models of the skin, intestine, and lung are increasingly used in research, industry, and regulatory toxicology as alternatives to animal testing, employing ex vivo tissues, reconstructed in vitro models, chip technologies, synthetic membranes, and in silico approaches. An international workshop of academia, industry, and regulatory experts reviewed the current state of non‑animal epithelial barrier models and outlined future research, industry, and regulatory priorities for developing and refining these models. The report summarizes the workshop’s findings on the current status and future directions for epithelial barrier models.

Abstract

Models of the outer epithelia of the human body – namely the skin, the intestine and the lung – have found valid applications in both research and industrial settings as attractive alternatives to animal testing. A variety of approaches to model these barriers are currently employed in such fields, ranging from the utilization of ex vivo tissue to reconstructed in vitro models, and further to chip-based technologies, synthetic membrane systems and, of increasing current interest, in silico modeling approaches. An international group of experts in the field of epithelial barriers was convened from academia, industry and regulatory bodies to present both the current state of the art of non-animal models of the skin, intestinal and pulmonary barriers in their various fields of application, and to discuss research-based, industry-driven and regulatory-relevant future directions for both the development of new models and the refinement of existing test methods. Issues of model relevance and preference, validation and standardization, acceptance, and the need for simplicity versus complexity were focal themes of the discussions. The outcomes of workshop presentations and discussions, in relation to both current status and future directions in the utilization and development of epithelial barrier models, are presented by the attending experts in the current report.