Emulating the gut-liver axis: Dissecting the microbiome's effect on drug metabolism using multiorgan-on-chip models.

The homeostatic relationship between the gut, its microbiome, and the liver is crucial for the regulation of drug metabolism processes. Gut microbes are known to influence human health and disease by enhancing food metabolism and providing a first line of defense against pathogens. In addition to this, the gut microbiome also plays a key role in the processing of exogenous pharmaceutical compounds. Modeling the highly variable luminal gut environment and understanding how gut microbes can modulate drug availability or induce liver toxicity remains a challenge. However, microfluidics-based technologies such as organ-on-chips could overcome current challenges in drug toxicity assessment assays because these technologies are able to better recapitulate complex human responses. Efforts are being made to create in vitro multiorgan platforms, tailored for an individual patient's microbial background. These platforms could be used as a tool to predict the effect of the gut microbiome on pharmacokinetics in a personalized way.

Intestinal Stem Cell-on-Chip to Study Human Host-Microbiota Interaction.

The gut is a tubular organ responsible for nutrient absorption and harbors our intestinal microbiome. This organ is composed of a multitude of specialized cell types arranged in complex barrier-forming crypts and villi covered by a mucosal layer controlling nutrient passage and protecting from invading pathogens. The development and self-renewal of the intestinal epithelium are guided by niche signals controlling the differentiation of specific cell types along the crypt-villus axis in the epithelium. The emergence of microphysiological systems, or organ-on-chips, has paved the way to study the intestinal epithelium within a dynamic and controlled environment. In this review, we describe the use of organ-on-chip technology to control and guide these differentiation processes in vitro. We further discuss current applications and forthcoming strategies to investigate the mechanical processes of intestinal stem cell differentiation, tissue formation, and the interaction of the intestine with the microbiota in the context of gastrointestinal diseases.