Biology subjects

Sontheimer-Phelps, A.

Publications and source records attributed to Sontheimer-Phelps, A..

3 recordsLinked to original sources

bioRxiv2019

Human colon-on-a-chip enables continuous in vitro analysis of colon mucus layer accumulation and physiology

Background & AimsThe mucus layer in the human colon protects against commensal bacteria and pathogens, and defects in its unique bilayered structure contribute to intestinal disorders, such as ulcerative colitis. However, our understanding of colon physiology is limited by the lack of in vitro models that replicate human colonic mucus layer structure and function. Here, we investigated if combining organ-on-a-chip and organoid technologies can be leveraged to develop a human-relevant in vitro model of colon mucus physiology. MethodsA human colon-on-a-chip (Colon Chip) microfluidic device lined by primary patient-derived colonic epithelial cells was used to recapitulate mucus bilayer formation, and to visualize mucus accumulation in living cultures non-invasively. ResultsThe Colon Chip supports spontaneous goblet cell differentiation and accumulation of a mucus bilayer with impenetrable and penetrable layers, and a thickness similar to that observed in human colon, while maintaining a subpopulation of proliferative epithelial cells. Live imaging of the mucus layer formation on-chip revealed that stimulation of the colonic epithelium with prostaglandin E2, which is elevated during inflammation, causes rapid mucus volume expansion via an NKCC1 ion channel-dependent increase in its hydration state, but no increase in de novo mucus secretion. ConclusionThis study is the first to demonstrate production of colonic mucus with a physiologically relevant bilayer structure in vitro, which can be analyzed in real-time non-invasively. The Colon Chip may offer a new preclinical tool to analyze the role of mucus in human intestinal homeostasis as well as diseases, such as ulcerative colitis and cancer.

cell biology↗

bioRxiv2019

A robotic platform for fluidically-linked human body-on-chips experimentation

Here we describe of an Interrogator instrument that uses liquid-handling robotics, a custom software package, and an integrated mobile microscope to enable automated culture, perfusion, medium addition, fluidic linking, sample collection, and in situ microscopic imaging of up to 10 Organ Chips inside a standard tissue culture incubator. The automated Interrogator platform maintained the viability and organ-specific functions of 8 different vascularized, 2-channel, Organ Chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier (BBB), and brain) for 3 weeks in culture when fluidically coupled through their endothelium-lined vascular channels using a common blood substitute medium. When an inulin tracer was perfused through the multi-organ Human Body-on-Chips (HuBoC) fluidic network, quantitative distributions of this tracer could be accurately predicted using a physiologically-based multi-compartmental reduced order (MCRO) in silico model of the experimental system derived from first principles. This automated culture platform enables non-invasive imaging of cells within human Organ Chips and repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling, which should facilitate future HuBoc studies and pharmacokinetics (PK) analysis in vitro.

bioengineering↗

bioRxiv2019

Species-specific enhancement of enterohemorrhagic E. Coli pathogenesis mediated by microbiome metabolites

BackgroundSpecies-specific differences in tolerance to infection are exemplified by the high susceptibility of humans to enterohemorrhagic E. coli (EHEC) infection whereas mice are relatively resistant to this pathogen. This intrinsic species-specific difference in EHEC infection limits the translation of murine research to human. Furthermore, studying the mechanisms underlying this differential susceptibility is a difficult problem due to complex in vivo interactions between the host, pathogen, and disparate commensal microbial communities.\n\nResultsWe utilize organ-on-a-chip (Organ Chip) microfluidic culture technology to model damage of the human colonic epithelium induced by EHEC infection, and show that epithelial injury is greater when exposed to metabolites derived from the human gut microbiome compared to mouse. Using a multi-omics approach, we discovered four human microbiome metabolites -- 4-methyl benzoic acid, 3,4-dimethylbenzoic acid, hexanoic acid, and heptanoic acid -- that are sufficient to mediate this effect. The active human microbiome metabolites preferentially induce expression of flagellin, a bacterial protein associated with motility of EHEC and increased epithelial injury. Thus, the decreased tolerance to infection observed in humans versus other species may be due in part to the presence of compounds produced by the human intestinal microbiome that actively promote bacterial pathogenicity.\n\nConclusionOrgan on chip technology allowed the identification of specific human microbiome metabolites modulating EHEC pathogenesis. These identified metabolites are sufficient to increase susceptibility to EHEC in our human Colon Chip model and they contribute to species-specific tolerance. This work suggests that higher concentrations of these metabolites could be the reason for higher susceptibility to EHEC infection in certain human populations, such as children. Furthermore, this research lays the foundation for therapeutic-modulation of microbe products in order to prevent and treat human bacterial infection.

bioengineering↗