An integrated MPS platform with "virtual humans" for chemical toxicity testing

People are exposed to diverse chemicals through food, soil, air, water, consumer and industrial products. Some individuals are more sensitive and/or susceptible than others. The goal of this project is to provide new cost- effective screening solutions that incorporate human genetic diversity for chemical risk assessment. The “virtual human population” screen will assess the variability in inter-human thresholds, and identify individuals that respond adversely to lower doses of toxic chemicals or through different dose-dependent mechanisms. To achieve this goal, we will develop and validate an integrated microphysiological screening platform (MPSS) with a sufficient number of “representative humans” to elucidate the inter-donor variabilities using human induced pluripotent stem cell-derived organotypic culture models. Mitochondrial toxicity and acetylcholinesterase (AChE) inhibition are well-established toxicity mechanisms that have been implicated in neurodegenerative diseases. A recent analysis of the FDA’s Adverse Event Reporting System for drug-induced liver injury showed that mitochondrial toxicity is 1.43 times more likely to cause drug attrition and withdrawal from the market than other mechanisms of toxicity. The brain is only 2% of body weight but consumes 20% of the available oxygen. It is vulnerable to mitochondrial toxicity because each neuron has about two million respiring and ATP-producing mitochondria (about 1,000 times more than a hepatocyte) and a limited regenerative capacity compared to the liver. Our commercial products, Perfused Organ Panel microphysiological system (MPS), SeedEZ 3D cell culture scaffold and synthetic hemoglobin increase cellular oxygen consumption 4-fold and the activity of CYP450 drug metabolism enzymes 10-fold (compared to Petri dish cultures). This trifecta provides human-relevant oxidative metabolism and drug metabolism outside of humans and makes the cells vulnerable to mitochondrial toxicity. The 96-well MPS screening platform will use key elements of our commercial 48-well MPS and combine it with our highly sensitive assays which detect toxicity at doses that are reported to cause adverse effects in humans. Our assays and products discriminate between structurally similar, toxic and non-toxic drugs. This gives us the confidence to asses potential dose-dependent transitions in the mechanisms of toxicity that can differ between an “average” and a “vulnerable” human. The key deliverables will be dose-response curves for an array of mix- and-measure biochemical assays, calculated IC20, IC50 and IC80, IC50 compared to TD50, analyzed potential dose-dependent transitions and inter-donor variability, sensitive and resilient individuals identified, and data analyzed based on groups looking at sex, ethnicity, and donor health. To develop the “virtual human population platform” for chemical toxicity screening, we assembled a multidisciplinary team with the experts in toxicology, pharmacology, genome biology, induced pluripotent stem cells, tissue engineering, organotypic cultures, microphysiological systems, assay development and oxidative stress.