Development of 3D Rat Nerve-on-a-Chip Model for Chemical Toxicity Screening

Abstract Development ofD organotypic cellular models utilizing animal cells is important for the validation of these systems by direct comparison to animal dataA few organizations have been successful in providing such assays for various organ systemsHoweverdevelopment of peripheral nerve assays is laggingCommonly used peripheral neural culture preparations are not predictive of clinical toxicitypartially since they typically utilize apoptosis or neurite elongation as measurable endpointswhereas adult peripheral neurons are fully grown and known to resist apoptosisNerve conduction testing and histomorphometry of biopsies are the most clinicallyrelevant measures of neuropathyNeverthelessno culture models that provide such metrics currently existVarious brain culture systemssuch asD neural constructscerebral organoids or neurospheres to assess neurotoxicity were developedHowevernone recapitulated the biomimetic complexity of the nervous system especially peripheral nervous systemD neural toxicity assays that seek to recapitulate the most relevant anatomic and physiological toxic pathology in a simple model require a stronger focus on system architectureWe have developed an innovative sensory nerve on a chip model by culturing dorsal root ganglia in micropatterned hydrogel constructs to constrain axon growth in aD arrangement analogous to peripheral nerve anatomyFurtherelectrically evoked population field potentials resulting from compound action potentialsCAPsmay be recorded reproducibly in these model systemsThese early results demonstrate the feasibility of using microengineered neural tissues that are amenable to morphological and physiological measurements analogous to those of animaland clinicaltestsFrom a single in vitro preparationwe can measure CAP amplitude and conduction velocityand then subsequently section the tissue to measure histomorphological parameters such as axon diameteraxon densityand myelinationWe hypothesize that thisD organotypic system is capable of detecting neural toxicity parameters in ways that mimic clinical neuropathologyThis versatile system could also further be used for performingomicsstudies and thus will eventually be used for determining a large spectrum of toxicological parameters resulting in understanding mechanisms of action as well as improved understanding of biological processesThe objective of this project is to demonstrate that certain chemical toxins known for causing neurotoxicity in rats will induce toxicity in microengineered neural tissue that can be quantified using morphological and physiological measures analogous to clinical metricsWe will approach this objective by first enhancing the throughput of our system by engineeringD microelectrodes for testing electrophysiological characteristics of the model systemNextwe will determine the baseline variability and characterize structure function relationships using theD microelectrodesWe will then quantify changes induced by acute application of specific chemical toxins in order to demonstrate the technical merit of using the compound action potentialcAPwaveform as a preclinical assay of neurotoxicity Narrative While animal neural toxicity testing provides more specific anatomical and physiological parameters after chemical exposurethe cost and time of performing such experiments precludes their use for screening thousands of compoundsWe have developed an innovative sensory nerve on a chip model of cultured rat dorsal root ganglia in aD arrangement analogous to peripheral nerve anatomy that can record compound action potential amplitude and conduction velocity as well as measure histomorphological parameters such as axon diameteraxon densityand myelinationIf successfulthe assay would be used as an animal neural toxicity screening assayscreening candidate compounds for neural toxicitypredicting compound in vivo toxicity profileThussignificantly obviating costly and cumbersome animal studies currently required for drug development