High-Throughput NMJ Assay for Botox Potency Screening

PROJECT SUMMARY The Botulinum Toxin Potency Assay using Tissue Chips program from FDA and NCATS highlights the need for novel engineered systems capable of reliably evaluating botulinum toxin (BoT) potency. Human induced pluripotent stem cell (iPSC)-derived motor neurons and muscle cells have been previously maintained in co- culture and shown to form functional synaptic contacts representing in vivo neuromuscular junctions (NMJs). However, the ability to effectively model NMJ functional responses to BoT using in vitro platforms amenable to high-throughput screening has yet to be achieved due to the complexity of generating mature and functionally competent NMJs in culture. The development of a high-throughput platform capable of promoting NMJ development across a multiplexed assay will have a substantial positive impact on BoT production, as well as advanced therapy development, drug efficacy/toxicity screening, and mechanistic studies of neuronal and NMJ pathophysiology in neurodegenerative diseases. Based on preliminary work and published data, we posit that a culture platform integrating electrode-based stimulation of neuronal firing and magnet-based measurement of engineered muscle contraction will enable real-time analysis of NMJ development and function at baseline and in response to BoT exposure. Using iPSC-derived motor neurons and muscle cells, we will establish organized co-cultures within a culture plate that is compatible with our company’s existing muscle contractility assay, MantarrayTM. Microchannels in the walls separating the cells will allow neuronal processes to grow into the muscle compartment, facilitating synaptic contact. Tests with reference batches of BoT, in terms of their ability to alter synaptic communication between our cell populations, will then be used to demonstrate the suitability of this model for assaying NMJ function and BoT potency in vitro (Phase 1). Once validated, our NMJ assay will be further evaluated to determine its accuracy, precision, specificity, and reproducibility in modeling BoT responses in human tissues (Phase 2). Reference batches of BoT will be tested across a wide range of donor cell sources and in comparison to an array of reference compounds with known and predictable effects on NMJ function. The central hypothesis of this work is that differences in NMJ function between engineered skeletal muscle and motor neuron co-cultures treated with different doses of BoT will enable stratification of phenotypes that can be successfully used to plot dose response curves comparable to output data from mouse lethality bioassays (the current gold standard for BoT potency screening). Successful completion of this study will provide a new prototype human-based platform for modeling human peripheral neuropathies as well as a valuable preclinical screening tool for assessing novel therapeutics. The consumable plate will be integrated with Curi’s existing hardware/software packages and so can be quickly disseminated to customers upon validation.