Investigating the role of Alzheimer's disease familial mutations in neuromuscular physiology

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Project Summary There are few in vitro models that examine Alzheimer’s disease (AD) pathology outside the central nervous system. Several studies have indicated the lack of appropriate preclinical Alzheimer’s Disease and Related Dementias (ADRD) models as one of the barriers for successful development of AD/ADRD therapeutics. Motor impairment is a common feature of early AD pathology and the link between motor function and the risk of developing AD has been increasingly recognized. Gait abnormalities have been found to precede the onset of dementia by many years. It is now becoming apparent that treatment windows and thus clinical trials must shift to the mild cognitive impairment (MCI) or better yet the pre-MCI stage to be effective, however, there are few if any diagnostics to predict who will develop AD at this stage of the disease. Studies have demonstrated that motor dysfunction early in AD seems to predict cognitive and functional decline, institutionalization, and mortality. Thus, a preclinical screening model based on a functional assay composed of human cells to evaluate the effects of amyloidopathy and tauopathy in the motor and sensory segments of the peripheral nervous system (PNS) enables a platform for understanding multiplicative effects in AD and potentially identify biomarkers that could identify high risk AD patients at the preclincial stage, thus improving their clinical outcomes. We seek to use UCF’s functional systems to investigate AD in terms of deficits in sensory and motor function in collaboration with Dr. Morgan at MSU to complement our CNS AD functional models in response to the NOSI: Sensory and Motor System Changes as Predictors of Preclinical Alzheimer’s Disease (NOT-AG-20-053). Recently, Hickman published a model of the neuromuscular junction (NMJ) composed of human motoneurons (MNs) and human primary skeletal muscle (SkM) myotubes cultured in a serum-free medium for applications to ALS using iPSC derived mutant MNs. The system, with two chambers linked by microtunnels, supports axonal outgrowth to the muscle chamber and facilitated MN-stimulated SkM contraction as well as direct stimulation-induced SkM contraction. We also have established a functional sensory neuronal system where intrafusal fibers can be innervated by sensory neurons, stretched and the AP generation monitored at the neuronal cell body that can be integrated with piezoelectric sensors and actuators. We propose establishing a PNS model for AD using Aβ42 and tau oligomer dosed healthy systems in addition to motor and sensory systems composed of AD mutant iPSC-derived NMJ systems as an extension of our recently published CNS AD model. We hypothesize our AD PNS systems will exhibit characteristic disease pathology as well as uncover distinct functional deficits useful in a preclinical diagnostic capacity. We will determine functional deficits induced by the oligomers as well as monitor biomarkers in the medium to identify which biomarkers could be used in a companion blood test. We have preliminary data that Aβ oligomers have a deleterious effect on MN and NMJ function. Development of in vitro models of the PNS without cortical neuron components could establish definitively the effects of AD in the PNS.