The “beta-amyloid cascade hypothesis” of Alzheimer's disease (AD) has provided a major framework for AD drug discovery and has led to many current clinical trials. However, to date, no single in vitro or in vivo AD model has been able to recapitulate the presumed patient pathophysiology: beta-amyloid deposition directly leads to tangles and neurodegeneration. Recently, we created a novel three dimensional (3-D) human neural cell culture model of AD using genetically engineered human neural stem cells. Using this unique model, we showed that expression of APP and PSEN1 with familial AD mutations is sufficient to induce extracellular beta-amyloid deposits and robust tauopathy, including hyperphosphorylated tau and detergent-resistant, silver-positive neurofibrillary tangles for the first time (Choi et al., 2014). This human 3-D culture model has great potential to innovate and accelerate the current AD drug screening process. We now propose to use high-throughput drug screening in combination with our 3-D human cellular AD model to identify and characterize novel AD drugs and drug targets that can reduce both beta-amyloid and tau pathologies, which is not feasible using current AD mouse models.
In Aim 1, we will develop a high-throughput screening (HTS) system based on 3-D human cellular AD models (3-D AD-HTS). In Aim 2, we will carry out 3-D AD-HTS using FDA-approved drug libraries and validate the primary hits that reduce beta-amyloid and/or tau pathologies and finally, in Aim 3, we will explore whether the validated candidate drugs rescue the neuronal injuries and functional deficits in the 3-D AD culture model. The overarching goals of this study are to 1) establish a 3-D HTS AD drug screening system based on human 3-D neural cell culture models; 2) find potential AD drug candidates among the FDA-approved drugs (drug repurposing); and 3) identify novel cellular pathways that can regulate both beta-amyloid and tau pathologies. Since no current AD mouse model of beta-amyloid deposition leads to tangles and neurodegeneration, which are both critical aspects of the disease, the human neural cell culture model could serve as a novel, crucial drug discovery platform for AD.