A three-dimensional human neural cell culture model of Alzheimer’s disease

Abstract

Alzheimer’s disease (AD) is the most common form of dementia, characterized by two pathological hallmarks: β-amyloid plaques and neurofibrillary tangles1. The amyloid hypothesis of AD posits that excessive accumulation of β-amyloid peptide (Aβ) leads to neurofibrillary tangles composed of aggregated hyperphosphorylated tau2,3. However, to date, no single disease model has serially linked these two pathological events using human neuronal cells. AD mouse models with familial AD (FAD) mutations exhibited Aβ-induced synaptic and memory deficits but they were not able to fully recapitulate other key pathological events of AD including clear neurofibrillary tangle pathology4,5. AD patient-derived human neurons showed elevated levels of toxic Aβ species and phosphor-tau (p-tau) but they also could not replicate β-amyloid plaques or neurofibrillary tangles6-11. Here we show that FAD mutations in the amyloid-β precursor protein (APP) and presenilin (PS) 1 genes are able to induce robust extracellular deposition of Aβ, including β-amyloid plaques, in a human neural stem cell-derived three-dimensional (3D) culture system. More importantly, the 3D-differentiated neuronal cells expressing FAD mutations exhibited high levels of detergent-resistant, silver-positive aggregates of p-tau in the soma and neurites. Immunoelectron microscopy also demonstrated the presence of filamentous tau, only in detergent-resistant fractions from 3D-cultured cells expressing FAD mutations. Inhibition of Aβ generation with β- or γ-secretase inhibitors not only decreased Aβ pathology, but also attenuated tauopathy. We also found that glycogen synthase kinase 3 (GSK3) regulated Aβ-mediated tau phosphorylation. In summary, we have successfully recapitulated Aβ and tau pathology in a single 3D human neural cell culture system for the first time. Our unique strategy for recapitulating AD pathology in a 3D neural cell culture model should also serve to facilitate the development of more precise human neural cell models for other neurodegenerative disorders.