A 3D bioengineered neural tissue model generated from patient-derived iPSCs develops Alzheimer‘s disease-related phenotypes

Background Current models to study Alzheimer’s disease (AD) include cell cultures and animal models. Human diseases, however, are often poorly reproduced in animal models. Developing techniques to differentiate human brain cells from induced pluripotent stem cells (iPSCs) provides a novel approach to studying AD. Three-dimensional (3D) cultures to model AD are represented by organoids, neurospheroids, and scaffold-based cultures. Methods We developed a 3D bioengineered model of iPSC-derived neural tissue that combines a porous scaffold composed of silk fibroin protein with an intercalated collagen hydrogel to support the growth of neurons and glial cells into complex and functional networks. This biomaterial scaffold, designed to match the mechanical properties of brain tissue, can support 3D neural cultures for an extended time without necrosis, a fundamental requisite for aging studies. We have optimized our protocol by seeding neural precursor cells (NPCs) into these scaffolds. Having NPCs stocks derived from multiple subjects allows synchronization of their differentiation and minimizes experimental variability. Cultures were generated from iPSC lines obtained from two subjects carrying the familial AD (FAD) APP London mutation, two well-studied control lines, and an isogenic control. Cultures were analyzed at 2 and 4.5 months. Results An elevated Aβ42/40 ratio was detected in FAD cultures at both time points, as previously reported in 2D cultures derived from the same FAD lines. Extracellular Aβ42 deposition and enhanced neuronal excitability were observed in FAD culture at 4.5 months. Notably, neuronal hyperexcitability has been described in AD patients early in the disease. Transcriptomic analysis revealed deregulation of multiple gene sets in FAD samples. Such alterations were similar to those observed in human AD brains in a large study that performed a co-expression meta-analysis of harmonized data from Accelerating Medicines Partnership for Alzheimer’s Disease (AMP-AD) across three independent cohorts. Conclusions Our 3D tissue model supports the differentiation of healthy iPSC-derived cultures in a porous silk-collagen composite sponge with an optically clear central region. This design facilitates nutrient delivery to meet the metabolic demand of long-term cultures. These data provide evidence that our bioengineered model from patient-derived FAD iPSCs develops AD-related phenotypes, including AD transcriptomic features. Thus, it can represent a valuable model for studying AD-related pathomechanisms. ### Competing Interest Statement The authors have declared no competing interest. * 2D : Two-Dimensional 3D : Three-Dimensional Aβ : Amyloid Beta AD : Alzheimer’s Disease AMP-AD : Accelerating Medicines Partnership for Alzheimer’s Disease AP : Action Potential APP : Amyloid Precursor Protein CBE : Cerebellum CSF : Cerebrospinal Fluid DEG : Differentially Expressed Gene DIAN : Dominantly Inherited Alzheimer’s Network EB : Embryoid Body EP : Evoked Potential FAD : Familial Alzheimer’s Disease GFAP : Glial Fibrillary Acidic Protein GSA : Gene Set Analysis hNeuron : Human Neuron IFG : Inferior Frontal Gyrus iPSC : Induced Pluripotent Stem Cell LOAD : Late-Onset Alzheimer’s Disease LFP : Local Field Potential MAP2B : Microtubule-Associated Protein 2B MSD : Meso Scale Discovery NFH : Neurofilament Heavy Chain NFT : Neurofibrillary Tangles NPC : Neural Precursor Cell Oct4 : Octamer-Binding Transcription Factor 4 PHG : Parahippocampus Gyrus PSEN1 : Presenilin 1 PSEN2 : Presenilin 2 ROSMAP : Religious Order Study Rush Memory and Aging Project SYN : Synaptophysin TCX : Temporal Cortex Tuj1 : Neuron-Specific Class III Beta-Tubulin