From Amyloid Exposure to Genetic Causality: Converging hiPSC-Based Models of Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder in which genetic susceptibility, aging, protein aggregation, and neuroglial dysfunction converge to drive progressive neuronal loss. Although animal models and conventional cell systems have provided fundamental insights into pathomechanisms, they only partially reproduce the human-specific and multifactorial nature of AD. Human induced pluripotent stem cell (hiPSC)-based models have emerged as a powerful platform to investigate disease-relevant processes within a patient-specific genetic background while enabling the generation of multiple neural cell types and multicellular systems. In this review, we present the evolution of hiPSC-based AD modeling, from reductionist paradigms based on exogenous amyloid-β exposure to CRISPR-engineered isogenic models addressing causal mutations and genetic risk variants associated with either familial or sporadic forms. We examine the contribution of three-dimensional brain organoids and neuroglial co-culture systems in recapitulating cell-cell interactions, neuroinflammatory responses, and tissue-level pathological processes. We focus on current challenges, including the limited representation of neuronal aging, variability among organoids, and the need for standardized protocols. Finally, we discuss the translational potential of hiPSC-derived systems for target identification, drug discovery, and regenerative medicine. Collectively, these advances position hiPSC-based platforms as essential complementary models for elucidating AD pathogenesis and accelerating the development of precision therapeutic strategies.