Comparing the Characteristics of Microglia Preparations Generated Using Different Human iPSC-Based Differentiation Methods to Model Neurodegenerative Diseases

Abstract

As the resident immune cells of the healthy nervous system, homeostatic microglia can rapidly become activated in response to injury/disease. Dysregulated microglia activation is a hallmark of nervous system disorders including neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease. The elucidation of the biological and pathological roles of microglia has recently benefitted from the development of microglia-like cells using human induced pluripotent stem cell (iPSC)-based approaches. The success of iPSC-derived microglia preparations as a disease-relevant model system depends on their representation of the in vivo spatial and temporal heterogeneity of microglia under pathological conditions. Little is currently known about the potential of human iPSC-derived microglia generated using different methods for the study of neurodegenerative diseases. We compared the transcriptomes of human iPSC-derived microglia generated using two frequently used in vitro differentiation methods to determine whether separate strategies can generate microglia with distinct transcriptional signatures in vitro. We show that microglia derived using different differentiation methods display distinct maturation characteristics after equivalent times in culture. We also reveal that iPSC-derived microglia preparations generated using these two methods are composed of different subpopulations with transcriptomic signatures resembling those of in vivo regionally distinct microglia subtypes, specifically white-matter and gray-matter microglia. These findings highlight the need to better characterize the subtype composition of each microglia preparation prior to its use to model neurodegenerative diseases.

Microglial contribution to the pathology of neurodevelopmental disorders in humans

“…While hiPSC-derived microglia have been used to study neurodegenerative disorders [ 82 , 177 , 190 ], few studies to date have harnessed this model for SZ research. A study modelling early-life stress by exposing microglial precursors to glucocorticoids found that an increased type I interferon signalling and cellular senescence in the matured cells [ 211 ].…”

Modeling brain macrophage biology and neurodegenerative diseases using human iPSC-derived neuroimmune organoids

“…Since its inception, the iPSC technology has offered an almost unlimited access to in vitro models of human brain cells that are otherwise difficult to obtain from primary human brain tissue (Takahashi et al, 2007;Yu et al, 2007;Shi et al, 2017;Li et al, 2018;Li and Shi, 2020;Tong et al, 2021). Various protocols to differentiate macrophage-and microglia-like cells (iMGs) from iPSCs have been developed (Abud et al, 2017;Lee et al, 2018;McQuade et al, 2018;Pocock and Piers, 2018;Hasselmann and Blurton-Jones, 2020;Tang et al, 2022;Washer et al, 2022). Notably, iPSC differentiation into iMGs entails mesodermal specification and transition of the differentiating cells through an erythromyeloid-like progenitor, reminiscent of primitive hematopoiesis (Buchrieser et al, 2017;Lee et al, 2018).…”