Deterministic programming of human pluripotent stem cells into microglia facilitates studying their role in health and disease

• DOI: 10.1073/pnas.2123476119
• Publication Date: 2022-10-17T19:10:57Z
• Authors: Anna M. Speicher; Lisanne Korn; Júlia Csatári; Laura Gonzalez-Cano; Michael Heming; Christian Thomas; Christina B. Schr...; David Schafflick; Xiaolin Li; Lukas Gola; Alexander Engler; Thilo Kaehne; Ludovic Vallier; Sven G. Meuth; Gerd Meyer zu Hörste; Stjepana Kovac; Heinz Wiendl; Hans R. Schöler; Matthias Pawlowski
• Keywords: Central Nervous System; Neurons; Pluripotent Stem Cells; 0301 basic medicine; brain organoids; Macrophages; neurodegeneration; microglia; reprogramming; Cell Differentiation; Biological Sciences; 03 medical and health sciences; stem cells; Humans; Microglia

Microglia, the resident immune cells of the central nervous system (CNS), are derived from yolk-sac macrophages that populate the developing CNS during early embryonic development. Once established, the microglia population is self-maintained throughout life by local proliferation. As a scalable source of microglia-like cells (MGLs), we here present a forward programming protocol for their generation from human pluripotent stem cells (hPSCs). The transient overexpression of PU.1 and C/EBPβ in hPSCs led to a homogenous population of mature microglia within 16 d. MGLs met microglia characteristics on a morphological, transcriptional, and functional level. MGLs facilitated the investigation of a human tauopathy model in cortical neuron–microglia cocultures, revealing a secondary dystrophic microglia phenotype. Single-cell RNA sequencing of microglia integrated into hPSC-derived cortical brain organoids demonstrated a shift of microglia signatures toward a more-developmental in vivo–like phenotype, inducing intercellular interactions promoting neurogenesis and arborization. Taken together, our microglia forward programming platform represents a tool for both reductionist studies in monocultures and complex coculture systems, including 3D brain organoids for the study of cellular interactions in healthy or diseased environments.