Research Scientist H. Lundbeck A/S Copenhagen, Denmark
Abstract: Microglia, as resident immune cells of the central nervous system (CNS), play pivotal roles in maintaining neural homeostasis, synaptic pruning, and immune responses. Investigating human microglia biology is essential for understanding neurodevelopment, neuroinflammation, and neurodegenerative disorders. Induced pluripotent stem cells (iPSCs) offer a powerful platform for generating human microglia-like cells, which enable the study of drug mechanisms of action, efficacy, and potency, as well as patient-specific microglia to investigate disease molecular mechanisms. Challenges associated with iPSC models for pharmacology studies include substantial genetic variability across different iPSC lines and variability between differentiation batches within the same iPSC line. These variations can impact microglia behavior, functional properties, and responses to stimuli. Therefore, to have good reproducibility and consistency in iPSC-microglia models, we have stablished rigorous quality control (QC) measures for a widely used iPSC microglia differentiation protocol. In our QC process, we combine qualitative assessments based on morphology, activation capacity and marker expression with quantitative analyses. For the latter we specifically evaluate cell dependency on MCSF—a critical growth factor for microglial survival— to estimate health and purity of the microglia culture and have defined an acceptance threshold. Additionally, comparing IC50 values and efficacy of CSFR inhibition using Plexicon over a large number of successive differentiations has allowed us to identify a normal range of performance. By integrating both the qualitative and quantitative approaches to qualify batches, we have established a QC framework for every microglia batch. Using this framework has led to excellent reproducibility between experiments and hence robust data in downstream pharmacology assays.
