iPSC-derived macrophages: An in vitro model to study human disease-relevant macrophage biology

Abstract Human macrophages differ from their mouse counterparts in multiple metabolic pathways, surface protein expression, and transcription factor biology. Monocyte-derived macrophages (MDMs) from blood are generally used to study human macrophage biology in vitro. However, the use of MDMs as a human macrophage model is limited by donor-to-donor variability, total cell availability, preactivation effects, and relative resistance to genetic manipulation. Here, we explored stem cell–derived macrophages to study in vitro disease-relevant macrophage phenotypes. We compared induced pluripotent stem cell–derived macrophages (iDMs) with primary human stem cell–derived macrophages from cord blood–derived macrophages or bone marrow–derived macrophages (BMDMs) in their ability to elaborate tissue and disease-relevant phenotypes in comparison with conventional blood MDMs. Analyses of phenotypical and functional features revealed that iDMs were highly similar to cord blood–derived macrophages and BMDMs, and resembled MDMs. Importantly, all macrophages, and particularly iDMs adopted expected disease-relevant phenotypes in vitro when stimulated with disease-associated mediators. RNA sequencing analyses of in vitro macrophages stimulated with tissue relevant factors revealed that their transcriptomes mapped to human in vivo inflammatory conditions. Using this approach, we found a close correlation between stimulation and expected disease-association counterpart in vivo. In conclusion, we established a streamlined system to link stem cell–derived macrophage phenotypes to relevant macrophage phenotypes in disease states. Thus, enabling conditions for in vitro replication of complex human macrophage biology observed in single-cell RNA sequencing from human diseased tissue.