Comparative lipidomics of iPSC-derived microglia protocols reveal lipid droplet and immune differences mediated by media composition

TL;DR

Different methods to make microglia-like cells from stem cells lead to big differences in their lipid content, which affects their function and could impact Alzheimer's research.

Contribution

The study reveals that media composition, particularly B-27 and L-carnitine, strongly influences the lipidome and immune state of iPSC-derived microglia.

Findings

iMGL generated via different protocols show major differences in lipid classes like triglycerides.

B-27 and L-carnitine reduce triglyceride levels and promote a homeostatic microglial state.

B-27 makes iMGL metabolically responsive to immune stimuli.

Abstract

Altered microglial lipid metabolism is heavily implicated in Alzheimer’s disease (AD) and aging. Recently, protocols were developed to generate human induced pluripotent stem cell-derived microglia-like cells (iMGL) to study microglial function in vitro, including embryoid body-based methods and induced transcription factor (iTF)-dependent approaches. Here, we performed comparative lipidomics on iMGL from these methods and report major differences in multiple lipid classes, including triglycerides (TGs), a storage form of fatty acids implicated in microglial reactivity. TGs are strongly increased in iTF microglia due to the absence of a media supplement (B-27). Supplementing iTF microglia with B-27, or its component L-carnitine, reduces TGs and promotes a homeostatic state. B-27 also renders iTF microglia metabolically responsive to immune stimuli. Overall, our data show that iMGL differentiation methods have a major impact on microglial lipidomes and warrant attention when studying AD and neuroinflammatory processes involving lipids.

•iMGL from different generation methods shows major differences in lipid metabolism•B-27 supplement drastically alters the iMGL lipidome and microglial state markers•The B-27 effect is mainly driven by L-carnitine, a cofactor in mitochondrial fatty acid import

iMGL from different generation methods shows major differences in lipid metabolism

B-27 supplement drastically alters the iMGL lipidome and microglial state markers

The B-27 effect is mainly driven by L-carnitine, a cofactor in mitochondrial fatty acid import

Van der Kant and colleagues uncover that the lipidome of iPSC-derived microglia is strongly affected by the selection of differentiation protocol and media supplements. The authors show that the B-27 supplement, and specifically the L-carnitine present in B-27, reduces fatty acid storage in triglycerides, thereby decreasing lipid droplet content and inducing a more homeostatic microglial state.

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