HAPI Cells are SIM-A9-related Mouse Microglial Cells Useful for In Vitro Modeling of Microglial Immunometabolism
Year: 2026
Type: preprint
Abstract: Highly aggressively proliferating immortalized (HAPI) cells were initially described as a spontaneously immortalized rat cell line isolated from a mixed neonatal rat glial population. It was demonstrated that HAPI cells are phagocytic, stain for macrophage-/microglia-specific markers like CD11b and GLUT5, and exhibit lipopolysaccharide (LPS)-induced nitric oxide (NO) and tumor necrosis factor-alpha (TNF-α) release. These characteristics led to their widespread use as a rat microglial cell line. Here, we report that HAPI cells are mouse cells, not rat cells, but further establish that they have a microglia-like identity and properties useful for in vitro modeling. Cell line authentication by short tandem repeat (STR) profiling, a method that detects identifying DNA signatures, indicates that HAPI cells are a 100% match for SIM-A9 cells, a mouse microglial cell line reported to be spontaneously immortalized from primary cell culture. We find that both HAPI cells and SIM-A9 cells express the microglia-selective gene Tmem119 , as well as the microglia-/macrophage-selective marker Cx3cr1 , supporting a microglial origin. Like primary rodent microglia or macrophages, HAPI cells respond to combined stimulation with LPS and the Type II interferon, interferon-gamma (IFN-γ), with a pro-inflammatory morphology, NO production, NO-dependent suppression of mitochondrial oxygen consumption, and increased extracellular acidification (an indicator of glycolysis). The Type I interferon, interferon-alpha (IFN-α), also reduces mitochondrial oxygen consumption when administered alone or in combination with LPS. Overall, results indicate that HAPI cells are SIM-A9-related mouse cells of microglial origin and support their continued use to study microglial behavior in vitro , including immunometabolism.
Institution: University of Maryland, Baltimore
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Awards: Novel Mechanisms of Microglial Neurotoxicity at Physiological Oxygen, Training Program in Integrative Membrane Biology, Reprogramming proinflammatory microglia by restoring mitochondrial function, Advanced components for an existing spinning disk confocal in an established core imaging facility, G9000053251, G9000085474, Targeting mitochondrial Complex I in neonatal hypoxia-ischemia
OpenAlex ID: W7128932220