The human microglial clone 3 (HMC3) cell line has long been a staple for microglia research, widely used, readily available, and easy to culture. But as expectations around data relevance and human fidelity increase, many researchers are beginning to ask: Are HMC3 cells still the right model?
This blog walks through why labs are replacing HMC3 cells with ioMicroglia, a human iPSC-derived microglia developed by bit.bio. It compares the biology, highlights practical considerations, and shows how you can make the switch with minimal disruption.
HMC3 is a human microglial cell line established in the 1990s through SV40 immortalisation. These cells have been widely adopted because they are easy to maintain and proliferate indefinitely. However, recent analyses reveal several critical issues1.
Known limitations of HMC3 cells
Limited microglial identity | HMC3 cells lack key microglia markers like P2RY12, TREM2, and IBA1. In fact, they express markers more typical of pericytes.
Reduced functionality | HMC3 cells demonstrate limited phagocytosis and a narrow, blunted cytokine response.
Phenotypic drift | As with many immortalised cell lines, long-term culture leads to inconsistency across labs and over passages.
If your goal is to model neuroinflammation, neuron-microglia interactions, or human-relevant microglial responses, the immortalised HMC3 cell line is a weak proxy.
ioMicroglia are derived from human iPSCs using opti-ox™ deterministic cell programming, resulting in:
In short, they behave more like primary human microglia, while offering the consistency of a manufactured cell product.
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Feature
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HMC3 (immortalised)
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ioMicroglia (iPSC-derived, deterministically programmed)
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Identity
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Pericyte-like, lacks key microglia markers |
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Function
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Low phagocytosis, weak cytokine release |
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Proliferation
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Divides indefinitely |
Post-mitotic after programming |
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Reproducibility
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Drift with passage number |
Consistent programming to a defined human microglia phenotype, lot-controlled, consistent functionality |
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Co-culture
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Medium compatibility, issues with neurons |
If you currently use HMC3 cells for phagocytosis or inflammatory readouts, and you are looking for a more phenotypically and physiologically relevant model, you can run the same assays with ioMicroglia, often with stronger and more reproducible results.
No. In most cases, you can apply your existing protocols with only minor adjustments:
There is a short learning curve for handling and adopting workflows (e.g., gentle handling, day 10 differentiation). For an easy start, a video tutorial shows you step by step how to thaw, seed, and culture ioMicroglia.
In addition, we provide a detailed User Manual, Protocols, and Cell Culture Hacks that are designed for translational workflows and our Technical Support Team is always on hand.
Try ioMicroglia in your lab
See the difference in your own results, with our evaluation packs of ioMicroglia (3 vials for $995) so you can run side-by-side comparisons with your current HMC3 cell line setup. Each vial yields >1.0 million viable cells, enough for multiple assays.
If you are still using HMC3 cells, now is the time to re-evaluate. ioMicroglia offers a path to more physiologically relevant, functionally active, and consistent microglial models. With straightforward protocols and strong assay compatibility, the switch is easier than you might think.
Upgrading your microglial model is not about novelty; it is about getting better, translational data.