Description
Microglia are the resident immune cells of the central nervous system and are thought to play key roles in retinal disease. However, distinguishing microglia from infiltrating macrophages remains a challenge, as both cell types share overlapping transcriptional and functional profiles. This complicates interpretation of immune activation in retinal disorders such as age‑related macular degeneration (AMD) and limits the precision of in‑vitro disease models.
To address this, microglia‑specific markers were identified in induced pluripotent stem cell‑derived microglia (iPSC‑MG) through comparison with iPSC‑macrophages (iPSC‑MP). Bulk RNA sequencing and qPCR were used to compare transcriptional profiles of iPSC‑MG with iPSC‑MP and their precursors. These datasets were also compared with publicly available primary microglia and macrophage datasets. Candidate markers were then assessed for stability across different cell lines and additional cell types.
Commonly used “microglia‑specific” markers showed substantial overlap between iPSC‑MG and iPSC‑MP in both bulk RNA‑seq and qPCR analyses. New microglia‑enriched markers were identified and demonstrated repeated specificity in iPSC‑derived cells, although this specificity was not reflected in immortalised microglia (HMC3) or macrophages (THP‑1‑derived). Despite these differences, comparative analysis of iPSC‑MG with primary microglial datasets showed significant transcriptional overlap, supporting microglia‑like behaviour of the iPSC‑derived cells.
Refining a reliable set of microglial markers contributes to clearer biological definitions of microglial identity and provides practical tools for distinguishing microglia from macrophages in retinal research. Establishing these markers is essential for improving in‑vitro disease models, strengthening interpretation of immune responses, and ultimately supporting more accurate studies of AMD and other neuroinflammatory conditions.
Lay Abstract
Microglia are important immune cells that help protect our central nervous system, including the eye. They are involved in many eye diseases, but studying them is difficult because they closely resemble another immune cell type called macrophages, which can enter the eye from the bloodstream. Because these two cell types look and behave similarly, it can be hard to know which one is responsible for specific immune activities.
To address this, we compared stem‑cell‑derived microglia with stem‑cell‑derived macrophages to identify markers truly specific to microglia. We used two techniques that measure the “instructions” inside cells that tell them which proteins to make, and we compared our results with publicly available datasets from real human microglia to see how closely our cells match those in the eye.
We found that many commonly used “microglia‑specific” markers were present in both microglia and macrophages, but we identified new markers consistently enriched in microglia across different stem‑cell lines. An overall comparison with real human microglia also showed that our stem‑cell‑derived microglia behave in a microglia‑like way.
Developing a reliable set of microglial markers will help researchers better distinguish microglia from macrophages in eye research, improving disease models and supporting better studies of eye diseases.
| Lay Title | Understanding the Eye’s Immune Cell Differences to Improve Disease Research |
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| Role | PhD Student |