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A subpopulation of bone marrow-derived macrophage-like cells shares a unique ion channel pattern with microglia
R B Banati1, D Hoppe, K Gottmann
1Department of Neuromorphology, Max-Planck-Institute for Psychiatry, Martinsried, Federal Republic of Germany.
Abstract:
Rat microglia share a number of antigenic, functional, and morphological similarities with macrophages from other tissues, but are characterized by a distinctly different pattern of ion channels in the cellular membrane (Kettenmann et al., J Neurosci Res 26:278-287, 1990). Macrophages typically express outward and inward K+ currents. In contrast, microglia lack outward currents and only show inwardly rectifying K+ currents, regardless of the isolation or cultivation method employed for microglia. In this study we demonstrate that a subpopulation of bone marrow-derived macrophage-like cells possesses inward rectifier K+ currents, but no outward currents and thus with regard to the electrophysiological characteristics closely resembles microglia. A second population of bone marrow-derived macrophage-like cells shows the usual channel pattern described for other body macrophages. Our results strengthen the hypothesis that in the bone marrow distinct pools of precursor cells exist, possibly reflecting an early differential lineage determination for body and brain macrophages, i.e., microglia.
Insights
Rat microglia, immune cells in the brain, exhibit unique ion channel patterns compared to other macrophages. Bone marrow cells show similar patterns, suggesting distinct precursor pools for brain and body macrophages.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia, the resident immune cells of the brain, share similarities with tissue macrophages but possess distinct electrophysiological properties.
- Macrophages typically exhibit both outward and inward potassium (K+) currents, while microglia lack outward currents, showing only inwardly rectifying K+ currents.
Purpose of the Study:
- To investigate the electrophysiological characteristics of bone marrow-derived macrophage-like cells.
- To determine if distinct precursor cell populations exist in the bone marrow that could give rise to microglia and other tissue macrophages.
Main Methods:
- Electrophysiological recordings (patch-clamp) were used to analyze ion channel activity in bone marrow-derived macrophage-like cells.
- Comparison of K+ current patterns between two distinct subpopulations of bone marrow-derived cells and rat microglia.
Main Results:
- A subpopulation of bone marrow-derived macrophage-like cells exhibited inward rectifier K+ currents but lacked outward currents, closely resembling microglia.
- A second population of bone marrow-derived cells displayed the typical K+ channel pattern observed in other tissue macrophages.
Conclusions:
- The findings support the hypothesis of distinct precursor cell pools within the bone marrow.
- This suggests an early lineage determination for brain macrophages (microglia) and other body macrophages.