Origin of macrophages in central nervous tissue. A study using intraperitoneal transplants contained in Millipore diffusion chambers
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Updated: Nov 8, 2026
Analysis of Microglia and Monocyte-derived Macrophages from the Central Nervous System by Flow Cytometry
Published on: June 22, 2017
Abstract:
In order to determine the origin of brain phagocytes brain slices and optic nerve segments from adult Lewis rats were transplanted into the peritoneal cavity of syngenic recipients. The specimens were contained in Millipore diffusion chambers fitted with membranes of either 0.22 or 5.0 microns pore size. The either blocked or allowed the access of non-resident cells. Each recipient rat received both a 0.22 and 5.0 microns pore chamber. Later (3-16 days), the specimens were recovered and analyzed by monoclonal antibody techniques and electron-microscopy. Endothelia, GFAP+ astrocytes, ED1-/ED2+/RCA-1+/OX-6-perivascular cells and ED1-/ED2-/RCA-1+/lysozyme--microglia were found to have survived the procedure. Cells of the macrophage phenotype (ED1+/ED2+/RCA-1+/lysozyme+/vimentin+ with phagocytic vacuoles), however, were only found in large numbers in specimens kept within 5.0 microns pore size chambers, giving access to non-resident cells, and were exceedingly rare in specimens from 0.22-micron pore chambers. It has been concluded that the majority of brain phagocytes found after lesions do not originate from microglia or perivascular monocytic cells, but rather from invading cells.
Insights
Brain phagocyte origins were investigated using transplanted rat tissues. The study found that most brain phagocytes after injury originate from invading cells, not resident microglia.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Understanding the origin of phagocytic cells in the central nervous system is crucial for neuroinflammatory and neurodegenerative disease research.
- Resident microglia and perivascular cells are considered potential sources of brain phagocytes.
Purpose of the Study:
- To determine the origin of phagocytes in the brain following injury.
- To differentiate between resident and infiltrating cell contributions to the phagocyte population.
Main Methods:
- Adult rat brain slices and optic nerve segments were transplanted into syngenic recipients' peritoneal cavities within diffusion chambers.
- Chambers had pore sizes of 0.22 or 5.0 microns to control non-resident cell access.
- Recovered specimens were analyzed using monoclonal antibody techniques and electron microscopy.
Main Results:
- Resident brain cells (endothelia, astrocytes, perivascular cells, microglia) survived transplantation.
- Macrophage-phenotype cells with phagocytic vacuoles were abundant in 5.0-micron chambers (allowing cell entry).
- These macrophage-phenotype cells were rare in 0.22-micron chambers (blocking cell entry).
Conclusions:
- The majority of brain phagocytes observed after injury are not derived from resident microglia or perivascular cells.
- Infiltrating cells from the periphery are the primary source of brain phagocytes following lesions.
- This finding has significant implications for understanding brain immune responses.
