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Updated: Jul 14, 2026
Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Microglia repetitively isolated from in vitro mixed glial cultures retain their initial phenotype
1Department of Pharmacology, Physiology & Therapeutics, University of North Dakota School of Medicine and Health Sciences, Neuroscience Building, 504 Hamline Street, Grand Forks, ND 58202-9037, United States.
Abstract:
In vitro culture of rodent microglia is a common system used to model proinflammatory changes in the brain. However, typical postnatal brain isolation protocols are time consuming and cell numbers acquired are often a rate-limiting factor for experimental progress. Large studies that rely on the use of primary microglia can, therefore, require excessive numbers of animals at considerable expense, additional technical support and culture incubator space. Although the addition of mitogens such as macrophage colony-stimulating factor, granulocyte macrophage-colony stimulating factor, and epidermal growth factor to the cultures can facilitate a higher yield, this adds additional expense and likely alters the microglial phenotype. We have defined a simple, inexpensive modification of our standard culture protocol that allows us to repetitively isolate microglia. In order to define a method for improving microglia yield, we utilized our standard mixed glial culture preparation derived from postnatal day 1-3 mouse brains. After isolating microglia from mixed cultures at 14 days in vitro, we added fresh media to the cultures for an additional 7 and 14 days to monitor microglial proliferation. We acquired a constant number of cells at each successive time point although the numbers were reduced from the first isolation. More importantly, in order to determine if our successive microglia isolates differed phenotypically we characterized several parameters of function. We compared their ability to secrete the proinflammatory cytokines interleukin-6 and tumor necrosis factor alpha after LPS stimulation. We also contrasted the phagocytic ability, morphology, and specific immunoreactivity (CD11b, CD68, CD45 and MHC II) of the culture ages. Our data demonstrate that microglia can be obtained from extended-time cultures provided periodic isolation is performed. Moreover, the cells retain a comparable in vitro phenotype. This demonstrates that cells from all ages can be combined for any given study. These findings are a viable and inexpensive way to increase and extend the microglial yield without increasing the number of animals used or adding costly mitogens. This method will be particularly useful for the preparation of microglia cultures from limited transgenic colonies.
Insights
This study presents a simple, inexpensive method to increase microglia yield from rodent brain cultures. The modified protocol allows for repeated isolation of microglia, maintaining their phenotype and reducing animal use.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- In vitro rodent microglia cultures are crucial for studying brain inflammation.
- Standard isolation protocols are time-consuming and yield limited cells, increasing animal use and costs.
- Mitogens can increase yield but alter microglial phenotype and add expense.
Purpose of the Study:
- To develop a simple, inexpensive method for increasing microglia yield from rodent brain cultures.
- To assess if microglia isolated from extended cultures retain their phenotype and function.
- To provide a viable alternative for researchers needing larger microglia numbers, especially from limited transgenic colonies.
Main Methods:
- Utilized standard mixed glial cultures from postnatal day 1-3 mouse brains.
- Performed serial microglia isolation from cultures maintained for an additional 7 and 14 days post-initial isolation.
- Assessed microglial phenotype and function by measuring cytokine secretion (IL-6, TNF-α), phagocytic ability, morphology, and immunoreactivity (CD11b, CD68, CD45, MHC II) after LPS stimulation.
Main Results:
- A constant number of microglia were acquired at each successive isolation time point.
- Microglia from extended cultures retained a comparable in vitro phenotype and function to initially isolated cells.
- The method allows for increased and extended microglial yield without additional animals or costly mitogens.
Conclusions:
- Extended culture time with periodic isolation is a viable strategy to increase microglial yield.
- Microglia harvested at different time points maintain a consistent phenotype, allowing pooling for studies.
- This cost-effective modification is particularly beneficial for experiments requiring large microglia numbers or utilizing limited transgenic resources.
