Characteristics of primary rat microglia isolated from mixed cultures using two different methods
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Updated: Mar 2, 2026
Primary Microglia Isolation from Mixed Glial Cell Cultures of Neonatal Rat Brain Tissue
Published on: August 15, 2012
Li Lin1,2, Rakhi Desai2, Xiaoying Wang2
1School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, China.
Background:
Microglial cultures comprise a critically important model system for investigating inflammatory mechanisms in almost all CNS disorders. Mild trypsinization and shaking are the two most commonly used methods to isolate primary microglia from mixed glial cultures. In this study, we characterized and compared microglia obtained using these two methods.
Methods:
Primary rat microglia cultures were prepared from cerebral cortices of 1-2-day-old neonatal Sprague-Dawley rats. After achieving confluency at about 14 days in vitro, microglia were isolated from mixed glial cultures via either mild trypsinization or shaking. The purity of microglia was estimated by flow cytometry. Quantitative real-time PCR was used to measure mRNA expression. TNFα, IL-1β, IL-10, and IGF-1 in cell culture supernatant were measured using ELISA kits. Phagocytic function was assessed using fluorescein-labeled Escherichia coli K-12 BioParticles.
Results:
Mild trypsinization generated a higher yield and purity than shaking. Microglia isolated by mild trypsinization appeared to be in a quiescent state with ramified morphology. Microglia isolated by shaking showed a more heterogenous morphology, including cells with rounded shapes suggestive of activation. Compared with shaking, microglia isolated by trypsinization also had lower baseline phenotype markers (iNOS, CD86, CD206, and arginase 1) and lower levels of cytokines (TNFα, IL-1β, IL-10, and IGF-1) as well as reduced phagocytic capability. Both methods yielded microglia that were responsive to various stimuli such as IL-4, lipopolysaccharide (LPS), or interferon-γ (IFNγ). Although stimulated patterns of gene expression and cytokine release were generally similar, there were also significant differences in terms of absolute response. LPS treatment induced significantly higher levels of TNFα and IL-10 in microglia isolated by mild trypsinization versus shaking. IFNγ induced a lower response in TNFα in microglia obtained by mild trypsinization versus shaking.
Conclusions:
Our results suggest that isolating microglia with the shaking method may induce slight activation even at baseline, and this may affect stimulus responses in subsequent experiments. Caution and attention should be warranted when choosing isolation protocols for primary microglia cultures.
Insights
Mild trypsinization yields purer, quiescent microglia than shaking. Shaking may induce baseline activation, impacting experimental results. Choose isolation methods carefully for reliable microglial research.
Area of Science:
- Neuroscience
- Immunology
Background:
- Microglial cultures are vital for studying central nervous system (CNS) disorders.
- Investigating inflammatory mechanisms in CNS disorders relies heavily on microglial models.
- Common methods for isolating primary microglia include mild trypsinization and shaking.
Purpose of the Study:
- To characterize and compare microglia isolated by mild trypsinization versus shaking.
- To evaluate the purity, yield, and baseline activation state of microglia from different isolation methods.
- To assess the impact of isolation methods on microglial response to stimuli.
Main Methods:
- Primary rat microglia were isolated from neonatal rat cerebral cortices using either mild trypsinization or shaking.
- Microglial purity was assessed by flow cytometry.
- Gene expression (mRNA), cytokine levels (TNFα, IL-1β, IL-10, IGF-1), and phagocytic function were quantified.
Main Results:
- Mild trypsinization yielded higher purity and quiescent microglia compared to shaking.
- Shaking resulted in more heterogeneous morphology and signs of baseline activation.
- Trypsinized microglia exhibited lower baseline markers and cytokine levels but maintained responsiveness to stimuli, with some quantitative differences in response magnitude.
Conclusions:
- The shaking method may induce subtle baseline microglial activation, potentially influencing experimental outcomes.
- Choosing appropriate microglial isolation protocols is crucial for reliable and reproducible research.
- Results highlight the importance of method selection for microglial culture integrity.
