Primary Microglia
Quick Facts
| Feature | Information |
|---|---|
| Cell Type | Primary CNS Immune Cells |
| Species | Mouse, Rat, Human |
| Tissue of Origin | Brain or Spinal Cord |
| Common Isolation Stage | Neonatal Rodents (P0-P3) |
| Growth Mode | Semi-adherent to Adherent |
| Morphology | Small, ramified cells that become amoeboid upon activation |
| Recommended Medium | DMEM High Glucose + 10% FBS |
| Surface Coating | Standard Tissue Culture Plastic |
| Incubation Conditions | 37°C, 5% CO₂, ≥95% humidity |
| Proliferation | Limited |
| Major Applications | Neuroinflammation, Phagocytosis, Neurodegeneration, Neuroimmune Signaling |
Overview
Primary microglia are the resident innate immune cells of the central nervous system. Unlike peripheral macrophages, they originate from embryonic yolk sac-derived progenitors and continuously monitor the brain microenvironment. Upon injury, infection, or neurodegeneration, they become activated and regulate inflammatory responses, phagocytosis, synaptic remodeling, and tissue repair.
Cell Source
Primary microglia are commonly isolated from:
- Mouse (P0-P3)
- Rat (P0-P3)
- Human brain tissue (specialized studies)
Neonatal rodent brains are the most common source because they provide higher cell yields and easier isolation than adult tissue.
Growth Characteristics
| Characteristic | Description |
|---|---|
| Growth Mode | Semi-adherent to Adherent |
| Proliferation | Limited |
| Morphology | Ramified under resting conditions and amoeboid following activation |
| Culture Lifetime | Short-term cultures are preferred to preserve physiological characteristics |
Culture Notes
Primary microglia are commonly isolated from mixed glial cultures, where astrocytes form an adherent monolayer and microglia are harvested by gentle shaking. Supplementation with IL-34 and TGF-β helps maintain a homeostatic microglial phenotype.
Biological Characteristics
Major Functions
Primary microglia are responsible for:
- Immune surveillance of the CNS
- Phagocytosis of pathogens and cellular debris
- Synaptic pruning during development
- Cytokine and chemokine production
- Regulation of neuroinflammation
- Tissue repair following injury
Microglial Markers
Common markers include:
- IBA1
- TMEM119
- P2RY12
- CX3CR1
- CD11b
Activated microglia may also express:
- CD68
- MHC-II
- CD86
- iNOS
Experimental Relevance
Primary microglia are widely used to investigate:
- Neuroinflammation
- Alzheimer's disease
- Parkinson's disease
- Multiple sclerosis
- Phagocytosis
- Oxidative stress
- Neuron-microglia interactions
Culture Conditions
Recommended Medium
- DMEM High Glucose
- 10% Fetal Bovine Serum (FBS)
- L-Glutamine
- Penicillin-Streptomycin (optional)
To better preserve homeostatic characteristics, cultures may be supplemented with:
- IL-34
- TGF-β
Incubation Conditions
| Parameter | Value |
|---|---|
| Temperature | 37°C |
| CO₂ | 5% |
| Relative Humidity | ≥95% |
Medium Changes
Replace the culture medium every 2-3 days while minimizing unnecessary handling to reduce spontaneous activation.
Major Applications
Primary microglia are widely used for:
- Neuroinflammation studies
- Cytokine signaling
- Phagocytosis assays
- Alzheimer's disease research
- Parkinson's disease research
- Multiple sclerosis models
- Neuron-glia co-culture systems
- Drug screening
Advantages
- Highly physiologically relevant immune model
- Authentic inflammatory and phagocytic responses
- Gold-standard model for neuroimmune research
- Suitable for studying neuron-microglia interactions
- Closely resembles in vivo microglial biology
Limitations
- Limited proliferative capacity
- Easily activated during isolation and culture
- Neonatal microglia differ from adult microglia
- Phenotype changes during prolonged culture
- Batch-to-batch variability between isolations
Quality Control
Healthy cultures should demonstrate:
- High expression of IBA1, TMEM119, and P2RY12
- Ramified morphology under resting conditions
- Robust response to inflammatory stimuli
- Minimal astrocyte contamination
- Consistent phagocytic activity
References
- Saura J. Microglial cells in astroglial cultures. Methods (2007).
- Bohlen CJ et al. Diverse requirements for microglial survival and function. Neuron (2017).
- Butovsky O et al. Identification of a unique TGF-β-dependent molecular signature in microglia. Nature Neuroscience (2014).
- Henn A et al. The suitability of BV2 cells as a substitute for primary microglia. Brain Research (2009).