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Updated: Mar 26, 2026
Identifying Microglia and Peripheral Infiltrating Macrophages in the Injured Spinal Cords Using Flow Cytometry
Published on: June 24, 2025
Microglial polarization dynamics in dorsal spinal cord in the early stages following chronic sciatic nerve damage
Fangting Xu1, Juan Huang2, Zhenghua He1
1Department of Anesthesiology, Xiangya Hospital of Central South University, Changsha 410008, China.
Abstract:
Peripheral nerve injury can lead to activation of spinal microglia, which can mediate neuroinflammation and contribute to neuropathic pain following nerve injury. Activated microglia may manifest with either pro-inflammatory M1 phenotype or anti-inflammatory M2 phenotype, which may lead to detrimental or beneficial roles in the nervous system. In this study, microglia numbers, morphology and gene profiles were examined in the dorsal spinal cord of rats over 14 days following sciatic nerve chronic constriction injury (CCI). The morphology of some microglia changed from a surveying to an activated state within 1 day of CCI. Neuropathic pain developed within seven to 14 days following injury and microglia numbers were increased, with almost all in the dorsal spinal cord morphologically defined as activated. At day one after CCI, both M1 and M2 microglia-related genes were increased but only M1 microglia-related genes remained elevated at day seven and 14 thereafter. These results indicate that both M1 and M2 microglia were activated in the dorsal spinal cord one day after CCI but the microglia skewed towards M1 phenotype during the following seven and 14 days.
Insights
Peripheral nerve injury activates spinal microglia, initially both M1 and M2 phenotypes. After 7-14 days, microglia shift to a pro-inflammatory M1 phenotype, contributing to neuropathic pain.
Area of Science:
- Neuroscience
- Immunology
- Pain Research
Background:
- Peripheral nerve injury triggers spinal microglia activation, a key factor in neuroinflammation and neuropathic pain.
- Microglia can adopt pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, influencing nervous system outcomes.
- Understanding microglia dynamics post-injury is crucial for developing targeted pain therapies.
Purpose of the Study:
- To investigate microglia activation, phenotype, and gene expression in the dorsal spinal cord following sciatic nerve chronic constriction injury (CCI) in rats.
- To correlate microglial changes with the development of neuropathic pain over a 14-day period.
Main Methods:
- Sciatic nerve chronic constriction injury (CCI) model in rats.
- Analysis of microglia numbers and morphology in the dorsal spinal cord.
- Examination of M1 and M2 microglia-related gene profiles at days 1, 7, and 14 post-injury.
Main Results:
- Microglia morphology shifted to an activated state within 1 day of CCI.
- Neuropathic pain emerged between 7 and 14 days post-CCI, accompanied by increased numbers of activated microglia.
- Initially, both M1 and M2 microglia gene markers were upregulated at day 1.
- By days 7 and 14, only M1 microglia gene markers remained significantly elevated, indicating a shift towards a pro-inflammatory phenotype.
Conclusions:
- Both M1 and M2 microglia are activated early after peripheral nerve injury.
- The sustained elevation of M1 markers suggests a shift towards a pro-inflammatory microglial response, potentially driving neuropathic pain development.
- These findings highlight the evolving role of microglia in neuropathic pain pathogenesis.
