A multidimensional optimization strategy for high-purity primary rat microglia isolation with preserved functional responsiveness.

BACKGROUND

Primary microglia are essential for studying neuroinflammation and microglia-mediated neuropathology. However, conventional shaking-based isolation methods often yield unstable purity, astrocytic contamination, and heterogeneous activation states.

NEW METHOD: We developed a multidimensional optimization strategy for primary rat microglia isolation by systematically integrating three key parameters: neonatal developmental stage, culture vessel geometry, and Percoll density gradient purification. Microglial purity, identity, viability, and functional responsiveness were evaluated by flow cytometry, immunofluorescence, Western blotting, qPCR, and ELISA.

RESULTS

Compared with postnatal day 7 (P7), postnatal day 3 (P3) tissue provided higher isolation efficiency, greater culture homogeneity, and reduced astrocytic contamination. Culture in 6-cm dishes improved cell adhesion and morphological consistency. Percoll density gradient purification further increased microglial purity by approximately 20-30% while maintaining acceptable cell recovery. The optimized protocol consistently yielded cultures with stable purity (80-90%), high IBA1 positivity (>90%), increased metabolic activity, and lower basal activation. Following lipopolysaccharide stimulation, purified microglia exhibited robust inflammatory responses, including increased cytokine secretion and inflammatory gene expression.

COMPARISON WITH EXISTING

METHODS

Compared with conventional shaking-based isolation, the optimized workflow improves purity, reduces contamination, enhances reproducibility, and preserves functional responsiveness without requiring specialized equipment.

CONCLUSIONS

This study provides a practical and reproducible strategy for improving microglial purity and experimental consistency and offers a reliable experimental platform for neuroinflammation research and mechanistic studies.