Comparative morphology and phagocytic capacity of primary human adult microglia with time-lapse imaging

Area of Science:

• Neuroimmunology
• Cell Biology
• Microglial Function

Background:

• Microglia are the primary immune cells of the central nervous system, providing immune surveillance.
• Microglia exhibit diverse morphologies, including ramified, amoeboid, and pseudopodic forms.
• The functional significance of microglial morphology, particularly in adult humans, remains poorly understood due to limited sample availability.

Purpose of the Study:

• To investigate the phagocytic capabilities of different human adult microglial morphologies.
• To compare the phagocytic efficiency of pseudopodic and amoeboid microglia with ramified microglia and monocyte-derived dendritic cells.

Main Methods:

• Primary human microglia were isolated from normal-appearing white matter.
• Phagocytosis assays were performed using E. coli bioparticles.
• Microglial morphology and phagocytic activity were analyzed.

Main Results:

• Pseudopodic and amoeboid microglia demonstrated significant phagocytic activity, internalizing E. coli bioparticles.
• These morphologies utilized ruffled cell membrane sheets and retrograde transport for particle uptake.
• Both pseudopodic and amoeboid microglia were more effective phagocytes than ramified microglia and monocyte-derived dendritic cells.

Conclusions:

• Amoeboid and pseudopodic microglial morphologies are highly effective phagocytes within the human brain.
• These forms of microglia play a crucial role as brain scavengers.
• Understanding microglial morphology-function relationships is vital for neuroimmunology research.