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

•Various microglial morphologies exist, including ramified, amoeboid, and pseudopodic.•Human, adult microglia were isolated from normal-appearing white matter resected from temporal lobe surgery.•Pseudopodic and amoeboid microglia were equally effective phagocytes, more so than ramified microglia or dendritic cells.•E.coli bioparticles were taken up via ruffled cell membrane sheets into an acidic compartment in the cell body.•F-actin densities were observed at membrane edges consistent with phagocytic cups.

Microglia provide immune surveillance within the brain and spinal cord. Various microglial morphologies include ramified, amoeboid, and pseudopodic. The link between form and function is not clear, especially for human adult microglia which are limited in availability for study. Here, we examined primary human microglia isolated from normal-appearing white matter. Pseudopodic and amoeboid microglia were effective phagocytes, taking up E. coli bioparticles using ruffled cell membrane sheets and retrograde transport. Pseudopodic and amoeboid microglia were more effective phagocytes as compared to ramified microglia or monocyte-derived dendritic cells. Thus, amoeboid and pseudopodic microglia may both be effective as brain scavengers.

Graphical abstractDownload high-res image (275KB)Download full-size image