Abstract

Microglia play a central role in the
clearance of debris resulting from neuronal damage and depending on the
context, may contribute to or help resolve neuropathology. Studying these cells
in a human system remains challenging. We have optimised a protocol to generate
human monocyte-derived microglia to study the phagocytosis of myelin. The
induced microglia show a progressive increase in TMEM119 expression during
their differentiation alongside other microglial markers. Using high-content,
kinetic confocal imaging, we studied the uptake of a pHrodo-labelled myelin
membrane preparation prepared from human brains. The cells displayed robust
phagocytic activity albeit with kinetics distinct from monocyte-derived
macrophages. As expected, phagocytic uptake was highly sensitive to disruption
of the actin cytoskeleton with cytochalasin D. As the model was of suitable
throughput for 96-well plate format, we further used this system to screen a
range of compounds and identified a set of modulators of this phagocytic
process. The impact of these modulators displayed sensitivity to the
microenvironment suggesting the impact of pathways upon the clearance of
neuronal debris may be disease or context dependent. We suggest this model
provides a useful human model system for phenotypic screening and to identify
pathways involved in the clearance of neuronal debris in a range of diseases.