Chimeric human organoid and mouse brain slice co-cultures to study microglial function

Area of Science:

• Neuroscience
• Stem Cell Biology
• Developmental Biology

Background:

• Modeling human microglia in vitro is challenging for studying brain development and neurodegenerative diseases.
• Human organoids (hORGs) model neuronal development but lack mature human microglia.
• Existing models do not fully replicate the human brain microenvironment for microglia.

Purpose of the Study:

• To develop an in vitro chimeric model for studying human microglia in a brain-like environment.
• To investigate cross-species interactions between human organoids and mouse brain slices.
• To establish a platform for long-term functional studies of human microglia.

Main Methods:

• Co-culturing human induced pluripotent stem cell-derived organoids (hORGs) with mouse brain slice cultures (mBSCs).
• Pre-differentiating human iPSC-derived microglia in mBSCs before introduction into hORGs.
• Utilizing laser-induced injury to assess microglial response and functionality.

Main Results:

• The chimeric model demonstrated earlier cortical neuronal differentiation markers in hORGs.
• Human iPSC-derived microglia migrated into hORGs and adopted mature ramified morphology.
• Microglia remained viable for months and responded to injury, showing long-term functionality.

Conclusions:

• The developed in vitro chimeric model supports long-term study of human microglia.
• This system facilitates mechanistic studies and compound screening for microglial function.
• The model provides a more accurate representation of the human brain microenvironment for microglia research.