Microglia Increase Inflammatory Responses in iPSC-Derived Human BrainSpheres

Area of Science:

• Neuroscience
• Stem Cell Biology
• Immunology

Background:

• Human induced pluripotent stem cells (iPSCs) and advanced cell culture methods offer improved human physiology models.
• Current 3D brain models often lack microglial populations, limiting their ability to represent neuroinflammation.
• Microglia are crucial for CNS inflammatory responses, development, and neuronal health.

Purpose of the Study:

• To introduce human microglia into iPSC-derived brain spheres (BrainSpheres, BS) to create a more physiologically relevant model.
• To investigate the inflammatory response in this new microglial-inclusive brain sphere model (μBS).
• To assess the utility of the μBS model in studying host-pathogen interactions and infectious diseases.

Main Methods:

• Co-culturing Immortalized Human Microglia - SV40 cells with iPSC-derived BrainSpheres to create the μBS model.
• Exposing the μBS model to lipopolysaccharides (LPS) and flavivirus (Zika and Dengue Virus).
• Analyzing the gene expression of inflammatory cytokines (e.g., IL-6, IL-10, IL-1β, TNF-α, CCL2) post-exposure.

Main Results:

• The μBS model demonstrated an inflammatory response to LPS and flavivirus infection only when microglia were present.
• LPS exposure (20 ng/mL) increased inflammatory cytokine gene expression, peaking at 6-12 hours.
• Infection with Zika and Dengue Virus in μBS led to increased expression of IL-6, IL-1β, TNF-α, and CCL2, indicating a robust inflammatory response.

Conclusions:

• The μBS model, incorporating human microglia, is a more physiologically relevant platform for studying brain inflammation.
• This model effectively elicits inflammatory responses to pathogens, making it valuable for infectious disease research.
• The μBS model shows significant potential for advancing research in host-pathogen interactions within the human central nervous system.