Functional analysis of human brain endothelium using a microfluidic device integrating a cell culture insert

Area of Science:

• Neuroscience
• Biomedical Engineering
• Pharmacology

Background:

• The blood-brain barrier (BBB) controls molecular transport into the brain.
• Existing BBB-on-chip models face accessibility challenges due to complex microfluidics.
• Understanding BBB regulation by microenvironmental cues is crucial for drug development.

Purpose of the Study:

• To develop a simple, accessible microfluidic device for studying human blood-brain barrier (BBB) regulation.
• To investigate the impact of fluid shear stress (FSS) on BBB endothelial cells and drug transport.
• To assess the P-glycoprotein (P-gp) activity in response to FSS in a functional BBB model.

Main Methods:

• A user-friendly microfluidic device integrated with a cell culture insert was designed.
• Immortalized (HBMEC/ci18) and primary human brain microvascular endothelial cells (HBMECs) were cultured under varying FSS (0.1-1 dyn/cm²).
• Bidirectional permeability assays were used to measure P-glycoprotein (P-gp) efflux activity after perfusion culture.

Main Results:

• A stable BBB endothelial barrier was formed under low FSS without compromising barrier tightness.
• Key BBB transporter and receptor expression levels dynamically changed with FSS, plateauing around 1 dyn/cm².
• FSS-stimulated BBB endothelium showed a 1.9-fold increase in P-gp activity compared to static cultures.

Conclusions:

• The developed microfluidic system effectively mimics FSS regulation of the human BBB.
• This simple device enhances P-gp activity, providing a valuable tool for studying drug transport across the BBB.
• The system facilitates research into the bidirectional transport of drugs and their regulation by FSS.