Variable fluid flow regimes alter human brain microvascular endothelial cell-cell junctions and cytoskeletal...

Area of Science:

• Cell Biology
• Biomechanics
• Neuroscience

Background:

• The brain microvasculature endothelium is crucial for brain function and is exposed to diverse fluid flow conditions.
• Endothelial cell responses to flow involve coordinated actions of cell-cell junctions and the cytoskeleton.
• Understanding these mechanobiological responses is key to comprehending brain health and disease.

Purpose of the Study:

• To investigate how different fluid flow regimes impact the structural organization of endothelial cell-cell junctions and the cytoskeleton.
• To analyze changes in cell morphology, including cell area and eccentricity, under various flow conditions.
• To elucidate the specific responses of key junctional proteins (ZO-1, claudin-5, JAM-A, VE-Cad) and F-actin to distinct flow patterns.

Main Methods:

• Human cerebral microvascular endothelial cells were subjected to controlled fluid flow for 24 hours.
• Flow conditions included low laminar (1 dyne·cm⁻²), high laminar (10 dyne·cm⁻²), low oscillatory (±1 dyne·cm⁻²), and high oscillatory (±10 dyne·cm⁻²).
• Immunofluorescence microscopy was used to assess the distribution of ZO-1, claudin-5, JAM-A, VE-Cad, and F-actin. Cell area and eccentricity were quantified.

Main Results:

• Low laminar flow induced the most significant reorganization of ZO-1 and JAM-A.
• Claudin-5 showed substantial reorganization under both low and high laminar flow conditions.
• VE-Cad exhibited its greatest response to high laminar flow, while cell area and eccentricity were most affected by high laminar and low oscillatory flow, respectively.

Conclusions:

• Different fluid flow regimes elicit distinct and specific structural responses in endothelial cell-cell junctions and cytoskeletal components.
• The mechanobiological response of the brain microvasculature is protein-specific and flow-regime dependent.
• These findings contribute to the understanding of cell mechanics and mechanobiology in the context of the brain's microvasculature.