A Microfluidic Platform for Investigating Transmembrane Pressure-Induced Glomerular Leakage

Area of Science:

• Nephrology
• Biomedical Engineering
• Cell Biology

Background:

• Renal failure is often linked to transmembrane pressure across the glomerular filter barrier.
• Studying renal failure is challenging due to the lack of in vitro models that control transmembrane pressure.
• Podocytes, crucial for kidney filtration, are difficult to model in vitro under controlled pressure conditions.

Purpose of the Study:

• To develop and validate a microfluidic platform for investigating podocyte function under controlled transmembrane pressure.
• To analyze the impact of varying transmembrane pressure on glomerular filtration and podocyte integrity.
• To explore the relationship between transmembrane pressure, glomerular leakage, and podocyte cellular changes.

Main Methods:

• Cultivation of podocytes on a porous anodic aluminum oxide membrane with collagen coating within a microfluidic device.
• Application of controlled transmembrane pressure (ΔP) across the podocyte-seeded membrane.
• Evaluation of glomerular filtration using fluorescently labeled dextrans of various molecular weights (20 kDa, 70 kDa, 500 kDa).
• Assessment of podocyte cellular changes, including synaptopodin expression and actin cytoskeleton organization.

Main Results:

• The microfluidic platform successfully simulated kidney filtration, blocking 500 kDa dextran at ΔP < 60 mmHg and allowing passage at ΔP ≥ 60 mmHg.
• Glomerular leakage occurred at pressures ≥ 60 mmHg, mimicking hypertension-induced damage.
• Podocyte synaptopodin expression and actin cytoskeleton integrity were compromised at ΔP > 30 mmHg, indicating cellular dysfunction.

Conclusions:

• The developed microfluidic platform provides a robust in vitro model for studying transmembrane pressure-induced glomerular filtration and podocyte injury.
• This model accurately replicates healthy kidney filtration and hypertension-induced glomerular leakage.
• Findings highlight the correlation between elevated transmembrane pressure, reduced synaptopodin, and actin disorganization, offering insights for understanding renal failure mechanisms and potential therapeutic targets.