Engineered extracellular matrices with controlled mechanics modulate renal proximal tubular cell epithelialization

Area of Science:

• Biomaterials Science
• Renal Physiology
• Cell Biology

Background:

• Acute kidney injury (AKI) is a prevalent condition with high morbidity and mortality.
• Recovery from AKI often involves renal proximal tubular epithelial cell (RPTEC) proliferation.
• The role of the microenvironment, particularly substrate mechanics, in RPTEC recovery is not well understood.

Purpose of the Study:

• To investigate the influence of substrate mechanical properties on human RPTEC proliferation using a tunable poly(ethylene glycol) (PEG) hydrogel platform.
• To model kidney recovery from AKI by studying RPTEC behavior on substrates with controlled stiffness.

Main Methods:

• Development of poly(ethylene glycol) diacrylate hydrogels with independent control over mechanics and cell-adhesion properties.
• Culture of human RPTECs on hydrogels of varying stiffness.
• Assessment of cell spreading, proliferation, apoptosis, and YAP nuclear localization.
• Analysis of focal adhesion formation, cytoskeletal organization, and activation of FAK and ERK signaling pathways.
• Evaluation of epithelial monolayer formation, including tight junctions, polarity, and basement membrane organization in long-term cultures.

Main Results:

• Increased substrate stiffness significantly promoted RPTEC spreading and proliferation.
• Apoptosis and YAP nuclear localization were not significantly affected by substrate stiffness.
• Focal adhesion formation, cytoskeletal organization, FAK, and ERK activation were enhanced on stiffer substrates.
• ERK pathway activation was identified as a key mediator of stiffness-dependent proliferation.
• Long-term culture on stiffer hydrogels resulted in more organized epithelial monolayers with improved barrier function.

Conclusions:

• Substrate stiffness is a critical microenvironmental factor influencing RPTEC behavior during recovery from AKI.
• Enhanced focal adhesion, cytoskeletal organization, and ERK signaling contribute to stiffness-mediated RPTEC proliferation.
• Increased substrate stiffness may offer a beneficial microenvironment for renal tubular epithelial repair after AKI.