The Stiffness-Sensitive Transcriptome of Human Tendon Stromal Cells

Area of Science:

• Biomaterials Science
• Cell Biology
• Mechanobiology

Background:

• Extracellular matrix (ECM) stiffness significantly influences cellular states.
• Current stiffness-sensing studies often use cells with "mechanical memory" from rigid environments, potentially obscuring true mechanosensing.
• Tissue culture plastic (TCP) can induce phenotypic drift in cells, limiting research accuracy.

Purpose of the Study:

• To develop advanced biomaterials for studying matrix stiffness effects on cell behavior.
• To investigate the mechanosensing programs of human tendon-derived stromal cells.
• To understand how matrix biophysical cues regulate cellular transcriptional identity.

Main Methods:

• Development of 2D mechanovariant silicone substrates with scalable biofunctionalization.
• Large-scale cell culture expansion on developed substrates.
• RNA sequencing to map stiffness-mediated mechano-responses.
• Computational inference to identify signaling hubs.

Main Results:

• Matrix elasticity near tendon microscale stiffness (≈35 kPa) promoted chromatin remodeling and Hippo signaling.
• Compliant stiffnesses (≈2 kPa) enriched stemness, synapse assembly, and angiogenesis pathways.
• Mechanovariant substrates prevented phenotypic drift seen on TCP; tenogenic stiffnesses induced tendon-specific transcriptional programs.
• AKT1 and ERK1/2 were identified as key stiffness-sensing signaling hubs.

Conclusions:

• Matrix stiffness is a critical determinant of tendon cell transcriptional identity.
• Mechanovariant substrates offer a superior platform for studying cell mechanosensing without mechanical memory.
• Matrix mechano-reciprocity regulates underappreciated mechanosensitive processes in tendon fibroblasts.