Changes in Physiological Tendon Substrate Stiffness Have Moderate Effects on Tendon-Derived Cell Growth and Immune...

Area of Science:

• Biomaterials Science
• Cell Biology
• Orthopedics

Background:

• Tendinopathy involves pathological changes in tendon matrix and cells.
• The sequence of these changes and cellular responses to matrix alterations are not fully understood.

Purpose of the Study:

• To investigate the effects of substrate stiffness on tendon-derived cells (TDCs) and THP-1 macrophages.
• To understand cellular responses to varying matrix stiffness relevant to tendinopathy.

Main Methods:

• Tendon-derived cells and THP-1 macrophages were cultured on polydimethylsiloxane (PDMS) substrates with varying stiffness (0.61 MPa, 1.88 MPa, 3.17 MPa).
• Cell growth, morphology, and phenotypic marker expression (SCX, COL1A1, IL1B, IL8) were analyzed using alamarBlue™ assay, f-actin staining, and real-time PCR.

Main Results:

• TDC growth increased on soft gels (0.61 MPa).
• SCX expression decreased on soft gels, while COL1A1 increased on stiff gels (3.17 MPa).
• THP-1 macrophages showed increased IL1B on soft gels and inhibited IL8 on stiffer gels.

Conclusions:

• Tendon cells and macrophages respond to changes in matrix stiffness.
• Macrophage responses suggest a more inflammatory phenotype on non-physiological stiffness substrates.
• Subtle matrix stiffness alterations may contribute to tendinopathy onset and progression.