Comparison of cellular strain with applied substrate strain in vitro

Area of Science:

• Biomedical Engineering
• Cell Biology
• Mechanobiology

Background:

• Understanding cellular strain in tenocytes is crucial for tissue engineering and mechanobiology.
• Previous studies lacked precise quantification of strain magnitudes within tenocytes under substrate tensile strain.

Purpose of the Study:

• To investigate and quantify strain magnitudes within tenocytes cultured on flexible substrates under equibiaxial and uniaxial tensile strain.
• To determine the relationship between applied substrate strain and cellular strain in tenocytes.

Main Methods:

• Tenocytes were cultured on a flexible substrate and subjected to equibiaxial or uniaxial tensile strain using a vacuum-operated device.
• Intracellular calcium (Fura-2) and mitochondrial (MitoFluor Green) labeling were used.
• A custom texture correlation program analyzed image displacements to compute cellular strain magnitudes.

Main Results:

• Cultured tenocytes experienced approximately 37% of equibiaxial and 63% of uniaxial substrate strain.
• Cellular strain was highest in tenocytes oriented parallel to the uniaxial strain direction.
• Significant heterogeneity in strain magnitudes was observed within and among tenocytes.

Conclusions:

• Cultured tenocytes experience a moderate fraction of applied substrate strain, not a direct reflection of substrate strain.
• Cellular strain heterogeneity is influenced by factors like cell orientation, stiffness, cytoskeleton, and cell-substrate interactions.
• These findings provide critical insights into cell-matrix mechanical coupling in tenocyte research.