Intranuclear mesoscale viscoelastic changes during osteoblastic differentiation of human mesenchymal stem cells

Area of Science:

• Biophysics
• Cell Biology
• Stem Cell Biology

Background:

• Cell nuclei exhibit viscoelastic properties crucial for biological processes.
• Intranuclear mesoscale viscoelasticity regulates force propagation and gene expression.
• Changes in stem cell nuclear viscoelasticity during differentiation are not well understood.

Purpose of the Study:

• To quantify changes in intranuclear mesoscale viscoelasticity during human mesenchymal stem cell osteoblastic differentiation.
• To elucidate the biological significance of these viscoelasticity changes.

Main Methods:

• Quantification of intranuclear mesoscale viscoelasticity in differentiating human mesenchymal stem cells.
• Analysis of chromatin decondensation and DNA density effects on viscoelasticity.
• Correlation of viscoelasticity with gene expression patterns.

Main Results:

• Intranuclear region transitions from a viscoelastic solid (early differentiation) to a viscoelastic liquid (terminal differentiation).
• Viscoelasticity changes correlate with altered force transmission efficiency and gene expression robustness.
• Chromatin condensation state, gap size, and meshwork flexibility significantly influence mesoscale viscoelasticity.

Conclusions:

• Nuclear viscoelasticity dynamically regulates mechanosensitivity and gene expression during stem cell differentiation.
• Chromatin condensation state is a key determinant of nuclear viscoelasticity.
• Viscoelasticity plays a vital role in lineage specification and stem cell differentiation.