Biomechanical analysis predicts decreased human mesenchymal stem cell function before molecular differences.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Regenerative Medicine

Background:

• Multipotent human mesenchymal stem cells (hMSCs) are crucial for regenerative medicine.
• Ex vivo expansion for clinical use can lead to cellular senescence and functional decline.
• Molecular changes during senescence are known, but mechanical properties are less understood.

Purpose of the Study:

• To investigate the mechanical and cytoskeletal properties of hMSCs during ex vivo expansion.
• To identify early indicators of functional decline in hMSCs before classical senescence markers appear.
• To correlate in vitro mechanical changes with in vivo therapeutic potential.

Main Methods:

• Single-cell mechanical property analysis using atomic force microscopy and micropipette aspiration.
• Cytoskeletal staining and imaging.
• Collagen gel contraction assays.
• Xenographic wound healing model in mice.

Main Results:

• A subpopulation of 'non-functioning' hMSCs with altered mechanical properties emerges early during expansion.
• These cells exhibit reduced cytoskeletal stiffening and morphological flexibility.
• Extended culture exacerbates these changes, decreasing hMSC motility and collagen gel contraction.
• In vivo, these mechanically altered hMSCs show reduced efficacy in wound healing.
• Cytoskeletal inhibition partially mitigated the observed functional decline.

Conclusions:

• Single-cell mechanical properties are critical early indicators of hMSC dysfunction during expansion.
• Assessing mechanical markers alongside molecular markers is essential for evaluating hMSCs for therapeutic applications.
• Understanding and potentially modulating mechanical properties could improve the efficacy of hMSC-based therapies.