Dynamically Modulated Core-Shell Microfibers to Study the Effect of Depth Sensing of Matrix Stiffness on Stem Cell...

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• Extracellular matrix (ECM) stiffness influences cell fate and dynamics.
• Current methods for in situ ECM stiffness modulation often alter matrix structure, causing unintended cellular effects.

Purpose of the Study:

• To develop a novel core-shell microfiber system for dynamic and independent modulation of the cellular mechanical microenvironment.
• To investigate the impact of dynamically tunable matrix stiffness on human mesenchymal stem cell differentiation.

Main Methods:

• Fabrication of core-shell microfibers with a collagen core and a dynamically stiffenable alginate shell.
• Modulation of alginate shell stiffness via strontium ion (Sr ²⁺ ) addition to calcium ion (Ca ²⁺ ) cross-linked structures.
• Assessment of effective matrix modulus experienced by cells and its effect on osteogenesis differentiation.

Main Results:

• The core-shell microfiber system allowed dynamic stiffening of the alginate shell using Sr ²⁺ .
• Despite a soft collagen core, the effective matrix stiffness significantly increased, promoting osteogenesis in human mesenchymal stem cells (hMSCs).
• The stiffening effect was more pronounced in the dynamic microfiber compared to static controls.

Conclusions:

• This core-shell microfiber platform enables independent and dynamic control of mechanical stimuli in the cellular microenvironment.
• The system maintains biochemical properties while modulating stiffness, offering a versatile tool for studying dynamic cellular processes like osteogenesis.