Modulating iMSC Spheroid Function with Mechanically Tunable Hydrogels to Strengthen the Bone-Muscle Axis

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Stem Cell Biology

Background:

• Bone fractures frequently cause combined bone and muscle damage, necessitating advanced regenerative therapies.
• Current treatments often address bone and muscle injuries separately, highlighting a need for integrated approaches.

Purpose of the Study:

• To develop a gelatin-based hydrogel system with adjustable stiffness for guiding induced pluripotent stem cell (iPSC)-derived mesenchymal stromal cell (iMSC) spheroids.
• To investigate the role of hydrogel stiffness and reciprocal cell signaling in promoting simultaneous bone and muscle regeneration.

Main Methods:

• Fabrication of gelatin hydrogels using hydrogen peroxide and horseradish peroxidase, with tunable stiffness (1.6–9.3 kPa).
• Encapsulation of iMSC spheroids within hydrogels to facilitate localized secretome release.
• Culture of iMSC spheroids in varying stiffness hydrogels and in response to C2C12 myoblast secretome.

Main Results:

• Soft hydrogels (1.6 kPa) with iMSC spheroids promoted myogenic differentiation of C2C12 myoblasts through paracrine signaling.
• Stiffer hydrogels (9.3 kPa) enhanced osteogenic differentiation of iMSCs when exposed to the myoblast secretome.
• Demonstrated synergistic effects of stiffness and secretome signaling on iMSC differentiation.

Conclusions:

• Tunable hydrogels can direct iMSC behavior for distinct tissue regeneration outcomes.
• This platform offers a promising "two-in-one" strategy for combined musculoskeletal tissue repair.
• Highlights the potential of biomaterial stiffness and cell-cell communication in regenerative medicine.