Embedded bioprinting of dense cellular constructs in bone allograft-enhanced hydrogel matrices for bone tissue...

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Tissue Engineering

Background:

• Critical-sized bone defects pose significant clinical challenges.
• Biomimetic scaffolds are crucial for promoting bone repair and regeneration.
• Current strategies often require external growth factors to stimulate osteogenesis.

Purpose of the Study:

• To develop a material extrusion-based embedded bioprinting approach for fabricating dense cellular constructs.
• To investigate the impact of bioactive microparticles (bone allograft or tricalcium phosphate) within methacrylated hyaluronic acid (MeHA) hydrogels.
• To evaluate the rheological, mechanical, and osteoinductive properties of the fabricated constructs.

Main Methods:

• Utilized material extrusion-based embedded bioprinting to create cellular constructs in MeHA hydrogels.
• Incorporated human bone allograft or tricalcium phosphate (TCP) microparticles into the hydrogel matrix.
• Assessed cell viability, strand dimensions, rheological properties, mechanical stability, and osteogenic differentiation of human mesenchymal stem cells (hMSCs).

Main Results:

• Achieved high cell viability (>95%) and uniform strand dimensions during bioprinting.
• Incorporation of bone or TCP particles did not compromise hydrogel viscosity, crosslinking, or mechanical properties.
• Bone allograft particles significantly enhanced osteogenic differentiation (ALP activity, calcium deposition) of hMSCs, even in basal media.

Conclusions:

• Embedded bioprinting with bioactive MeHA hydrogels is a viable method for creating dense cellular constructs.
• Bone allograft particles possess intrinsic osteoinductive properties, stimulating bone regeneration without external growth factors.
• This platform offers a scalable and clinically relevant approach for bone tissue engineering and defect repair.