A chitosan-based composite scaffold as a bioactive strontium-delivery system mediating accelerated bone regeneration

Area of Science:

• Biomaterials Science
• Orthopaedic Surgery
• Tissue Engineering

Background:

• Bone defects pose significant clinical challenges due to limitations of current bone graft materials.
• Existing materials often exhibit inadequate osteogenic capacity, donor site morbidity, and poor mechanical strength.
• There is a critical need for advanced biomaterials to improve bone regeneration outcomes.

Purpose of the Study:

• To develop and evaluate a novel composite bone regeneration scaffold (CS/SF@SrAlg).
• To assess the scaffold's biocompatibility, mechanical properties, and efficacy in promoting osteogenesis.
• To elucidate the underlying molecular mechanisms of scaffold-mediated bone regeneration.

Main Methods:

• Fabrication of a composite scaffold using chitosan, silk fibroin fibers, and strontium alginate microspheres via microfluidic electrospray and fiber fragmentation-recombination.
• In vitro assessment of cell proliferation, migration, and osteogenic mineralization.
• In vivo evaluation in a rat calvarial defect model to quantify bone regeneration, angiogenesis, and osteogenesis.
• RNA transcriptomics analysis to identify key signaling pathways involved in osteogenesis.

Main Results:

• The CS/SF@SrAlg scaffold demonstrated excellent biocompatibility, enhanced mechanical properties, and controlled strontium ion release.
• In vitro studies showed significant enhancement in cell proliferation (>120%) and osteogenic differentiation.
• In vivo results indicated substantial bone regeneration (81.8% ± 1.48% coverage at 8 weeks) and robust angiogenesis.
• Transcriptomic analysis revealed modulation of the PI3K-Akt signaling pathway, promoting osteogenesis.

Conclusions:

• The developed CS/SF@SrAlg composite scaffold is a promising biomaterial for repairing bone defects.
• Its hierarchical porous structure, mechanical integrity, and strontium release contribute to enhanced osteogenesis and angiogenesis.
• The scaffold shows significant potential for clinical translation in orthopaedic applications.