Injectable mineralized microsphere-loaded composite hydrogels for bone repair in a sheep bone defect model

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Surgery

Background:

• Cell-based therapies require biomaterials to deliver cells and promote bone regeneration.
• Hydrogels can deliver cells but often lack osteoconductive properties for bone healing.
• Biomineralized microspheres integrated into hydrogels can enhance osteogenesis.

Purpose of the Study:

• To develop and evaluate a composite hydrogel for delivering mesenchymal stromal cells (MSCs) to promote bone healing.
• To investigate the osteogenic potential of MSCs within a novel hydrogel scaffold.
• To assess the efficacy of the cell-laden hydrogel in a large animal bone defect model.

Main Methods:

• Entrapment of ovine MSCs within an alginate/hyaluronate hydrogel containing biomineralized polymeric microspheres.
• Incorporation of Arginine-Glycine-Aspartic Acid (RGD) peptide to enhance cell differentiation.
• Evaluation of bone healing in a critical-sized ovine iliac crest defect model at 12 weeks post-implantation.

Main Results:

• The composite hydrogel with RGD promoted greater osteogenic differentiation of MSCs in vitro.
• Implants with MSCs in composite hydrogels showed significantly increased bone formation compared to controls.
• Enhanced vascularization and osteoid formation were observed in defects treated with the cell-laden hydrogel.

Conclusions:

• Osteoconductive hydrogels can effectively deliver autologous MSCs to promote bone healing in a large animal model.
• This composite hydrogel serves as a promising vehicle for cell-based bone regeneration therapies.
• The findings support the clinical translation of advanced biomaterials for orthopedic applications.