A Needlelike Nano-hydroxyapatite-Based Hydrogel Accelerates Critical Bone Defect Regeneration via Osteo-/Angiogenesis...

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Critical-sized bone defects pose significant clinical challenges.
• Existing nano-hydroxyapatite (nHap) materials have limited immunomodulatory effects for bone regeneration.
• Novel biomaterials are needed to enhance bone healing and vascularization.

Purpose of the Study:

• To fabricate and evaluate needlelike nHap (NnHap)-based scaffolds (NnHap@CP) for bone defect management.
• To investigate the immunomodulatory effects of NnHap@CP on macrophages and its impact on osteogenesis.
• To explore the potential signaling pathways involved in NnHap@CP-mediated osteogenesis.

Main Methods:

• Fabrication of NnHap@CP scaffolds using polylactic acid derivative and carboxymethyl chitosan.
• In vitro assessment of NnHap@CP's effect on M2 macrophage polarization and rat bone-marrow-derived mesenchymal stem cell (rBMSC) osteogenesis.
• In vivo evaluation of NnHap@CP in a rat model of critical-sized cranial bone defects.
• Mass spectrometry analysis to identify potential signaling pathways.

Main Results:

• NnHap@CP demonstrated effective M2 subtype polarization in macrophages.
• In vitro studies showed enhanced osteogenesis in rBMSCs treated with NnHap@CP.
• In vivo results indicated significant new bone regeneration and neovascularization in rat cranial defects.
• Osteoprotegerin/RANK/RANKL pathway identified as a potential mechanism.

Conclusions:

• NnHap@CP scaffolds possess favorable immunomodulatory and osteogenic properties.
• The material effectively promotes bone regeneration and vascularization in critical-sized defects.
• NnHap@CP represents a promising innovative therapeutic strategy for bone defect repair.