Cell-free scaffolds with different stiffness but same microstructure promote bone regeneration in rabbit large bone...

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Orthopedic Research

Background:

• Bone repair biomaterials often incorporate growth factors to enhance healing.
• The role of scaffold matrix mechanics, independent of microstructure, on endogenous osteoprogenitor cell differentiation requires further investigation.

Purpose of the Study:

• To investigate the in vivo bone repair efficiency of cell-free scaffolds with varying stiffness but identical microstructures.
• To elucidate the underlying mechanisms by which matrix mechanics influence bone fracture healing.

Main Methods:

• Fabrication of 3D scaffolds using decellularized bone coated with collagen/hydroxyapatite (HA) mixtures, varying collagen ratios to achieve different stiffness levels.
• In vivo evaluation in a rabbit radius critical-sized segmental defect model.
• Assessment of bone repair using micro-computed tomography (μ-CT), X-ray, and histological analysis.

Main Results:

• Scaffolds with optimal stiffness significantly promoted bone defect repair and reconstruction quality.
• Hypoxia and stromal cell-derived factor-1α (SDF-1α) mediated mesenchymal stem cells (MSCs) migration was identified as a key mechanism.
• Matrix mechanics influenced bone fracture healing through modulation of MSCs migration.

Conclusions:

• Modulating cell-free scaffold matrix stiffness is a crucial strategy for promoting bone healing.
• Optimal scaffold stiffness can induce osteogenic differentiation and enhance bone regeneration by recruiting endogenous cells.
• The findings highlight the potential of mechanical properties in designing advanced bone repair biomaterials.