Gradient nano-engineered in situ forming composite hydrogel for osteochondral regeneration

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Fabricating anisotropic osteochondral scaffolds with distinct mineralized subchondral and cartilaginous zones is challenging.
• Existing methods struggle to create gradient interfaces crucial for mimicking natural osteochondral tissue.

Purpose of the Study:

• To develop an injectable, semi-interpenetrating network hydrogel construct mimicking osteochondral tissue.
• To create a gradient interface using chondroitin sulfate nanoparticles (ChS-NPs) and nanohydroxyapatite (nHA) for enhanced osteochondral regeneration.

Main Methods:

• Fabrication of a biphasic hydrogel with ChS-NPs in the chondral zone and nHA in the subchondral zone.
• Characterization using microcomputed tomography (μCT) and rheology.
• In vivo evaluation in rabbit osteochondral defects comparing gradient, biphasic, and control groups.

Main Results:

• The gradient hydrogel exhibited an interconnected porous structure with spatial variation of nHA and ChS-NPs.
• In vivo studies showed complete defect closure in the gradient group after 8 weeks, with significant collagen and glycosaminoglycan deposition.
• μCT and biomechanical tests confirmed enhanced mineralized tissue formation and load-bearing capacity in the gradient hydrogel group.

Conclusions:

• The developed nano-engineered gradient hydrogel effectively promotes hyaline cartilage regeneration and subchondral bone formation.
• The gradient design enhances cell-specific retention, cell-cell interactions, and integration with host tissues.
• This approach offers a promising strategy for treating osteochondral defects.