A sonication-induced silk-collagen hydrogel for functional cartilage regeneration

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Cartilage defects have limited self-regeneration, and current treatments often lead to suboptimal fibrocartilage formation.
• Pure collagen hydrogels show potential for chondrogenesis but suffer from poor mechanical properties and rapid degradation.
• Mesenchymal stem cells (MSCs) are key targets for cartilage regeneration strategies.

Purpose of the Study:

• To develop and evaluate a sonication-induced silk-collagen composite hydrogel (COL + SF(S)) for enhanced cartilage regeneration.
• To compare the physicochemical and biological properties of COL + SF(S) with pure collagen (COL) and non-sonicated silk-collagen (COL + SF(NS)) hydrogels.
• To assess the in vivo cartilage regeneration capacity of the developed hydrogel in a rabbit knee defect model.

Main Methods:

• Fabrication of silk-collagen composite hydrogels with and without sonication treatment.
• Characterization of hydrogel physicochemical properties, including mechanical strength and stability.
• In vitro assessment of chondrogenic potential using mesenchymal stem cells (MSCs), evaluating gene expression (SOX9) and matrix deposition (sGAG).
• In vivo evaluation of cartilage regeneration in rabbit knee defects over a 6-month period.

Main Results:

• Sonication induced antiparallel β-sheet formation and increased negative charge in silk fibroin, enhancing hydrogel mechanical properties.
• The COL + SF(S) hydrogel demonstrated superior stability during cell culture and promoted early SOX9 gene expression and sGAG deposition without exogenous growth factors.
• In vivo, the COL + SF(S) group showed well-integrated articular hyaline cartilage regeneration, closely resembling native tissue after 6 months.

Conclusions:

• The sonication-induced silk-collagen composite hydrogel (COL + SF(S)) offers improved mechanical properties and stability compared to pure collagen hydrogels.
• COL + SF(S) effectively promotes chondrogenesis and functional hyaline cartilage regeneration in vivo.
• This composite hydrogel represents a promising scaffold for addressing cartilage defects and advancing regenerative medicine strategies.