Injectable polysaccharide-based composite hydrogel promotes regeneration of critical-sized bone defects

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Nanotechnology

Background:

• Critical-sized bone defects (CSDs) pose significant challenges for spontaneous regeneration.
• Current treatments like bone grafts and growth factors have limitations including cost, availability, and safety concerns.
• Existing tissue engineering scaffolds often require exogenous growth factors and invasive procedures.

Purpose of the Study:

• To develop a minimally invasive, injectable, and biocompatible hydrogel for bone regeneration.
• To create a scaffold that provides osteoinductive, osteoconductive, and antibacterial properties without external additives.
• To evaluate the efficacy of the developed hydrogel in promoting bone regeneration in vivo.

Main Methods:

• Fabrication of a hydrogel (CCD@HapSi) via Schiff-base reaction between carboxymethyl chitosan and oxidized dextran.
• Incorporation of nanohydroxyapatite and silica nanoparticles into the hydrogel matrix.
• In vitro assessment of hydrogel properties (gelation, mechanical strength, degradation) and cellular responses (stem cell adhesion, proliferation, osteogenic gene expression).
• In vivo evaluation of bone regeneration in a critical-sized calvarial defect model in rodents.

Main Results:

• CCD@HapSi hydrogel demonstrated ultrafast gelation, optimal mechanical properties, and controlled degradation.
• The hydrogel supported stem cell adhesion, proliferation, and osteogenic differentiation.
• In vivo studies showed substantial bone regeneration in critical-sized defects treated with CCD@HapSi, outperforming control groups.
• The material exhibited osteoinductive, osteoconductive, and antibacterial properties without exogenous growth factors or toxic crosslinkers.

Conclusions:

• CCD@HapSi is a safe, cost-effective, and fully biocompatible injectable hydrogel for bone regeneration.
• The developed hydrogel overcomes limitations of conventional treatments and current scaffold-based approaches.
• This platform shows significant potential for clinical translation in treating critical-sized bone defects.