Acid-Triggered Dual-Functional Hydrogel Platform for Enhanced Bone Regeneration.

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Tissue Engineering

Background:

• Stem cell implantation for bone repair carries risks like pathogen transmission.
• Recruiting endogenous stem cells is crucial for in situ bone regeneration.
• Bone injury creates an acidic microenvironment.

Purpose of the Study:

• To develop a dual-intelligent-switch composite hydrogel for bone regeneration.
• To leverage the acidic microenvironment of bone injury for controlled drug release.
• To promote coupled osteogenesis and angiogenesis for enhanced bone healing.

Main Methods:

• Incorporated stromal cell-derived factor-1α (SDF-1α), arginine carbon dots (Arg-CDs), and calcium ions (Ca2+) into an oxidized hyaluronic acid/gelatin methacryloyl (HG) hydrogel.
• Engineered a dual-control intelligent switch function triggered by the acidic microenvironment.
• Investigated the hydrogel's ability to release SDF-1α and promote nitric oxide (NO) production.

Main Results:

• The HG-AA1:1-SDF-1α hydrogel exhibited a dual-intelligent-switch function.
• Acidic conditions (pH 5.5) significantly increased SDF-1α release (≈2.5 times higher than pH 7.4).
• Recruited mesenchymal stem cells (MSCs) activated NO production, promoting angiogenesis via the NO/cGMP pathway.

Conclusions:

• The engineered HG-AA1:1-SDF-1α composite hydrogel effectively recruits endogenous stem cells and promotes angiogenesis.
• This approach offers a promising strategy for coupled osteogenesis and angiogenesis in bone regeneration.
• The dual-intelligent-switch hydrogel provides a safer and more effective alternative to stem cell implantation for bone repair.