Size-Optimized LDH Nanoplatelet-Reinforced GelMA Hydrogels Orchestrate Osteoimmunomodulation for Critical-Sized Bone...

Area of Science:

• Biomaterials Science
• Nanotechnology
• Regenerative Medicine

Background:

• Large bone defects pose significant challenges for healing, requiring both osteogenesis and a supportive immune microenvironment.
• Layered double hydroxides (LDHs) are bioactive nanomaterials with potential for bone regeneration, but the impact of nanoparticle size on their osteoimmunomodulatory effects is not well understood.

Purpose of the Study:

• To investigate the influence of MgAl-LDH nanoparticle size on osteoimmunomodulation and bone repair.
• To evaluate MgAl-LDH/GelMA hydrogels in a murine calvarial defect model for bone regeneration.

Main Methods:

• Synthesis and characterization of 50 nm and 100 nm MgAl-LDH nanoparticles.
• Assessment of cellular uptake, cytocompatibility, macrophage polarization, and BMSC osteogenic differentiation.
• In vivo evaluation of GelMA-LDH hydrogels in a murine critical-sized calvarial defect model.
• Transcriptomic profiling to elucidate regenerative mechanisms.

Main Results:

• Both 50 nm and 100 nm LDH formulations were cytocompatible and stable.
• 50 nm LDH showed enhanced cellular uptake and effectively promoted a pro-regenerative macrophage phenotype compared to 100 nm LDH.
• LDH treatment, particularly with 50 nm particles, significantly enhanced BMSC osteogenic differentiation and bone regeneration in vivo.
• RNA sequencing revealed activation of Wnt/β-catenin signaling and attenuation of NF-κB inflammatory pathways.

Conclusions:

• Size-optimized MgAl-LDH nanoplatelets (50 nm) effectively couple immunomodulation with osteogenesis, serving as a potent nano-bio interface.
• GelMA-LDH nanocomposite hydrogels represent a promising nanomedicine strategy for repairing critical-sized bone defects.
• Further mechanistic studies are needed to fully validate the regenerative potential.