The hydrophilic amorphous layer around bone apatite promotes osteogenesis
Stanislas Von Euw1, Kian F Eichholz2, Olwyn R Mahon2
1Trinity Centre for Bioengineering (TCBE), Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, D02 R590, Ireland; Department of Mechanical, Manufacturing, and Biomedical Engineering, School of Engineering, Trinity College Dublin, Dublin 2, D02 R590, Ireland; Bio-inspired mineralization laboratory (BIOML), School of Biological and Chemical Sciences (SBCS), College of Science and Engineering, University of Galway, University Road, Galway H91 TK33, Ireland.
Acta Biomaterialia
|December 5, 2025
Summary
Synthetic bone regeneration materials benefit from biomimetic hydroxyapatite nanoparticles with amorphous surface layers. These biomimetic particles enhance osteogenic differentiation of human mesenchymal stem cells for improved bone repair therapies.
Area of Science:
- Biomaterials Science
- Stem Cell Biology
- Nanotechnology
Background:
- Bone regeneration therapies often use synthetic calcium phosphate particles.
- These synthetic particles lack the complexity of natural bone mineral.
- Existing materials fail to replicate the heterogeneity of bone mineral.
Purpose of the Study:
- To investigate the role of amorphous surface layers on hydroxyapatite nanoparticles in bone regeneration.
- To understand how biomimetic material design influences stem cell differentiation.
- To provide mechanistic insights into the success of autologous bone grafts.
Main Methods:
- Created organic-inorganic composites with proxies for biogenic calcium phosphate particles.
- Examined particles at successive stages of bone biomineralization.
- Assessed osteogenic differentiation of human mesenchymal stem cells on these materials.
Main Results:
- Partially crystalline hydroxyapatite nanoparticles with ≥35% amorphous surface layer significantly increased osteogenic differentiation.
- This amorphous coating, naturally decreasing with age in bone particles, may explain autologous bone graft success.
- A hydration shell on the amorphous layer enhances extracellular signaling molecule binding, promoting osteogenic commitment.
Conclusions:
- Biomimetic hydroxyapatite nanoparticles with specific amorphous surface layers outperform highly crystalline counterparts.
- Truly bone-mimetic material designs are crucial for next-generation bone regenerative therapies.
- Nanoscale surface features and amorphous chemical environments play a critical role in directing stem cell function for bone repair.
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