Strontium-Substituted Hydroxyapatite Applications in Bone Regeneration

Strontium-substituted hydroxyapatite (Sr-HAp) represents a class of bioactive ceramics in which strontium ions replace a fraction of calcium within the hydroxyapatite lattice. This ionic substitution confers a dual mode of action: promotion of osteoblast proliferation and differentiation alongside inhibition of osteoclast-mediated bone resorption. Structurally analogous to the mineral phase of bone, Sr-HAp may be processed into pastes, gels, coatings, nanofibres, membranes or three-dimensional scaffolds, each format tailored to clinical requirements such as minimally invasive delivery or load-bearing reconstruction. In vitro and in vivo studies demonstrate enhanced alkaline phosphatase activity, elevated expression of osteogenic markers and improved bone matrix deposition when compared with undoped hydroxyapatite. Mesoporous Sr-HAp constructs further allow sustained release of therapeutic agents or ions, while composite systems incorporating polymers or carbon substrates achieve long-term osteointegration with negligible adverse response. Collectively, these advances highlight the global significance of Sr-HAp in addressing critical bone defects, osteoporosis and the engineering of biomimetic grafts for orthopaedic and dental applications.

Research from Nature Portfolio

Studies employing strontium-substituted hydroxyapatite nanoparticles have revealed a capacity to counteract microgravity-induced bone loss and to accelerate osteogenic commitment in human mesenchymal stem cells. In simulated Earth and space environments, exogenous application of strontium-doped hydroxyapatite nanoparticles augmented alkaline phosphatase activity, up-regulated bone marker genes and promoted mineral deposition. Furthermore, these nanoparticles conferred protection against the reduction in osteoblastic function under simulated microgravity conditions, illustrating potential for both terrestrial osteoporosis therapy and space medicine countermeasures.

Strontium-Substituted Hydroxyapatite Applications in Bone Regeneration publication trend

The graph below shows the total number of articles in strontium-substituted hydroxyapatite applications in bone regeneration across all publications each year (not limited to Nature Index journals).

Technical terms

Hydroxyapatite: A naturally occurring calcium phosphate mineral (Ca10(PO4)6(OH)2) that constitutes the primary inorganic component of bone and teeth.

Strontium substitution: The partial replacement of calcium ions in hydroxyapatite by strontium ions, altering lattice parameters and modulating biological activity.

Osteoconductivity: The property of a material to serve as a scaffold for new bone growth along its surface.

Osteoinduction: The capacity of a material to induce undifferentiated cells to commit to the osteoblastic lineage.

Osteointegration: The direct structural and functional connection between living bone tissue and the surface of an implant or graft.

Mesoporous structure: A pore architecture characterised by pore diameters between 2 and 50 nm, enabling controlled delivery of ions or biomolecules.

References

1. The NATO project: nanoparticle-based countermeasures for microgravity-induced osteoporosis. Scientific Reports (2019).
2. Long-Term Fate and Efficacy of a Biomimetic (Sr)-Apatite-Coated Carbon Patch Used for Bone Reconstruction. Journal of Functional Biomaterials (2023).
3. Influence of the Components and Orientation of Hydroxyapatite Fibrous Substrates on Osteoblast Behavior. Journal of Functional Biomaterials (2022).
4. Nanoscale Strontium-Substituted Hydroxyapatite Pastes and Gels for Bone Tissue Regeneration. Nanomaterials (2021).
5. Fabrication and Characterization of Strontium-Substituted Hydroxyapatite-CaO-CaCO3 Nanofibers with a Mesoporous Structure as Drug Delivery Carriers. Pharmaceutics (2018).