Hydroxyapatite/polylactide biphasic combination scaffold loaded with dexamethasone for bone regeneration

Current bone graft substitutes lack the structural and functional complexity of natural bone. While hydroxyapatite and polylactide are known for their osteoconductive and biodegradable properties, respectively, their integration into a single scaffold remains a challenge. Prior research has shown that biphasic scaffolds can improve mechanical and biological performance. However, the precise fabrication of interconnected, functionally graded structures has not been fully resolved. This gap motivated the development of a scaffold that mimics both the cortical and trabecular regions of bone. The study addresses the need for a material that supports cell proliferation and drug delivery. It was already known that dexamethasone can influence mesenchymal cell behavior. No prior work had resolved how to integrate drug release with structural mimicry in a single scaffold.

The aim of this research was to design a biphasic scaffold that replicates the hierarchical architecture of natural bone. The specific problem addressed is the lack of integration between structural and functional components in existing bone grafts. The motivation stems from the need for a scaffold that supports both mechanical stability and biological activity. The study focused on combining hydroxyapatite and polylactide into a single structure. The outer shell was intended to mimic cortical bone, while the inner core was designed to resemble trabecular bone. The scaffold also needed to facilitate controlled drug release. The researchers proposed that a biphasic structure would better support tissue regeneration. This approach was chosen to test the hypothesis that structural and functional integration could improve bone graft performance.

The researchers fabricated a biphasic scaffold using a polymeric template-coating technique for the outer hydroxyapatite shell. The inner core was produced via a particle leaching/gas forming method to create porous polylactide. Dexamethasone was loaded into the polylactide section. The scaffold’s microstructure was analyzed using micro-computed tomography to assess its similarity to natural bone. The boundary between the two scaffold components was examined for continuity and gaps. A biomimetic process was used to form an apatite layer on the scaffold surface. Drug release was monitored over a one-month period in vitro. Cell proliferation and differentiation were evaluated using human embryonic palatal mesenchyme cells.

The fabricated scaffold demonstrated open and interconnected pores in both hydroxyapatite and polylactide sections. The boundary between the two parts was tightly connected without gaps. Micro-computed tomography confirmed that the scaffold’s structure resembled natural bone. A dense apatite layer formed on the scaffold surface through a biomimetic process. Dexamethasone was released from the polylactide core over a 1-month period. This release stimulated cell proliferation and differentiation in vitro. Human embryonic palatal mesenchyme cells produced extracellular matrix and formed tissue. The study found that the scaffold supported both structural and functional bone regeneration.

The authors concluded that the biphasic scaffold mimics the structure of natural bone and supports tissue regeneration. The scaffold’s interconnected pore structure and drug release properties were key findings. The apatite layer formation and controlled dexamethasone release were highlighted as important features. The study suggests that the scaffold could serve as a bone-substitute material. The researchers propose that this design improves the performance of bone grafts. The results indicate that the scaffold supports cell proliferation and differentiation. The authors suggest that this approach may be useful in bone regeneration applications. The study did not claim that the scaffold is essential for all bone repair scenarios.