Diatomite-incorporated hierarchical scaffolds for osteochondral regeneration

Osteochondral regeneration involves the highly challenging and complex reconstruction of cartilage and subchondral bone. Silicon (Si) ions play a crucial role in bone development. Current research on Si ions mainly focuses on bone repair, by using silicate bioceramics with complex ion compositions. However, it is unclear whether the Si ions have important effect on cartilage regeneration. Developing a scaffold that solely releases Si ions to simultaneously promote subchondral bone repair and stimulate cartilage regeneration is critically important. Diatomite (DE) is a natural diatomaceous sediment that can stably release Si ions, known for its abundant availability, low cost, and environmental friendliness. Herein, a hierarchical osteochondral repair scaffold is uniquely designed by incorporating gradient DE into GelMA hydrogel. The adding DE microparticles provides a specific Si source for controlled Si ions release, which not only promotes osteogenic differentiation of rBMSCs (rabbit bone marrow mesenchymal stem cells) but also enhances proliferation and maturation of chondrocytes. Moreover, DE-incorporated hierarchical scaffolds significantly promoted the regeneration of cartilage and subchondral bone. The study suggests the significant role of Si ions in promoting cartilage regeneration and solidifies their foundational role in enhancing bone repair. Furthermore, it offers an economic and eco-friendly strategy for developing high value-added osteochondral regenerative bioscaffolds from low-value ocean natural materials. Schematic illustration showing DE-incorporated hierarchical scaffold designed for osteochondral regeneration. The DE-incorporated hierarchical scaffold offers a conducive physiological microenvironment for the adhesion and proliferation of chondrocytes and rBMSCs. Moreover, the DE-incorporated hierarchical scaffold significantly stimulates the regeneration of hyaline cartilage and subchondral bone through the release of Si ions from the DE microparticles. Note: Bioink A and Bioink B are GelMA bioinks incorporated with different concentrations of DE microparticles. [Display omitted] •Provided an economic and eco-friendly strategy for developing osteochondral regenerative bioscaffolds from natural materials.•The DE microparticles in scaffold provide a specific Si source for controlled Si ions release.•The scaffold promotes osteogenic differentiation of rBMSC but also enhances the proliferation and maturation of chondrocytes.•DE-incorporat