Bioactive-glass ceramic with two crystalline phases (BioS-2P) for bone tissue engineering

Bone tissue engineering requires materials that support cell proliferation and guide bone regeneration. While bioglasses like 45S5 have been used, their performance in directing osteogenic differentiation remains under investigation. Current studies often compare synthetic scaffolds with natural bone matrices. Established knowledge shows that osteoblasts and mesenchymal stem cells respond to surface properties and chemical cues. However, the specific role of two-phase bioactive ceramics in osteoinduction is unclear. This uncertainty drives the need for new scaffold materials that can both support cell growth and induce bone formation. No prior work has resolved how two-phase ceramics compare to single-phase bioglasses in osteogenic outcomes. This gap motivated the current investigation into BioS-2P's potential.

The study aimed to assess the osteogenic and osteoinductive properties of a two-phase bioactive glass ceramic called BioS-2P. Researchers wanted to determine if BioS-2P could enhance bone cell activity and bone formation compared to the standard Bioglass 45S5. The motivation came from the need for improved scaffolds in bone tissue engineering. The specific problem addressed was whether BioS-2P could support osteoblast proliferation and mineralization better than existing materials. The study also explored if BioS-2P could guide mesenchymal stem cell differentiation into bone-forming cells. A key question was whether adding MSCs to BioS-2P scaffolds would enhance in vivo bone repair. The researchers sought to compare BioS-2P with a well-characterized bioglass and a control material like polystyrene. This work aimed to provide insights into the design of next-generation bone scaffolds.

Researchers tested BioS-2P using in vitro and in vivo models to assess its osteogenic and osteoinductive properties. UMR-106 osteoblastic cells were cultured on BioS-2P and Bioglass 45S5 discs in osteogenic medium. Mesenchymal stem cells were used to evaluate osteoinduction on BioS-2P, Bioglass 45S5, and polystyrene. Cell proliferation, alkaline phosphatase activity, and mineralization were measured to assess osteogenic potential. Gene and protein expression levels of key osteogenic markers were analyzed using qPCR and immunoblotting. For in vivo testing, rat calvarial defects were implanted with BioS-2P scaffolds alone or seeded with MSCs. Morphometric and histological analyses were performed at 4, 8, and 12 weeks to evaluate bone repair. The study design allowed for direct comparisons between BioS-2P and the control materials in both cell culture and animal models.

UMR-106 cells showed similar proliferation on BioS-2P and Bioglass 45S5. However, alkaline phosphatase activity and mineralization were significantly higher on BioS-2P. Gene expression of bone sialoprotein, RUNX2, and osteopontin was elevated in cells cultured on BioS-2P compared to Bioglass 45S5. Protein levels of these markers also increased on BioS-2P. For mesenchymal stem cells, ALP activity was highest on Bioglass 45S5 and lowest on polystyrene. Gene expression was consistently higher on bioactive glasses than on polystyrene. In vivo, BioS-2P scaffolds promoted bone formation at 4, 8, and 12 weeks with no significant differences in morphometric parameters. Combining BioS-2P with MSCs did not enhance new bone formation compared to BioS-2P alone.

The findings suggest that BioS-2P supports osteoblast activity and mineralization better than Bioglass 45S5 in vitro. The material also promotes gene and protein expression of key osteogenic markers. While Bioglass 45S5 induced higher ALP activity in mesenchymal stem cells, BioS-2P still showed strong osteoinductive potential. The in vivo results indicate that BioS-2P scaffolds can stimulate bone formation without additional MSC seeding. These outcomes support the use of BioS-2P as a scaffold for bone tissue engineering. The material may be particularly useful in applications requiring sustained osteogenic activity. The study did not find evidence that adding MSCs to BioS-2P improves bone repair outcomes. These conclusions align with the observed in vitro and in vivo performance of BioS-2P.