Three-dimensional bioprinting of tragacanth/hydroxyapaptite modified alginate bioinks for bone tissue engineering with tunable printability and bioactivity

摘要

Three-dimensional (3D) bioprinting of composite scaffolds using biodegradable natural polymers are very promising approach for bone tissue engineering. In this research, we hypothesized that the use of tragacanth gum with alginate could improve the printability and rheological properties of alginate. We showed that the blending of 1 wt tragacanth with the 3 wt alginate-based bioink significantly improved the compressive strength, viscosity and printability properties, resolution, and shape fidelity of alginate bioink. In addition, the presence of tragacanth decreased the rate of degradation in alginate scaffold within 21 days. On the other hand, hydroxyapatite (HA) could support alginate as an osteoconductive component in alginate-tragacanth composite scaffolds. HA was in situ incorporated into an alginate-tragacanth bioink. ALP activity, calcium deposition and BMP-2 and osteocalcin genes expression showed an increase over time indicating differentiation of MC3T3 cells into osteoblasts in the presence of HA particles than that in the alginate-tragacanth group. In addition, the expression of CD105, CD44, and CD90, as specific surface markers, were significantly increased in differentiated osteoblasts. The in vitro results demonstrated that HA particles dispersed in the alginate-tragacanth matrix could promote osteogenic differentiation of MC3T3 cells in a 3D-bioprinted construct and this scaffold material could be considered to repair large bone tissue defects.