Page 106 - Development of Functional Scaffolds for Bone Tissue Engineering Using 3D-Bioprinting of Cells and Biomaterials - Yasaman Zamani

ABSTRACT
Tissue engineering, relying on the combination of scaffolds, cells, and biological molecules has developed as a promising strategy for treatment of bone defects. Cellularization of scaffolds has typically been performed by seeding the cells after scaffold fabrication. Additive manufacturing technology and in particular 3D-printing, now allows bioprinting of cells encapsulated in a hydrogel simultaneously with the scaffold material. Here, we aimed to investigate whether bioprinting or cell seeding post-printing is more effective in enhancing cell seeding efficiency, pre-osteoblasts proliferation and differentiation. We incorporated MC3T3-E1 pre-osteoblasts in poly(lactic-co- glycolic acid)/β-tricalcium phosphate (PLGA/β-TCP) scaffolds by either seeding the cells after scaffold printing, or by bioprinting alginate-encapsulated cells layer-by-layer between the PLGA/β- TCP struts, and investigated whether differences existed in pre-osteoblasts responses. Cell retention was 51 ± 5% in cell-seeded and 87 ± 3% in bioprinted scaffolds, whereas cell viabilities were 87 ± 2% and 78 ± 4%, respectively. Cell proliferation was higher on cell-seeded scaffolds (day 7: 2.5-fold, day 14: 4.0-fold, day 21: 4.7-fold) compared with bioprinted scaffolds (1.2-fold, 2.1-fold, and 3.9-fold, respectively). After 21 days of culture, the voids between the PLGA/β-TCP struts were covered with cell-deposited collagenous matrix in both scaffold types. Alkaline phosphatase activity was significantly higher (3.4-fold) on cell-seeded scaffolds compared with bioprinted scaffolds. Our data demonstrate that encapsulation of MC3T3-E1 pre-osteoblasts in alginate and printing inside PLGA/β-TCP scaffolds enhances cell retention but decreases cell proliferation and osteogenic differentiation compared to seeding the cells on the scaffolds post- printing. This might have important implications for bone tissue engineering.
Keywords
Alginate, bioprinting, cell retention, osteogenic differentiation, PLGA/β-TCP, pre-osteoblasts
104