In vitro evaluation of 3D bioprinted tri-polymer network scaffolds for bone tissue regeneration

In vitro evaluations provide vital information on the ability of tissue engineered scaffolds to support cell life and promote natural physiological behaviors in culture. Such assessments are necessary to conduct before implementation of the scaffolds for tissue healing in vivo. The scaffold extracellular matrix must provide the biochemical and mechanical cues necessary to promote cellular attachment, migration and proliferation before differentiation and new tissue deposition can occur. In this study, an in vitro evaluation was conducted to assess the ability of scaffolds three-dimensional (3D) printed with a previously developed alginate-polyvinyl alcohol-hydroxyapatite formulation to promote proliferation of encapsulated MC3T3 cells. A systematic investigation was conducted to increase cell proliferation, and it was determined that the concentration and duration of the calcium bath have a less effect on proliferation than the composition of the formulation itself. Collagen gel was incorporated into the formulation to provide cells with adhesion sites necessary to sufficiently attach to the matrix. Enhanced proliferation was achieved within scaffolds of increased collagen content and sufficient crosslinking. This highlighted the importance of the synergistic effect created as a result of sufficient ligand density coupled with appropriate scaffold mechanical rigidity to provide a suitable environment for proliferation. Thus, these 3D printed tri-polymer scaffolds have the ability to support cell proliferation and have potential to promote cell differentiation and new bone tissue deposition. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3262-3272, 2017.