Scaffold mesh size affects the osteoblastic differentiation of seeded marrow stromal cells cultured in a flow perfusion bioreactor

• Published in: Journal of biomedical materials research 2005-08, Vol.74A (2), p.171-180
• Main Authors: Holtorf, Heidi L., Datta, Néha, Jansen, John A., Mikos, Antonios G.
• Format: Article
• Language: English
• Subjects: Alkaline Phosphatase - metabolism; Animals; bioreactor; Bioreactors; Bone Marrow Cells - cytology; Bone Marrow Cells - enzymology; Bone Marrow Cells - metabolism; bone regeneration; Calcium - metabolism; Cell Differentiation; Cells, Cultured; flow perfusion; marrow stromal cell; Microscopy, Electron, Scanning; osteoblast; Osteoblasts - cytology; Osteoblasts - enzymology; Osteoblasts - metabolism; Osteopontin; Perfusion; Rats; scaffold; Sialoglycoproteins - secretion; Stromal Cells - cytology; Stromal Cells - enzymology; Stromal Cells - metabolism; tissue engineering; Titanium
• ISSN: 1549-3296; 0021-9304; 1552-4965; 1097-4636
• DOI: 10.1002/jbm.a.30330

In this study, we cultured marrow stromal cells on titanium fiber meshes in a flow perfusion bioreactor and examined the effect of altering scaffold mesh size on cell behavior in an effort to develop a bone tissue construct composed of a scaffold, osteogenic cells, and extracellular matrix. Scaffolds of differing mesh size, that is, distance between fibers, were created by altering the diameter of the mesh fibers (20 or 40 μm) while maintaining a constant porosity. These scaffolds had a porosity of 80% and mesh sizes of 65 μm (20‐μm fibers) or 119 μm (40‐μm fibers). Cell/scaffold constructs were grown in static culture or under flow for up to 16 days and assayed for osteoblastic differentiation. Cellularity was higher at early time points and Ca2+ deposition was higher at later time points for flow constructs over static controls. The 20‐μm mesh had reduced cellularity in static culture. Under flow conditions, mass transport limitations are mitigated allowing uniform cell growth throughout the scaffold, and there was no difference in cellularity between mesh types. There was greater alkaline phosphatase (ALP) activity, osteopontin levels, and calcium under flow at 8 days for the 40‐μm mesh compared to the 20‐μm mesh. However, by day 16, the trend was reversed, suggesting the time course of differentiation was dependent on scaffold mesh size under flow conditions. However, this dependence was not linear with respect to time; larger mesh size was conducive to early osteoblast differentiation while smaller mesh size was conducive to later differentiation and matrix deposition. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005