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International Journal of Biomaterials
Volume 2012 (2012), Article ID 915620, 10 pages
http://dx.doi.org/10.1155/2012/915620
Research Article

Perfusion Flow Enhances Osteogenic Gene Expression and the Infiltration of Osteoblasts and Endothelial Cells into Three-Dimensional Calcium Phosphate Scaffolds

1Department of Biomedical Engineering, Michigan Technological University, 1400 Townsend, Houghton, MI 49931, USA
2School of Forestry and Natural Resources and Department of Genetics, The University of Georgia, 111 Riverbend Road, Athens, GA 30602, USA
3Department of Mechanical Engineering, Colorado State University, 1602 Campus Delivery, Fort Collins, CO 80523, USA

Received 13 March 2012; Accepted 4 July 2012

Academic Editor: Giovanni Vozzi

Copyright © 2012 Matthew J. Barron et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Maintaining cellular viability in vivo and in vitro is a critical issue in three-dimensional bone tissue engineering. While the use of osteoblast/endothelial cell cocultures on three-dimensional constructs has shown promise for increasing in vivo vascularization, in vitro maintenance of cellular viability remains problematic. This study used perfusion flow to increase osteogenic and angiogenic gene expression, decrease hypoxic gene expression, and increase cell and matrix coverage in osteoblast/endothelial cell co-cultures. Mouse osteoblast-like cells (MC3T3-E1) were cultured alone and in co-culture with mouse microvascular endothelial cells (EOMA) on three-dimensional scaffolds for 1, 2, 7, and 14 days with or without perfusion flow. mRNA levels were determined for several osteogenic, angiogenic, and hypoxia-related genes, and histological analysis was performed. Perfusion flow downregulated hypoxia-related genes (HIF-1α, VEGF, and OPN) at early timepoints, upregulated osteogenic genes (ALP and OCN) at 7 days, and downregulated RUNX-2 and VEGF mRNA at 14 days in osteoblast monocultures. Perfusion flow increased cell number, coverage of the scaffold perimeter, and matrix area in the center of scaffolds at 14 days. Additionally, perfusion flow increased the length of endothelial cell aggregations within co-cultures. These suggest perfusion stimulated co-cultures provide a means of increasing osteogenic and angiogenic activity.