Gene expression by marrow stromal cells in a porous collagen–glycosaminoglycan scaffold is affected by pore size and mechanical stimulation
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Marrow stromal cell (MSC) populations, which are a potential source of undifferentiated mesenchymal cells, and culture scaffolds that mimic natural extracellular matrix are attractive options for orthopaedic tissue engineering. A type I collagen–glycosaminoglycan (CG) scaffold that has previously been used clinically for skin regeneration was recently shown to support expression of bone-associated proteins and mineralisation by MSCs cultured in the presence of osteogenic supplements. Here we follow RNA markers of osteogenic differentiation in this scaffold. We demonstrate that transcripts of the late stage markers bone sialoprotein and osteocalcin are present at higher levels in scaffold constructs than in two-dimensional culture, and that considerable gene induction can occur in this scaffold even in the absence of soluble osteogenic supplements. We also find that bone-related gene expression is affected by pore size, mechanical constraint, and uniaxial cyclic strain of the CG scaffold. The data presented here further establish the CG scaffold as a potentially valuable substrate for orthopaedic tissue engineering and for research on the mechanical interactions between cells and their environment, and suggest that a more freely-contracting scaffold with larger pore size may provide an environment more conducive to osteogenesis than constrained scaffolds with smaller pore sizes.
KeywordsAverage Pore Size Cyclic Strain Osteogenic Medium UMR106 Cell Osteogenic Supplement
This work was funded by the Programme for Research in Third Level Institutions (Trinity Centre for Bioengineering) administered by the Higher Education Authority, Ireland. We thank Dr. Ionnais Yannas and Dr. Brendan Harley (Massachusetts Institute of Technology) for the generous gift of scaffold used in some of the experiments, Mr. Alan Reid and Mr. Gabriel Nicholson (Trinity Centre for Bioengineering) for rig design and fabrication, respectively, and Prof. Noel Claffey (Dublin Dental School and Hospital) for advice on statistical analysis.
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