Effects of electromagnetic stimulation on calcified matrix production by SAOS-2 cells over a polyurethane porous scaffold

There is increasing interest in designing new biomaterials that could potentially be used in the form of
scaffolds as bone substitutes. In this study we used a hydrophobic crosslinked polyurethane in a typical
tissue-engineering approach, that is, the seeding and in vitro culturing of cells using a porous scaffold.
Using an electromagnetic bioreactor (magnetic field intensity, 2 mT; frequency, 75 Hz), we investigated
the effect of the electromagnetic stimulation on SAOS-2 human osteoblast proliferation and calcified
matrix production. Cell proliferation was twice as high; expression of decorin, osteocalcin, osteopontin,
type I collagen, and type III collagen was greater (1.3, 12.2, 12.1, 10.0, and 10.5 times as great, respectively);
and calcium deposition was 5 times as great as under static conditions without electromagnetic
stimulation. RT-PCR analysis revealed the electromagnetically upregulated transcription specific for
decorin, fibronectin, osteocalcin, osteopontin, transforming growth factor-b, type I collagen, and type III
collagen. The immunolocalization of the extracellular matrix constituents showed their colocalization in
the cell-rich areas. The bioreactor and the polyurethane foam were designed to obtain cell colonization
and calcified matrix deposition. This cultured biomaterial could be used, in clinical applications, as an
osteoinductive implant for bone repair.