| The influence of mechanical compression on the onset of secondary osteoarthritis is not well understood. The process by which a chondrocyte can signal changes in its mechanical environment to the nucleus to elicit changes in gene expression is known as mechanotransduction. In this study, a tool to study the mechanotransduction process in chondrocytes was developed and used to observe the responsiveness of isolated chondrocytes and enzymatic chondrons embedded in agarose gels to mechanical compression. This tool was a plasmid, consisting of the B18 fragment of the rat aggrecan promoter spliced in front of green fluorescent protein (GFP), which could be transfected into live cells. The B18-GFP plasmid was used in this study to differentiate the greater aggrecan promoter responsiveness of enzymatic chondrons (ECs) to mechanical compression when compared to isolated chondrocytes (ICs). The plasmid was used to investigate the effects of varying frequencies and magnitudes of loads for ECs using a well-characterized cell-gel experimental system. The cytoskeleton and its associated structures were characterized for chondrocytes in vivo. The role of the cytoskeleton and some associated structures was discussed along with the possibility of intercellular communication between paired cells in chondrons. Finally, cell division and the phenotypic stability in culture were investigated for ECs in gels. Results from the compression studies may be used as a baseline from which to compare future in vitro studies using the cell-gel experimental system. |
