Cell shape and gene expression in human intervertebral disc cells: in vitro tissue engineering studies

The objective of the present study was to examine the relation between gene expression and the shape of human intervertebral disc cells cultured in vitro in three-dimensional (3D) scaffolds. Disc cells from 19 subjects were seeded into either a collagen sponge or collagen gel and cultured for 10 days. In situ hybridization was performed on serial sections of paraffin embedded specimens and assessed for expression of selected genes important for extracellular matrix formation: Types I and II collagen, aggrecan and chondroitin-6 sulfotransferase. Rounded cells grown in collagen gel showed expression of Types I and II collagen, aggrecan and chondroitin-6 sulfotransferase; expression of these genes was absent in spindle shaped cells. Cells in the collagen sponge that lay on the sponge margin were frequently spindle shaped; these cells expressed type I collagen, but not type II collagen, aggrecan or chondroitin-6 sulfotransferase. Results presented here provide novel data concerning disc cell gene expression with collagen 3D constructs. This information is useful for future tissue engineering studies that have the challenging goal of selectively modulating gene expression.