A three-dimensional collagen matrix as a suitable culture system for the comparison of cyclic strain and hydrostatic pressure effects on intervertebral disc cells

Abstract

Object. To study intervertebral disc cell mechanobiology, the authors developed experimental systems that allow the application of cyclic strain and intermittent hydrostatic pressure (IHP) on isolated disc cells under equal three-dimensional (3D) culture conditions. The purpose of the study was to characterize disc cell proliferation, viability, morphology, and gene expression in 3D collagen matrices. Methods. The effects of cyclic strain (1, 2, 4, and 8% strain; 1 Hz) and IHP (0.25 MPa, 0.1 Hz) on gene expression (real-time polymerase chain reaction) of anabolic and catabolic matrix proteins were investigated and compared with those derived from mechanically unstimulated controls. Intervertebral disc cells proliferated in the collagen gels (mean viability 91.6%) and expressed messenger RNA for collagen I, collagen II, aggrecan, matrix metalloproteinase (MMP)—2, and MMP-3. Morphologically, both spindle-shaped cells with longer processes and rounded cells were detected in the collagen scaffolds. Cyclic str...