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Abstract
Intervertebral disc degeneration has been associated with changes in the tensile stress environment of the annulus fibrosus and to changes in cell phenotype. Cells are hypothesised to sense their environment through deformation. However, no system is available to test the effect of cyclical tensile loading on cell deformation in a three-dimensional culture. The purpose of this study was to develop a method to enable cyclical tensile loading and to enable the measurement of connective tissue cell deformation in three-dimensional gel culture. Chondrocytes, fibroblasts, and inner and outer annulus fibrosus cells were embedded in rings of fibrin gel, where they were cyclically loaded during six days of culture. The tangent modulus of the gel remained stable over the culture period and the forces and displacements applied to all gels were comparable. The 18% grip-to-grip static strain applied to the gel produced internal tensile deformations which varied regionally in the ring. The average gel internal tensile deformation was approximately 7.0% at day 0, 7.8% after six days of culture and 10.0% after six days of cyclical loading culture. Cell deformation under static tensile load was observed by confocal microscopy for all cell types at day 0 and after 6 days of culture with or without cyclical loading. This system should be a useful tool to study the effects of tensile loading and cell deformation on tissue health.
