Cell viability in scoliotic discs in relation to disc deformity and nutrient levels.
Bibby SR., Fairbank JC., Urban MR., Urban JP.
STUDY DESIGN: Intervertebral disc tissue was analyzed during or removed at routine surgery for correction of scoliosis. Tissue was analyzed for glucose, lactate, oxygen, glycosaminoglycan, collagen concentrations, and cell viability. OBJECTIVES: To investigate the cell viability of the scoliotic disc on the concave and convex sides and in relation to curve apex, and to relate cell viability to concentrations of nutrients, metabolites, and extracellular matrix components. SUMMARY OF BACKGROUND DATA: Compositional differences have been measured in relation to the deformation of scoliotic discs. However, the causes of these in relation to cellular activity or viability are unknown. METHODS: Oxygen concentration was measured at surgery using a microelectrode. A segment of disc then was removed and sections at defined locations measured for cell viability and glucose, lactate, glycosaminoglycan, and collagen concentrations. RESULTS Cell viability was lower toward the convex side of the curve, with the greatest difference between the sides in the apical disc. The apical disc had the lowest oxygen and highest lactate concentrations, and lowest total number of cells. Glucose concentration correlated with the number of live cells. Concentrations of glycosaminoglycans and collagen per dry weight of tissue were similar on both sides of the disc. CONCLUSIONS: Differences in cell viability correlated with changes in nutrient and metabolite levels, and also with disc deformity (convex concave and distance from curve apex). Thus asymmetrical loads, tissue deformation, and nutrient supply may work separately or in combination to cause cell death. A loss of matrix macromolecules was not seen, possibly because the period between cell death and surgery was too short, as compared with long matrix turnover times. Cell death is expected eventually to have a deleterious effect on cell matrix and disc function.