Quantitative Analysis of Chondroitin Sulfate Isomers in Intervertebral Disk Chondrocyte Culture Using Capillary Electrophoresis.

Chondroitin sulfate (CS) isomers, 6-sulfate (CS6) and 4-sulfate (CS4), change their ratio to each other in cartilaginous tissues with aging. In this study, a quantitative measurement method of CS6 and CS4 was developed, using capillary electrophoresis (CE). Various buffer solutions, pH, and digestion times were studied, and the use of 0.1 M Tris-HCl at pH of 8.0 allowed the isolation of CS6 and CS4 from CS most efficiently when combined with chondrotinase ABC at a concentration of 1 mU/microg of the substrate during a 3 hr digestion period. Amounts of newly synthesized CS6 and CS4 in the intervertebral disk chondrocyte three-dimensional culture were quantified by this method after the proteoglycans were extracted by equilibrium density centrifugation.