Age-related changes in proteoglycans of human ligamentum flavum

Age-related changes in proteoglycans of human ligamentum flavum were studied using specimens obtained from patients divided into four age groups. The proteoglycans were purified by ion-exchange and gel-filtration chromatography. A low-molecular-weight proteoglycan with the same molecular size was present in all each age groups. Conversely, high-molecular-weight proteoglycan increased with advancing age. Properties of the sugar chains, glycosaminoglycans, in these proteoglycans were studied using cellulose acetate membrane electrophoresis and chondroitinase digestion. It was found that the high-molecular-weight proteoglycan consisted mainly of chondroitin 6-sulfate, whereas the low-molecular-weight proteoglycan consisted mainly of dermatan sulfate, although the ratio of chondroitin 6-sulfate increased with age. These results indicate that proteoglycans of human ligamentum flavum show changes in amount and composition with age.