Sulphate (35SO4) Uptake by Chondrocytes in Relation to Histological Changes in Osteo-Arthritic Human Articular Cartilage
Authors: D. H. Collins, T. F. McElligott
Journal: Annals of the Rheumatic Diseases (1960)

Quantitative studies of sulphate uptake by the cells of human cartilage (McElligott and Collins, 1960) have shown that chondrocyte activity increases in articular cartilage as age advances, while it decreases in costal cartilage.A considerably enhanced activity of articular over costal cartilage cells was recorded in cases where there was nakedeye evidence of destruction and fibrillation of the articular cartilage.We postulated a possible relationship between the increased sulphate utilization of ageing articular cartilage, the degree of osteo-arthritis, and the peculiar rearrangement and grouping of chondrocytes that are known to occur in these conditions.In order to investigate this, a large number of autoradiographs of cartilage incubated with labelled sulphate have been prepared and studied side by side with parallel sections stained by various methods including those that demonstrate mucopolysaccharides.It is the results of these studies that we now report. Material and MethodsA patella was removed at each of 34 necropsies from persons ranging in age from 4 to 83 years.Specimens were processed as soon as possible after removal and in all cases within 2 hours.During this delay the specimens were stored at 40 C. in the incubation medium, a procedure that reduces the rate of loss of chondrocyte activity.The intervals between death and autopsy and between the collection of the specimen and its processing were carefully noted.Preparation of Specimens.The patellae were inspected and changes of osteo-arthritis, if present, were graded 0-4 according to the classification proposed by Collins (1949, p. 76).Blocks of cartilage down to the bone were removed from the complete transverse diameter of the patellae and processed for quantitative measurement of sulphate fixation in 31 cases, as previously described (McElligott and Collins, 1960).Another block of cartilage with its subjacent bone was then cut from the specimen; this second block of cartilage adjoining that removed for radiochemical assay was used for the histological procedures to be described.The cut surfaces of the cartilage were then shaved with a razor so as to produce a block of the com- plete depth of the articular cartilage 1 mm.or less in thickness resting on a broader supporting block of the underlying bone, since thicknesses of cartilage greater than 1 mm.impair the uptake of "5SO4 (Bostrom and MaInsson, 1953).Incubation Medium.-Themedium used for incubating the specimens and in which they were transported was that described by Kodicek and Loewi (1955).It is a salt solution containing glucose buffered to pH 7 3.For quantitative estimations of sulphate fixation, sulphate as sodium sulphate 4-8 mg. per litre was added.In the preparation of autoradiographs no sulphate was added as carrier, as Layton (1950) reports that higher uptake of radioactive sulphate occurs where carrier is omitted.Radiochemical Technique.-Thequantitative procedure, based on the methods fully set out by Layton (1949Layton ( , 1950) ) and by Kodicek and Loewi (1955), has been previously described (McElligott and Collins, 1960).In the preparation of autoradiographs the blocks of cartilage and bone were incubated in 10 ml.medium at 37°C. in a water bath, in flasks mounted in a mechani- cal rocker.Approximately 5 microcuries (,uc.) of 35S per ml.(carrier-free sulphate supplied by Radiochemical Centre, Amersham) was added to the incubation medium.After 4 hours incubation, the blocks were rinsed with ice-cold isotonic (2 5 per cent.)sodium sulphate and fixed in 10 per cent.neutral formalin.After decalci- fication, dehydration, and double embedding by Peterfi's method, sections were cut at 7,u.Autoradiographs were prepared by the stripping film technique of Doniach and Pelc (1950) using Kodak A.R. 10 film.The preparations were exposed in the dark in a refrigerator, generally for 60 days.Some sections were stained before mounting by the periodic acid-Schiff (P.A.S.) technique; others were stained with 1 per cent.safranin through the overlying film after exposure and development.318