Changes in the lipids of human articular cartilage with age

Histochemical and chemical studies demonstrated a significant increase in the lipods of articular cartilage with advancing age. Triglycerides, cholesterol, and phospholipids were identified chemically and were shown by comparative staining procedures to be present in intracellular and extracellular lipids. The distribution and the composition of the extracellular lipids were interpreted as indicating that the extracellular lipids are of cellular origin. Glycolipids were extracted from cartilage of all ages and were shown to account for a portion of the increase in total lipid with age. Glycolipids extracted from aged cartilage were partially characterized. Cerebrosides, sulfatides, and gangliosides were detected. Glycolipids were estimated to comprise from 5 to 10% of the total lipid of articular cartilage. Arachidonic acid concentrations increased maredly with age in the surface of cartilage but were present in trace amounts in deep cartilage, demonstrating clear-cut differences in the levels as well as the location of this fatty acid precursor of the prostaglandins (PGE2 and PGF2alpha).