Abstract
Fetal bovine cartilage contains a polypeptide(s) that has somatomedin-like effects on rat and rabbit costal chondrocytes in culture. This factor, named the cartilage-derived factor, was extracted from fetal bovine cartilage, fractionated with acetone, and purified by gel filtration on Toyopearl HW 55-F in 4 M guanidine hydrochloride, preparative isoelectric focusing, and subsequent gel filtration on Toyopearl HW 55-F in 1 M formic acid. The resulting preparation, which focused in the neutral pH region and eluted from a Toyopearl column in a fraction with apparent Mr 10,000--11,000, appeared homogenous by NaDodSO4 gel electrophoresis. The purified preparation markedly enhanced not only proteoglycan synthesis but also DNA synthesis in rabbit costal chondrocytes and, on a protein basis, it was 1000 times more active than insulin and 1,000,000 times more active than fetal calf serum in stimulating proteoglycan synthesis.