Control of repair in articular tissues and the development of osteoarthritis

Comparison of the stimulation of glycosaminoglycan synthesis in cultures of mononuclear cells from blood and of fibroblastic cells

A small molecular weight factor, derived from bovine bone ('matrigenin'), stimulated glycosaminoglycan and proteoglycan synthesis of cultured human fibroblastic cells but not of mononuclear cells from human blood. However, proteoglycan synthesis and secretion by the mononuclear cells was stimulated by the addition of concanavalin A. The proteoglycan from the concanavalin-A-stimulated mononuclear cells was of smaller molecular weight than the proteoglycan from the 'matrigenin'-stimulated fibroblastic cells. The major increase in proteoglycan synthesis and secretion occurred much later during the culture period for concanavalin-A-stimulated mononuclear cells than for 'matrigenin'-stimulated fibroblastic cells.

"Matrigenin" activity from bovine bone--I. Partial purification of activity

1. Bovine bone contains an extractable activity which stimulated the synthesis of glycosaminoglycans by bovine synovial, human synovial and mouse 3T3 fibroblastic cells in culture. Human cells were used to develop an assay for purification of the stimulatory activity ("matrigenin" activity) from bovine bone. 2. Partial purification of "matrigenin" activity was achieved by precipitation of the EDTA extract at pH 3.5 and Sepharose CL-6B chromatography in 4 M guanidinium HCl. Dissociative conditions were necessary to prevent aggregation. 3. On SDS-polyacrylamide gel electrophoresis the activity ran with a mobility equivalent to a Mr = 27,500 and could be recovered from the SDS gels.

"Matrigenin" activity from bovine bone--II. Effects on the glycosaminoglycans of bovine articular cartilage in culture

1. Bovine articular cartilage slices were studied in long term culture by periodically pulse-labelling the cultures with radiolabelled precursors of glycosaminoglycans and isolating the glycosaminoglycans from cartilage. 2. Pretreatment of the cartilage slices with bacterial collagenase resulted in stimulation of the incorporation of radioactivity into the glycosaminoglycans. 3. The addition of a fraction from bovine bone, enriched in "matrigenin" activity, to cultures of cartilage pretreated with collagenase resulted in an additional increase in the stimulation of incorporation of radioactivity.

"Matrigenin" activity from bovine bone--III. Effects on glycosaminoglycans and proteoglycans of human synovial cells in culture

1. Human synovial fibroblastic cells were cultured in the presence and absence of an extract from bovine bone containing "matrigenin" activity. The rate of incorporation of radioactivity into the glycosaminoglycans of the medium of "matrigenin"-treated cultures increased after 24 hr of incubation, compared to "controls". 2. Higher serum concentrations had a greater effect on the incorporation of radioactivity into hyaluronic acid synthesized by "matrigenin"-treated cultures, than by "controls". 3. Incorporation of radioactive precursors into the proteoglycans isolated from the medium was greater in the "matrigenin"-treated cultures than in "controls". The synthesis of a large mol. wt proteoglycan was specifically stimulated.