Osteogenic protein 1 stimulates cells-associated matrix assembly by normal human articular chondrocytes: up-regulation of hyaluronan synthase, CD44, and aggrecan.

OBJECTIVE: To determine the effects of osteogenic protein 1 (OP-1) on hyaluronan (HA), CD44, and aggrecan biosynthesis as well as the contribution of these molecules in promoting matrix assembly by human articular chondrocytes.
METHODS: Normal human chondrocytes were cultured with or without OP-1 treatment. Changes in the relative expression of messenger RNA (mRNA) for HA synthases 2 and 3 (HAS-2 and HAS-3), CD44, and aggrecan were determined by competitive quantitative reverse transcriptase-polymerase chain reaction. Accumulation of HA was characterized by indirect staining, CD44 by flow cytometry, and aggrecan biosynthesis by 35SO4 incorporation.
RESULTS: OP-1 stimulated the expression of HAS-2, CD44, and aggrecan mRNA in a time-dependent manner, resulting in increased expression of HA, CD44, and aggrecan. Prominent increases in HA-rich cell-associated matrices were also observed.
CONCLUSION: OP-1 stimulates not only the synthesis of matrix macromolecules such as aggrecan, but also the synthesis of other molecules required for matrix retention, namely, HA and CD44.