The effect of transforming growth factor-β₁ on glycosaminoglycan production by human marrow cultures

We have assayed the effect of transforming growth factor-β₁ (TGF-β₁), a potent modulator of hematopoiesis, on glycosaminoglycan production in human marrow cultures. Glycosaminoglycans are a component of the extracellular matrix known to affect cell growth and differentiation. TGF-β₁ and [³⁵S]sulfate were added simultaneously to hematopoietically active human marrow cultures, and radiolabeled glycosaminoglycan production was determined by cetylpyridinium chloride precipitation. TGF-β₁ at 15 ng/ml for 72 h increased [³⁵S]sulfate incorporation into media glycosaminoglycans to 190% of control levels but did not affect the [³⁵S]sulfate incorporation into cell-associated glycosaminoglycans. Approximately 90% of the glycosaminoglycans in the media fraction and 85% of the glycosaminoglycans in the cell-associated fraction were susceptible to degradation by chrondroitin ABCase in both treated and control cultures. Pulse-chase experiments suggested that the increase in glycosaminoglycan [³⁵S]sulfate incorporation was not due to decreased glycosaminoglycan degradation. This concentration of TGF-β₁ did not alter nonadherent granulocyte-macrophage colony-forming unit (CFU-GM) number per flask but significantly decreased the more primitive adherent CFU-GM number per flask (by 50%-70%). These data suggest that the ability of TGF-β₁ to modulate hematopoiesis may be due, in part, to its effects on glycosaminoglycan production.