Heparin modulates human intestinal smooth muscle cell proliferation, protein synthesis, and lattice contraction.

The effect of heparin on human intestinal smooth muscle cell proliferation, collagen and noncollagen protein synthesis, and collagen lattice contraction was studied in vitro. Proliferation of serum-stimulated cells was inhibited in a concentration-related fashion by continuous exposure to heparin. The inhibition of proliferation was reversible when heparin was removed from the culture medium. Collagen synthesis was inhibited by 24-h exposure to heparin, but only during that phase of culture (8-12 days) when collagen synthesis was maximal. Noncollagen protein synthesis was down-regulated by 24-h exposure to heparin at all phases of culture tested (5-21 days). Heparin also abolished the contraction of collagen lattices populated by human intestinal smooth muscle cells. These studies demonstrate that heparin plays a significant role in the modulation of human intestinal smooth muscle cell behavior in vitro and suggest that a similar role is played by heparinlike components of the extracellular matrix in vivo.