Distribution of hyaluronan during extracellular matrix remodeling in human restenotic arteries and balloon-injured rat carotid arteries.

The glycosaminoglycan hyaluronan (HA) is present in developing tissues and healing wounds and forms a loose, hydrated extracellular matrix (ECM) that promotes processes such as cell migration. To investigate the potential contribution of HA to the pathogenesis of restenosis, we studied (1) human lesions obtained by directional atherectomy and (2) experimentally induced neointima formation in balloon-injured rat carotid arteries. A biotinylated proteoglycan fragment that binds specifically to HA was used to stain atherectomy specimens from 29 human restenotic lesions (mean restenosis interval, 6.0+/-4.4 months) and 8 human primary lesions. The loose myxoid ECM typical of human restenotic arteries demonstrated intense, diffuse staining for HA. The intensity was inversely related to the density of immunostaining for collagen types I and III and was lowest in hypocellular primary atherosclerotic plaque. Among 24 rat carotid arteries retrieved 3, 7, 14, 28, 42, or 56 days after balloon injury and immunostained as well for proliferating cell nuclear antigen, staining for HA in the neointima reached a maximum 7 days after balloon injury and was associated with the presence of proliferating, PCNA-positive smooth muscle cells. Hyaluronan is a characteristic constituent of the loose myxoid ECM in human restenotic arteries and of the neointima in experimentally injured arteries. The presence of hyaluronan may be a marker for an initial phase of the extracellular matrix remodeling that occurs during the development of a fibroproliferative lesion and could facilitate biological processes such as cell migration.