In vitro regulation of endothelial cell migration, proliferation and tube formation by the hyaluronan receptors RHAMM and CD44

The glycosaminoglycan hyaluronan (HA) has been implicated in angiogenesis. HA interacts with the cell-associated receptors CD44 and RHAMM, and CD44 has been implicated in neovascularization. We hypothesized that endothelial cell (EC) migration, proliferation and tube formation would be regulated by HA receptors. By FACS, both receptors were expressed on the surface of EC. Migration (measured using Matrigelcoated Transwell filters), proliferation (by MTS assay), and tube formation (tube length/well in EC plated on Matrigel) were determined in the presence and absence of specific receptor-blocking or control antibodies (0 - 100 μg/ml). Results are shown as % of bovine serum albumin as a control ± SEM (* p < 0.05, ANOVA, n = 3/group). Antibody Proliferation Migration Tube Formation Control Ab 87 ± 5 102 ± 15 98 ± 4 (MHC-1) Anti-RHAMM 84 ± 3 55 ± 15 * 65 ± 4 * (R36) Anti-CD44 50 ± 8 * 92 ± 4 60 ± 4 * (J173). We conclude that HA regulation of angiogenesis likely occurs through receptor interaction. Further, CD44 regulates EC proliferation, RHAMM regulates EC migration, and both receptors contribute to EC tube formation. These data suggest that both receptors are involved in angiogenesis, but that they may mediate their effects through distinct mechanisms.