Different effects of angiogenesis inhibitors IFN-alpha and TIMP-1 on lymphangiogenesis

This study was designed to examine the effects of angiogenesis inhibitors IFN-alpha and TIMP-1 on lymphangiogenesis. We cultured lymphatic endothelial (LE) cells from pig thoracic ducts and performed morphological observations using light microscopy, TEM, and confocal microscopy to confirm their lymphatic origin. We tested these cells for growth inhibition by angiogenesis inhibitors IFN-alpha and TIMP-1 using both the scraping line and MTT methods. In addition, we analyzed apoptosis using the Hoechst and Caspase staining methods. Finally, we tested IFN-alpha and TIMP-1 using in vivo inhibitory assays. By morphological observations, all LE cells in vivo and in vitro were found to be of very similar morphology. Both in vitro inhibitory assays of scraping line and MTT showed significant differences for the IFN-alpha treatment (p < 0.01) and no significant difference for TIMP-1. Hoechst and Caspase apoptosis assays demonstrated that IFN-alpha could induce apoptosis of LE cells, and TIMP-1 had little effect. IFN-alpha and TIMP-1 inhibitory in vivo assays showed a lack of healing following IFN-alpha treatment compared to control and TIMP-1 treatment. In summary, these different angiogenesis inhibitors have different effects on lymphangiogenesis. IFN-alpha inhibits proliferation and migration of LE cells in a dose-dependent fashion and induces apoptosis of LE cells while TIMP-1 has no significant inhibitory effects on proliferation, migration, or inducing apoptosis.