Intravitale Analyse der tumor-induzierten Neovaskularisation in Matrix Metalloproteinase-19 defizienten Mäusen

Abstract

Background: the family of zinc-dependent matrix metalloproteinases is supposed to play a major part during the angiogenesis process. In this study we analyzed the tumor-induced angiogenic response in mice lacking the matrix metalloproteinase-19 (MMP-19). Methods: Mice genetically deficient in MMP-19 (−/−) and corresponding wild type (+/+) were used (n = 16). Murine melanoma cells were seeded onto prepared striated skin muscle. New vessel growth and neoformation of microvessel network were visualized by intravital florescence microscopy. Fluorescein isothiocyanate labeled Dextran was used as a plasma marker. Standard microcirculatory parameters (functional vessel density, vessel diameter, red-blood cell velocity, and plasma extravasation) were analyzed. Functional vessel density (FVD) served as a quantitative parameter for neovascularization. Results: Tumor growth and increasing formation of new microvasculature occurred in both groups. The transplanted tumor cells induced the development of vessel sprouts that rapidly infiltrated the seeded muscle and invaded the host tissue by remodelling the architecture of the mature microvascular network. Neoformation of tumor-induced microvasculature was reduced in MMP-19-proficient animals on day 8 and 12. FVD [mm/mm²] was found significantly increased in MMP-19-deficient mice on day 12 (196 ± 8 vs.162 ± 4) after cell transplantation (mean ± SEM, Mann-Whitney Rank Sum Test, p < 0.05). Conclusion: The direct dynamic visualization of new vessel growth and quantification of FVD indicate that MMP-19-deficiency is associated with an increased angiogenic response. These findings point the important role of MMP-19 in tumor-induced angiogenesis.