Vascular occlusive disease is a major cause of death; however there is evidence that growth of collateral arteries developing from pre-existing anastomoses, known as arteriogenesis, could prevent patients from developing infarction. Mast cells, which are known to release vasoactive substances, seem to play an important role in this process. The aim of this work was to investigate the involvement of mast cells in the process of arteriogenesis.To evaluate the role of mast cells, wild type (wt) mice and PI3 kinase (PI3K) gamma knockout mice were subjected to right femoral artery ligation in order to induce arteriogenesis; the left side was sham operated. Relative perfusion recovery of hind limbs was monitored before and post ligation at days 3, 7, 14 and 21 by Laser Doppler Imaging. For in vitro experiments, mouse endothelial and smooth muscle cells were isolated from mouse aorta and mast cells from mouse bone marrow. After treating isolated mast cells with degranulating agents like ionomycin in vitro, supernatants were collected and used for measurements of proliferation of endothelial and smooth muscle cells as well as other biochemical investigations such as RNA isolation.In vivo, treatment of wt-mice with mast cell degranulating compound 48/80 (C48/80) improved the outcome of arteriogenesis. Collateral growth in PI3Kgamma -/- mice was reduced in comparison to wt-mice. Furthermore, treatment of PI3Kgamma -/- mice with C48/80 had no effect on collateral growth indicating an important role of the PI3Kgamma on mast cell degranulation. Furthermore, treatment of mice with a leukotriene synthesis inhibitor, MK-886, had no effect on the outcome of arteriogenesis in comparison to the controls indicating that leukotrienes might not be essential for arteriogenesis.In vitro studies demonstrated that the proliferation of endothelial cells and smooth muscle cells was enhanced 1.2- and 1.7-fold, respectively, by supernatants derived from degranulated mast cells. The mast cell supernatants were found to contain an average of 1.29 ± 0.13µg/ml RNA but no RNase activity, suggesting that mast cells release RNA upon stimulation, which might function to recruit leukocytes.Together, these findings suggest that cell mediators released from activated mast cells might influence the process of arteriogenesis by enhancing the proliferation of vessel wall cells, dependent on PI3Kgamma-related mast cell degranulation.
Verknüpfung zu Publikationen oder weiteren Datensätzen
