Influence of VEGF stimulated human macrophages on the proliferation of dermal microvascular endothelial cells: Coculture experiments

Monocytes/macrophages are known to exhibit pro-angiogenic activities after VEGF stimulation. Recently, it was shown that VEGF stimulated macrophages can support growth of microvascular endothelial cells from the lung when both cell types were cocultured using a cell ratio of 1 : 1. However, endothelial cells can have different phenotypic characteristics and metabolism depending on the originating vascular bed and tissues, and only few data have been published regarding the regiospecific sensitivity of microvascular endothelial cells for angiogenic stimuli. Reports about differences in the microvascular bed of the lung and the skin motivated to investigate angiogenic effects of VEGF stimulated macrophages (m Phi a) on the doubling time and the cell growth behaviour of skin derived microvascular endothelial cells (HMVEC/S). During the study period of 60 days, m Phi a supported growth and proliferation of the HMVEC/S, when m Phi a and HMVEC/S were cocultured at a ratio of 0.5 : 1. However, these effects were not seen in a 1 : 1 coculture. This result indicates that there is a positive correlation between the pro-angiogenic effects of m Phi a and the number of endothelial cells in the direct neighbourhood of the m Phi a and also suggests a different sensitivity of microvascular endothelial cells to angiogenic stimuli depending on the tissue from which they were isolated.