To elucidate the underlying mechanisms of adipose tissue remodeling and vascular malfunction in metabolic syndrome, we have developed a visualization technique based on laser confocal microscopy that enabled us to evaluate the precise three-dimensional structures and cell-cell dynamics including adipocyte, endothelial cells, platelets, and leukocytes in vivo with high time and spatial resolutions. Close interactions (rolling / adhesion) of platelets, leukocytes, and endothelial cells in vessel wall was observed in microcirculation of obese adipose tissue. Blood flow velocity was reduced, and tissue hypoxia is remarkable. Vascular permeability was increased indicating endothelial dysfunction. These findings demonstrate that obese adipose tissue can be considered as a site of inflammation and that activation of the leukocyte adhesion cascade is crucial for initiation and progression of inflammatory changes in obese adipose tissue.
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