Image cytometry and topographical analysis of proliferation of endothelial cells in vitro during Bartonella (Rochalimaea) infection.

Bartonella quintana and Bartonella henselae are clinically associated with proliferative neovascular lesions. The effect of Bartonella infection on human endothelial cells was evaluated in vitro by quantitative image analysis. Particular emphasis is placed on reporting the methodologies employed. Human umbilical vein endothelial cells were infected in vitro with the two Bartonella species. Cell proliferation (cell density), cell morphology (cell surface, form and elongation factors) and spatial reorganization (global topographical analysis and hierarchical cluster detection) were monitored over a 3-day period of infection. Firstly, infection stimulated endothelial cell proliferation. Secondly, infection induced obvious morphological changes; infected cells became larger, more elongated and spindle-shaped. Cytoskeletal reorganization was confirmed by staining of F actin. Thirdly, infection altered the spatial organization of cells within the monolayer; this could not have been due solely to the morphological modifications they experienced. This model demonstrates that Bartonella infection provoked endothelial cell proliferation, topographical rearrangements and morphological changes because of modifications of the cytoskeleton. These experimental findings provide a physiopathological explanation to the abnormal angiogenesis observed in bacillary angiomatosis.