In vitro assays of iron-labeled S. aureus bacteria on HUVEC cells and macrophages. Iron-labeled and non-labeled S. aureus bacteria (strain 6850) were compared to each other with regards to growth behavior, their cytotoxicity and invasiveness in HUVEC cells as well as their phagocytosis by macrophages. (A) In growth curves of S. aureus wild type cells (6850 wt) and electro-competent cells with (6850 comp cells w /iron) and without (6850 comp cell) iron particles, no significant differences were observed for the three cell cultures. (B) The fluorescence microscopic image shows how iron-labeled bacteria are phagocytized by macrophages. (C) In the cytotoxicity assay, cell death of HUVEC cells was compared and quantified upon treatment with S. aureus wild type cells, electro-competent and iron labeled bacteria. (D) In the invasion assay the invasiveness of the laboratory strain Cowan I was set as 100%, the non-invasive laboratory strain TM300 was used as a negative control. Neither growth behavior, cytotoxicity, invasiveness nor phagocytosis by macrophages was affected by the iron label.
Hoerr et al. BMC Biology 2013 11:63 doi:10.1186/1741-7007-11-63