Figure 2
Morphological changes induced in bone marrow-derived mesenchymal stem cells (BMMSCs) by bacterial infection. BMMSCs (line 412) were infected with bacteria, and after 3- and 6-hour incubation the cells were stained with Trypan blue and studied microscopically. An inoculum size of approximately 103 bacteria was selected for experiments. (a) Control cells were Trypan blue-negative after 3 and 6 hours of culture. (b) Pseudomonas aeruginosa PA01-infected cells at 3 and 6 hours. After 6 hours of infection, the morphological changes were seen as a rounding of the cells and thus they lost their characteristic spindle-like morphology. (c) Staphylococcus aureus Cowan I- and (d) S. aureus KK1089-infected cells at 3 and 6 hours. Both S. aureus strains formed aggregates after 6 hours of infection. (e) Staphylococcus epidermidis ATCC 14990- and (f) S. epidermidis KK1087-infected cells at 3 and 6 hours. The morphology of the cells remained normal, but some Trypan blue-positive nuclei were evident. Magnification was 200 × in all panels. Red circles indicate Trypan blue-positive nuclei. Red squares indicate changes in morphology. Black squares indicate the S. aureus-produced aggregates.