Fig. 5

Tumour formation potential in different mouse strains. Representative BLI of longitudinal tumour monitoring in four strains of mouse following IC administration of mMSCs. a Immunocompromised BALB/c SCID, b immunocompetent BALB/c, c FVB or d MF1 mice. BALB/c mice showed very similar tumour formation potential to BALB/c SCID mice, with respect to timing, size and location of tumour development. After 21 days, the strong signal originating from the tumours required a colour scale two orders of magnitude greater than that at 0 h to accurately display the tumour location. FVB and MF1 mice displayed weaker BLI foci at day 28, and not all animals displayed the same tumour distribution. BALB/c SCID data in a has been partially reproduced from Fig. 4a to facilitate comparison between strains. e Mean whole-body quantification of the bioluminescence signal up to day 28. Error bars represent SE. f Photograph of the hindquarters of a BALB/c mouse after removal of the skin. Multiple tumour foci are indicated with arrows, demonstrating their presence in the skeletal muscle close to the femurs, hips and spine. g ex vivo BLI of tumours harvested 30 days post administration of mMSCs, confirming that tumours originated from the administered cells and not host tissue. h–k Histological examination of tumour tissue. h H&E staining and corresponding i epifluorescence imaging of the ZsGreen reporter. Differences in cell composition between the tumour (**) and normal tissue (*) are denoted. Scale bars represent 100 μm. j, k Higher magnification of tumour tissue showing cancer cells arranged in densely cellular monomorphic areas. Scale bars correspond to 50 μm, and arrow indicates mitotic figures, one of which is shown in the inset. k corresponds to an area where the tumour is moderately cellular with production of unmineralised osteoid (black arrowhead) and partially mineralised matrix (red arrowhead)