Fig. 3
The effect of chemotherapy-exposed MSC on triple-negative breast cancer xenografts in vivo. (A) Scheme of experiment design. (B) Tumor volume evaluation. We observed faster tumor growth in groups where MSC were co-injected with cancer cells, but these changes were not statistically significant. (C) Tumor weights were measured after the experiment termination. We observed higher weight of tumors in groups containing DOX- and PAC-MSC, but these changes were not significant. (D) Representative pictures of Ki-67/VIM immunohistochemically stained xenografts’ periphery showed increased ability of tumor cells to invade into the surrounding stroma in xenografts formed by MDA cells co-injected with DOX- and PAC-MSC. (E) Increased metastatic potential of cancer cells in MDA + DOX-MSC group was additionally confirmed by VIM staining of metastatic cancer cells along the adipose tissue. (F) The percentage of the tumor perimeter with tumor cells infiltrative interface with the surrounding adipose tissue. Significantly higher tumor cell invasion was observed in groups, where MSC were exposed to DOX and PAC (MDA only vs. MDA + PAC-MSC, p = 0.038; MDA + MSC vs. MDA + PAC-MSC, p = 0.006; MDA + MSC vs. MDA + DOX-MSC, p = 0.042) compared to the group with unexposed MSC (G) Representative ex vivo image of lungs containing metastatic cells in group with DOX-MSC. Imaging was performed immediately after mice were sacrificed using IVIS Caliper. Two lungs from each group were used for imaging, metastases were detected by the red fluorescence of subcutaneously injected MDA cells. On the scale of fluorescence intensity, yellow color represents the strongest emission. 1 = MDA only, 2 = MDA + MSC, 3 = MDA + DOX-MSC, 4 = MDA + PAC-MSC. (H) RT² Profiler™ PCR Array Human Tumor Metastasis was used to assess gene expression changes in selected mice tumors. Only four out of 84 genes showed higher than 2.5-fold up- or down- regulation in MDA + unexposed or DOX-/PAC-exposed MSC tumors compared to MDA only group. Statistically significant results are highlighted with asterisks at p < 0.05 (*), p < 0.01 (**), p < 0.001 (***)