Fig. 4
In vivo effect of pIL6-TRAIL + -GFP + -UC-MSCs on MM growth. a Timeline elucidating the experimental design of SCID mice xenografted intratibially (IT) with 2 × 105 Red-Luc+U266 cells (D0), followed after 3 days (D3) by injection intracardially (IC) with PBS (group A), 2.5 × 105 GFP +-UC-MSCs (group B), or 2.5 × 105 pIL6-TRAIL + -GFP +-UC-MSCs (group C) (N = 14 for each group). Three mice for each group were sacrificed randomly, respectively at 12 h (h12) and 48 h (h48) after injection IC for ex vivo evaluation of UC-MSC distribution and tumor apoptosis. The remaining mice were investigated at defined time points (D3, D10, D20 and D30) by bioluminescence imaging with IVIS Lumina. b The biodistribution of pIL6-TRAIL + -GFP +-UC-MSC, revealed by PCR analysis for GFP after injection IC, confirmed the presence of these cells in tibiae as well as in lung, heart, and kidney, while transduced cells were not observed in spleen and liver. Actin was used as loading control. c Representative bioluminescence images at different time points of MM-bearing mice, injected IC with PBS (group A), GFP +-UC-MSCs (group B), or pIL6-TRAIL + -GFP +-UC-MSCs (group C). The color scale ranged from blue (just higher than background noise; set to 1 × 107 photons/s/cm2/sr) to red (at least 2.5 × 108 photons/s/cm2/sr). Quantitative analysis of tumor growth in mice was assessed by Living Image Software. Data represent the relative increase of median photon flux (photon/s) within ROI areas in each group at different time points. Tumor growth was timely reduced in mice treated with pIL6-TRAIL + -GFP + -UC-MSCs as compared to both PBS and GFP +-UC-MSC treated groups (p < 0.03). Error bars represent the standard error of the mean (SEM); *p value calculated by Student’s t test. d Hindlimb radiographs of MM bearing mice was performed 27 days after injection IC of transduced UC-MSCs or PBS. Representative images of the three experimental groups show a minor expansion of the osteolytic lesions in mice systemically injected with pIL6-TRAIL +-GFP +- UC-MSCs compared to those of groups A and B. GFP green fluorescent protein, MM multiple myeloma, MSC mesenchymal/stromal stem cell, PBS phosphate buffered saline, UC umbilical cord, NTC no template control