Research Article

Monitoring the Bystander Killing Effect of Human Multipotent Stem Cells for Treatment of Malignant Brain Tumors

Figure 9

Quantification of in vivo imaging data to monitor suicide gene therapy using hMultistem as cellular vehicles in the hU87 glioblastoma model. (a) Quantification of the volume of hypointense voxels in animals receiving SPIO labeled eGFP-fLuc-HSV-tk+ hMultistem cells indicates sufficient contrast to detect the therapeutic cells in the hU87 tumor model (sham (no cells): , PBS treated: , and GCV treated: ). (b) Bioluminescent imaging data using D-luciferin as a substrate for fLuc expressing hMultistem cells showed that the stem cells were detectable through BLI. A decrease in stem cell viability was detected for both PBS and GCV treated animals, which indicates that the stem cells are unable to survive well in the tumor microenvironment. (c) Bioluminescent imaging data using coelenterazine-h as a substrate for rLuc to investigate tumor viability indicated tumor growth in the sham operated and PBS treated group but not in the GCV treated group. (d) Tumor volume measurements proved no statistical differences between sham operated, PBS treated, or GCV treated animals (green bar: hMultistem injection; red bar: duration of GCV/PBS treatment). (e) T1-weighted MRI pre- and postcontrast injection showed BBB integrity loss in the hU87 tumor compared to the contralateral hemisphere and the extracranial muscle at all time points (). Levels of significance are expressed as , , , and .