Figure 4.

Ablation of teratoma formation using HSVttk reporter and suicide gene. mESCs were stably transduced with a triple-fusion (ESC-TF) reporter gene that consisted of monomeric red fluorescence protein (mRFP), Fluc and HSVttk or a double-fusion (ESC-DF) reporter gene that consisted of enhanced GFP and Fluc. Stably transduced ESC-TF and ESC-DF cells (1 × 10⁶ each group) were transplanted into right and left shoulders of adult nude mice, respectively. (a) BLI and (b) PET imaging were performed at various time points using d-luciferin and [¹⁸F]-FHBG reporter probes, respectively. The marked difference in PET activities is consistent with the expression of HSVttk reporter gene in ESC-TF cells but not ESC-DF cells. Ganciclovir (GCV) treatment was started at week 2 and continued until week 5. After three weeks, ESC-TF cells (right shoulder) were completely ablated by GCV treatment, whereas ESC-DF cells were not affected as they lack HSVttk. Reprinted with permission from Cao et al. (2007).