Molecular imaging of embryonic stem cell misbehavior and suicide gene ablation.
Numerous studies have demonstrated the potential use of stem cells for the repair and regeneration of injured tissues. However, tracking transplanted stem cell fate and function in vivo remains problematic. To address these issues, murine embryonic stem (ES) cells were stably transduced with self-inactivating lentiviral vectors carrying either a triple fusion (TF) or double fusion (DF) reporter gene construct. The TF consisted of monomeric red fluorescence protein (mrfp), firefly luciferase (Fluc), and herpes simplex virus truncated thymidine kinase (HSV-ttk) reporter genes. The DF consisted of enhanced green fluorescence protein (egfp) and Fluc reporter genes but lacked HSV-ttk. Stably transduced ES-TF or ES-DF cells were selected by fluorescence activated cell sorting based on either mrfp (TF) or egfp (DF) expression. Afterwards, cells were injected subcutaneously into the right (ES-TF cells) and left (ES-DF cells) shoulders of adult female nude mice. Cell survival was tracked noninvasively by bioluminescence and positron emission tomography imaging of Fluc and HSV-ttk reporter genes, respectively. Imaging signals progressively increased from day 2 to day 14, consistent with ES cell survival and proliferation in vivo. However, teratoma formation occurred in all nude mice after 5 weeks. Administration of ganciclovir (GCV), targeting the HSV-ttk gene, resulted in selective ablation of teratomas arising from the ES-TF cells but not ES-DF cells. These data demonstrate the novel use of multimodality imaging techniques to (1) monitor transplanted ES cell survival and proliferation in vivo and (2) assess the efficacy of suicide gene therapy as a backup safety measure against teratoma formation.
Cao
Feng
F
The Department of Radiology and Bio-X Program, Stanford University School of Medicine, Stanford, California 94305-5344, USA.
Drukker
Micha
M
Lin
Shuan
S
Sheikh
Ahmad Y
AY
Xie
Xiaoyan
X
Li
Zongjin
Z
Connolly
Andrew J
AJ
Weissman
Irving L
IL
Wu
Joseph C
JC
D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D053595:Embryonic Stem Cells / Q000378:metabolism* / Q000473:pathology; D005260:Female; D015774:Ganciclovir / Q000494:pharmacology; D041722:Genes, Transgenic, Suicide; D005819:Genetic Markers; D015316:Genetic Therapy; D008163:Luminescent Measurements; D051379:Mice; D008819:Mice, Nude; D049268:Positron-Emission Tomography; D011859:Radiography; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics; D033581:Stem Cell Transplantation / Q000009:adverse effects; D013724:Teratoma / Q000000981:diagnostic imaging / Q000209:etiology / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control; D013937:Thymidine Kinase / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D013997:Time Factors; D014764:Viral Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics
D000998:Antiviral Agents; D005819:Genetic Markers; D014764:Viral Proteins; D013937:Thymidine Kinase; D015774:Ganciclovir