Noninvasive detection of human-induced pluripotent stem cell (hiPSC)-derived teratoma with an integrin-targeting agent (99m)Tc-3PRGD2.
OBJECTIVE
Since their discovery in 2006, induced pluripotent stem cells (iPSCs) have gained increasing interest for tissue regeneration and transplantation therapies. However, teratoma formation after iPSC transplantation is one of the most serious drawbacks that may limit their further clinical application. We investigated here whether human iPSC-derived teratomas could be detected by an integrin-targeting agent (99m)Tc-PEG(4)-E[PEG(4)-c(RGDfK)](2) ((99m)Tc-3PRGD2).


METHODS
Human-induced pluripotent stem cells (hiPSCs) were generated and characterized. In vitro integrin α(v)β(3) expression levels of hiPSC- and hiPSC-derived teratoma cells were determined by flow cytometry. (99m)Tc-3PRGD2 was prepared, and planar gamma imaging and biodistribution studies were carried out in teratoma-bearing severe combined immunodeficient (SCID) mice. Positron emission tomography (PET) imaging of teratomas with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) was also performed for comparison. Integrin α(v)β(3) expression in teratoma tissues was determined by immunofluorescence staining.


RESULTS
(99m)Tc-3PRGD2 showed high (2.82 ± 0.21 and 2.69 ± 0.73%ID/g at 0.5 and 1 h pi, respectively) and specific (teratoma uptake decreased from 2.69 ± 0.73 to 0.53 ± 0.26%ID/g after blocking with cold 3PRGD2) uptake in teratoma tissues, and planar gamma imaging demonstrated the feasibility of noninvasively detecting the teratoma formation with (99m)Tc-3PRGD2. (18)F-FDG showed low teratoma uptake and thus failed to detect the teratomas. Ex vivo immunofluorescence staining validated the integrin α(v)β(3) expression in the vasculature during teratoma formation.


CONCLUSIONS
Gamma imaging with (99m)Tc-3PRGD2 is a promising approach for the noninvasive monitoring of tumorigenicity after hiPSCs transplantation.
Stem Cell Research Center and Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing 100191, China.
Yang
Y
Li
Zhaofei
Z
Liu
Chengyan
C
Dong
Peng
P
He
Xujie
X
Liu
Zhaohui
Z
Zhu
Bing
B
Jia
Fang
F
Li
Fan
F
Wang
D000704:Analysis of Variance; D000818:Animals; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D057026:Induced Pluripotent Stem Cells / Q000737:chemistry / Q000166:cytology / Q000000981:diagnostic imaging*; D039302:Integrin alphaVbeta3 / Q000032:analysis* / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D016513:Mice, SCID; D057054:Molecular Imaging / Q000379:methods*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D010456:Peptides, Cyclic / Q000493:pharmacokinetics; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D013724:Teratoma / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000473:pathology; D014018:Tissue Distribution
D039302:Integrin alphaVbeta3; D015609:Organotechnetium Compounds; D010456:Peptides, Cyclic; D019275:Radiopharmaceuticals; C561921:technetium 99m (HYNIC-3PRGD(2))(tricine)(TPPTS)