title: Quantification of early adipose-derived stem cell survival: comparison between sodium iodide symporter and enhanced green fluorescence protein imaging.
abstract: OBJECTIVE
  Strategies to overcome the problem of extensive early stem cell loss following transplantation requires a method to quantitatively assess their efficacy. This study compared the ability of sodium/iodide symporter (NIS) and enhanced green fluorescent protein (EGFP) imaging to monitor the effectiveness of treatments to enhance early stem cell survival.
  
  
  METHODS
  Human adipose-derived stem cells (ADSCs) transduced with an adenoviral vector to express both NIS and EGFP were mixed with culture media (control), matrigel (matrigel group) or pro-survival cocktail (PSC group), and 5×10(6) cells were injected into thigh muscles of C57BL/6 mice. Animals underwent serial optical imaging and (99m)TcO(4)(-) scintigraphy. Image-based EGFP fluorescence and (99m)TcO(4)(-) uptake was measured by region-of-interest analysis, and extracted tissues were measured for (99m)Tc activity. Fluorescent intensity measured from homogenized muscle tissue was used as reference for actual amount of viable ADSCs.
  
  
  RESULTS
  ADSCs were efficiently transduced to express EGFP and NIS without affecting proliferative capacity. The absence of significant apoptosis was confirmed by annexin V FACS analysis and Western blots for activated caspase-3. Both fluorescence optical imaging and (99m)TcO(4)(-) scintigraphy visualized implanted cells in living mice for up to 5days. However, optical imaging displayed large variations in fluorescence intensity, and thus failed to detect difference in cell survival between groups or its change over time. In comparison, (99m)TcO(4)(-) scintigraphy provided more reliable assessment of within-in group donor cell content as well as its temporal change. As a result, NIS imaging was able to discern beneficial effects of matrigel and pro-survival cocktail treatment on early ADSC survival, and provided quantitative measurements that correlated to actual donor cell content within implanted tissue.
  
  
  CONCLUSIONS
  NIS reporter imaging may be useful for noninvasively assessing the efficacies of strategies designed to improve early survival of transplanted stem cells.
authors.affiliation: Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, South Korea.
authors.forename: Cung Hoa Thien
authors.initials: CH
authors.lastname: Quach
authors.forename: Kyung-Ho
authors.initials: KH
authors.lastname: Jung
authors.forename: Jin-Young
authors.initials: JY
authors.lastname: Paik
authors.forename: Jin-Won
authors.initials: JW
authors.lastname: Park
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Lee
authors.forename: Kyung-Han
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D001692:Biological Transport; D002454:Cell Differentiation; D002470:Cell Survival; D005822:Genetic Vectors / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D057054:Molecular Imaging / Q000379:methods*; D061848:Optical Imaging; D015609:Organotechnetium Compounds / Q000378:metabolism; D011877:Radionuclide Imaging; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism*; D027981:Symporters / Q000235:genetics*; D013848:Thigh / Q000000981:diagnostic imaging / Q000601:surgery; D014162:Transfection; D000099209:Sodium-Iodide Symporters
chemical_list: D049452:Green Fluorescent Proteins; D015609:Organotechnetium Compounds; D027981:Symporters; D000099209:Sodium-Iodide Symporters; C485184:enhanced green fluorescent protein