title: Infrared fluorescent protein 1.4 genetic labeling tracks engrafted cardiac progenitor cells in mouse ischemic hearts.
abstract: Stem cell therapy has a potential for regenerating damaged myocardium. However, a key obstacle to cell therapy's success is the loss of engrafted cells due to apoptosis or necrosis in the ischemic myocardium. While many strategies have been developed to improve engrafted cell survival, tools to evaluate cell efficacy within the body are limited. Traditional genetic labeling tools, such as GFP-like fluorescent proteins (eGFP, DsRed, mCherry), have limited penetration depths in vivo due to tissue scattering and absorption. To circumvent these limitations, a near-infrared fluorescent mutant of the DrBphP bacteriophytochrome from Deinococcus radiodurans, IFP1.4, was developed for in vivo imaging, but it has yet to be used for in vivo stem/progenitor cell tracking. In this study, we incorporated IFP1.4 into mouse cardiac progenitor cells (CPCs) by a lentiviral vector. Live IFP1.4-labeled CPCs were imaged by their near-infrared fluorescence (NIRF) using an Odyssey scanner following overnight incubation with biliverdin. A significant linear correlation was observed between the amount of cells and NIRF signal intensity in in vitro studies. Lentiviral mediated IFP1.4 gene labeling is stable, and does not impact the apoptosis and cardiac differentiation of CPC. To assess efficacy of our model for engrafted cells in vivo, IFP1.4-labeled CPCs were intramyocardially injected into infarcted hearts. NIRF signals were collected at 1-day, 7-days, and 14-days post-injection using the Kodak in vivo multispectral imaging system. Strong NIRF signals from engrafted cells were imaged 1 day after injection. At 1 week after injection, 70% of the NIRF signal was lost when compared to the intensity of the day 1 signal. The data collected 2 weeks following transplantation showed an 88% decrease when compared to day 1. Our studies have shown that IFP1.4 gene labeling can be used to track the viability of transplanted cells in vivo.
authors.affiliation: Department of Cardiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, China; Department of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Chen
authors.affiliation: Keck Graduate Institute, Claremont, California, United States of America.
authors.forename: M Ian
authors.initials: MI
authors.lastname: Phillips
authors.affiliation: Affiliated Hospital of Guangdong Medical College, Zhanjiang, China.
authors.forename: Hui-Lai
authors.initials: HL
authors.lastname: Miao
authors.affiliation: Affiliated Hospital of Guangdong Medical College, Zhanjiang, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Zeng
authors.affiliation: Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
authors.forename: Gangjian
authors.initials: G
authors.lastname: Qin
authors.affiliation: Vascular Biology Center, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Il-man
authors.initials: IM
authors.lastname: Kim
authors.affiliation: Department of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America; Vascular Biology Center, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Neal L
authors.initials: NL
authors.lastname: Weintraub
authors.affiliation: Department of Medicine, University of Cincinnati, Cincinnati, Ohio, United States of America; Vascular Biology Center, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia, United States of America.
authors.forename: Yaoliang
authors.initials: Y
authors.lastname: Tang
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D034301:Deinococcus; D016086:Lentivirus; D008164:Luminescent Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D017202:Myocardial Ischemia / Q000378:metabolism* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000378:metabolism* / Q000473:pathology; D014161:Transduction, Genetic
chemical_list: D001426:Bacterial Proteins; D008164:Luminescent Proteins