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.
Highlights
Recent studies show that stem/progenitor cells may regenerate cardiac tissue directly by inducing neovasculogenesis and cardiogenesis [1]
We found that the IFP1.4-labeled cardiac progenitor cells (CPCs) can be readily detected in the infarcted hearts noninvasively in vivo after biliverdin injection
Phenotypic Characterization of CPC Cells CPC cells were obtained with a 2-step procedure
Summary
Recent studies show that stem/progenitor cells may regenerate cardiac tissue directly by inducing neovasculogenesis and cardiogenesis [1]. Proteins with excitation and emission maxima within a near-infrared window from ,650 nm to 900 nm can be used for in vivo imaging as they have lower absorbance and scattering in tissues [11,12]. Tsien and his colleagues [13] developed nearinfrared fluorescent protein (IFP) from the DrBphP bacterial phytochrome of Deinococcus radiodurans. They discovered a mutant form named IFP1.4, to be powerful for in vivo imaging of adenovirus infected mammalian liver. Yu D and his colleagues [13] recently used IFP labeling to image brain tumor in mice, and show promise in the application of IFPs for protein labelling and in vivo imaging
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
