Abstract
Near-infrared fluorescence (NIRF) imaging by using infrared fluorescent protein (iRFP) gene labelling is a novel technology with potential value for in vivo applications. In this study, we expressed iRFP in mouse cardiac progenitor cells (CPC) by lentiviral vector and demonstrated that the iRFP-labelled CPC (CPCiRFP) can be detected by flow cytometry and fluorescent microscopy. We observed a linear correlation in vitro between cell numbers and infrared signal intensity by using the multiSpectral imaging system. CPCiRFP injected into the non-ischaemic mouse hindlimb were also readily detected by whole-animal NIRF imaging. We then compared iRFP against green fluorescent protein (GFP) for tracking survival of engrafted CPC in mouse ischaemic heart tissue. GFP-labelled CPC (CPCGFP) or CPC labelled with both iRFP and GFP (CPCiRFP GFP) were injected intramyocardially into mouse hearts after infarction. Three days after cell transplantation, a strong NIRF signal was detected in hearts into which CPCiRFP GFP, but not CPCGFP, were transplanted. Furthermore, iRFP fluorescence from engrafted CPCiRFP GFP was detected in tissue sections by confocal microscopy. In conclusion, the iRFP-labelling system provides a valuable molecular imaging tool to track the fate of transplanted progenitor cells in vivo.
Highlights
Cell-based therapy is a promising therapeutic strategy for regeneration of ischaemic and injured tissues
Using infrared fluorescent protein (iRFP) labelling for cell quantification and cell migration assay in vitro We first evaluated the correlation between near-infrared signal and the number of seeded cells
Near-infrared-based fluorescence imaging using iRFP gene labelling is a novel technology with potential utility for in vivo applications
Summary
Cell-based therapy is a promising therapeutic strategy for regeneration of ischaemic and injured tissues. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine Absorption than visible light in most tissues [6, 7] These characteristics suggest that iRFP can overcome the limitations of GFP-like fluorescent proteins for imaging engrafted stem cells in vivo. Lentiviral-iRFP cell labelling technology represents a novel approach for monitoring stem-cell homing and survival in living animals, and cell differentiation/apoptosis ex vivo by histological staining. These findings broaden the application of iRFP systems for stem-cell studies
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