Viability imaging of stem cell using a MRI reporter gene and MEMRI
© Chung et al; licensee BioMed Central Ltd. 2009
Published: 28 January 2009
Embryonic stem cells have demonstrated the potential to restore the myocardium. MRI is an ideal method to evaluate myocardial cell therapy. Superparamagnetic iron oxide nanoparticle (SPIO) has been widely used to monitor stem cell therapy. However, this technique does not provide any biologic information of cell viability.
This novel reporter gene (RG) is designed to express antigenic epitopes on the surface of embryonic stem cell (ESC). Employing SPIO-conjugated monoclonal antibodies, MRI signal specific to hESC viability can be generated. Mn2+ is known to be able to enter viable cells through the voltage gated Ca2+ channel and subsequently can shorten T1 relaxation time generating bright signal on T1 weighted sequence.
MRI RG was constructed driven by EF1α promoter to express c-myc, HA epitopes and firefly luciferase (Luc) on the cell surface. This fusion protein has been designed to be anchored on the cell surface by PDGFR transmembrane domain. Both c-myc and HA epitopes are the molecular targets for MRI viability signal using SPIO conjugated monoclonal antibodies. H9 hESC female line was tranduced with this RG using a p2K7 lentiviral vector. hESC-RG incubated with anti c-myc and HA microbeads were scanned by 3 T MRI using a high array knee coil. For MEMRI, 0.5 mL of 5 mM MnCl2 was injected intraperitoneally after transplanting mESC onto mouse hindlimbs. Mice were scanned using Spin echo sequence by 3 T MRI.
The novel MRI RG enabled viable embryonic stem cells to generate significant molecular MRI signal. In vivo molecular signal of hESC viability will be feasible using this innovative MRI RG. MEMRI enabled in vivo evaluation of viability of stem cells.
This article is published under license to BioMed Central Ltd.