Generation of a Human Induced Pluripotent Stem Cell Line Expressing a Magnetic Resonance Imaging Reporter Gene

The objective of the current study is to develop a new method for tracking transplanted human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) using magnetic resonance imaging (MRI). The CRISPR/dCas9 activation system is employed to overexpress ferritin heavy chain (FHC) in hiPSC-CMs. The mRNA and protein expression of FHC in hiPSC and hiPSC-CMs significantly increased after transfection. Iron chloride does not affect the cell viability in a concentration range from 0 to 2000 µm. hiPSCs overexpressing FHC (hiPSC- FHC^OE) and hiPSC-CMs overexpressing FHC (hiPSC-CM-FHC^OE) significantly enhanced cellular uptake of iron chloride but with no changes in electrophysiological properties compared to hiPSC-CM-Control. Furthermore, hiPSC-CM-FHC^OE presented robust contrast and lower T₂* values, signifying their potential as highly effective candidates for cardiac MRI. Next, hiPSC-CM-FHC^OE is injected into mouse hearts and after 3 days of transplantation, MR images are obtained. hiPSC-CM-FHC^OE cells exhibited clear signals in the hearts with lower T₂* and rapid signal decay. Collectively, data from this proof-of-concept study demonstrated that endogenous labeling with FHC in hiPSC-CMs can be a potent strategy for enhancing the accuracy of cardiac MRI. This technology represents a significant step forward in tracking the transplanted hiPSC-CMs in the hearts of live animals.