A new bioorthogonal PET reporter gene for cardiac regenerative medicine binding to DTPA-lanthanide complexes
The lack of non-invasive, quantitative methods to track the location and proliferation of transplanted cells hampers the clinical translation of cardiac regenerative therapies. Here, we establish a PET reporter for tracking human induced pluripotent stem cell (hiPSC)-derived cardiac cells across complementary two-dimensional (2D) and three-dimensional (3D) cardiac tissue models. Methods hiPSCs…
The article details the development of a novel non-invasive imaging technique to monitor the behavior of human induced pluripotent stem cell (hiPSC)-derived cardiac cells during cardiac regenerative therapy. This breakthrough could significantly advance clinical translation of these promising treatments.
The team engineered hiPSCs to express a bioorthogonal PET reporter (DTPA-R) using CRISPR-Cas9 technology. This engineered gene specifically binds to radiolabeled DTPA-metal complexes, enabling precise tracking of the transplanted cells. The engineered cells were differentiated into either ventricular progenitors or cardiomyocytes. Researchers evaluated the stability of the reporter expression and its effects on the cells' differentiation and functionality.
In vitro studies showed that DTPA-R expression remained stable throughout the differentiation stages without negatively impacting migration, differentiation, or functional integration of the cells. PET imaging allowed for the specific detection of DTPA-R labeled hiPSC-derived cells in both intact and injured myocardial slices. The amount of detected activity corresponded to cell-equivalent numbers, ranging from 3.2 x 10^6 HVPs to 5.5 x 10^6 CMs.
Interestingly, the study found that PET detectability was strongly influenced by the local concentration and distribution of the reporter-expressing cells. A compact 200 uL source remained clearly detectable for 6 hours, while a more dispersed 1,000 uL source gradually approached background activity, highlighting the importance of activity concentration on PET detectability.
This study establishes a robust bioorthogonal PET reporter gene platform for quantitative imaging of hiPSC-derived cardiac cells, with no adverse effects on the biological parameters studied. This technology could pave the way for future translational and in vivo imaging studies in cardiac regenerative medicine, potentially benefiting other hiPSC-derived cell products beyond cardiac cells as well.
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