Noninvasive PET Imaging and Tracking of Engineered Human Muscle Precursor Cells for Skeletal Muscle Tissue Engineering

摘要

id="p-2">Transplantation of human muscle precursor cells (hMPCs) is envisioned for the treatment of various muscle diseases. However, a feasible noninvasive tool to monitor cell survival, migration, and integration into the host tissue is still missing. >Methods: In this study, we designed an adenoviral delivery system to genetically modify hMPCs to express a signaling-deficient form of human dopamine D₂ receptor (hD2R). The gene expression levels of the receptor were evaluated by reverse transcriptase polymerase chain reaction, and infection efficiency was evaluated by fluorescent microscopy. The viability, proliferation, and differentiation capacity of the transduced cells, as well as their myogenic phenotype, were determined by flow cytometry analysis and fluorescent microscopy. 18F-fallypride and 18F-fluoromisonidazole, two well-established PET radioligands, were assessed for their potential to image engineered hMPCs in a mouse model and their uptakes were evaluated at different time points after cell inoculation in vivo. Biodistribution studies, autoradiography, and PET experiments were performed to determine the extent of signal specificity. To address feasibility for tracking hMPCs in an in vivo model, the safety of the adenoviral gene delivery was evaluated. Finally, the harvested tissues were histologically examined to determine whether survival of the transplanted cells was sustained at different time points. >Results: Adenoviral gene delivery was shown to be safe, with no detrimental effects on the primary human cells. The viability, proliferation, and differentiation capacity of the transduced cells were confirmed, and flow cytometry analysis and fluorescent microscopy showed that their myogenic phenotype was sustained. 18F-fallypride and 18F-fluoromisonidazole were successfully synthesized. Specific binding of 18F-fallypride to hD2R hMPCs was demonstrated in vitro and in vivo. Furthermore, the 18F-fluoromisonidazole signal was high at the early stages. Finally, sustained survival of the transplanted cells at different time points was confirmed histologically, with formation of muscle tissue at the site of injection. >Conclusion: Our proposed use of a signaling-deficient hD2R as a potent reporter for in vivo hMPC PET tracking by 18F-fallypride is a significant step toward potential noninvasive tracking of hD2R hMPCs and bioengineered muscle tissues in the clinic.