Imaging gene expression in human mesenchymal stem cells: From small to large animals

Jürgen K. Willmann, Ramasamy Paulmurugan, Martin Rodriguez-Porcel, William Stein, Todd J. Brinton, Andrew J. Connolly, Carsten H. Nielsen, Amelie M. Lutz, Jennifer Lyons, Fumiaki Ikeno, Yoriyasu Suzuki, Jarrett Rosenberg, Ian Y. Chen, Joseph C. Wu, Alan C. Yeung, Paul Yock, Robert C. Robbins, Sanjiv S. Gambhir

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71 Scopus citations

Abstract

Purpose: To evaluate the feasibility of reporter gene imaging in implanted human mesenchymal stem cells (MSCs) in porcine myocardium by using clinical positron emission tomography (PET)-computed tomography (CT) scanning. Materials and Methods: Animal protocols were approved by the Institutional Administrative Panel on Laboratory Animal Care. Transduction of human MSCs by using different doses of adenovirus that contained a cytomegalovirus (CMV) promoter driving the mutant herpes simplex virus type 1 thymidine kinase reporter gene (Ad-CMV-HSV1-sr39tk) was characterized in a cell culture. A total of 2.25 × 106 transduced (n = 5) and control nontransduced (n = 5) human MSCs were injected into the myocardium of 10 rats, and reporter gene expression in human MSCs was visualized with micro-PET by using the radiotracer 9-(4-[fluorine 18]-fluoro-3-hydroxymethylbutyl)-guanine (FHBG). Different numbers of transduced human MSCs suspended in either phosphate-buffered saline (PBS) (n = 4) or matrigel (n = 5) were injected into the myocardium of nine swine, and gene expression was visualized with a clinical PET-CT. For analysis of cell culture experiments, linear regression analyses combined with a t test were performed. To test differences in radiotracer uptake between injected and remote myocardium in both rats and swine, one-sided paired Wilcoxon tests were performed. In swine experiments, a linear regression of radiotracer uptake ratio on the number of injected transduced human MSCs was performed. Results: In cell culture, there was a viral dose-dependent increase of gene expression and FHBG accumulation in human MSCs. Human MSC viability was 96.7% (multiplicity of infection, 250). Cardiac FHBG uptake in rats was significantly elevated (P < .0001) after human MSC injection (0.0054% injected dose [ID]/g ± 0.0007 [standard deviation]) compared with that in the remote myocardium (0.0003% ID/g ± 0.0001). In swine, myocardial radiotracer uptake was not elevated after injection of up to 100 × 106 human MSCs (PBS group). In the matrigel group, signal-to-background ratio increased to 1.87 after injection of 100 × 106 human MSCs and positively correlated (R2 = 0.97, P < .001) with the number of administered human MSCs. Conclusion: Reporter gene imaging in human MSCs can be translated to large animals. The study highlights the importance of co-administering a "scaffold" for increasing intramyocardial retention of human MSCs.

Original languageEnglish (US)
Pages (from-to)117-127
Number of pages11
JournalRadiology
Volume252
Issue number1
DOIs
StatePublished - Jul 1 2009

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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    Willmann, J. K., Paulmurugan, R., Rodriguez-Porcel, M., Stein, W., Brinton, T. J., Connolly, A. J., Nielsen, C. H., Lutz, A. M., Lyons, J., Ikeno, F., Suzuki, Y., Rosenberg, J., Chen, I. Y., Wu, J. C., Yeung, A. C., Yock, P., Robbins, R. C., & Gambhir, S. S. (2009). Imaging gene expression in human mesenchymal stem cells: From small to large animals. Radiology, 252(1), 117-127. https://doi.org/10.1148/radiol.2513081616