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Tracking the fate of stem cell implants with fluorine-19 MRI.

Gaudet JM, Ribot EJ, Chen Y, Gilbert KM, Foster PJ - PLoS ONE (2015)

Bottom Line: The 19F signal decreased over time in both models, with a more rapid decrease in the syngeneic model.In the xenograft model, all mice had detectable signal at endpoint.However, in certain circumstances the transfer of cellular label to other bystander cells may confuse interpretation of the long-term fate of the transplanted cells.

View Article: PubMed Central - PubMed

Affiliation: Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada; Department of Medical Biophysics, University of Western Ontario, London, ON, Canada.

ABSTRACT

Background: In this study we used cellular magnetic resonance imaging (MRI) to detect mesenchymal stem cells (MSC) labeled with a Fluorine-19 (19F) agent. 19F-MRI offers unambiguous detection and in vivo quantification of labeled cells.

Methods: We investigated two common stem cell transplant mouse models: an immune competent, syngeneic transplant model and an immune compromised, xenograft transplant model. 19F labelled stem cells were implanted intramuscularly into the hindlimb of healthy mice. The transplant was then monitored for up to 17 days using 19F-MRI, after which the tissue was excised for fluorescence microscopy and immunohistochemisty.

Results: Immediately following transplantation, 19F-MRI quantification correlated very well with the expected cell number in both models. The 19F signal decreased over time in both models, with a more rapid decrease in the syngeneic model. By endpoint, only 2/7 syngeneic mice had any detectable 19F signal. In the xenograft model, all mice had detectable signal at endpoint. Fluorescence microscopy and immunohistochemistry were used to show that the 19F signal was related to the presence of bystander labeled macrophages, and not original MSC.

Conclusions: Our results show that 19F-MRI is an excellent tool for verifying the delivery of therapeutic cells early after transplantation. However, in certain circumstances the transfer of cellular label to other bystander cells may confuse interpretation of the long-term fate of the transplanted cells.

Show MeSH
Cellular viability and loading with the 19F-agent.(A) Cellular viability was investigated before and after labeling with the 19F-agent, Cell Sense. Although a statistically significant difference was observed in hMSC after labeling, the viability remained high (>80%) in all experiments. There was no significant difference in mMSC viability. (B) Cellular loading was determined by performing NMR on a known number of cells alongside a reference peak with a known number of 19F atoms. We observed variation in cellular loading of both hMSC and mMSC between experiments. However, this variation does not affect in vivo 19F quantification since each transplant was only compared to its specific cellular loading.
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pone.0118544.g001: Cellular viability and loading with the 19F-agent.(A) Cellular viability was investigated before and after labeling with the 19F-agent, Cell Sense. Although a statistically significant difference was observed in hMSC after labeling, the viability remained high (>80%) in all experiments. There was no significant difference in mMSC viability. (B) Cellular loading was determined by performing NMR on a known number of cells alongside a reference peak with a known number of 19F atoms. We observed variation in cellular loading of both hMSC and mMSC between experiments. However, this variation does not affect in vivo 19F quantification since each transplant was only compared to its specific cellular loading.

Mentions: Fig. 1 shows that labeling with the 19F agent did not negatively affect the mMSC cellular viability. The viability of the hMSC was slightly decreased following labeling. Previous work by our group demonstrated that the perfluorocarbon, Cell Sense, did not negatively impact differentiation of labeled hMSC into osteogenic or adipogenic lineages.[19] NMR revealed the cellular loading of 19F varied between experiments and cell types within the range of 8.2x1010 to 2.4x1011 atoms.


Tracking the fate of stem cell implants with fluorine-19 MRI.

Gaudet JM, Ribot EJ, Chen Y, Gilbert KM, Foster PJ - PLoS ONE (2015)

Cellular viability and loading with the 19F-agent.(A) Cellular viability was investigated before and after labeling with the 19F-agent, Cell Sense. Although a statistically significant difference was observed in hMSC after labeling, the viability remained high (>80%) in all experiments. There was no significant difference in mMSC viability. (B) Cellular loading was determined by performing NMR on a known number of cells alongside a reference peak with a known number of 19F atoms. We observed variation in cellular loading of both hMSC and mMSC between experiments. However, this variation does not affect in vivo 19F quantification since each transplant was only compared to its specific cellular loading.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358825&req=5

pone.0118544.g001: Cellular viability and loading with the 19F-agent.(A) Cellular viability was investigated before and after labeling with the 19F-agent, Cell Sense. Although a statistically significant difference was observed in hMSC after labeling, the viability remained high (>80%) in all experiments. There was no significant difference in mMSC viability. (B) Cellular loading was determined by performing NMR on a known number of cells alongside a reference peak with a known number of 19F atoms. We observed variation in cellular loading of both hMSC and mMSC between experiments. However, this variation does not affect in vivo 19F quantification since each transplant was only compared to its specific cellular loading.
Mentions: Fig. 1 shows that labeling with the 19F agent did not negatively affect the mMSC cellular viability. The viability of the hMSC was slightly decreased following labeling. Previous work by our group demonstrated that the perfluorocarbon, Cell Sense, did not negatively impact differentiation of labeled hMSC into osteogenic or adipogenic lineages.[19] NMR revealed the cellular loading of 19F varied between experiments and cell types within the range of 8.2x1010 to 2.4x1011 atoms.

Bottom Line: The 19F signal decreased over time in both models, with a more rapid decrease in the syngeneic model.In the xenograft model, all mice had detectable signal at endpoint.However, in certain circumstances the transfer of cellular label to other bystander cells may confuse interpretation of the long-term fate of the transplanted cells.

View Article: PubMed Central - PubMed

Affiliation: Imaging Research Laboratories, Robarts Research Institute, London, ON, Canada; Department of Medical Biophysics, University of Western Ontario, London, ON, Canada.

ABSTRACT

Background: In this study we used cellular magnetic resonance imaging (MRI) to detect mesenchymal stem cells (MSC) labeled with a Fluorine-19 (19F) agent. 19F-MRI offers unambiguous detection and in vivo quantification of labeled cells.

Methods: We investigated two common stem cell transplant mouse models: an immune competent, syngeneic transplant model and an immune compromised, xenograft transplant model. 19F labelled stem cells were implanted intramuscularly into the hindlimb of healthy mice. The transplant was then monitored for up to 17 days using 19F-MRI, after which the tissue was excised for fluorescence microscopy and immunohistochemisty.

Results: Immediately following transplantation, 19F-MRI quantification correlated very well with the expected cell number in both models. The 19F signal decreased over time in both models, with a more rapid decrease in the syngeneic model. By endpoint, only 2/7 syngeneic mice had any detectable 19F signal. In the xenograft model, all mice had detectable signal at endpoint. Fluorescence microscopy and immunohistochemistry were used to show that the 19F signal was related to the presence of bystander labeled macrophages, and not original MSC.

Conclusions: Our results show that 19F-MRI is an excellent tool for verifying the delivery of therapeutic cells early after transplantation. However, in certain circumstances the transfer of cellular label to other bystander cells may confuse interpretation of the long-term fate of the transplanted cells.

Show MeSH