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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.

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Related in: MedlinePlus

Representative endpoint MRI, fluorescence microscopy, and immunohistochemistry acquired at 10x magnification from both implant models.(A) By day 16, 5/7 immune competent mice had no 19F signal remaining as shown by the representative MRI. The reference tube is marked by “R”. (B) Fluorescence microscopy of the muscle tissue revealed little red fluorescence remaining in the immune competent mice. No GFP+ mMSC were detectable by fluorescence microscopy, suggesting the original mMSC are no longer present. (C) H&E staining reveals the presence of cells at the implant site which correlate well with the remaining 19F red fluorescence. (D) Immunohistochemistry staining of adjacent tissue sections with the anti-F4/80 antibody reveals the presence of a few macrophages at this location in the immune competent model. (E) At endpoint, all immune compromised mice had detectable 19F-MRI signal remaining. (F) We observed more red fluorescence from the 19F-label at the transplant site in the immune compromised mice. (G) Once again, H&E staining in the immune compromised model correlates well with the regions of red fluorescence. (H) Macrophage staining of the immune compromised model reveals many more F4/80 positive cells at the site of implantation. Furthermore, the fluorescence microscopy of neighboring tissue sections reveals that the red fluorescence from the 19F agent is in the same location as the macrophages. Once again, scale bars represent 250μm.
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pone.0118544.g005: Representative endpoint MRI, fluorescence microscopy, and immunohistochemistry acquired at 10x magnification from both implant models.(A) By day 16, 5/7 immune competent mice had no 19F signal remaining as shown by the representative MRI. The reference tube is marked by “R”. (B) Fluorescence microscopy of the muscle tissue revealed little red fluorescence remaining in the immune competent mice. No GFP+ mMSC were detectable by fluorescence microscopy, suggesting the original mMSC are no longer present. (C) H&E staining reveals the presence of cells at the implant site which correlate well with the remaining 19F red fluorescence. (D) Immunohistochemistry staining of adjacent tissue sections with the anti-F4/80 antibody reveals the presence of a few macrophages at this location in the immune competent model. (E) At endpoint, all immune compromised mice had detectable 19F-MRI signal remaining. (F) We observed more red fluorescence from the 19F-label at the transplant site in the immune compromised mice. (G) Once again, H&E staining in the immune compromised model correlates well with the regions of red fluorescence. (H) Macrophage staining of the immune compromised model reveals many more F4/80 positive cells at the site of implantation. Furthermore, the fluorescence microscopy of neighboring tissue sections reveals that the red fluorescence from the 19F agent is in the same location as the macrophages. Once again, scale bars represent 250μm.

Mentions: Fig. 5 shows representative MR image data, H&E, F4/80 immunohistochemistry and fluorescence microscopy obtained at the experimental endpoint. By day 16 post implantation no 19F signal from the mMSC was detectable in 5/7 of the immune competent mice. One of these mice is shown in Fig. 5A where the only 19F signal comes from the reference tube. In contrast, 19F signal was still detectable in all of the immune compromised mice at day 17, an example is shown in Fig. 5E.


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

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

Representative endpoint MRI, fluorescence microscopy, and immunohistochemistry acquired at 10x magnification from both implant models.(A) By day 16, 5/7 immune competent mice had no 19F signal remaining as shown by the representative MRI. The reference tube is marked by “R”. (B) Fluorescence microscopy of the muscle tissue revealed little red fluorescence remaining in the immune competent mice. No GFP+ mMSC were detectable by fluorescence microscopy, suggesting the original mMSC are no longer present. (C) H&E staining reveals the presence of cells at the implant site which correlate well with the remaining 19F red fluorescence. (D) Immunohistochemistry staining of adjacent tissue sections with the anti-F4/80 antibody reveals the presence of a few macrophages at this location in the immune competent model. (E) At endpoint, all immune compromised mice had detectable 19F-MRI signal remaining. (F) We observed more red fluorescence from the 19F-label at the transplant site in the immune compromised mice. (G) Once again, H&E staining in the immune compromised model correlates well with the regions of red fluorescence. (H) Macrophage staining of the immune compromised model reveals many more F4/80 positive cells at the site of implantation. Furthermore, the fluorescence microscopy of neighboring tissue sections reveals that the red fluorescence from the 19F agent is in the same location as the macrophages. Once again, scale bars represent 250μm.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0118544.g005: Representative endpoint MRI, fluorescence microscopy, and immunohistochemistry acquired at 10x magnification from both implant models.(A) By day 16, 5/7 immune competent mice had no 19F signal remaining as shown by the representative MRI. The reference tube is marked by “R”. (B) Fluorescence microscopy of the muscle tissue revealed little red fluorescence remaining in the immune competent mice. No GFP+ mMSC were detectable by fluorescence microscopy, suggesting the original mMSC are no longer present. (C) H&E staining reveals the presence of cells at the implant site which correlate well with the remaining 19F red fluorescence. (D) Immunohistochemistry staining of adjacent tissue sections with the anti-F4/80 antibody reveals the presence of a few macrophages at this location in the immune competent model. (E) At endpoint, all immune compromised mice had detectable 19F-MRI signal remaining. (F) We observed more red fluorescence from the 19F-label at the transplant site in the immune compromised mice. (G) Once again, H&E staining in the immune compromised model correlates well with the regions of red fluorescence. (H) Macrophage staining of the immune compromised model reveals many more F4/80 positive cells at the site of implantation. Furthermore, the fluorescence microscopy of neighboring tissue sections reveals that the red fluorescence from the 19F agent is in the same location as the macrophages. Once again, scale bars represent 250μm.
Mentions: Fig. 5 shows representative MR image data, H&E, F4/80 immunohistochemistry and fluorescence microscopy obtained at the experimental endpoint. By day 16 post implantation no 19F signal from the mMSC was detectable in 5/7 of the immune competent mice. One of these mice is shown in Fig. 5A where the only 19F signal comes from the reference tube. In contrast, 19F signal was still detectable in all of the immune compromised mice at day 17, an example is shown in Fig. 5E.

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
Related in: MedlinePlus