Real-time in vivo monitoring of viable stem cells implanted on biocompatible scaffolds |
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Authors: | Do Won Hwang Sung June Jang Yun Hui Kim Hyun Joo Kim In Kyong Shim Jae Min Jeong June-Key Chung Myung Chul Lee Seung Jin Lee Seung U Kim Soonhag Kim Dong Soo Lee |
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Institution: | Programs in Neuroscience, Seoul National University, Seoul, South Korea. |
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Abstract: | Purpose Three-dimensional fibrous scaffolds provide an environment that enhances transplanted stem cell survival in vivo and facilitates
imaging their localization, viability, and growth in vivo. To assess transplanted stem cell viability on biocompatible polymer
scaffolds in vivo, we developed in vivo imaging systems for evaluation of implanted viable neural stem cells (NSC) and mesenchymal
stem cells (MSC) on scaffolds using luciferase or sodium/iodide symporter (NIS) genes.
Methods Firefly luciferase stably expressing-C6 cell was established (C6-Fluc). The human neural stem cell, F3, was infected with
adenoviral vector carrying luciferase gene (F3-Fluc) and MSC expressing NIS controlled by ubiquitin C promoter using lentiviral
vector was established by treating blasticidine for 2 weeks (MSC-NIS). Chitosan and poly l-lactic acid (PLLA) scaffolds were used for in vivo image. In vivo expression of luciferase and human NIS was examined by
bioluminescence image or 99mTc-pertechnetate gamma camera image, respectively. The cell/scaffold complex was implanted into subcutaneous or abdominal
area of BALB/C nude mouse. For quantitative evaluation of cell viability, regions of interest were drawn on 99mTc-pertechnetate scintigraphy by manual.
Results The gradual increase of luciferase activity was observed in C6-Fluc seeded with chitosan according to the increase in the
number of cells. C6-Fluc/chitosan complex subcutaneously implanted into nude mice showed longitudinal bioluminescence image
until 34 days. Luciferase image of abdominal-injected C6-Fluc/PLLA complex was saturated in only 14 days, showing great cell
growth due to abundant nutrients. F3 cells showed well-incorporated pattern with fibrous chitosan scaffold using scanning
electron microscopy. F3 infected with Ad-Fluc showed >100-fold higher luciferase activity than luciferase activity in F3.
Cell-number-dependent increase of luciferase activity was shown in F3-Fluc seeded on chitosan. F3-Fluc incorporation into
chitosan after abdominal injection was clearly visible on bioluminescence image up to 11 days. Radionuclide imaging showed
higher uptake by MSC-NIS on PLLA scaffolds than by MSC-NIS not seeded on a scaffold. Quantitative data showed significantly
better survival of MSC-NIS on PLLA scaffolds than without scaffold at 72 h post-implantation, which concurred with histologic
findings.
Conclusion These results suggest that NSC-Fluc and MSC-NIS cells incorporated within polymer scaffolds can be monitored on a long-term
basis by serial in vivo imaging. We believe that a biocompatible scaffold-based imaging system could be used to assess stem
cell viabilities in a non-invasive way to aid the development of regenerative therapeutics.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Soonhag Kim and Dong Soo Lee contributed equally to this investigation as corresponding authors and Do Won Hwang and Sung
June Jang equally contributed as co-first author. |
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Keywords: | Polymer scaffold Stem cell imaging Neural stem cell Mesenchymal stem cell Molecular imaging |
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