Anal Sci. 2017;33(2):143-146. doi: 10.2116/analsci.33.143.

Transduction Function of a Magnetic Nanoparticle TMADM for Stem-Cell Imaging with Quantum Dots.

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We have recently developed a novel dextran hydroxypropyltrimethyl ammonium chloride-coated magnetic iron oxide nanoparticle (TMADM-03). TMADM-03 shows efficient labeling of stem cells, and transplanted stem cells labeled with TMADM-03 can be highly detected in mice using a magnetic resonance (MR) imaging technology [1]. In this report, we noted that TMADM-03 serves as a transfection agent for quantum dots (QDs) that expected as a fluorescence probe in stem cell imaging. This finding is very beneficial for bioimaging of transplanted stem cells and thought to be noticed very rapidly.

QDs655 (2 nM) and TMADM-03 (60 mg-Fe/ml) were mixed for 15 min at room temperature, and then added to ASCs in a medium which was regulated for transduction (transduction medium) (DMEM/F12 containing 2% FBS and 100 U/mL penicillin/streptomycin) at 37°C. After 24 h incubation, the ASCs were washed using a flesh transduction medium. Then, the transduction of QDs655 into ASCs were observed by phase-contrast fluorescence microscopy (Fig.1). ASCs incubated with QDs655 only was confirmed to be labeled with QDs655, however the red fluorescence derived from QDs655 was found to be very weak. On the other hand, ASCs incubated with QDs655 using TMADM-03 was confirmed to be labeled with QDs655, and the red fluorescence derived from QDs655 was much stronger than that in QDs655 only labeling. The transduction efficiency and fluorescence intensity of QDs655 in ASCs were analyzed using flow cytometry (Fig. 2).

The transduction efficiencies in QDs655 only and using TMADM-03 conditions transfection were 97.8±1.11% and 99.6±0.10%, respectively (Fig. 2a). On the other hand, the mode of fluorescence intensity of non-labeled ASCs was 2, QDs655 only labeling was 50, and QDs655 using TMADM-03 was 500. The fluorescence intensity of QDs655 in ASCs using TMADM-03 was about seven times higher than that of QDs655 only labeling. These data suggest that more QDs were transduced into ASCs by TMADM-03. Therefore, TMADM-03 could be useful as a transfection agent for QDs (Fig. 2b).

 

 

Figure 1. A: Labeling methods for ASCs by QDs only (a) or QDs-TMADM-03 complexes (b).

 

 

Figure 2. Labeling efficiency (a) of QDs only or QDs-TMADM-03 complexes for ASCs, and fluorescence intensity (b) of ASCs labeled with QDs or QDs-TMADM-03 complexes.

 

 

References

  1. Yukawa H., Nakagawa S., Yoshizumi Y., Watanabe M., Saito H., Miyamoto Y., Noguchi H.,Oishi K., Ono K., Sawada M., Kato I., Onoshima D., Obayashi M., Hayashi Y., Kaji N., Ishikawa T., Hayashi S., Baba Y. Nobel positively charged nanoparticle labeling for in vivo imaging of adipose tissue-derived stem cells. PLoS One, 2014; 9(11): e110142.