title: Polyamidoamine dendrimer-conjugated quantum dots for efficient labeling of primary cultured mesenchymal stem cells.
abstract: Monitoring of cells in vivo after transplantation could supply important information for determining the efficacy of stem cell therapy. The use of quantum dots (QDs) has several advantages for in vivo imaging, such as remarkable resistance to photo bleaching, high fluorescence efficiency, and size-tunable emission. After they are taken up by cells via endocytosis, QDs lose their fluorescence intensity in endosomes/lysosomes at low pH because the intensity cannot survive under acidic conditions. Moreover, the amount of QD uptake by mesenchymal stem cells (MSCs) is extremely small. Therefore, for effective labeling of MSCs and long observation of MSCs labeled by QDs in vivo, it is essential both to increase cellular uptake of QDs and to promote endosomal escape into the cytosol. The polyamidoamine (PAMAM) dendrimer had plenty of cationic charge, which promoted cellular uptake though electrostatic interactions, and a "buffering capacity," which enhanced endosomal escape into the cytosol. In this study, QDs were modified with PAMAM dendrimer for the efficient labeling of MSCs by QDs. The uptake efficiency and cytosolic distribution of QDs in primary cultured MSCs were increased by the modification of the PAMAM dendrimer. The fluorescence intensity in MSCs labeled by PAMAM dendrimer-conjugated QDs lasted for a longer time in harvested culture plates or in cell-transplanted mice than that in MSCs labeled by non-conjugated QDs.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi, Sakyo-ku, Kyoto 606-8501, Japan. higuchi@pharm.kyoto-u.ac.jp
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Higuchi
authors.forename: Can
authors.initials: C
authors.lastname: Wu
authors.forename: Kai-Ling
authors.initials: KL
authors.lastname: Chang
authors.forename: Kei
authors.initials: K
authors.lastname: Irie
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kawakami
authors.forename: Fumiyoshi
authors.initials: F
authors.lastname: Yamashita
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Hashida
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D002478:Cells, Cultured; D050091:Dendrimers / Q000737:chemistry* / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D008297:Male; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D045663:Quantum Dots
chemical_list: D001672:Biocompatible Materials; D050091:Dendrimers; D005456:Fluorescent Dyes; C104700:PAMAM Starburst