Bioconjugate Chemistry
Communication
much weaker compared to those at time 0. These data confirm
that PTX-F32 has been released from hMSC in the medium
and taken up by tumor cells. The same experiment performed
with PTX-F35 loaded hMSC revealed that the compound is
not completely released by the host cells within 24 h (Figure
4B). Right after incubation, hMSC start to suffer and detach,
being unable to efficiently transfer the drug to U87-RFP cells
that in turn are motile, proliferative, and only slightly
fluorescent (Figure 4B). In order to verify that this behavior
was not caused by the higher potency of PTX-F35 compared to
PTX-F32 (Table S1), we decided to repeat the experiment
using a lower concentration of PTX-F35 (e.g., 2 μM instead of
4 μM). However, even under these conditions PTX-F35 was
only barely able to cross over the medium to reach U87-RFP
cells, which after 24 h were faintly stained displaying only
weakly compromised morphology (Figure S6).
In summary, we described the synthesis of novel thiophene
based fluorophore−paclitaxel conjugates as promising tools for
in vitro drug tracking. We demonstrated that such compounds
could be effectively internalized in several cell lines. Further, in
the case of PTX-F32, we were able to monitor, by fluorescence
microscopy, the fluorescent taxane trafficking from hMSC
toward tumor cells. The different behavior of PTX-F35 loaded
hMSC co-cultured with U87 cells could be ascribed either to a
different mechanism of action or, more likely, to the specific
nature of the thiophene fluorophore that might induce
aggregate formation through π-stacking interactions. However,
the high tunability of these fluorophores in terms of chemical
and photochemical properties, paves the way to future
investigations in the field. In view of the high expectations of
hMSC use as drug carriers, our work suggests a novel possibility
to perform extensive and high quality fluorescence-based
analysis to better understand the cellular mechanisms involved
in drug trafficking, such as microvescicle/exosome mediated
release.22
REFERENCES
■
(1) Caplan, A. I. (2007) Adult mesenchymal stem cells for tissue
engineering versus regenerative medicine. J. Cell. Physiol. 213, 341−7.
(2) Gao, Z., Zhang, L., Hu, J., and Sun, Y. (2013) Mesenchymal stem
cells: a potential targeted-delivery vehicle for anti-cancer drug, loaded
nanoparticles. Nanomedicine 9, 174−84.
(3) Studeny, M., Marini, F. C., Champlin, R. E., Zompetta, C., Fidler,
I. J., and Andreeff, M. (2002) Bone marrow-derived mesenchymal
stem cells as vehicles for interferon-beta delivery into tumors. Cancer
Res. 62, 3603−8.
(4) Kauer, T. M., Figueiredo, J.-L., Hingtgen, S., and Shah, K. (2012)
Encapsulated therapeutic stem cells implanted in the tumor resection
cavity induce cell death in gliomas. Nat. Neurosci. 15, 197−204.
(5) Loebinger, M. R., Eddaoudi, A., Davies, D., and Janes, S. M.
(2009) Mesenchymal stem cell delivery of TRAIL can eliminate
metastatic cancer. Cancer Res. 69, 4134−42.
(6) Gjorgieva, D., Zaidman, N., and Bosnakovski, D. (2013)
Mesenchymal stem cells for anti-cancer drug delivery. Recent Pat.
Anticancer Drug Discovery 8, 310−318.
(7) Duchi, S., Sotgiu, G., Lucarelli, E., Ballestri, M., Dozza, B., Santi,
S., Guerrini, A., Dambruoso, P., Giannini, S., Donati, D., and Varchi, G.
(2013) Mesenchymal stem cells as delivery vehicle of porphyrin
loaded nanoparticles: Effective photoinduced in vitro killing of
osteosarcoma. J. Controlled Release 168, 225−237.
(8) Pessina, A., Bonomi, A., Cocce,
Cavicchini, L., Sisto, F., Ferrari, M., Vigano,
E., Cappelletti, G., Cartelli, D., Arnaldo, C., Parati, E., Marfia, G.,
Pallini, R., Falchetti, M. L., and Alessandri, G. (2011) Mesenchymal
stromal cells primed with paclitaxel provide a new approach for cancer
therapy. PLoS One 6, e28321.
̀
V., Invernici, G., Navone, S.,
L., Locatelli, A., Ciusani,
̀
(9) Nicolaou, K. C., and Valiulin, R. A. (2013) Synthesis and
biological evaluation of new paclitaxel analogs and discovery of potent
antitumor agents. Org. Biomol. Chem. 11, 4154−63.
(10) Gropeanu, R. A., Baumann, H., Ritz, S., Mailander, V., Surrey,
T., and Del Campo, A. (2012) Phototriggerable 2′,7-caged paclitaxel.
PLoS One 7, e43657.
̈
(11) Mastropaolo, D., Camerman, a, Luo, Y., Brayer, G. D., and
Camerman, N. (1995) Crystal and molecular structure of paclitaxel
(taxol). Proc. Natl. Acad. Sci. U. S. A. 92, 6920−4.
(12) Fu, Y., Li, S., Zu, Y., Yang, G., Yang, Z., Luo, M., Jiang, S., Wink,
M., and Efferth, T. (2009) Medicinal chemistry of paclitaxel and its
analogues. Curr. Med. Chem. 16, 3966−3985.
(14) Durso, M., Gentili, D., Bettini, C., Zanelli, A., Cavallini, M., De
Angelis, F., Grazia Lobello, M., Biondo, V., Muccini, M., Capelli, R.,
and Melucci, M. (2013) π-Core tailoring for new high performance
thieno(bis)imide based n-type molecular semiconductors. Chem.
Commun. (Camb.) 49, 4298−300.
(15) Oliva, M. M., Casado, J., Raposo, M. M. M., Fonseca, A. M. C.,
Hartmann, H., Hernandez, V., and Lopez Navarrete, J. T. (2006)
́ ́
ASSOCIATED CONTENT
* Supporting Information
■
S
Experimental procedures, spectroscopic data, and copies of
1H/13C NMR of new compounds; additional figures and tables
on biological experiments. This material is available free of
AUTHOR INFORMATION
Corresponding Author
*Phone: +39 0516398283; Fax +39 0516398349; E-mail: greta.
■
Structure-property relationships in push-pull amino/cyanovinyl end-
capped oligothiophenes: quantum chemical and experimental studies.
J. Org. Chem. 71, 7509−20.
(16) Duca, M., Dozza, B., Lucarelli, E., Santi, S., Di Giorgio, A., and
Barbarella, G. (2010) Fluorescent labeling of human mesenchymal
stem cells by thiophene fluorophores conjugated to a lipophilic carrier.
Chem. Commun. (Camb.) 46, 7948−50.
(17) Sotgiu, G., Galeotti, M., Samorí, C., Bongini, A., and Mazzanti,
A. (2011) Push-pull amino succinimidyl ester thiophene-based
fluorescent dyes: synthesis and optical characterization. Chemistry 17,
7947−52.
(18) Zambianchi, M., Barbieri, A., Ventola, A., Favaretto, L., Bettini,
C., Galeotti, M., and Barbarella, G. (2007) Testing oligothiophene
fluorophores under physiological conditions. Preparation and optical
characterization of the conjugates of bovine serum albumin with
oligothiophene N-hydroxysuccinimidyl esters. Bioconjugate Chem. 18,
1004−9.
Author Contributions
S. Duchi, P. Dambruoso, and E. Martella equally contributed to
this work.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Research was supported by Progetto FIRB-Accordi di
programma 2010 COD. RBAP10447, Italian Ministry of Health
(Project IOR-2006-422755), that financed the research fellow-
ship for Elisa Martella and Serena Duchi.
ABBREVIATIONS
PTX, Paclitaxel; hMSC, human Mesenchymal Stem Cell;
Thiophene-based fluorophore, TbF
■
654
dx.doi.org/10.1021/bc5000498 | Bioconjugate Chem. 2014, 25, 649−655