Thiophene-based compounds as fluorescent tags to study Mesenchymal Stem Cells uptake and release of taxanes.

Bioconjugate chemistry

PubMedID: 24628247

Duchi S, Dambruoso P, Martella E, Sotgiu G, Guerrini A, Lucarelli E, Pessina A, Coccè V, Bonomi A, Varchi G. Thiophene-based compounds as fluorescent tags to study Mesenchymal Stem Cells uptake and release of taxanes. Bioconjug Chem. 2014;.
Human Mesenchymal stromal cells (hMSC) are multipotent cells that display among different features the unique ability to home and engraft in tumor stroma. This remarkable tumor tropic property generated a great deal of interest in many clinical settings. Recently, we showed that hMSC represent an excellent base for cell-mediated anticancer therapy since they are able to internalize paclitaxel (PTX) and to release it in an amount sufficient to inhibit tumor cells proliferation. In order to shed light into the dynamics of drug uptake and release, in the present paper we describe the synthesis of two novel thiophene-based fluorophores-paclitaxel conjugates, namely PTX-F32 and PTX-F35, as tools for in vitro drug tracking. We aimed to study the ability of these novel derivatives to be efficiently internalized by hMSC and, in a properly engineered co-culture assay, to be released in the medium and up-taken by tumor cells. In order to ensure a better stability of the conjugates towards enzymatic hydrolysis, the selected oligothiophenes were connected to the taxol core at the C7 position through a carbamate linkage between PTX and the di-amino linker. Antiproliferative experiments on both tumor cells and stromal cells clearly indicate that, in good correlation with the parent compound, cells are sensitive to nM concentrations of the fluorescent conjugates. Moreover, in the co-culture assay we were able to monitor, by fluorescence microscopy, PTX-F32 trafficking from hMSC towards glioblastoma U87 tumor cells. Our work paves the way for novel possibilities to perform extensive and high quality fluorescence-based analysis in order to better understand the cellular mechanisms involved in drugs' trafficking, such as microvescicle/exosome mediated release, in hMSC vehicle cells.