Scintigraphic imaging and increment in mice survival using theranostic liposomes based on Gadolinium-159

Theranostic nanosystems have attracted the attention of many scientists in worldwide due to its ability to accumulate and release selectively, in specific sites, compounds capable to generate images and to treat tumors, allowing simultaneously, the diagnose and treatment of cancer. Radioactive Gadolinium-159, a beta e gamma radiation emitter, has the properties to generate scintigraphic images and simultaneously, to conduct cancer cells to the death through high radiation doses. In this sense, the purpose of this study was to prepare PEG-coated and folate-PEG-coated long-circulating and pH-sensitive liposomes loaded with 159Gd, and to evaluate the feasibility of these systems as theranostic probes in tumor-bearing mice. Liposomes were prepared by loading 159Gd and Poly-l-Lysine, with a mean diameter of 120 nm in a monodisperse formulation. Scintigraphic images performed in Ehrlich tumor-bearing mice indicated that folate-coated liposome accumulation was more than 3-times higher than liposomes with no coating. Animals also showed higher survival rates when treated with folate-coated liposomes loaded with 159Gd. Therefore, 159Gd-FTSpHL improved the survival of the animals and showed higher tumor uptake, indicating that 159Gd-FTSpHL possesses potential applications as a theranostic probe.

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