engleski

First non-invasive biodistribution study of a 68Ga-Gallium radiolabelled amphipilic cationic porphyrins, potentially useful as PDT agents, by PET-imaging

Amphiphilic porphyrins, usually quaternised to increase hydrosolubility and conjugated with a long alkyl chain to facilitate cell uptake, are being intensively investigated as photosensitizers for photodynamic therapy (PDT)[1]. However, pharmacokinetic profile and in vivo biodistribution of this type of porphyrins is not well studied. Known as good metal chelators, porphyrins can be easily labelled with radiometals allowing a real time monitoring of their biodistribution using positron emission tomography (PET)[2]. PET is functional nuclear imaging technique based on use of biologically active molecules labelled with positron emiting radionuclides, such as 18F- Fluorine or 68Ga-Gallium. An emitted positron undergoes a fast annihilation with an electron, generating in coincidence two almost oposite 511 keV gamma rays detected by a PET camera[3]. 68Ga- Gallium has a short nuclear decay half-life of 68 min, compatible with a biological half-life of fast biodistributing small molecules, and is freely available from 68Ge/68Ga generator[4]. In this work, we designed, synthesised and labelled with 68Ga or natGa-Gallium a group of four tricationic porphyrins carrying variable lenght alkyl chains (C1, C10, C14, C18), and inverstigated their properties, such as lipophilicity (logD), metal chelate stability, and serum and carrier added formulation stability (bovine serum albumin (BSA) and low density lipoprotein (LDL). In vivo biodistribution was studied by PET imaging in a naive mouse model. Studies in a tumour bearing mouse model are on- going.

PET imaging ; amphiphilic porphyrin ; 68Ga radionuclide

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