Nuclear Medicine & Radiation Therapy

Comparison of 5-Aminolaevulinic Acid and its Heptyl Ester-induced Protoporphyrin IX and its Photobleaching in Human Adenocarcinoma WiDr Cells and in Athymic Nude Mice Healthy Skin

Abstract

Xiao Pudroma and Gongsangduoji

5-aminolevulinic acid heptyl ester (heptyl 5-aminolevulinate), a potential prodrug for fluorescence diagnosis and Photodynamic Therapy (PDT), was investigated in human adenocarcinoma WiDr cells and in healthy skin of athymic nude mice in comparison with 5-aminolevulinic acid (ALA). Incubation of WiDr cells with ALA and ALA heptyl ester resulted in the production of Protoporphyrin IX (PpIX). Concentrations higher than 0.01 mM for ALA heptyl ester and 1 mM for ALA were cytotoxic. Similar amounts of PpIX production and same photobleaching rate were observed in WiDr cells, although a 100 times lower concentration of ALA heptyl ester was needed in comparison with ALA. In contrast to cells culture, topical application of 2% of ALA and ALA heptyl ester gave similar fluorescence of PpIX and PpIX photobleaching in mouse model. But a faster PpIX pbotobleaching was observed in vivo compared to in vitro.