A simple method for stem cell labeling with fluorine 18

Hexadecyl-4-[18F]fluorobenzoate ([18F]HFB), a long chain fluorinated benzoic acid ester, was prepared in a one-step synthesis by aromatic nucleophilic substitution of [18F]fluoride ion on hexadecyl-4-(N,N,N-trimethylammonio)benzoate. The radiolabeled ester was obtained in good yields (52% decay corrected) and high purity (97%). [18F]HFB was used to radiolabel rat mesenchymal stem cells (MSCs) by absorption into cell membranes. MicroPET imaging of [18F]HFB-labeled MSCs following intravenous injection into the rat showed the expected high and persistent accumulation of radioactivity in the lungs. [18F]HFB is thus simple to prepare and uses labeling agent for short-term distribution studies of injected stem cells.