Quantitative imaging of a therapeutic peptide in biological tissue sections by MALDI MS.

Therapeutic peptides and proteins are being increasingly explored as potential therapeutic agents for molecular-targeted therapy, and the requirement for quantitative bioanalytical tools for such molecules has been discussed. The distribution of octreotide, a synthetic octapeptide analog of somatostatin, in the liver and kidney of mice administered with the analog was clearly visualized by MALDI-Imaging MS (IMS). The developed MALDI-IMS analytical method successfully quantified the amount of octreotide on tissue sections (accuracy was 76-127%) and the 2,5-dihydroxybenzoic acid-based normalization method was effective. The results of this study suggest that MALDI-IMS enables the quantification of an administered therapeutic peptide on biological tissue sections, as well as visualization of the in vivo distribution of the peptide.