In vivo fluorescence imaging of the transport of charged chlorin e6 conjugates in a rat orthotopic prostate tumour

• Published in: British journal of cancer 1999-09, Vol.81 (2), p.261-268
• Main Authors: Hamblin, M R, Rajadhyaksha, M, Momma, T, Soukos, N S, Hasan, T
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer Research; Drug Resistance; Epidemiology; Male; Medical sciences; Microscopy, Fluorescence; Molecular Medicine; Oncology; Photochemotherapy; Photoradiation therapy and photosensitizing agent; Photosensitizing Agents - pharmacokinetics; Polymers - pharmacokinetics; Porphyrins - pharmacokinetics; Prostatic Neoplasms - blood supply; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Rats; Rats, Sprague-Dawley; regular-article; Treatment with physical agents; Treatment. General aspects; Tumor Cells, Cultured; Tumors
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/sj.bjc.6690686

Summary Polymeric drug conjugates are used in cancer therapy and, varying their molecular size and charge, will affect their in vivo transport and extravasation in tumours. Partitioning between tumour vasculature and tumour tissue will be of particular significance in the case of photosensitizer conjugates used in photodynamic therapy, where this partitioning can lead to different therapeutic effects. Poly-l-lysine chlorin e6 conjugates (derived from polymers of average M r 5000 and 25 000) were prepared both in a cationic state and by poly-succinylation in an anionic state. A fluorescence scanning laser microscope was used to follow the pharmacokinetics of these conjugates in vivo in an orthotopic rat prostate cancer model obtained with MatLyLu cells. Fluorescence was excited with the 454–528 nm group of lines of an argon laser and a 570 nm long pass filter used to isolate the emission. Results showed that the conjugates initially bound to the walls of the vasculature, before extravasating into the tissue, and eventually increasing in fluorescence. The anionic conjugates produced tissue fluorescence faster than the cationic ones, and surprisingly, the larger M r conjugates produced tissue fluorescence faster than the smaller ones with the same charge. These results are consistent with differences in aggregation state between conjugates.