Initiation of apoptosis by photodynamic therapy using a novel positively charged and water-soluble near infra-red photosensitizer and white light irradiation

Stanislaw Schastak, Y. Yafai, W. Geyer, G. Kostenich, A. Orenstein, P. Wiedemann

Research output: Contribution to journalArticlepeer-review

Abstract

Our aim was to investigate the photophysical and photodynamic properties of a new, water-soluble positively charged and chemicaly stable photosensitizer: tetrahydroporphyrin tetratosylat (THPTS). Absorption, fluorescence and 1H NMR spectra and the intracellular distribution of THPTS were measured. The apoptosis in choroidal melanoma cells was measured using cell death detection ELISA and caspase-8 activity assay. THPTS-PDT efficiency was studied in Balb/c mice bearing C26 colon carcinoma. Subcutaneously located tumors were irradiated with a white light source at a fluence rate of 100 mW/cm2. THPTS was administrated 3 h before illumination. The tumoricidal effect was examined 24 h after THPTS-PDT by vital staining with 0.4-ml 1% Evans blue solution, intrapertonially injected to each mouse. THPTS showed a strong absorption band at 760 nm. Its purity, measured by 1H NMR, is better than 99%. At 24-h incubation period, CLSM revealed THPTS fluorescence in mitochondria and cell nucleus. THPTS possesses no toxic effect in preincubated CM cells without irradiation, and THPTS-PDT causes efficient apoptosis. THPTS-PDT using white light irradiation at a dose of 480 J/cm 2 caused necrosis with a depth of 8 mm in subcutaneously located C26 colon carcinoma in Balb/c-mice. In accordance with the present results, the THPTS seems to be of interest for further in vivo investigations with broad-band white light sources.

Original languageEnglish
Pages (from-to)17-23
Number of pages7
JournalMethods and Findings in Experimental and Clinical Pharmacology
Volume30
Issue number1
DOIs
StatePublished - Jan 2008
Externally publishedYes

Keywords

  • BALB/c mice tumor model
  • Choroidal melanoma cell
  • Photodynamic therapy
  • Photosensitizer

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