Assessment of photosensitizer dosimetry and tissue damage assay for photodynamic therapy in advanced-stage tumors.

Published

Journal Article

Photodynamic therapy (PDT) efficacy is a complex function of tissue sensitivity, photosensitizer (PS) uptake, tissue oxygen concentration, delivered light dose and some other parameters. To better understand the mechanisms and optimization of PDT treatment, we assessed two techniques for quantifying tissue PS concentration and two methods for quantifying pathological tumor damage. The two methods used to determine tissue PS concentration kinetic were in vivo fluorescence probe and ex vivo chemical extraction. Both methods show that the highest tumor to normal tissue PS uptake ratio appears 4 h after PS administration. Two different histopathologic techniques were used to quantify tumor and normal tissue damage. A planimetry assessment of regional tumor necrosis demonstrated a linear relationship with increasing light dose. However, in large murine tumors this finding was complicated by the presence of significant spontaneous necrosis. A second method (densitometry) assessed cell death by nuclear size and density. With some exceptions the densitometry method generally supported the planimetry results. Although the densitometry method is potentially more accurate, it has greater potential subjectivity. Finally, our research suggests that the tools or methods we are studying for quantifying PS levels and tissue damage are necessary for the understanding of PDT effect and therapeutic ratio in experimental in vivo tumor research.

Full Text

Duke Authors

Cited Authors

  • Sheng, C; Pogue, BW; Wang, E; Hutchins, JE; Hoopes, PJ

Published Date

  • June 2004

Published In

Volume / Issue

  • 79 / 6

Start / End Page

  • 520 - 525

PubMed ID

  • 15291303

Pubmed Central ID

  • 15291303

International Standard Serial Number (ISSN)

  • 0031-8655

Digital Object Identifier (DOI)

  • 10.1562/mu-03-33.1

Language

  • eng

Conference Location

  • United States