Gallery of images.

NewsEtc., April, 1998. Steven Jacques, Oregon Medical Laser Center

This month we emphasize killing cells with photodynamic therapy.

The purposes of this gallery are:

  • to provide images that portray our field of biomedical optics and medical lasers.
  • to point interested viewers toward sites that report their development of optical technologies for medicine.
  • to encourage the many other labs doing research in this field to post some images illustrating their work so that the general surfing audience can view our collective progress.

    Links are provided to the websites and viewers are encouraged to visit the original sites which have more pictures, discussions, references to papers, job opportunities, software, lists of staff, etc.

    Photodynamic therapy (PDT) is a light-activated chemotherapy which uses light to activate a photosensitizing agent that causes oxidative damage to cells. PDT is being used for cancer therapy and is being developed for other therapies such as clearing psoriasis, alleviating arthritis, and destroying virus.

    Rat mammary adenocarcinoma cells (MTF7 cells, derived by Steven Tomosovic, MD Anderson Cancer Center) were incubated in media containing Photofrin. Illumination with blue light elicits red fluorescence which is viewed through a long-pass filter that blocks blue light.
    CLICK HERE to expand figure.

    Accumulation of fluorescent photosensitizer in cancer cells.

    Photosensitizing agents are often fluorescent which allows visualization of how the agent distributes in cells. In this case, Photofrin (trademark, Quadralogic Technologies Inc.) appears as red fluorescence that has accumulated in membranes and mitochondria of cells.
    Univ. of Texas M. D. Anderson Cancer Center
    Prepared by Xian-Yan He and Steven Jacques.

    th_cell1.GIF CLICK HERE to expand figure

    th_cell2.GIF CLICK HERE to expand figure

    th_cell3.GIF CLICK HERE to expand figure

    MTF7 cancer cells were incubated in ALA (delta-aminolevulenic acid, a precursor for porphyrin synthesis) for 20 hrs which caused the cells to accumulate PPIX (protoporphrin IX, the final step in porphyrin synthesis before adding heme in the synthesis of hemoglobin). PPIX is a potent photosensitizer. An argon laser (blue light, 488 nm) was directed down through the microscope to cause activation of the PPIX. These pictures were taken with a cutoff filter blocking the argon laser light and video taped on a recorder. The formation of blebs occured within the first two minutes of irradiation and is attributed to oxidative damage to cell membranes. Figure 1: before activating PPIX. Figure 2: after about 1 minute of blue light activation. Figure 3: after about 2 minutes of blue light activation.

    Killing a cancer cell with PDT

    This sequence of pictures shows a cancer cell being killed with PDT within the first 2 minutes of light activation of the photosensitizer PPIX which has accumulated in the cell after incubation in media with precursor ALA. The PDT causes oxidative damage to cell membranes which yields the membrane "blebs" in Figures 2 and 3.
    Univ. of Texas M. D. Anderson Cancer Center
    Prepared by Kunio Awazu and Steven Jacques.

    April issue
    NewsEtc. Index
    OMLC home page