This study investigates a novel approach to tumor destruction using photoimmunotherapy in immunodeficient mice. The method involves the use of an antibody-photosensitizer conjugate and near-infrared radiation to induce necrotic death in tumor cells.
Take an immunodeficient mouse that exhibits tumor growth in the pleura, a double-layered membrane lining the chest cavity.
The engineered tumor cells express the enzyme luciferase.
Intravenously inject an antibody-photosensitizer conjugate, or APC, comprising a tumor antigen-specific antibody bound to a photoabsorber dye.
The control tumor-bearing mouse does not receive the injection.
In the treated mouse, APCs reach the pleural cavity and bind to tumor cell-surface antigens.
Anesthetize the mouse and expose the chest to near-infrared radiation.
Radiation-induced dye photolysis changes the APC shape, inducing stress and increasing transmembrane water flow, resulting in tumor cell bursting and necrotic death.
In the control mouse, tumor cells remain unaffected.
Intraperitoneally inject the bioluminescent substrate luciferin. Upon entering viable tumor cells, luciferin gets oxidized by luciferase, emitting light.
Measure the bioluminescence at predetermined intervals.
A decreased bioluminescence in the treated mouse compared to the increased bioluminescence in the control mouse from tumor growth confirms photoimmunotherapy-mediated tumor destruction.
Before performing near-infrared phototherapy of the tumor-injected mice, use a power meter to measure the light dose of a 690-nanometer wavelength laser, and adjust the output to 100 milliwatts per square centimeter. 24 hours before the treatment, intravenously inject 100 micrograms of antibody photosensitizer conjugate in 50 to 200 microliters of PBS, via the tail vein of the tumor-injected animal.
On the day of the phototherapy treatment, place the anesthetized conjugate injected tumor-laden mouse in the supine position and shield the non-target sites with aluminum foil. When all of the shields have been placed, use a 100 joules per square centimeter laser to irradiate the thoracic cavity with near-infrared light for about 30 seconds. When the irradiation is complete, and the mouse has awoken return the animal to its cage, and measure the bioluminescence daily.
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