This study demonstrates a method for imaging prostate cancer tumors in nude mice using PSMA-specific antibodies conjugated to a radiotracer. The technique allows for the visualization of tumor locations through positron-emission tomography (PET) scanning.
Take prostate cancer cells and inject them subcutaneously into an anesthetized, immunocompromised nude mouse.
The lack of an immune response allows the injected cells to survive and multiply, forming a tumor.
The tumor cells overexpress a prostate-specific membrane antigen or PSMA, a cell-surface protein.
Take PSMA-specific antibodies conjugated to a radiotracer and inject them intravenously into the tail of the tumor-bearing mouse.
Antibodies reach the tumor cells and bind to PSMA, labeling the tumor.
Place the anesthetized mouse in a positron-emission tomography or PET scanner and obtain a scan.
The produced image shows the distribution of the radiotracer, highlighting areas of high antibody uptake, which correspond to the tumor location.
In male athymic nude mice, subcutaneously implant 5 x 106 LNCaP prostate cancer cells, allowing these to grow to a 100 to 150 millimeter-cubed xenograft. Three to four weeks after inoculation, the tumors should be ready.
For imaging, dilute the 89Zr-DFO-J591 radio immunoconjugate to a concentration of 1 millicuries per milliliter in 0.9% sterile saline. Next, inject 200 microliters of the 89Zr-DFO-J591 solution into the lateral tail vein of the xenograft-bearing mice.
At the desired imaging time point, anesthetize the mouse with a 2% isoflurane:oxygen gas mixture. Place the mouse on a small animal PET scanner bed. Verify anesthesia using the toe-pinch method, and apply veterinary ointment to the eyes of the mouse to prevent drying during anesthesia.
Maintain anesthesia during the scan using a 1% isoflurane:oxygen gas mixture. Following this, acquire the PET data for the mouse via static scan with a minimum of 40 million coincident events using an energy window of 350 to 700 kiloelectron volts and a coincidence timing window of six nanoseconds.
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