Although the research has only just begun at the newly established In vivo Cellular and Molecular Imaging Centers, or ICMICs, the researchers have jumped in and are covering many cancer research bases. Here are basic descriptions of activities under way at each of the centers.
Massachusetts General Hospital/ Harvard Medical School
At Massachusetts General Hospital/Harvard Medical School, virtually all imaging modalities are being put to the test, including optical near infrared fluorescence imaging and tomographic fluorescence imaging, technologies that are similar to fluorescence microscopy, but allow access --up to 10 centimeters--within animal tissues. "There is no single imaging modality that is uniquely suited to answer all the questions," says Ralph Weissleder, director of the Center for Molecular Imaging Research, and principal investigator (P.I.) of this ICMIC. "It's like in a laboratory--you use a light microscope, a fluorescence microscope, a confocal, and so on. It all depends on the question really." The four primary projects, and the P.I.s are:
- Imaging of specific enzymes in intact tumor environments using smart optical probes; P.I. is Weissleder.
- In vivo imaging of angiogenesis and novel antiangiogenic treatment; P.I. is biochemist Alex Bogdanov.
- In vivo imaging of gene expression using new vectors and imaging marker genes; P.I. is neuroscientist Xandra Breakefield.
- In vivo tracking of progenitor and hematopoietic stem cells; P.I. is hematologist, oncologist David Scadden.
Memorial Sloan-Kettering Cancer Center
The program at MSKCC is centered around three modalities: nuclear, MRI/MRS and optical imaging. "The nuclear component is heavily weighted toward PET, but also SPECT, and some autoradiographyl," according to Ronald G. Blasberg, head of the NeuroOncology PET program and P.I. of this ICMIC. "One of the programs involves magnetic resonance spectroscopy ... to optimize chemotherapy and gene therapy," he offers. "MR spectroscopy is not quite imaging, but it allows you to identify specific molecular species--namely, the active form of a drug--as its concentration develops in the tissue (tumor)." The four primary projects, and their P.I.s, are:
- Imaging of transcriptional activation, post-transcriptional modulation, and specific protein-protein interactions at specific steps of several transduction pathways using reporter transgenes; P.I. is physician-neurobiologist Juri Tjuvajev.
- Pharmacokinetic and molecular imaging for optimizing chemotherapy; P.I. is physician-physicist Jason Koutcher.
- In vivo molecular imaging of the anti-tumor effects of ansamycins; P.I. is physician-biologist Neal Rosen.
- Imaging the expression of the androgen receptor gene in various stages of prostate cancer to detect disease progression and response in human patients; P.I. is physician Steven M. Larson, chief of nuclear medicine service.
University of California, Los Angeles
At the University of California, Los Angeles, the modality of choice is PET, although some optical imaging instruments are being put to use because the technology is inherently more affordable to use. Since PET's co-developer Michael E. Phelps is ensconced at UCLA, however, "we are known for PET and now MicroPET," says Harvey R. Herschman, director of basic research at the Jonsson Comprehensive Cancer Center. "MicroPET, the small animal imaging technology, which has been functional since 1997 and recently was commercialized, gives us incredible resolution for our studies in mouse models." The four primary projects, and their P.I.s, are:
- Imaging the path of the adenovirus infection in gene therapy and redirection of Therapeutic viruses, in collaboration with the University of Alabama; P.I. is Herschman.
- Imaging angiogenesis induced by tumors in living animals and using reporter systems to view the expression of the genes necessary for the growth of new blood vessels; P.I. is Gambhir.
- Imaging gene therapy on prostate tumor cells; P.I. is cancer physician Charles Sawyers, director of the prostate cancer program at the Jonsson Center
- Imaging tumor suppressor genes via a novel system using reporter genes to look at the inactivation of tumor suppressor genes and the initiation of the progression of tumors in model animal systems; P.I. is physician-biologist Hong Wu .