Ralph Weissleder

My primary research interests lie in the field of in vivo molecular imaging. Specific research interests over the last 10 years have included the development of novel contrast agents for MR, methods to image cell trafficking and homing, imaging of gene expression in vivo and development of novel imaging technologies, in particular different magnetic resonance and optical imaging methods. These basic research interests go hand-in hand with my clinical interests in abdominal and interventional radiology. Specific examples of translational research have included the development of novel monocrystalline iron oxides for MR detection of lymph nodes metastases; the development of enzyme activatable probes for the detection of early cancers by minimally invasive techniques such as laparoscopy; and clinical testing of long circulating polymers for angiogenesis imaging.

One primary research interest has been imaging of gene delivery and gene expression during gene therapy. Since such methods did not exist until very recently, a major focus of my research has been the development, testing and application of different strategies using nuclear, magnetic resonance and optical imaging. Specific examples of engineered proteins and reporters include mutant tyrosinases, GFP fusion proteins, the development of technetium binding proteins, enzyme systems and internalizing receptor such as mutants of the transferrin receptor. In collaboration with colleagues from other departments and institutions many of these reporter systems are now undergoing pre-clinical testing.

Another long standing research interest has been the imaging and tracking of individual cell populations in vivo including stem and progenitor cells. While I discovered methods of superparamagnetic cell labeling over 10 years ago, it has not been until very recently that the use of membrane translocation signals has afforded the much required higher loading capacity of cells. Having the necessary tools at hand, I am now interested in exploring how the localization and retrieval of cell populations in vivo will enable detailed analysis of specific stem cell and organ interactions critical for advancing the therapeutic use of stem cells.