[Status and perspectives of non invasive cell tracking]

The interaction of different cells is an important regulator in the development of many diseases, including cancer. Some cells are recruited directly from the local tissue environment, others reach the pathological focus via the circulation. Using non-invasive cell tracking methods, the distribution and migration of labeled cells can be studied in experimental animal models, and the role of these cells on the pathogenesis of disease can thus be elucidated. Scintigraphy and SPECT, and especially MRI and optical imaging, are frequently used for this purpose. Studies are mostly performed with macrophages and granulocytes (inflammatory cells), which accumulate in nephritis, encephalitis, and tumors. At present, the understanding of progenitor cell migration and differentiation is gaining increasing interest in neurological disorders (for example Parkinson's disease) and in cardiac diseases (for example myocardial infarction). Non-invasive cell tracking is already established in basic research; in the future, a clinical application of cell tracking is foreseeable in the framework of cell therapy.