STEM CELL TRACKING: IN VITRO AND IN VIVO APPLICATIONS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To track labeled stem/progenitor adherent cells as they migrate and seed thoughout in-vivo tissue segements. The goals are: - To help determine the best seeding techniques (e.g. either within tissues or via arterial/venus injections) that would allow most adherent stem cells to remain at the injured tissue sites. - To develop unique cell monitoring capabilities, using PET, of in-vivo stem cells. In this process stem cells are pre-labeled with a thimadine kinase (TK) constructs using lenti vector technologies. After cell labeling, the inherent TK cleaves an FHBG PET probe to activate PET signaling. Here, long term investiagations of in-vivo cell migration and aggregation may be analyzed by allowing pre-labeled TK stemcells to adhere inside tissue components over nonspecific time fames - then activate PET signaling prior to image acquisition. - Using negative contrast MRI, we will concurrently (along with PET) monitor in-vivo stem cells as they are seeded within tissues sites. For this imaging modality, unique micro iron particles that include either A)outer dextran coatings, or B)specific receptor-ligand communications (e.g. EpCAM), are used to promote endocytosis of iron particles such that distinctive iron concentrations are located within the cells cytoplasm. This labeling proces is used to disrupt MR signaling and promote negative signal imaging. - To quantify the amount of cells needed to induce tissue repair. - To visualize a stem cell signal of the smallest aggregate size (hopefully single cell suspensions) as they seed themselves inside capillary beds of injured tissues. At present, stem cell therapies assume that seeded cells remain within the tissues of interest. In reality, many cells flow through the damaged tissues and implant themselves inside various capillary beds throughout the body. Improved tacking methods are necessary to visualize the dispersion of cells, to visualize cell aggregate sizes, and to specifically quantify stem cell numbers that remain at the tissue injury sites.