title: In vivo imaging of changes in tumor oxygenation during growth and after treatment.
abstract: A novel procedure for in vivo imaging of the oxygen partial pressure (pO2) in implanted tumors is reported. The procedure uses electron paramagnetic resonance imaging (EPRI) of oxygen-sensing nanoprobes embedded in the tumor cells. Unlike existing methods of pO2 quantification, wherein the probes are physically inserted at the time of measurement, the new approach uses cells that are preinternalized (labeled) with the oxygen-sensing probes, which become permanently embedded in the developed tumor. Radiation-induced fibrosarcoma (RIF-1) cells, internalized with nanoprobes of lithium octa-n-butoxy-naphthalocyanine (LiNc-BuO), were allowed to grow as a solid tumor. In vivo imaging of the growing tumor showed a heterogeneous distribution of the spin probe, as well as oxygenation in the tumor volume. The pO2 images obtained after the tumors were exposed to a single dose of 30-Gy X-radiation showed marked redistribution as well as an overall increase in tissue oxygenation, with a maximum increase 6 hr after irradiation. However, larger tumors with a poorly perfused core showed no significant changes in oxygenation. In summary, the use of in vivo EPR technology with embedded oxygen-sensitive nanoprobes enabled noninvasive visualization of dynamic changes in the intracellular pO2 of growing and irradiated tumors.
authors: Center for Biomedical EPR Spectroscopy and Imaging, Ohio State University, Columbus, Ohio, USA.
authors: Anna
authors: A
authors: Bratasz
authors: Ramasamy P
authors: RP
authors: Pandian
authors: Yuanmu
authors: Y
authors: Deng
authors: Sergey
authors: S
authors: Petryakov
authors: John C
authors: JC
authors: Grecula
authors: Nilendu
authors: N
authors: Gupta
authors: Periannan
authors: P
authors: Kuppusamy
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005260:Female; D005354:Fibrosarcoma / Q000378:metabolism* / Q000473:pathology; D008665:Metalloporphyrins; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D010100:Oxygen / Q000378:metabolism*; D010313:Partial Pressure
chemical_list: D008665:Metalloporphyrins; C481390:lithium 5,9,14,18,23,27,32,36-octa-n-butoxy-2,3-naphthocyanine; D010100:Oxygen