RESUMEN
Genetically modified natural killer (NK) cells that recognize tumor-associated surface antigens have recently shown promise as a novel approach for cancer immunotherapy. To determine NK cell therapy response early, a real-time, noninvasive method to quantify NK cell homing to the tumor is desirable. The purpose of this study was to evaluate if MR imaging could provide a noninvasive, in vivo diagnosis of NK cell accumulation in epithelial cell adhesion molecule (EpCAM)-positive prostate cancers in a rat xenograft model. Genetically engineered NK-92-scFv(MOC31)-ζ cells, which express a chimeric antigen receptor specific to the tumor-associated EpCAM antigen, and nontargeted NK-92 cells were labeled with superparamagnetic particles of iron-oxides (SPIO) ferumoxides. Twelve athymic rats with implanted EpCAM positive DU145 prostate cancers received intravenous injections of 1.5×10(7) SPIO labeled NK-92 and NK-92-scFv(MOC31)-ζ cells. EpCAM-positive prostate cancers demonstrated a progressive and a significant decline in contrast-to-noise-ratio data at 1 and 24 h after injection of SPIO-labeled NK-92-scFv(MOC31)-ζ cells. Conversely, tumor contrast-to-noise-ratio data did not change significantly after injection of SPIO-labeled parental NK-92 cells. Histopathology confirmed an accumulation of the genetically engineered NK-92-scFv(MOC31)-ζ cells in prostate cancers. Thus, the presence or absence of a tumor accumulation of therapeutic NK cells can be monitored with cellular MR imaging. EpCAM-directed, SPIO labeled NK-92-scFv(MOC31)-ζ cells accumulate in EpCAM-positive prostate cancers.
Asunto(s)
Rastreo Celular/métodos , Inmunoterapia Adoptiva/métodos , Células Asesinas Naturales/patología , Células Asesinas Naturales/trasplante , Imagen por Resonancia Magnética/métodos , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/cirugía , Animales , Línea Celular Tumoral , Masculino , Pronóstico , Ratas , Ratas Desnudas , Coloración y Etiquetado/métodos , Resultado del TratamientoRESUMEN
The purpose of this study was to track fluorophore-labeled, tumor-targeted natural killer (NK) cells to human prostate cancer xenografts with optical imaging (OI). NK-92-scFv(MOC31)-zeta cells targeted to the epithelial cell adhesion molecule (EpCAM) antigen on prostate cancer cells and nontargeted NK-92 parental cells were labeled with the near-infrared dye DiD (1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine). The fluorescence, viability, and cytotoxicity of the labeled cells were evaluated. Subsequently, 12 athymic rats with prostate cancer xenografts underwent OI scans before and up to 24 hours postinjection of DiD-labeled parental NK-92 cells or NK-92-scFv(MOC31)-zeta cells. The tumor fluorescence intensity was measured and compared between pre- and postinjection scans and between both groups using t-tests. OI data were confirmed with fluorescence microscopy. In vitro studies demonstrated a significant increase in the fluorescence of labeled cells compared with unlabeled controls, which persisted over a period of 24 hours without any significant change in the viability. In vivo studies demonstrated a significant increase in tumor fluorescence at 24 hours postinjection of tumor-targeted NK-92-scFv(MOC31)-zeta cells but not parental NK cells. Ex vivo OI scans and fluorescence microscopy confirmed a specific accumulation of NK-92-scFv(MOC31)-zeta cells but not parental NK cells in the tumors. Tumor-targeted NK-92-scFv(MOC31)-zeta cells could be tracked to prostate cancer xenografts with OI.