In Vivo Magnetic Resonance Imaging of CD8+ T Lymphocytes Recruiting to Glioblastoma in Mice

Abstract

Noninvasive in vivo tracking of adopted immune cells would help improve immunotherapy on glioblastoma. In this study, the authors tried to track adoptive CD8+ T lymphocytes in an in situ GL261 glioblastoma mouse model with magnetic resonance imaging (MRI). CD8+ T lymphocytes from spleen of preimmunized GL261 glioblastoma mice were labeled with superparamagnetic iron oxide, with polylysine as transfection agent. From Prussian blue staining, the labeling efficiency was 0.77% ± 0.06%, without altering cell viability and function. From anti-CD8, and anti-dextran staining, superparamagnetic iron oxide could be seen in the cytoplasm. In vitro imaging of agar gel mixtures with different concentrations of labeled CD8+ T lymphocytes was done with a 3.0T MR T2*WI sequence. Higher cell concentrations showed lower signal values. Twenty-four hours after tail vein injection of labeled and unlabeled CD8+ T lymphocytes, imaging of GL261 mice brain showed black spots at the periphery of the tumor in the labeled group only. Brain tumor pathology further verified infiltration of labeled CD8+ T lymphocytes in the tumor. Thus, preimmunized CD8+ T lymphocytes could be efficiently labeled with superparamagnetic iron oxide and tracked both in vitro and in vivo with 3.0T MRI.