Detection of prostaglandin E2-induced dendritic cell migration into the lymph nodes of mice using a 1.5 T clinical MR scanner

Abstract

The control of dendritic cell (DC) migration into lymph nodes (LNs) is important for the development of more effective DC-based immunotherapies. This study was undertaken to evaluate, dynamically and noninvasively, prostaglandin E2 (PGE2)-enhanced migration of DCs using a 1.5 T clinical MR scanner. DC2.4 cells were labeled with superparamagnetic iron oxide (SPIO), a clinically approved MRI contrast agent. DCs were stimulated with tumor necrosis factor-α and interferon-γ in the presence or absence of PGE2. Before and after subcutaneous injection of labeled DCs into the hind leg footpads of mice, MRI detailing the extent of DC migration into popliteal LNs was performed using a 1.5 T clinical MR scanner. SPIO labeling did not influence the viability, endocytic activity, migratory ability and/or co-stimulatory molecule expression of DCs. PGE2 enhanced significantly chemokine receptor-7 expression and the migration of DCs (p < 0.05). After subcutaneous injection of DCs, there were decreases in MR signal intensity in popliteal LNs at 24 h post-injection; in PGE2-treated cells, the MR signal intensity was significantly lower (decrease of 86.6 ± 2.5%) than in PGE2-untreated cells (decrease of 70.0 ± 4.2%) (p < 0.05). Histological analyses with the conventionally used Prussian blue stain demonstrated that the PGE2-treated DCs migrated more deeply into the center of LNs. PGE2-enhanced migration of SPIO-labeled DCs into LNs can be detected using a 1.5 T clinical MR scanner. Our results suggest that in vivo MRI of DC migration is a useful imaging method to predict DC therapy with a high rate of efficacy and to improve DC-based immunotherapy, thereby reducing costs compared with current treatments in clinical trials.