Magnetic targeting of adoptively transferred tumour-specific nanoparticle-loaded CD8+ T cells does not improve their tumour infiltration in a mouse model of cancer but promotes the retention of these cells in tumour-draining lymph nodes

Abstract

Background: Adoptive T cell-transfer (ATC) therapy is a highly promising cancer-treatment approach. However, in vivo-administered T cells tend to disperse, with only a small proportion reaching the tumour. To remedy this, magnetic targeting of T cells has been recently explored. Magnetic nanoparticles (MNPs) functionalised with antibodies were attached to effector T cells and magnetically recruited to tumour sites under MRI guidance. In this study, we investigated whether 3-aminopropyl-triethoxysilane (APS)-coated MNPs directly attached to CD8 + T cell membranes could also magnetically target and accumulate tumour-specific CD8 + T cells in solid tumours using an external magnetic field (EMF). As it has been shown that T cells associated with APS-coated MNPs are retained in lymph nodes (LNs), and tumour-draining LNs are the most common sites of solid-tumour metastases, we further evaluated whether magnetic targeting of APS-MNP-loaded CD8 + T cells could cause them to accumulate in tumour-draining LNs. Results: First, we show that antigen-specific CD8 + T cells preserve their antitumor activity in vitro when associated with APS-MNPs. Next, we demonstrate that the application of a magnetic field enhanced the retention of APS-MNPloaded OT-I CD8 + T cells under flow conditions in vitro. Using a syngeneic mouse model, we found similar numbers of APS-MNP-loaded OT-I CD8 + T cells and OT-I CD8 + T cells infiltrating the tumour 14 days after cell transfer. However, when a magnet was placed near the tumour during the transfer of tumour-specific APS-MNP-loaded CD8 + T cells to improve tumour infiltration, a reduced percentage of tumour-specific T cells was found infiltrating the tumour 14 days after cell transfer, which was reflected in a smaller reduction in tumour size compared to tumour-specific CD8 + T cells transferred with or without MNPs in the absence of a magnetic field. Nonetheless, magnet placement near the tumour site during cell transfer induced infiltration of activated tumour-specific CD8 + T cells in tumour-draining LNs, which remained 14 days after cell transfer. Conclusions: The use of an EMF to improve targeting of tumour-specific T cells modified with APS-MNPs reduced the percentage of these cells infiltrating the tumour, but promoted the retention and the persistence of these cells in the tumour-draining LNs.

Loading of Primary Human T Lymphocytes with Citrate-Coated Superparamagnetic Iron Oxide Nanoparticles Does Not Impair Their Activation after Polyclonal Stimulation

“…Both CD4 + and CD8 + T cells showed a higher cell surface expression of Tim-3 after 120 h of stimulation. These data are in line with findings by others who showed that cell surface markers on Jurkat cells, primary murine T cells as well as on antigen-specific OT-1 CD8 + T cells were not altered by magnetic nanoparticle loading [25,66]. Taken together, our results demonstrate that SPION Citrate had only a minor effect on the stimulatory capacity of primary human T cells and might even support the differentiation of naive into central memory T cells.…”

Improving Tumor Retention of Effector Cells in Adoptive Cell Transfer Therapies by Magnetic Targeting

“…Measuring this process can be used as a surrogate for the cytotoxic capacity of NK cells (and cytotoxic T lymphocytes) [141]. We found that MNP treatment increased in a dose-dependent manner the spontaneous degranulation of NK cells [79], but not of CD8 + T cells [77]. The degranulation of MNP-loaded NK cells after stimulation also increased compared to unloaded cells, but this was quantitatively similar to the increase in baseline degranulation levels.…”

“…Among those, interferon (IFN)-γ is one of the most important pro-inflammatory cytokines produced by this type of cell [143]. We and others have reported that MNP treatment did not affect IFN-γ production in human or murine NK cells, as well as CD8 + T cells, in response to various stimuli [77,79,88,95,131]. NK cells have been reported to produce other cytokines and chemokines that modulate immunity, such as IL-5, IL-10 or CCL5 for instance [144][145][146][147].…”

“…We and others have recently demonstrated the feasibility of this approach and analyzed the effects of the combined use of magnetic nanoparticles and the application of an external magnetic field, to promote the accumulation and retention of lymphoid cells [77][78][79][80][81]. The following sections of this review will highlight some of the recent findings on the effects of MNPs on lymphoid cells, their specific targeting through the application of external magnetic fields and the possibility to use this platform to solve some of the limitations such as the low efficiency in lymphocyte trafficking, that some current antitumor immunotherapies present.…”

“…MNP presence on the cell membrane of NK or T cells did not affect the effector cell conjugation capacity to target cells in two-color flow cytometry [77,79]. Since MNP can affect cytoskeleton remodeling [137][138][139][140], we also assessed by confocal microscopy the formation and polarization of the microtubule organizing center (MTOC) in the synapse between primary NK cell and target cells (Figure 4).…”