Cellular therapy is rapidly expanding within modern medicine; with numerous applications in both regenerative medicine and immunotherapy. Treatment relies on the specialization and modification of cells in vitro, which are administered into a patient to treat a specific target. While experimental results have shown that cellular therapy can be successful, the field has struggled to produce consistent clinical results. One barrier arises in that it can take months before diagnostic feedback and if the cells are providing any therapeutic benefit.

With Magnetic Particle Imaging, cell tracking reveals the in vivo fate of these therapeutic cells.
MPI provides a non-invasive and quantitative window to:
  • Validate dose administration
  • Visualize location
  • Assess the ongoing status of the treatment
By tagging therapeutic cells with iron oxide tracers prior to administration, MPI will give a full understanding of cell biodistribution and retention. A combination of high sensitivity to the tracer and lack of tissue attenuation means as few as 250 cells can be detected after injection.

Clinically approved iron tracers are already available, and they have been shown to not influence cell viability or functionality1.

Tracking & detection
down to a few
hundred cells


Inflammatory cells such as macrophages and monocytes can be tracked to localize regions of inflammation in situ. This can be accomplished by pre-loading therapeutic cells or allowing inflammatory cells to load particles in situ, by presenting particles in the blood volume. Non-invasive immune cell tracking with MPI enables researchers to obtain more data on the success of therapy and expedites the clinical translation pathway2,3.

Ideal for:
  • Macrophages and monocytes to detect inflammation
  • CAR-T and T-cell delivery and retention to the tumor
  • APC (Dendritic cells and B-cell) migration to the lymph node

MPI is highly quantitative, allowing for accurate measurement of the number of cells present in a region.

MPI signal from a titration of pelleted macrophage cells from 1K – 1M cells.

25K RAW264.7 cells (macrophages) administered intracranially and imaged with MPI.
Iron loaded cells infiltrating a tumor are visualized ex vivo with the Perls Prussian blue (PPB) stain.

Regenerative Medicine

The restorative effects of regenerative medicine rely on the arrival and survival of therapeutic stem cells at the targeted destination. The underlying behavior of these cells can be obtained by tracking the stem cells with MPI. Imaging of nanoparticle tagged stem cells prior to administration can assess the biodistribution of the cells after delivery, ensuring the required number of stem cells reach and are retained in the target tissue4-8.

Ideal for:
  • Measuring changes in stem cell grafts over time
  • Ensuring delivery of cells to the correct tissues
  • Improving understanding of transplant rejection and graft versus host disease
  1. Song et al. Janus Iron Oxides @ Semiconducting Polymer Nanoparticle Tracer for Cell Tracking by Magnetic Particle Imaging. Nano Lett. 2018; 182-189.
  2. Zhou et al. Magnetic particle imaging for radiation-free, sensitive and high-contrast vascular imaging and cell tracking. Current opinion in chemical biology 2018; 45: 131–138.
  3. Gaudet et al. Imaging Cancer Immunology: Tracking Immune Cells in vivo with Magnetic Particle Imaging. J Immunol. 2019;202(1): 130-7.
  4. Zheng et al. Magnetic particle imaging tracks the long-term fate of in vivo neural cell implants with high image contrast. Sci Rep. 2015; 5: 14055.
  5. Zheng et al. Quantitative magnetic particle imaging monitors the transplantation, biodistribution, and clearance of stem cells in vivoTheranostics. 2016; 6(3): 291-301.
  6. Nejadnik et al. Ferumoxytol can be used for quantitative magnetic particle imaging of transplanted stem cells. Mol Imaging Biol. 2019;21(3): 465-472.
  7. Lemaster et al. A trimodal contrast agent for stem cell tracking combining ultrasound, photoacoustics, and magnetic particle imaging (Conference Presentation). Reporters, Markers, Dyes, Nanoparticles, and Molecular Probes for Biomedical Applications XI. Vol. 10893. International Society for Optics and Photonics. 2019.
  8. Wang et al. Magnetic particle imaging of islet transplantation in the liver and under the kidney capsule in mouse models. Quant Imaging Med Surg. 2018;8(2): 114-122.