Molecular Imaging and Biology

, Volume 13, Issue 5, pp 819–824

On the Use of Micron-Sized Iron Oxide Particles (MPIOS) to Label Resting Monocytes in Bone Marrow

Brief Article

DOI: 10.1007/s11307-010-0437-3

Cite this article as:
Tang, K.S., Hann, B. & Shapiro, E.M. Mol Imaging Biol (2011) 13: 819. doi:10.1007/s11307-010-0437-3

Abstract

Purpose

The use of MRI to monitor immune cell infiltration into various pathologies is well established. In an effort to boost the magnetic material within immune cells, this work attempted to label resting monocytes within bone marrow, in mice, by intravenous administration of micron-sized iron oxide particles (MPIOs), similar in fashion to the administration of (U)SPIO.

Procedures

MPIOs were incubated with various immune cells both in culture, and in whole blood. Flow cytometry and histology were used to analyze magnetic cell labeling. Also, MPIOs were injected intravenously into mice. In vivo, high-resolution 3-D MRI was performed on mouse legs, and signal changes were quantified. Flow cytometry and histology were used to analyze magnetic cell labeling of bone marrow resident cells.

Results

It is demonstrated here that monocytes and neutrophils can indeed endocytose MPIOs both in cell culture and ex vivo in whole blood. However, despite rapid accumulation of MPIOs within the bone marrow following injection, MPIOs did not label monocytes or any other hematopoietic cell type in the marrow. Hypotheses are drawn to explain these results in light of recent usage of MPIOs for immune cell tracking.

Conclusions

Systemic administration of various MPIO formulations showed that MPIOs arrive in bone marrow rapidly following injection and remain there for at least 7 days. Data also shows slow clearance of some particles from the tissue over this period. While MPIOs can efficiently label monocytes in culture and in whole blood ex vivo, they were not found to label bone marrow resident monocytes.

Key words

MRIIron oxideMonocytesBone marrow

Copyright information

© Academy of Molecular Imaging and Society for Molecular Imaging 2010

Authors and Affiliations

  • Kevin S. Tang
    • 2
  • Bradley Hann
    • 2
  • Erik M. Shapiro
    • 1
    • 2
  1. 1.Department of Diagnostic RadiologyYale University School of MedicineNew HavenUSA
  2. 2.Department of Biomedical EngineeringYale University School of MedicineNew HavenUSA