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Magnetically labeled cells can be detected by MR imaging
R Weissleder1, H C Cheng, A Bogdanova
1Department of Radiology, Massachusetts General Hospital, Boston, USA.
Abstract:
To determine the feasibility of MR imaging of magnetically labeled cells, different cell lines were labeled with monocrystalline iron oxide (MION) particles. Phantoms containing MION labeled cells were then assembled and imaged by MR at 1.5 T using T1-weighted and T2-weighted pulse sequences. MION uptake ranged from 8.5 x 10(4) to 2.9 x 10(5) particles/cell for tumor cells (9L and LX1, respectively) to 1.5 x 10(6) to 4.8 x 10(8) particles/cell for "professional phagocytes" (J774 and peritoneal macrophages, respectively). On the T1-weighted images, cell-internalized MION appeared hyperintense relative to agar and similar to MION in aqueous solution. On T2-weighted images, signal intensity varied according to concentration of MION within cells. Cell-internalized MION caused similar MR signal changes of cells as did free MION; however, at a dose that was an order of magnitude lower, depending on the pulse sequence used. The detectability of MION within cells was approximately 2 ng Fe, which corresponded to 10(5) tumor cells/well or 5 x 10(3) macrophages/well. We conclude that a variety of cells can be efficiently labeled with MION by simple incubation. Intracellular labeling may be used for MR imaging of in vivo cell tracking.
Insights
Magnetic iron oxide nanoparticles (MION) can be used to label various cells for MR imaging. This technique allows for sensitive detection of labeled cells, enabling in vivo cell tracking applications.
Area of Science:
- Biomedical Imaging
- Nanotechnology
- Cell Biology
Background:
- Magnetic labeling of cells is crucial for tracking their in vivo behavior.
- Monocrystalline iron oxide (MION) nanoparticles offer potential for cell labeling due to their magnetic properties.
Purpose of the Study:
- To assess the feasibility of using MION for magnetic resonance (MR) imaging of labeled cells.
- To evaluate the detectability and signal characteristics of MION within different cell types.
Main Methods:
- Various cell lines were labeled with MION particles through simple incubation.
- Labeled cell phantoms were imaged using MR at 1.5 T with T1- and T2-weighted pulse sequences.
- MION uptake and MR signal changes were quantified.
Main Results:
- MION uptake varied significantly between tumor cells and phagocytes.
- Cell-internalized MION produced detectable MR signal changes, comparable to free MION but at lower doses.
- The detection limit was approximately 2 ng Fe, corresponding to 10^5 tumor cells or 5x10^3 macrophages.
Conclusions:
- Efficient intracellular labeling of diverse cell types with MION is achievable via simple incubation.
- MION-based cell labeling is a sensitive method for MR imaging.
- This approach holds promise for in vivo cell tracking applications.