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Updated: May 26, 2026
In Vitro Assay to Study Tumor-macrophage Interaction
Published on: August 1, 2019
Longitudinal study of tumor-associated macrophages during tumor expansion using MRI
Yen-Yu I Shih1, Yi-Hua Hsu, Timothy Q Duong
1Functional and Micro-Magnetic Resonance Imaging Center, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
Abstract:
MRI is being used increasingly for the noninvasive longitudinal monitoring of cellular processes in various pathophysiological conditions. Macrophages are the main stromal cells in neoplasms and have been suggested to be the major cell type ingesting superparamagnetic iron oxide (SPIO) nanoparticles. However, no MRI study has described longitudinally the presence of tumor-associated macrophages (TAMs) during tumorigenesis with histological confirmation. To address this, we injected SPIO nanoparticles into the circulation of tumor-bearing mice and used MRI and post-mortem histology to monitor TAMs at different time points. The MRI results demonstrated that TAMs, as hypointense signals, appeared continually with the expansion of the tumor. The histological findings also revealed that SPIO-labeled TAMs tended to deposit closer to the vessel lumen with time prior to rapid tumor growth. The present study demonstrates the potential of using MRI to assess longitudinally TAM accumulation during tumorigenesis, and provides the first in vivo insight into the topographical arrangement of TAMs in relation to the progression of tumors. In vivo monitoring of the presence of TAMs could be useful for the development of tumor treatments that target TAM functions.
Insights
This study uses MRI to track tumor-associated macrophages (TAMs) in mice. MRI successfully monitored TAM accumulation during tumor growth, offering insights into their spatial arrangement and potential therapeutic targeting.
Area of Science:
- Biomedical Imaging
- Oncology
- Nanotechnology
Background:
- Macrophages are key stromal cells in tumors and can uptake nanoparticles.
- Longitudinal MRI monitoring of tumor-associated macrophages (TAMs) during tumorigenesis lacks histological validation.
- Superparamagnetic iron oxide (SPIO) nanoparticles are suitable for MRI contrast enhancement.
Purpose of the Study:
- To longitudinally monitor tumor-associated macrophages (TAMs) during tumorigenesis using MRI.
- To provide histological confirmation of TAM presence and distribution.
- To investigate the in vivo topographical arrangement of TAMs in relation to tumor progression.
Main Methods:
- Injected SPIO nanoparticles into tumor-bearing mice.
- Utilized MRI to detect SPIO-labeled TAMs as hypointense signals.
- Performed post-mortem histology for validation and detailed analysis.
Main Results:
- MRI revealed continuous appearance of TAMs (hypointense signals) with tumor expansion.
- Histology confirmed SPIO-labeled TAMs localized nearer to the vessel lumen over time before rapid tumor growth.
- Demonstrated MRI's capability for longitudinal assessment of TAM accumulation.
Conclusions:
- MRI can effectively monitor TAM accumulation longitudinally during tumorigenesis.
- Provides novel in vivo insights into TAM topographical arrangement relative to tumor progression.
- In vivo TAM monitoring may aid in developing targeted tumor therapies focused on TAM functions.
