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Updated: May 30, 2026
A Macrophage-Tumor Spheroid Co-Invasion Assay
Published on: January 24, 2025
Macrophage infiltration predicts a poor prognosis for human ewing sarcoma
Toshifumi Fujiwara1, Jun-ichi Fukushi, Shunsaku Yamamoto
1Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Abstract:
Ewing sarcoma-primitive neuroectodermal tumor (EWS) is associated with the most unfavorable prognosis of all primary musculoskeletal tumors. The objective of the present study was to investigate whether tumor-associated macrophages (TAMs) affect the development of EWS. TAMs were isolated from mouse xenografts using CD11b magnetic beads and examined for their cytokine expression and osteoclastic differentiation. To evaluate the role of TAMs in xenograft formation, liposome-encapsulated clodronate was used to deplete TAMs in mice. Macrophage infiltration and tumor microvascular density were histologically evaluated in 41 patients with EWS, and association with prognosis was examined using Kaplan-Meier survival analysis. In mouse EWS xenografts, TAMs expressed higher concentrations of cytokines including interleukin-6, keratinocyte-derived chemokine, and monocyte chemotactic protein-1. TAMs were more capable than normal monocytes of differentiating into tartrate-resistant acid phosphatase-positive giant cells. Depleting macrophages using liposome-encapsulated clodronate significantly inhibited development of EWS xenografts. In human EWS samples, higher levels of CD68-positive macrophages were associated with poorer overall survival. In addition, enhanced vascularity, increase in the amount of C-reactive protein, and higher white blood cell counts were also associated with poor prognosis and macrophage infiltration. TAMs seem to enhance the progression of EWS by stimulating both angiogenesis and osteoclastogenesis. Further investigation of the behavior of TAMs may lead to development of biologically targeted therapies for EWS.
Insights
Tumor-associated macrophages (TAMs) promote Ewing sarcoma progression by stimulating blood vessel growth and bone breakdown. Depleting TAMs inhibited tumor development, suggesting they are a therapeutic target for this aggressive cancer.
Area of Science:
- Oncology
- Immunology
- Cancer Biology
Background:
- Ewing sarcoma-primitive neuroectodermal tumor (EWS) is a rare and aggressive primary musculoskeletal tumor with a poor prognosis.
- The role of tumor-associated macrophages (TAMs) in the development and progression of EWS remains largely unexplored.
Purpose of the Study:
- To investigate the impact of TAMs on EWS development and progression.
- To explore the potential of targeting TAMs for EWS therapy.
Main Methods:
- TAMs were isolated from mouse xenografts and analyzed for cytokine expression and osteoclastic differentiation.
- TAMs were depleted using liposome-encapsulated clodronate in mouse models.
- Macrophage infiltration and tumor vascularity were assessed in human EWS samples.
- Survival analysis was performed using Kaplan-Meier methods.
Main Results:
- TAMs in mouse EWS xenografts expressed elevated levels of pro-inflammatory cytokines (IL-6, KC, MCP-1).
- TAMs exhibited enhanced osteoclastic differentiation capacity compared to normal monocytes.
- Depletion of TAMs significantly suppressed EWS xenograft growth.
- In human EWS, higher macrophage infiltration (CD68+) correlated with poorer overall survival, increased vascularity, elevated C-reactive protein, and higher white blood cell counts.
Conclusions:
- TAMs contribute to EWS progression by promoting angiogenesis and osteoclastogenesis.
- Targeting TAMs represents a promising therapeutic strategy for Ewing sarcoma.
