Related Experiment Video
Updated: Dec 6, 2025
Coculture Assays to Study Macrophage and Microglia Stimulation of Glioblastoma Invasion
Published on: October 20, 2016
Microglia/macrophages express alternative proangiogenic factors depending on granulocyte content in human
Anne Blank1, Irina Kremenetskaia1, Ruth M Urbantat1
1Department of Experimental Neurosurgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Abstract:
Myeloid cells are an inherent part of the microenvironment of glioblastoma multiforme (GBM). There is growing evidence for their participation in mechanisms of tumor escape, especially in the development of resistance following initially promising anti-VEGF/VEGFR treatment. Thus, we sought to define the capability of myeloid cells to contribute to the expression of proangiogenic molecules in human GBM. We investigated GBM specimens in comparison with anaplastic astrocytoma (WHO grade III) and epilepsy patient samples freshly obtained from surgery. Flow cytometric analyses revealed two distinct CD11b+ CD45+ cell populations in GBM tissues, which were identified as microglia/macrophages and granulocytes. Due to varied granulocyte influx, GBM samples were subdivided into groups with low (GBM-lPMNL) and high (GBM-hPMNL) numbers of granulocytes (polymorphonuclear leukocytes; PMNL), which were related to activation of the microglia/macrophage population. Microglia/macrophages of the GBM-lPMNL group were similar to those of astrocytoma specimens, but those of GBM-hPMNL tissues revealed an altered phenotype by expressing high levels of CD163, TIE2, HIF1α, VEGF, CXCL2 and CD13. Although microglia/macrophages represented the main source of alternative proangiogenic factors, additionally granulocytes participated by production of IL8 and CD13. Moreover, microglia/macrophages of the GBM-hPMNL specimens were highly associated with tumor blood vessels, accompanied by remodeling of the vascular structure. Our data emphasize that tumor-infiltrating myeloid cells might play a crucial role for limited efficacy of anti-angiogenic therapy bypassing VEGF-mediated pathways through expression of alternative proangiogenic factors. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Insights
Myeloid cells in glioblastoma (GBM) can resist anti-angiogenic treatments by producing alternative proangiogenic factors. These myeloid cells, including microglia/macrophages and granulocytes, contribute to tumor growth and vascular remodeling, limiting treatment efficacy.
Area of Science:
- Oncology
- Immunology
- Pathology
Background:
- Myeloid cells are key components of the glioblastoma microenvironment.
- They are implicated in tumor escape and resistance to anti-VEGF/VEGFR therapies.
Purpose of the Study:
- To investigate the role of myeloid cells in expressing proangiogenic molecules in human glioblastoma multiforme (GBM).
Main Methods:
- Analysis of human GBM, anaplastic astrocytoma, and epilepsy patient samples.
- Flow cytometry to identify myeloid cell populations (microglia/macrophages, granulocytes).
- Subdivision of GBM samples into low (GBM-lPMNL) and high (GBM-hPMNL) granulocyte groups.
Main Results:
- Two distinct myeloid populations, microglia/macrophages and granulocytes, were identified in GBM.
- GBM-hPMNL samples showed altered microglia/macrophages expressing CD163, TIE2, HIF1α, VEGF, CXCL2, and CD13.
- Both cell types produced proangiogenic factors (IL8, CD13), with microglia/macrophages also expressing VEGF.
- Microglia/macrophages in GBM-hPMNL were associated with tumor vasculature and remodeling.
Conclusions:
- Tumor-infiltrating myeloid cells contribute to GBM's proangiogenic state.
- These cells may drive resistance to anti-angiogenic therapies by bypassing VEGF pathways.
- Targeting myeloid cell-derived proangiogenic factors could enhance GBM treatment efficacy.
