Elusive Identities and Overlapping Phenotypes of Proangiogenic Myeloid Cells in Tumors

Medical School, University of Sheffield, Sheffield, S10 2RX, UK.
American Journal Of Pathology (Impact Factor: 4.59). 02/2010; 176(4):1564-76. DOI: 10.2353/ajpath.2010.090786
Source: PubMed


It is now established that bone marrow-derived myeloid cells regulate tumor angiogenesis. This was originally inferred from studies of human tumor biopsies in which a positive correlation was seen between the number of tumor-infiltrating myeloid cells, such as macrophages and neutrophils, and tumor microvessel density. However, unequivocal evidence was only provided once mouse models were used to examine the effects on tumor angiogenesis by genetically or pharmacologically targeting myeloid cells. Since then, identifying the exact myeloid cell types involved in this process has proved challenging because of myeloid cell heterogeneity and the expression of overlapping phenotypic markers in tumors. As a result, investigators often simply refer to them now as "bone marrow-derived myeloid cells." Here we review the findings of various attempts to phenotype the myeloid cells involved and discuss the therapeutic implications of correctly identifying-and thus being able to target-this proangiogenic force in tumors.

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Available from: Seth Coffelt, Nov 05, 2014
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    • "Tie2-expressing macrophages (TEMs) represent a TAM subset closely associated with the vasculature (33, 34). These cells appear to have a distinct gene signature (35) in spite of substantial overlaps between TAMs, TEMs, myeloid-derived suppressor cells (MDSCs), monocytes, and embryonic/fetal macrophages (35, 36). TEMs are also recruited at the tumor site after treatment with vascular disrupting agents, interfering with and antagonizing their action (37). "
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