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Vascular leukocytes contribute to tumor vascularization
Jose R Conejo-Garcia1, Ronald J Buckanovich, Fabian Benencia
1Abramson Family Cancer Research Institute, University of Pennsylvania, Philadelphia, USA.
Blood
|September 11, 2004
Summary
Researchers discovered a new type of white blood cell, called vascular leukocytes (VLCs), in ovarian tumors. These cells express both blood and blood vessel markers and can form new blood vessels, linking hematopoietic cells to postnatal vascular development.
Area of Science:
- Oncology
- Hematology
- Vascular Biology
Background:
- Postnatal vasculogenesis mechanisms remain incompletely understood.
- The contribution of hematopoietic cells to blood vessel formation in adults is not well-established.
Purpose of the Study:
- To identify and characterize novel cell populations involved in tumor vascularization.
- To investigate the potential role of hematopoietic cells in postnatal vasculogenesis.
Main Methods:
- Fluorescence-activated cell sorting (FACS) analysis of ovarian carcinoma ascites and tumor tissues.
- Protein expression analysis using flow cytometry for endothelial and leukocyte markers.
- mRNA detection of angiogenic markers.
- In vivo functional assays to assess blood vessel formation capacity.
Main Results:
- A novel leukocyte subset, termed vascular leukocytes (VLCs), was identified in ovarian tumors.
- VLCs coexpressed endothelial markers (VE-cadherin, P1H12, CD34, CD31) and leukocyte markers (CD45, CD11c, MHC class II).
- VLCs constituted a significant portion of tumor-infiltrating cells (39%) but were rare in peripheral blood and ascites.
- These cells expressed angiogenic markers (TEM1, TEM7, Thy-1) and demonstrated the capacity to form functional blood vessels in vivo.
Conclusions:
- Vascular leukocytes represent a critical link between hematopoietic precursors and postnatal vascular development.
- This finding challenges previous assumptions about the limited role of hematopoietic cells in adult blood vessel formation.
- VLCs present a potential novel therapeutic target for cancer treatment and other vascular-related diseases.