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Retroviral transformation of cerebral microvascular endothelial cells: macrophage-like and microvascular endothelial
D H Robinson1, M K Warren, L T Liang
1Diving Medicine Department, Naval Medical Research Institute, Bethesda, MD 20814-5055.
Abstract:
We report that L-cell-conditioned medium (LCM) transforms porcine cerebral microvascular (PCMV) endothelial cells into cells with macrophage-like properties. LCM is known to contain both cytokine(s) and the L-cell virus, a murine retrovirus found in the L929 cell and LCM. Our evidence suggests that both LCM cytokine(s) and the L-cell virus are involved in this PCMV endothelial cell transformation. Criteria for transformation include focus formation, decreased serum requirements for growth, changes in morphology including nonadherence, propagation in suspension culture, and a decreased growth response to stimulation with a known endothelial cell mitogen. Macrophage-like characteristics of this transformed cell, designated as RVTE, include pinocytosis of low-density lipoprotein, Fc receptor-mediated phagocytosis, phagocytosis of bacteria and zymosan, the expression of macrophage enzyme markers, and constitutive production of colony-stimulating factor 1. However, the transformed cell retains several properties of the nontransformed cell including the expression of FVIII:RAg and in vitro self-organization into capillary-like structures. Cloning of RVTE cells clearly shows that both macrophage-like and cerebral microvascular endothelial cell properties are present in the same cell. During self-organization, nontransformed cells express morphologic and functional characteristics classically associated with the macrophage. These findings suggest that some brain capillary pathophysiologies could involve macrophage-like cerebral microvascular endothelial cells. Furthermore, the "reticuloendothelial" phenotypic repertoire expressed by this transformed cerebral microvascular endothelial cell may show that the cerebral capillary endothelial cell in vivo is derived from a hematopoietic and/or phagocytic precursor.
Insights
L-cell-conditioned medium (LCM) transforms porcine cerebral microvascular (PCMV) endothelial cells into macrophage-like cells. This transformation, involving LCM cytokines and virus, suggests brain capillary cells may originate from phagocytic precursors.
Area of Science:
- Cell Biology
- Immunology
- Neuroscience
Background:
- L-cell-conditioned medium (LCM) is known to contain cytokines and the L-cell virus.
- Porcine cerebral microvascular (PCMV) endothelial cells are crucial for brain barrier function.
Purpose of the Study:
- To investigate the transformative effects of LCM on PCMV endothelial cells.
- To characterize the resulting transformed cells and their properties.
Main Methods:
- Treatment of PCMV endothelial cells with LCM.
- Assessing cellular transformation criteria (focus formation, growth requirements, morphology, adherence).
- Evaluating macrophage-like characteristics (pinocytosis, phagocytosis, enzyme markers, CSF-1 production) and retained endothelial cell properties (FVIII:RAg expression, capillary-like structure formation).
Main Results:
- LCM induced transformation of PCMV endothelial cells, exhibiting macrophage-like properties (e.g., phagocytosis, CSF-1 production).
- Transformed cells (RVTE) retained some endothelial characteristics, including FVIII:RAg expression and self-organization into capillary-like structures.
- Cloning confirmed that individual RVTE cells possess both macrophage-like and endothelial cell traits.
Conclusions:
- LCM, via cytokines and virus, transforms PCMV endothelial cells into cells with dual macrophage-like and endothelial characteristics.
- These findings suggest macrophage-like PCMV endothelial cells may be involved in brain capillary pathologies.
- The study proposes that cerebral capillary endothelial cells might originate from hematopoietic/phagocytic precursors.