Endothelial Cell Products as a Key Player in Hypoxia-Induced Nerve Cell Injury after Stroke.

Cho, Chul Min; Ha, Se Un; Bae, Hae Rahn; Huh, Jae Taeck

Original Article

Journal of Korean Neurosurgical Society 2006;40(2): 103-109.

Chul Min Cho, Se Un Ha, Hae Rahn Bae, Jae Taeck Huh

¹Department of Neurosurgery, College of Medicine, Dong-A University, Busan, Korea. jthuh@donga.ac.kr
²Department of Physiology, College of Medicine, Dong-A University, Busan, Korea.

ABSTRACT

OBJECTIVE
Activated endothelial cells mediate the cascade of reactions in response to hypoxia for adaptation to the stress. It has been suggested that hypoxia, by itself, without reperfusion, can activate the endothelial cells and initiate complex responses. In this study, we investigated whether hypoxia-induced endothelial products alter the endothelial permeability and have a direct cytotoxic effect on nerve cells.
METHODS
Hypoxic condition of primary human umbilical vein endothelial cells(HUVEC) was induced by CoCl2 treatment in culture medium. Cell growth was evaluated by 3,4,5-dimethyl thiazole-3,5-diphenyl tetrazolium bromide (MTT) assay. Hypoxia-induced products (IL-1beta, TGF-beta1, IFN-gamma, TNF-alpha, IL-10, IL-6, IL-8, MCP-1 and VEGF) were assessed by enzyme-linked immunosorbent assay. Endothelial permeability was evaluated by Western blotting.
RESULTS
Prolonged hypoxia caused endothelial cells to secrete IL-6, IL-8, MCP-1 and VEGF. However, the levels of IL-1, IL-10, TNF-alpha, TGF-beta, IFN-gamma and nitric oxide remained unchanged over 48 h hypoxia. Hypoxic exposure to endothelial cells induced the time-dependent down regulation of the expression of cadherin and catenin protein. The conditioned medium taken from hypoxic HUVECs had the cytotoxic effect selectively on neuroblastoma cells, but not on astroglioma cells.
CONCLUSION
These results suggest the possibility that endothelial cell derived cytokines or other secreted products with the increased endothelial permeability might directly contribute to nerve cell injury followed by hypoxia.

Key Words: Hypoxia; Primary human umbilical vein endothelial cells; Cytokines; Endothelial permeability; Neurotoxicity