Experimental Study on the Relationship between Heparin Sulfate Proteoglycans of Endothelial Cells and Cell Adhesion.

Objective: The human umbilical vein endothelial cells (hUVECs) were taken as experimental cells after successfully sub-cultured in vitro. Whether the HSPGs can express stably on the cultured hUVECs was determined firstly. The contents of HSPGs on the surface of endothelial cells were measured under the exterior intervening factors action, and the effect of exterior intervening factors on HSPGs were evaluated. The cell adhesion models, in which the mononuclear apart from circulate blood in normal human body can adhere to hUVECs, were used to evaluate the relation between the HSPGs contents and cell adhesion. The aim of the study was to explore the new ideas or methods on preventing or treatment for extramedullary infiltration in leukaemia patients.

Methods: Enzyme-digestion method was used to obtain hUVECs, and cell number can up to scratch for experiment study by sub-cultured in vitro. RT-PCR was performed to half-determine the expression of Syndecan-1, Glypican-1 on the surface of ECs. NaClO₃, 4-methylumbelliferyl-7-β-D-xyloside (4-β-DX), heparin, tumor necrosis factor α (TNFα), heparinaseIII and leukaemia serum were taken as intervening factors to work on the ECs. The RT-PCR method was used to determine the expression of Syndecan-1 and Glypican-1 on the surface of ECs, and biocolor measure method was used to evaluate the PGs contents in the ECs. The normal human mononuclear cell aparted from peripheral blood by density centrifugation were co-cultured with ECs, on which the HSPGs contents have been modified by intervening factors. Methyl thiazolyl tetrazolium (MTT) colorimetry method was used to determine the mononuclear-endothelial cell adhesion, inverted microscopy and scanning electron microscopy were used to observe the cell adhesion. The flow cytometry method was used to determine the ECs activated by exterior TNFα and leukaemia serum, the expression for CD62E antigen was evaluated to determine the effect of traditional adhesion molecular and confirm the function of HSPGs.

Results: The cultured human umbilical endothelial cells can passage stable. Syndecan-1 and Glypican-1 are two HSPGs families representations on the surface of cell, can be used to judge the expression level of HSPGs on the EC surface. The exterior intervening factor, such as TNFα, 4-methylumbelliferyl-7-β-D -xyloside, NaClO₃, heparin, heparanase and leukaemia serum, can work on the HSPGs expression on ECs in transcription and cell level. Affected by these intervening factors, mononuclear cells showed different exhibition on adhesion to cultured endothelial cells.

Conclusion: The traditional adhesion molecules can dominate the cell adhesion, the HSPGs expressed on the endothelial cells can participate in the process of cell adhesion. For the more, HSPGs can promote the cell adhesion progression. ALL serum can up-regulate the expression of Syndecan-1 on the hUVECs, and result in contents of HSPGs increasing, which is coincident with the phenomenon that more extramedullary infiltration can be found in ALL patients in clinic. The above-mentioned can indicated that the HSPGs on the surface of ECs may participate the leukemia cell adhesion process, and the research aimed on the cell surface HSPGs maybe represent an important direction to control the pathological cell adhesion.