Increased adhesion of human diabetic platelets to cultured valvular endothelial cells.
Diabetes is accompanied by impaired platelet function and accelerated vascular disease. To find out whether a correlation exists between these two complications, and if modifications occurring in diabetic platelets influence their relationship with endothelium, we have studied the interaction between platelets isolated from plasma of diabetic patients and bovine valvular endothelial cells (VEC), in culture. For quantitative analysis, normal and diabetic [3H]-adenine-labeled platelets were incubated with confluent VEC grown in Dulbecco's modified Eagle medium, containing 4.5 g/l glucose, for 30 min at 37 degrees C. After extensive washing and solubilization of the monolayer, the calculated adhesion index showed a two-fold increased adherence of diabetic platelets to VEC as compared to normal platelets. Statistical analysis (by Pitman randomization test) indicated that the adhesion was significantly higher (p = 0.0003) than that of normal platelets to VEC. To partially identify the membrane components implicated in the adhesion process, either platelets or VEC were treated with neuraminidase, trypsin or heparinase prior to the adhesion assay. Trypsin or neuraminidase treatment of platelets significantly diminished their adherence to VEC, suggesting a role of platelets sialylated glycoproteins in the adhesion process. Neuraminidase or heparinase treatment of VEC increased the adhesion of both normal and diabetic platelets, indicating that the cell membrane sialyl residues and heparan sulfate participate in the normal thromboresistant properties of VEC. Transmission and scanning electron microscopy revealed a close apposition between platelets and VEC with the formation of an adhesion plaque, characterized by fine fibrillar bridges between the plasma membranes of the two cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Manduteanu
I
I
Institute of Cellular Biology and Pathology, Bucharest, Romania.
Calb
M
M
Lupu
C
C
Simionescu
N
N
Simionescu
M
M
D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D002448:Cell Adhesion / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D003920:Diabetes Mellitus / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D019763:Heparin Lyase; D006801:Humans; D008297:Male; D008875:Middle Aged; D019158:N-Acetylneuraminic Acid; D009439:Neuraminidase / Q000494:pharmacology; D011133:Polysaccharide-Lyases / Q000494:pharmacology; D011509:Proteoglycans / Q000378:metabolism; D012794:Sialic Acids / Q000378:metabolism; D013927:Thrombosis / Q000503:physiopathology; D014357:Trypsin / Q000494:pharmacology
D011509:Proteoglycans; D012794:Sialic Acids; D009439:Neuraminidase; D014357:Trypsin; D011133:Polysaccharide-Lyases; D019763:Heparin Lyase; D019158:N-Acetylneuraminic Acid