Changes in cultured endothelial cell glycosaminoglycans under hyperglycemic conditions and the effect of insulin and heparin

Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada.
Cardiovascular Diabetology (Impact Factor: 4.02). 09/2009; 8(1):46. DOI: 10.1186/1475-2840-8-46
Source: PubMed

ABSTRACT Heparan sulfate proteoglycans (HSPGs) contain glycosaminoglycan (GAG) chains made primarily of heparan sulfate (HS). Hyperglycemia in diabetes leads to endothelial injury and nephropathy, retinopathy and atherosclerosis. Decreased HSPG may contribute to diabetic endothelial injury. Decreased tissue HS in diabetes has been reported, however, endothelial HS changes are poorly studied.
To determine total GAGs, including HS, in endothelium under hyperglycemic conditions and the protective effect of insulin and heparin.
Confluent primary porcine aortic endothelial cells (PAECs) were divided into control, glucose (30 mM), insulin (0.01 unit/ml) and glucose plus insulin treatment groups for 24, 48 and 72 hours. Additionally, PAECs were treated with glucose, heparin (0.5 microg/ml) and glucose plus heparin for 72 hours. GAGs were isolated from cells and medium. GAG concentrations were determined by the carbazole assay and agarose gel electrophoresis.
GAGs were significantly increased only in control and glucose plus insulin groups at 72 versus 24 hours. Glucose decreased cell GAGs and increased medium GAGs, and insulin alone decreased cell GAGs at all times compared to control. In the glucose plus insulin group, cell GAGs were less than control at 24 hours, and greater than glucose or insulin alone at 48 and 72 hours while GAGs in medium were greater than control at all times and glucose at 72 hours. Heparin increased GAGs in glucose treated cells and medium.
High glucose and insulin alone reduces endothelial GAGs. In hyperglycemic conditions, heparin or insulin preserves GAGs which may protect cells from injury. Insulin is an effective diabetic therapy since it not only lowers blood glucose, but also protects endothelium.

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Available from: Fuming Zhang, Sep 28, 2015
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    • "We postulate that normal mast cells play an important role in the protection of the integrity of endothelial cell layers and the vessel wall, probably via their paracrine activity, especially through the release of heparin. It is known that in hyperglycemic conditions heparin may protect cells from injury [26]. In diabetic patients, the nuclear pyknosis, degranulation and vacuolization of the mast cells in the CA indicate that they are damaged. "
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    • "To determine whether the enhanced inflammatory responses could be corrected by insulin, we stimulated T1D cells with PGN and LPS in the presence of insulin. The normal range of blood insulin has been reported to be 7-24 mU/l, and treatment with 10 U/l of insulin reduces the levels of glycosaminoglycan in cultured endothelial cells [49]. We applied insulin at 10 and 100 U/l to diabetic cells prior to stimulation with a TLR2 or TLR4 agonist. "
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