Diabetes, Vol 31, Issue 7 593-599, Copyright © 1982 by American Diabetes Association
In vitro injury of porcine aortic endothelial cells by very-low-density lipoproteins from diabetic rat serum
BW Arbogast, GM Lee and TL Raymond
Primary cultures of porcine aortic endothelial cells were used to detect
injurious agents in diabetic rat serum. Media containing normal or diabetic
serum (streptozotocin-induced) were incubated with subconfluent primary
cultures of endothelial cells. Cells exposed to 17% diabetic serum were
severely contracted and permeable to trypan blue after 18 h. Cultures in
normal serum contained significantly more protein (P less than 0.005) than
cultures in diabetic serum after 1 day. When normal and diabetic serum were
mixed in different proportions and added to cells at 17% total serum
concentration, a 50% reduction from growth in normal serum occurred at a
ratio of 1 part diabetic serum to 9 parts normal serum. The toxicity of
diabetic serum was not altered by heat inactivation. Administration of
insulin to diabetic rats reversed both cytotoxicity and elevated
triglyceride levels. Serum triglyceride levels were inversely correlated
with endothelial cell growth (r = -0.878, P less than 0.001). In vitro
addition of up to 1 U/ml insulin to cultures in diabetic serum did not
alter toxicity. Ultracentrifugal flotation of diabetic serum demonstrated
the toxic substance to be entirely localized in the very-low-density
lipoprotein fraction (d less than 1.006 g/ml). A pool of d greater than
1.006 fractions from diabetic serum supported growth equivalent to normal
serum. Diabetic serum contains a substance localized in the
very-low-density lipoprotein fraction that is severely toxic to aortic
endothelial cells in vitro. Very-low-density lipoprotein injury of
endothelial cells may play an important role in the development of arterial
vascular disease in insulin-dependent diabetes.