Abstract
Platelets contain platelet-derived growth factor (PDGF) and other growth factors capable of stimulating proliferation of vascular smooth muscle cells (VSMC). Over-proliferation of VSMC mayplay an important role in the pathogenesis of atherosclerosis, the morbidity of which is higher in diabetic patients than in the non-diabetic population.
In this study, growth-promoting activity (GPA) in platelet supernatant (PS) from insulindependent diabetic (IDDM) patients was measured by a bioassay using cultured VSMC from rat aorta. An incorporaion rate of 3H-thymidine into DNA was measured and results were expressed as the percent value of GPA in 10% calf serum in incubation medium.
GPA in PS from poorly controled IDDM (HbA1 12.3±2.5%, M±SD) was 33.1±2.5% significantly higher (p<0.001) than that from normal controls (16.5±1.5%). Meanwhile six other IDDM (HbA1 9.9±1.6) patients treated with insulin in the conventional way wer changed to intensive insulin therapy, that is, continuous subcutaneous insulin infusion (CSII) and Pen infuser, in that order, for 3 months each. GPA in PS from these six patients was 38.2±14.4% during conventional treatment, and decreased to 19.2±9.2 and to 15.7±4.5% during CSII and Pen infuser, respectively.
These results suggest GPA in PS from IDDM is increased and that this abnormality might lead such patients to atherosclerotic diseases. With respect to the possibility of preventing diabetic vascular complications, it is also important that an increased GPA could be normalized by intensive insulin treatments.
