Biochemistry of glomerular basement membrane of the normal and diabetic human

The histological appearance of kidneys from patients with diabetic nephropathy is characterized by a variety of findings. The most characteristic finding is a diffuse and/or nodular glomerulosclerosis, consisting of thickening of the peripheral basement membranes and an increase of the mesangial matrix. The nodular transformation of the mesangium leads to the classical Kimmelstiel-Wilson lesion. These typical morphological findings have directed attention to the process and nature of basement membrane thickening. Also, it has been recognized for a long time that basement membrane thickening is dependent on the duration and metabolic control of diabetes mellitus [1–4]. The question of how basement membrane thickening and diabetes mellitus are related biochemically was less clear. This lack of clarity was mainly due to the fact that the chemical structure of the basement membrane was not known. Earlier chemical analyses were beset by methodological drawbacks limiting the value of the results [5, 6], whereas recent studies on the chemical composition of normal and diabetic human glomerular basement membranes (HGBM) produced conflicting results [7–13]. The isolation procedure and the source of the kidneys, as well as other factors, have been considered responsible for the different results obtained by various investigators. This prompted us to carry out further biochemical analyses on normal and diabetic HGBM under more carefully controlled conditions. Special attention has been paid to the source of kidneys and the evaluation of contamination of the isolated basement membranes