Ultrastructural morphometry of capillary basement membrane thickness in normal and transgenic diabetic mice

Abstract

Capillary basement membrane (CBM) thickening is an ultrastructural hallmark in diabetic patients and in animal models of diabetes. However, the wide variety of tissues sampled and diverse methods employed have made the interpretation of thickness data difficult. We showed previously that acellular glomerular BMs in OVE26 transgenic diabetic mice were thickened beyond normal age-related thickening, and in the current study we hypothesized that other microvascular BMs likewise would show increased widths relative to age-matched controls. Accordingly, a series of tissues, including skeletal and cardiac muscle, ocular retina and choriod, peripheral nerve, lung, pancreas, and renal glomerulus was collected from 300 -350-day-old normal and transgenic mice. Transmission electron micrographs of cross sections through capillary walls were prepared, and CBM thickness (CBMT) was determined by the "orthogonal intercept" method. Morphometric analyses showed highly variable transgene-related BMT increases in the sampled tissues, with glomerular BM showing by far the greatest increase (ϩ87%). Significant thickness increases were also seen in the retina, pulmonary alveolus, and thoracoabdominal diaphragm. BMT increases were not universal; however, most were modestly widened, and those that were thickest in controls generally showed the greatest increase. Although the pathogenesis of diabetes-related increases in CBM is poorly understood, data in the current study showed that in OVE26 transgenic mice increased BMT was a frequent concomitant of hyperglycemia. Accordingly, it seems likely that hyperglycemia-induced microvascular damage may be a contributing factor in diabetic BM disease, and that microvessel cellular and extracellular heterogeneity may limit the extent of CBM thickening in diverse tissues. Anat Rec Part A 271A: 332-341, 2003. © 2003 Key words: diabetes; basement membrane thickness; electron microscopy; transgenic diabetic mice OVE26 transgenic mice are diabetic as a result of the specific overexpression of calmodulin in pancreatic beta cells (Epstein et al., 1989(Epstein et al., , 1992. Histological studies show that this results in beta cell destruction early in life, and by 30 -55 days of age glucose values exceed 450 mg/dl. At the same time, insulin levels are reduced to 42% of control levels. OVE26 mice are a particularly valuable model of diabetes, because beta cell toxins need not be administered to induce the disease, and the animals can survive well over a year without exogenous insulin administration (probably because of a small amount of residual insulin secretion). Moreover, because both males and females are fertile for several months without insulin therapy, the transgenic line has been maintained continuously for more than 14 years.Several studies have shown that the OVE26 diabetic model is useful for examining chronic complications of diabetes. This was particularly evident in a previous study of the kidney (Carlson et al., 1997) in which transmission electron microscopy (TEM) morphometry sh...

Significant glomerular basement membrane thickening in hyperglycemic and normoglycemic diabetic‐prone BB Wistar rats

“…In summary, it is difficult to reconcile our GBM thickness data with numerous morphometric studies, including our own (Carlson et al, 1997(Carlson et al, , 2003, that indicate increased microvascular basement membrane thickness is a concomitant of hyperglycemia. It is also difficult to escape the conclusion that high blood glucose may be sufficient but not required for excessive GBM thickening to occur.…”

“…Morphometry of peripheral GBM was carried out as previously described (Carlson et al, 2003). The method was a modification (Dische, 1992) of the orthogonal intercept procedure of Jensen et al (1979).…”

A Novel in Vivo Lecithin-Cholesterol Acyltransferase (LCAT)-Deficient Mouse Expressing Predominantly LpX Is Associated with Spontaneous Glomerulopathy

“…15 SREBP 1a transgenic mice (Sϩ), 18 bred into the C57Bl/6JxSJL background 16 were purchased from Jackson Laboratories (Bar Harbor, ME). The Sϩ lcatϪ/Ϫ double-mutant mice were generated by first cross-breeding the Sϩ mice with lcatϪ/Ϫ to yield Sϩ (hemizygotes)lcatϩ/Ϫ.…”

“…The glomerular basement membranes appeared normal thickness with a harmonic mean thickness of 191 nm. 17,18 At 10 months, SϩlcatϪ/Ϫ mice showed ultrastructural evidence of tubulointerstitial accumulation of lipid deposits ( Figure 6D). There were osmiophilic inclusions in proximal convoluted tubular epithelial cells, adjacent to tubular basement membranes, and in the cortical interstitium.…”

“…The glomerular basement membranes appeared normal thickness with a harmonic mean thickness of 174 nm. 17,18 Sixmonth-old S-lcatϪ/Ϫ mice showed a few mesangial and glomerular endothelial osmiophilic inclusions, many of which had a swirled lamellar appearance ( Figure 7B). There were no podocyte, glomerular basement membrane, tubulointerstitial, or macrophage osmiophilic inclusions identified.…”