Oral Presentation Australian Diabetes Society and the Australian Diabetes Educators Association Annual Scientific Meeting 2017

Three dimensional glomerular reconstruction: A novel approach to evaluate renal microanatomy in diabetic kidney disease (#42)

Niloufar Torkamani 1 2 , George Jerums 2 , Paul Crammer 3 , Alison Skene 1 4 , David Power 1 5 , Sianna Panagiotopoulos 1 , Michele Clarke 2 , Richard MacIsaac 6 , Elif I. Ekinci 1 2 7
  1. Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
  2. Department of Endocrinology, Austin Health, Melbourne, VIC, Australia
  3. Anatomical Pathology, Monash Medical Centre, Melbourne, VIC, Australia
  4. Department of Pathology, Austin Hospital, Melbourne, VIC, Australia
  5. Department of Nephrology, Austin Health, Melbourne, VIC, Australia
  6. Department of Endocrinology and Diabetes, St. Vincent’s Hospital Melbourne, Fitzroy, VIC, Australia
  7. Menzies School of Health Research, Darwin, Northern Territory, Australia

Background

Mesangial volumes are important metrics reflecting glomerular filtration surface area in diabetes. The point-sampled intercept (PSI) method is the conventional method used to calculate these parameters. However, this is time-consuming and is subject to underestimation. We introduce a novel technique to measure mesangial volumes using three-dimensional (3D) imaging.

Methods

Renal tissue from 22 patients with type 2 diabetes and estimated glomerular filtration rate of <60mL/min/1.73m2 were obtained. Patients were classified into normo-, micro-, or macroalbuminuria categories according to their 24h urine albumin excretion rate. Six ultra-thin serial sections were cut for Periodic acid–Schiff–diastase and Haematoxylin-Eosin staining. Up to five glomerular units from each section were photographed (x40). Three methods were used to quantify total glomerular area, mesangial volume, and mesangial/total area ratio. These included a transmission electron microscopy (TEM) based method (using computer-assisted measurement), the PSI method and our new 3D imaging method. A 3D representation was reconstructed from all glomeruli (320 glomeruli) using “Reconstruct” software for our new method. The correlation coefficient between results from the three methods was calculated using images from 8 patients with the TEM method being the gold-standard reference method.

Results

The correlation coefficient between TEM/3D, TEM/PSI and 3D/PSI methods was 0.98, 0.93, and 0.96 respectively. Our 3D method demonstrated that mesangial area increased progressively in normo- to macroalbuminuric patients. Significantly higher levels of mesangial proliferation were also seen in macroalbuminuric > normo and > microalbuminuric groups (p<0.05).

Conclusions

3D reconstruction was demonstrated to be a reliable method to calculate mesangial area and is more accurate than PSI. Moreover, this technique is less time consuming and is not dependent on electron microscopy. Due to its ease of use, 3D reconstruction may prove to be useful for studying renal biopsies and in clinical practice to quantify the glomerular changes in diabetic kidney disease.

 

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