3-Dimensional Structural and Volumetric Analysis of Glomeruli in Porcine Kidneys with Renal Artery Stenosis using Nano-Computed Tomography

Abstract

Ziele: Renovascular disease is one of the most important causes of hypertension and renal dysfunction, and may lead to renal microvascular remodeling. Therefore, renal microvascular alterations were obtained in pigs after ten weeks of unilateral renal artery stenosis (RAS) using nano-CT imaging. Methode: Seven female domestic pigs (45–55kg) were implanted through PTCA with local-irritant coils in the left renal artery, provoking formation of a unilateral RAS and thus a systemic renovascular hypertension. Blood pressure was recorded using a telemetry system. The degree of RAS was determined in vivo by renal angiography. After ten weeks, the animals were sacrificed. The contralateral kidneys were infused post mortem with contrast agent (Microfil®) and fixed in formalin. Kidneys of eight healthy female pigs (45–55kg) served as controls. The number of glomeruli, glomerular capillary volume, as well as the total vascular volume fraction were quantified and measured in nano-CT scans at 0.75µm, 2.0µm and 2.5µm. All results from nano-CT were complemented with co-localized histology. Ergebnis: Number of glomeruli per unit of area (mm2), as well as the glomerular capillary volume (µm3) was significantly higher in control compared to RAS animals (number of glomeruli per unit area 3.275±1.855 vs. 1.900±1.035, glomerular capillary volume 535 000±296 000µm3 vs. 223 000±111 000µm3, p<0.0001). The total vascular volume fraction per unit of volume (µm3) was significantly higher in control animals as compared to pigs with RAS (0.073±0.039 vs. 0.035±0.011, p=0.03). Schlussfolgerung: Using nano-CT, we observed a significant decrease of the total vascular volume fraction, glomerular capillary volume, and the number of glomeruli in pigs with RAS compared to healthy control animals. Nano-CT imaging is a promising new method for fast acquisition of quantitative and qualitative experimental information about parenchymal alterations in kidneys with RAS.