High-resolution three-dimensional digital imaging of the human renal microcirculation: An aid to evaluating microvascular alterations in chronic kidney disease in humans

We have developed a new virtual microscopy method, with two- and three-dimensional (2D, 3D) synchronization, that enables visualization of the human renal microvasculature. The method was used to evaluate 120-150 serially cut sections of paraffin-embedded human renal tissue from nephrectomized samples. Virtual microscopy images of sections double-immunostained with antibodies against CD34 (an endothelium marker) and smooth muscle actin (an arterial media marker) and stained with periodic acid-Schiff were processed using digital imaging analysis software. Image registration was conducted to generate 3D displays with red-green-blue color segmentation. The reconstructed images of the microvasculature, including the interlobular arteries and the glomeruli, allowed visualization of 3D structures and direct glomerular connections. Synchronizing these 3D images with the corresponding 2D images revealed the relationships between arteriosclerotic lesions and downstream glomeruli. Thus, interlobular arteries with moderate intimal thickening and afferent arterioles with segmental hyalinosis/sclerosis, as seen on the 2D images, exhibited wall irregularities on the corresponding 3D images. However, these lesions were not directly influenced by lesions in downstream glomeruli, such as sclerotic lesions. Our virtual-slide method based on 2D and 3D image synchronization provides a comprehensive view of the renal microcirculation and therefore novel insights into the pathogenesis of vascular-associated renal diseases.