Second harmonic microscopy to quantify renal interstitial fibrosis and arterial remodeling

Abstract

Interstitial fibrosis is a powerful pejorative predictor of progression of nephropathies in a variety of chronic renal diseases. It is characterized by the depletion of kidney cells and their replacement by extracellular matrix, in particular, type-I fibrillar collagen, a protein scarce in normal interstitium. However, assessment of fibrosis remains a challenge in research and clinical pathology. We develop a novel methodology based on second harmonic generation (SHG) microscopy, and we image collagen fibers in human and mouse unstained kidneys. We take into account the variability in renal shape, and we develop automated image processing for quantitative scoring of thick murine tissues. This approach allows quantitative 3-D imaging of interstitial fibrosis and arterial remodeling with high accuracy. Moreover, SHG microscopy helps to raise pathophysiological questions. First, imaging of a large volume within a mouse kidney shows that progression of fibrosis is a heterogeneous process throughout the different renal compartments. Second, SHG from fibrillar collagens does not overlap with the glomerular tuft, despite patent clinical and experimental glomerulosclerosis. Since glomerulosclerosis involves SHG-silent nonfibrillar collagens, our work supports pathophysiological differences between interstitial fibrosis and glomerulosclerosis, a clearly nonfibrotic process.

From molecular structure to tissue architecture: collagen organization probed by SHG microscopy

“…Another geometrical approach to score collagen was presented by Strupler et al [79,118]. This algorithm uses the fibers' areas for scoring: SHG images of fibrotic murine kidney were analyzed and the col- From the extracted fibers of healthy (upper triangle) and keloid (lower triangle) tissue the relevant parameters, i.e.…”

Wrinkle to fold transition: influence of the substrate response

“…Fruits and vegetables, 23,24 wrinkled and damaged skin, [25][26][27] organs like lungs 28 and arteries, 29 pollen grains 30 or geological folds 31 are some examples of natural systems developing such structures during global deformation induced by differential growth, a drying process or connement. Understanding the origin of these structures emerging from uniform states and identifying the role of mechanical forces in this process is one important aspect of morphogenesis.…”

Measurement of Friction-induced Changes in Pig Aorta Fibre Organization by Non-invasive Imaging as a Model for Detecting the Tissue Response to Endovascular Catheters

“…However, despite these advantages, it is only over the last few years that SHG imaging of collagen structures in tissue has begun to be adopted more widely. A recent review was published on the development and burgeoning use of SHG imaging in the clinic to investigate collagen remodelling in cancer in ex vivo and in vivo human tissue [28]; changes in collagen structure during fibrosis are also being monitored; ex vivo in humans, in vivo in animals, by SHG imaging [29][30][31]. In addition SHG imaging is now playing an important role in non-invasive imaging of collagen structure, formation and remodelling in tissue engineering and regenerative medicine, as reviewed recently by Vielreciher et al [32].…”