[Recent approaches of quantification of interstitial fibrosis in renal transplantation]

Chronic allograft injury can be diagnosed early at a pre-clinical stage by its histopathological changes. Interstitial fibrosis (IF), one of its main histopathological features, is currently assessed by semi-quantitative analysis according to the Banff classification. Subjective interpretation by the pathologist is the main limiting factor of such a method. Different morphometric approaches have been used to quantify IF. Point counting methods have been published but their use is very tedious. Thus, semi-automatic computerized measurements of IF in biopsy specimens immunostained for collagen III have been proposed. Most authors used Sirius Red-stained tissue examined under polarized or non-polarized light. However, morphometric methods are time-consuming. Automatic color segmentation image analysis is a new, rapid, and robust method to quantify IF on renal biopsies stained by light green trichrome. It can be recommended as being reliable and reproducible for routine use. Methodology based on second harmonic generation microscopy allows specific quantitative imaging of interstitial fibrosis with high reproducibility and may bring complementary informations in the future. The prognostic value of quantitative image analysis might be increased by techniques addressing the dynamics of fibrosis matrix generation.