Picrosirius Red Staining for Semiquantitative Histopathologic Evaluation of Collagen Deposition in Murine Models of Chronic Lung Allograft Rejection.

Fibrosis is the pathophysiologic hallmark of chronic rejection after lung transplantation and the foremost hurdle to long-term recipient survival. Several murine lung transplantation models are available for the study of chronic rejection. However, they display heterogeneous results regarding fibrotic changes of the graft, and the histologic extent of fibrosis is mostly reported qualitatively. Therefore, a spatially resolved approach that allows for statistical analysis can aid in evaluating fibrosis in these models. This study presents Picrosirius Red staining for a semiquantitative evaluation of collagen organization in murine lung allografts and compares it to standard Hematoxylin and Eosin, Masson's Trichrome, and Herovici's stains. Staining was performed on sections from two different murine transplantation models based on minor and major histocompatibility complex (MHC) mismatches. The method was established for semiquantitative analysis of collagen organization in whole lung sections. Thus, it can serve as a tool for murine experimental models of fibrotic lung diseases.