Spatial distribution and quantitative analysis of extracellular matrix remodelling in lung fibrosis using multiphoton microscopy

International audienceThe micro- and macro- organization of collagen during fibrotic processes is usually characterized by 2D assessment using histochemical stains on selected slides such as Masson's Trichrome or Sirius Red. However, these staining methods are limited to semi quantitative evaluation on restricted surfaces. Quantitative evaluation of collagen contents, such as Hydroxyproline or Sircol assays, performed on lung homogenates requires large amounts of tissue, are time consuming and do not give the spatial distribution of collagen. Non linear multimodal, multiphoton microscopy provides novel insights into collagen deposition in tissues. In this study, the micrometerscale three-dimensional spatial distribution of fi brosis was characterized in normal mouse lung (n=5) and in the murine model of bleomycininduced lung fi brosis (n=5) by second harmonic generation (SHG) of fi brillar collagen, using C56Bl/6 mice at day 14 post intra-tracheal instillation of bleomycin, 80 µg in 50 µl of 0.9 % sterile saline