发布: 2020年05月20日第10卷第10期 DOI: 10.21769/BioProtoc.3629 浏览次数: 9003
评审: Alka MehraVasiliki KoliarakiAnonymous reviewer(s)
Abstract
Expansion of fibrous connective tissue and abnormal deposition of extracellular matrix (ECM) are at the basis of many fibrotic diseases. Fibrosis can occur in response to both physiological and pathological cues, including wound healing, tissue remodeling/repair and inflammation. Chronic fibrosis can lead to severe tissue damage, organ failure and death. Assessing the extent of organ fibrosis is crucial for accurate diagnosis of this condition. The use of Masson’s trichrome staining of tissue sections from skeletal muscle is a fast method for detection of morphological alterations indicative of a fibrotic phenotype in this organ. This staining method detects the extent of collagen fibers deposition and, because it employs the combination of three dyes, can also distinguish muscle fibers (red), from collagen (blue) and nuclei (black), simultaneously.
Keywords: Masson’s Trichrome (masson三色染色)Background
Fibrosis is the formation of excessive fibrous connective tissue in an organ as a result of chronic inflammation, tissue damage/remodeling (for instance, following chemical or radiation therapy), persistent infections, autoimmune disease, allergic responses and cancer. During this process excessive extracellular matrix (ECM) components, including collagens, are deposited and accumulate. If progressive, fibrosis becomes chronic, ultimately leading to organ failure and even death (Rockey et al., 2015). Several types of fibrotic diseases have been described in humans, many of which are of unknown etiology. The organs most commonly affected are the lungs, kidneys, liver, heart and skeletal muscle (Hinderer et al., 2019; Majo et al., 2019; Mahdy, 2019). Idiopathic pulmonary fibrosis, for instance, is a common, progressive and often fatal disease associated with scarring of the lung tissue that gradually looses the capacity to oxygenate, leading to the patient’s inability to breathe properly (Lederer et al., 2018).
A fibrotic process entails the activation of fibroblasts into myofibroblasts, cells that acquire a stellate or spindle-shape morphology, are motile and contractile, express α-smooth muscle actin, and secrete/remodel the ECM, altering the stiffness, morphology and composition of the tissue (Gattazzo et al., 2014; Kendall et al., 2014; Rockey et al., 2015). In the skeletal muscle under healthy conditions fibrosis occurs in the form of scar tissue during the healing process following muscle injury. This is usually associated with infiltration of inflammatory cells that induce satellite cells to proliferate and differentiate into new myotubes and myofibers while simultaneously the ECM undergoes remodeling. In disease conditions, such as muscular dystrophies or myopathies, progressive expansion of the connective tissue and abnormal deposition of ECM components, consequent to myofiber degeneration, ultimately results in full-blown fibrosis (Mahdy, 2019). We have recently discovered that deficiency of the sialic acid processing enzyme neuraminidase 1 (NEU1) in the mouse model of the rare pediatric lysosomal storage disease sialidosis, triggers a persistent expansion of the connective tissue, leading to generalized fibrosis in several organs including the liver, kidney, heart and skeletal muscle (Zanoteli et al., 2010; van de Vlekkert et al., 2019). Detection of the fibrotic disease was carried out using Masson’s trichrome staining of tissue sections from skeletal muscle, lung, heart, kidney and liver (Figure 1). This method is generally more accurate and informative than the standard hematoxilin & eosin staining because Masson’s trichrome staining not only maintains intact the overall morphology of the tissues, but also has the advantage of utilizing three dyes that allow for the identification of multiple tissue structures. In skeletal muscle the three dyes, Weigert’s iron hematoxylin, Biebrich scarlet and aniline blue, applied sequentially, allow to distinguish nuclei, muscle fibers and erythrocytes, and collagen fibers, respectively (Figure 1). This method is suitable for the assessment of the extent and distribution of fibrosis in a quantifiable manner, and can be successfully applied for the detection/diagnosis of fibrotic diseases.
Figure 1. Masson’s Trichrome staining of multiple organs collected from the WT and Neu1–/– mice. Fibrotic regions in the Neu1–/– mouse are characterize by massive collagen deposition and therefore appear in blue (asterisks) (Images of WT and Neu1–/– kidney, liver and skeletal muscle are from van de Vlekkert et al., 2019). Blue = collagens; Red = erythrocytes and cytoplasm; Dark purple/black = nuclei. Scale bars: kidney and liver = 100 μm, heart, lung and skeletal muscle = 200 μm.
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Note: All reagents and materials should be kept at room temperature unless otherwise described. For the shelf life and storage temperature of reagents we refer to the manufacturer’s instructions.
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© 2020 The Authors; exclusive licensee Bio-protocol LLC.
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细胞生物学 > 组织分析 > 组织染色
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