**1. Extracellular matrix**

The extracellular matrix (ECM) is a noncellular component within all tissues and organs, and it is essential for the scaffolding of cellular constituents and also it plays a crucial role on tissue morphogenesis, differentiation and hemostasis [1]. It is an anchoring platform for epithelia, forms the basement membrane, and also surrounds capillaries and neural cells, and is part of the connective tissue [2].

In general, ECM molecules can be classified as fiber-forming and non–fiber-forming molecules [3, 4]. Collagens, elastins, laminins and fibronectins are the main fiber-forming ECM proteins. Proteoglycans which are main non–fiber-forming molecules fill the majority of the extracel‐

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lular interstitial space and they have a wide variety of functions that reflect their unique buffering, hydration, binding and force–resistance properties.
