Extracellular matrix
The extracellular matrix (ECM) is distributed in the outer space of tissue cells, and its composition is determined by the cell type. For example, fibroblasts secrete type I collagen and fibronectin to the outside of the cell, while epithelial cells secrete laminin. Different cell types phase The secretion in the vicinity will change.For example, the fibrous cells in the dermis and the epithelial glial cells in the epidermis are adjacent, and the extracellular matrix components secreted by the two cells form the basement membrane layer. The complexity of the extracellular matrix is ​​attached to it An important factor influencing the expression of the cell phenotype, the dynamic balance of the cell type attached to the extracellular matrix controls the composition of the matrix, which in turn affects the cell phenotype [Kleinman et al., 2003, Zoubiane et al., 2003, Fata et al., 2004]. Therefore, a proliferating, migrating fibroblast requires differentiation of epithelial cells or nerve cells to secrete different ECM components. Usually, the cultured cells themselves can produce extracellular matrix, but The primary culture of some artificial cells. Proliferation and differentiation induction require artificial supply of exogenous ECM.
The extracellular matrix is ​​composed of collagen. Laminin, fibronectin, hyaluronic acid, proteoglycans, and membrane-bound growth factors (or cytokines) and other components [ALBERTS ET AL., 1997, 2002]. The matrix can pass collagen It is prepared by mixing with purified components such as fibronectin, and can also be secreted directly by the cells to produce ECM, then rinse off the stromal cells, inoculate the cells to be studied, or directly produce the extracellular matrix from EHS mouse sarcoma cells. It is commercially available as matrigel.Matrigel is usually used in cell culture to promote cell differentiation and cell morphogenesis, and it is interwoven with epithelial cells or endothelial cell layers into a grid-like structure.
Already, it is determined that there are at least two processes that need to interact with the attachment surface: 1 adhesion to achieve cell attachment and spreading, which is necessary for cell proliferation [Folkman and Moscona, 1978]; 2 specific interactions, which are some special Necessary for functional expression, such as the interaction of epithelial cells and basement membranes, with other extracellular matrix components or with connective tissue cells. Rojkind et al. [1980], Vlodavsky et al. [1980] and other researchers studied the relationship between cells The growth of natural materials related to membranes, natural matrix and well-defined matrix macromolecules such as Matrigel, Natrigel, collagen, laminin, vitronectin, etc. (BD Biosciences, Invitriogen) are all suitable for studying matrix interactions.
ECM can improve the survival, proliferation and differentiation ability of cells. Due to the danger that primary animal bodies may produce harmful substances, artificial substances must be added to ECM [Ido et al., 2004]. Now fibronectin and laminin All are sold in the market.
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