Technology |
| Cells need the extracellular matrix |
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Pluripotent stem cells are notoriously difficult to stably expand in the culture dish over a long period of time. In order to support the expansion of stem cells and the survival of more lineage committed progeny, they need to grow on a special supportive structure – a growth matrix. |
Extracellular matrixAlmost all cells in the body need to attach to the extracellular matrix (ECM) to proliferate, migrate and differentiate—and, in many cases, even to survive. A substantial part of tissues in the body is the extracellular space occupied by the ECM. The ECM consists of mainly proteoglycans and fibrous proteins such as laminin, collagen, fibronectin, and elastin (Alberts, 2002). Between epithelia or endothelia on the one side and stromal tissue on the other, is an ultrathin basal lamina, which is crucial in e.g. cell adhesion, differentiation and migration. Other cell types like muscle fibers, adipocytes and nerves are covered by a basal lamina. |
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| The dependence of attachment onto a substratum for cell growth, proliferation, and survival is known as anchorage dependence (Assoian and Zhu, 1997). The ECM influences the organization of a cell's cytoskeleton, which can be vividly demonstrated by using transformed (cancer-like) fibroblasts in culture. Transformed cells often make less fibronectin than normal cultured cells and, thus, behave differently.
They adhere poorly to the culture substratum and fail to flatten out, or develop the organized intracellular bundles of actin filaments known as stress fibers (Järvinen et al., 1987). Decrease in fibronectin production and subsequently adhesion, may contribute to the tendency of cancer cells to break away from the primary tumor and spread to other parts of the body. |
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Basal laminaeThe basal lamina is a foundation for cells to grow on. Basal laminae are the natural substrates for nearly all types of cells in vivo, and are, therefore, the natural choice of matrices to grow organ cells on in vitro. Basal laminae underlie all epithelia and endothelia in the body, surround certain (nerve, muscle, fat) cells, and can be interposed between two sheets of cells (kidney glomerulus) (Alberts, 2002; Miner and Yurchenco, 2004). Thus, basal laminae have extremely diverse and essential functions for not only tissue structure and permeability, but also for cell polarity, metabolism, survival, migration, proliferation and differentiation. The basal lamina is composed of different structural proteins, like type IV collagen, laminins, proteoglycans and nidogens, which provide structural support and influence cell differentiation, migration and adhesion (Aumailley and Smyth, 1998). |
LamininsLaminins are the most abundant component of the basal laminae. Laminins are the foundation most cells grow on, giving cells the needed stability for cell growth. They are the first extracellular proteins to be expressed in the developing embryo. The expression starts already in the inner cell mass of the blastocyst. It has been shown that during embryo development cells temporally and spatially express specific laminin types and, in the adult, tissue-specific progenitors/mature cells essentially require different types of laminins (Ekblom et al., 2003; Lathia et al., 2007; Miner and Yurchenco, 2004).For example, LN-521/511, the laminins expressed earliest, are needed for embryonic cells, while epithelial cells need LN-332, muscle and nerve cells need LN-211 and endothelial cells need LN-411 combined with LN-511 (Domogatskaya et al., 2008; Loulier et al., 2009; Nikolova et al., 2006; Rodin et al., 2010; Sugawara et al., 2008). |
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There are 16 known laminin isoforms that have specific roles in cell adhesion, cell differentiation and migration. This has been verified in over 7000 published articles, since they were first identified at an NIH laboratory, in which Karl Tryggvason was working as a post-doctoral scientist 30 years ago (Timpl et al., 1979).
Laminins are large trimeric proteins that contain an α-chain, β-chain and γ-chain that can be found in five, three and three genetic variants, respectively. Laminin names derive from their chain composition (Aumailley et al., 2005). Therefore, Laminin-521 (LN-521) contains α5, β2 and γ1 chains. Laminins consist of several functional domains, binding to perlecan, nidogen, and to receptors on the cell surface (Timpl et al., 2000). |
| Human laminins have not been available for characterization since it has been almost impossible to purify and manufacture laminins due to their cross-linking, sticky character and large molecular weight (~600-1000 kDa). The Tryggvason laboratory has, however, solved this problem and has been able to characterize many of the existing laminins. This research has shown that laminins play an important role in cell adhesion, cell differentiation and migration and have cell lineage specific functions (Doi et al., 2002; Kortesmaa et al., 2000; Wondimu et al., 2006).
Of the matrices available on the market today, studies show that laminin-based ones provide the best support (Domogatskaya et al., 2008; Goetz et al., 2006; Rodin et al., 2010). The problem is that all of these matrices use laminin-111, which does not optimally support survival, proliferation and differentiation of different cell types. At BioLamina, we understand that one size does not fit all. After 20 years as leaders in this field, we know that different cell types require different substrate solutions! Our purified human biospecific matrices are the first, completely defined human matrix on the market, and they are produced for your primary, embryonic and adult stem cell cultures. We have successfully cloned the genes and transfected human embryonic kidney cancer cells (HEK293), which produce the proteins that are purified using chromatography. Today we offer you five biologically relevant products that support the survival, growth and specification of a wide range of different cells and cell lines. |
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Please click on each product to learn more! |
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