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International Journal of Bioprinting dECM bioink for in vitro disease modeling

A dysfunction in the matrix could lead to neurological Proteoglycans combine with hyaluronic acid to form a gel
pathology in the brain. For example, a breach in the in the ECM and regulate gas exchange with cells. The liver
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basement membrane compromises the BBB integrity, ECM maintains the structure of liver tissue by supporting
thereby inducing neuroinflammation, ischemia, and and fixing liver cells and blood vessels. It also contributes
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edema. In the case of a brain tumor, the levels of hyaluronic to the regulation of signaling and cell–cell interactions
acid, collagens, and CSPGs are upregulated owing to tumor necessary for liver function. 62
cell proliferation. 50,51 Thus, understanding the native brain- In the case of liver fibrosis, which is a typical liver disease,
like ECM is key to elucidating the pathological mechanism the ECM components of a fibrotic liver are similar to those
of brain disease. of a normal liver, but their volume is increased by a factor
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2.2.2. Extracellular matrix in cardiac tissue of approximately 3 to 5 times. Therefore, changes in the
Cardiac tissue is composed of a sophisticated ECM network ECM are closely linked to structural distortion and other
that includes fibrous proteins and non-fibrous proteins. important mechanisms such as liver cell regeneration and
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The spatial matrix is categorized as a basement membrane vascular redistribution. In addition to fibrous deposits,
with a pericellular matrix and an interstitial matrix, these mechanisms have severe consequences for liver
which provide physical strength to determine plasticity function. If fibrosis progresses, cirrhosis occurs, in which
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of cardiac tissue. 52,53 The basement membrane in cardiac most of the vascular spaces become interconnected.
tissue regulates cardiac cellular polarity and differentiation Recently, attempts have been made to treat fibrotic liver by
with fibronectin, type IV collagen, laminin, and various inducing changes in the ECM composition and reducing
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proteoglycans. In addition, the interstitial matrix of cardiac its absolute amount. As such, the composition of the
tissue provides mechanical support to the cells. The heart liver-specific ECM plays an important role in the overall
is developed with a collagen network and a combination of metabolism of liver tissue and is an important trigger
proteoglycans from embryonic stage. The changes in ECM and therapeutic target for liver disease; hence, it must be
composition from the embryonic stage to the fetal stage considered in studies on liver disease.
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lead to the formation of a cardiac-specific structure by 2.2.4. Extracellular matrix in tissues of
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promoting cardiac cell proliferation and formation of a respiratory system
layered structure. In the respiratory system, the ECM is an important
Adult heart, which is formed with mature cardiac tissue, component, equipped with various physiological
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may be vulnerable to pathological factors and events, such functions, of respiratory tissues. The ECM of respiratory
as fibrosis. Under the circumstance of fibrosis, the elevated tissues is composed of several components, such as
secretion of cytokines as well as thrombospondin, collagen, collagen, glycosaminoglycans (GAGs), hyaluronic acid,
and osteoglycin drives the scar formation. Adult cardiac proteoglycans, and elastin. Among these, collagen is the
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tissues are rarely regenerated in the pathological state; thus, most abundant and includes mainly types I, III, and IV.
the role of the ECM in regeneration and treatment must be Collagen provides tissue with strength and structure and
elucidated. In particular, it is important to decipher the life plays a role in maintaining the formation and function
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stage of cardiac ECM in various environments that allow of lung organelles. GAGs have important roles in gas
reconstruction of cardiac tissues using in vitro models. 52,56 exchange and gas transport. Hyaluronic acid fills the gaps
between mucous membranes and tissues in the respiratory
2.2.3. Extracellular matrix in liver tissues tract and facilitates gas exchange. On the other hand,
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Although ECM constitutes a small amount in liver proteoglycans regulate gas exchange within the ECM and
tissue, this component is an important ingredient for the form the gel state of the tissue, whereas elastin provides
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formation of complex tissue structures and various cells elasticity and assists in transporting gases and maintaining
that constitute the liver scaffold. The ECM of the liver the flexibility of respiratory tissues. In short, the major
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consists of several major components. functions of ECM in respiratory tissues are to significantly
Collagen is one of the most abundant components expand the gas exchange area, provide structural support
of the liver ECM, mainly consisting of type I and III necessary for gas transport, maintain elasticity, and assist
collagens. It provides strength and structure to liver tissue with repetitive contraction and relaxation of respiratory
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and supports the arrangement of liver cells and blood tissues. Besides, it regulates the behavior of immune
vessels. Fibrillin that exists between collagen fibers plays cells and molecules and regulates the immune responses
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an important role in regulating the elasticity and flexibility associated with respiratory infections and inflammation.
of liver tissue. As one of the gel-like ECM components Chronic inflammation is a hallmark in the typical
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of the liver, hyaluronic acid fills gaps between tissues. respiratory diseases including chronic obstructive
Volume 10 Issue 2 (2024) 136 doi: 10.36922/ijb.1970