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The therapeutic role of the components of Aloe vera in activating the factors that induce osteoarthritic joint remodeling
Published in Badal Jageshwar Prasad Dewangan, Maheshkumar Narsingrao Yenkie, Novel Applications in Polymers and Waste Management, 2018
Abhipriya Chatterjee, Patit Paban Kundu
They are protein polysaccharide molecules that constitute 1020% of the wet weight and provide a compressive strength to the articular carti lage. The fluid and electrolyte balance in the articular cartilage is main tained by proteoglycan.38 Chondrocytes produce these proteoglycans and secrete in the matrix. The subunits of proteoglycan, which are known as glycosaminoglycans, are of mainly two types, chondroitin sulfate and keratin sulfate. There are two major classes of proteoglycans found in articular cartilage, large aggregating proteoglycan monomers, or aggre cans and small proteoglycans, including decorin, biglycan, and fibro modulin.38 Aggrecan is the most abundant proteoglycan in the matrix and is composed of a central core protein bound to glycosaminoglycans by sugar bonds. The core protein stabilizes the structure with a central hyal uronic acid chain to form an intricate structure of the glycosaminoglycans molecule. There are two types of the chondroitin sulfate, type 4 and type 6. Type 6 remains constant throughout life, whereas type 4 decreases with the age. Depletion in proteoglycan level has been observed in experi mental arthritis.38
Structure and Function of Cartilage
Published in Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi, Articular Cartilage, 2017
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi
Aggrecan exists as a large, highly glycosylated proteoglycan with long, linear GAG chains of chondroitin sulfate and keratan sulfate molecules radiating from a central ∼230 kDa protein core, resulting in a bottle brush structure (Table 1.2). Aggrecan is posttranslationally modified by glycosylation in the late endoplasmic reticulum (specifically an initial xylosylation); the molecular mass of a single proteoglycan can reach more than 2 MDa (Watanabe et al. 1998). The protein core contains several distinct globular domains (G1, G2, and G3), an interglobular domain, and two extended domains where GAGs attach, the keratan sulfate (KS) and chondroitin sulfate (CS) domains (Figure 1.24). The globular domains are involved in aggregate formation, while the interglobular domain contains sites available for proteolytic cleavage and is likely involved in the turnover of aggrecan. The KS domain is absent in rodents (Kiani et al. 2002). The CS domain represents the largest domain in aggrecan and is encoded by a single exon (exon 12) representing a 120-repeat serine-glycine sequence. The carboxyl (COO−) and sulfate SO3− groups present on these attached GAGs produce a strong negative charge that in turn gives cartilage extracellular matrix a net negative charge known as a “fixed charge density,” with a charge spacing of 1–2 nm per GAG (Maroudas et al. 1969).
Biomolecules and Tissue Properties
Published in Joseph W. Freeman, Debabrata Banerjee, Building Tissues, 2018
Joseph W. Freeman, Debabrata Banerjee
Aggrecan has a size of 1–4 × 106 Da with a protein core of 220,000 to 250,000 Da, up to 50 keratan sulfate chains and 100 chondroitin sulfate chains attached. Aggrecan molecules can form macromolecular complexes of 300–400 × l06 Da. Aggrecan contributes to the mechanical and physicochemical properties of cartilage. Aggrecan monomers have two extended regions that carry the most of the GAGs and three globular domains, G1 and G2 at the N-terminus and G3 at the C-terminus of the core protein.
Low deacetylation degree chitosan oligosaccharide protects against IL-1β induced inflammation and enhances autophagy activity in human chondrocytes
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Ruiqi Cao, Haomiao Yu, Huibin Long, Hongrui Zhang, Chao Hao, Lin Shi, Yuguang Du, Siming Jiao, Ai Guo, Lifeng Ma, Zhuo Wang
The most significant pathological features of OA are the degradation of collagen II and aggrecan, two main components of extracellular cartilage matrix (ECM), causing the destruction of the biomechanical properties of articular cartilage [8]. The etiology of OA is multifactorial, and the exact pathogenesis has not been fully elucidated. Studies have shown that inflammatory factors such as interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) play vital roles in the progression of OA [9]. IL-1β initiates the activation of inflammation-related signal pathways, stimulates the expression of MMP13 and ADAMTS5 while inhibits collagen II synthesis and proteoglycan production [10,11]. At the same time, the release of inflammatory factors mediates the occurrence of pathophysiological processes such as chondrocyte apoptosis and autophagy, which in turn leads to anabolic disorders of chondrocytes, affects the steady state of ECM, and further causes OA [12]. Exploring drugs that could inhibit OA progression and investigating the mechanisms of related signal pathways are crucial to the clinical prevention and early treatment of OA.
Natural Polymeric Scaffolds for Tissue Engineering Applications
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Previous studies have shown that collagen 111 interacts with collagen 11, but there is need to provide more understanding on its’ role as a structural component of cartilage [161,162]. This is why Wang et al. [163] determined the effects of type 111 collagen presence on the structural integrity and biomechanical functions of articular cartilage and meniscus. This collagen 111 is an essential matrix present in both collagen 11-rich articular cartilage and collagen 1-dominated meniscus which shows its’ regenerative ability across different tissue types. This is because, the collagen ensured fibril homogeneity though its’ reduction increased fibrils heterogeneity, while inhibiting aberrant fibril thickening in type 11 collagen rich articular cartilage as well as the type 1 collagen—dominated meniscus since the collagen 11 demonstrates a lower inherent capability in forming thickened fibrils [164]. This is because of several reasons. First, collagen 111 determines the compressive properties of aggrecan networks in cartilage. This is through its’ influence on the integration of aggrecan with the collagen fibrilla network. Research has shown that a 50% compressive molecular strain is possible in unloaded cartilage, as the porous collagen fibrilla network prevents the aggrecan—HA aggregates [165].
Three-dimensional duck’s feet collagen/PLGA scaffold for chondrification: role of pore size and porosity
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Jeong Eun Song, Nirmalya Tripathy, Se Rom Cha, Sung Hyun Jeon, Soon Yong Kwon, Dong Sam Suh, Gilson Khang
RT-PCR was performed to confirm the phenotype of costal chondrocytes cultured at a density of 1 × 105 cells in 80 wt% DC/PLGA scaffolds. After the removal of culture medium, RNA was extracted from the scaffolds with cell using 1 mL of trizol(RNAiso Plus, Takara, Japan) and 0.2 mL chloroform (Sigma Aldrich, USA), which was then centrifuged at 12,000 rpm, 4 °C for 15 min. The supernatants were then transferred to a new tube and precipitated with 0.5 mL isopropanol (Sigma-Aldrich, USA) and 5 μL polyacryl carrier (Molecules Research Center, Inc., USA). The extracted RNA such as β-actin, aggrecan, type-I collagen and type-II collagen was transcribed with TOPscript™ One-step RT PCR DryMIX (Enzynomics, Korea). Amplified DNA after PCR separated via electrophoresis on 1.2% (w/v) agarose gel containing ethidium bromide (Sigma-Aldrich, USA) and visualized under UV light (Vilber Lourmat ETX-20.M, France) at 300 nm. The mRNA expressions of aggrecan, type-I collagen and type-II collagen were normalized according to the housekeeping gene, β-actin.