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Usage of Additive Manufacturing in Customised Bone Tissue-Engineering Scaffold
Published in Harish Kumar Banga, Rajesh Kumar, Parveen Kalra, Rajendra M. Belokar, Additive Manufacturing with Medical Applications, 2023
There are three distinct stages in bone healing that overlap each other – namely, a. early inflammatory stage, b. repair stage, and c. late remodelling stage. The inflammatory stage involves the development of a haematoma at the injury site within the first few hours or days. Monocytes, macrophages, polymorphonuclear cells, lymphocytes and fibroblasts form the infiltrate which enters the site of injury upon prostaglandin mediation. This process leads to the development of a granulation tissue, angiogenesis and mesenchymal cell migration. The nourishment at this stage of healing is provided by muscle and exposed cancellous bone. As the repair stage begins, fibroblasts initiate stroma formation which in turn provides support to vascular ingrowth. With the progression of vascular ingrowth, collagen matrix begins to become established with the laying down of osteoid which in turn undergoes mineralisation. These events eventuate into soft callus formation at the repair site (Bayliss et al., 2012).
Hormonal Regulation of Sodium, Potassium, Calcium, and Magnesium Ions
Published in Robert B. Northrop, Endogenous and Exogenous Regulation and Control of Physiological Systems, 2020
The action of PTH on bone cells is complex. There are three major types of bone cells involved with the control of [Ca++]: osteoclasts, which break down bone salts to release calcium and P04 ions, and osteoblasts and osteocytes. Osteoblasts build up bone, forming crystalline bone “salts” in an organic cell matrix. The principal bone salt is hydroxyapatite, with the formula Ca10(PO4)6(OH)2. Other bone salts can contain Mg, Ma, K, and HCO3−.59 Osteoblasts also lay down a collagen fiber matrix (osteoid) into which the bone salts are deposited. Some osteoblasts become entrapped in the interior of the osteoid; these are the osteocytes of mature bone. The osteocytes and osteoblasts form a thin, single-cell-thick membrane around each bone, called the osteocytic membrane system. The osteocytic membranes form a barrier between the bone and the extracellular fluid space. The small amount of fluid between the bone and the osteocytic membranes is called bone fluid. The osteocytic membrane system cells normally pump calcium ions from the bone fluid into the IF.
Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Published in Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White, Advances in Spinal Fusion, 2003
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White
Osteoblasts are bone-building cells and are responsible for bone formation, maintenance, and degradation through their influence on osteoclast function. They are mesenchymal stem cells (MSC) derivatives and proceed through a number of osteoblastic iterations throughout their lifecycle. This cycle begins after the MSC is exposed to the appropriate environmental cues, both chemical and mechanical, and starts to express various preosteoblast characteristics. This includes expression of nuclear transcription factors such as core binding factor alpha 1 (CBFA1), protein production to include alkaline phosphatase and collagen type I (col I), and responsiveness to growth factors and cytokines such as prostaglandin (PGE2), epidermal growth factor (EGF), and transforming growth factor (31 (TGF-(31) [1-3]. Determination of the osteoblast phenotype by morphology alone is near impossible; therefore, functional classification based on extracellular matrix (ECM) is preferred. As the osteoblast matures, protein production alters and the ECM develops into mature bone matrix with the addition of osteopontin, osteonectin, and osteocalcin, all of which are important for mineralization of the osteoid either in the development or in the ossifying callus of the spinal fusion site. Osteoclasts
The analogies between human development and additive manufacture: Expanding the definition of design
Published in Cogent Engineering, 2019
L. E. J. Thomas-Seale, J. C. Kirkman-Brown, S. Kanagalingam, M. M. Attallah, D. M. Espino, D. E. T. Shepherd
Intramembranous ossification which forms the skull bones is initiated by the proliferation of neural crest-derived mesenchymal cells; some form vessels and some differentiate into osteoblasts (Gilbert, 2003). The osteoblasts secrete an unmineralised osteoid matrix, into which calcium is deposited to form the calcified matrix, in which the osteocytes, become embedded (Moore et al., 2013a). Conversely, endochondral ossification, which forms the long bones, demonstrates an intermediate step where tissue is transformed from cartilage to bone. The mesenchymal cells, condense into nodules and differentiate into chondrocytes which secrete the molecules required for the extracellular matrix of cartilage (Schoenwolf et al., 2015). The subsequent hypertrophy of the chondrocytes has two key functions, firstly they secrete vesicles into the extracellular matrix, the enzymes of which initiate the mineralisation process (Gilbert, 2003) and secondly they lengthen the bone (Preston & Wilson, 2013).
Effect of cellulose nanocrystals on chitosan/PVA/nano β-TCP composite scaffold for bone tissue engineering application
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Asif Ali, Saleheen Bano, Satish Poojary, Ananya Chaudhary, Dhruv Kumar, Yuvraj Singh Negi
SEM images were used to study the morphology and density of attached cells on the matrix of biomaterials. All five samples exhibited cell attachment tendency. The cells observed under SEM were unevenly dispersed on the matrix and round in shape during initial phase of cell adhesion (24 h), On the contrary, spindle-shaped morphology of cells can be seen when the culture time was increased to 72 h (Figure 10). Such morphology is usually observed in the late stages of cell adhesion with the expression of lamellopodia and filopodia. Samples with 1% and 5% CNC content were observed to possess high cell density on biomaterial surface than other samples, along with filopodia extensions (72 h culture). Surface roughness, stiffness and nature of adsorbed proteins are some of the major factors governing cell adhesion and proliferation [29]. Since incorporation of β-TCP and CNC have altered stiffness and surface roughness of the biomaterial, a significant variation in cell attachment was observed on tuning CNC concentration in the matrix resulting from changes in cell-material interaction. The scaffolds also exhibited calcium deposition on the surface of scaffold matrix which were clearly observed after culture for 72 h (Figure 11) .These depositions are mainly laid down by osteoblasts. The calcium deposits are known to provide mechanical strength to osteoids or pre-mineralized bone. Osteoid mainly comprises of collagen, polysaccharides and fibrous proteins which after mineralization integrate to start new bone tissue formation. EDX results revealed highest calcium deposition of 29.48% by MG63 cells on 5%CNC scaffold. Increase in CNC concentration to 10% decreased calcium deposits to 2.01%. Increase in CNC content from 1 to 5% raised the calcium deposition to a significant level which clearly indicates that the calcium deposition on scaffold surface by osteoblast can be tuned by altering the concentration of CNC.