China
Africa
Explore chapters and articles related to this topic
Tissue Engineering of Articular 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
Emerging from developmental studies, scaffoldless culture has been proposed as a method to engineer functional articular cartilage of sufficient dimensions (Figure 4.17). For instance, a self-assembling process has been developed, based on the differential adhesion hypothesis, to produce robust cartilage constructs that contained two-thirds more glycosaminoglycan than native tissue, and collagen levels that reached one-third the amount of native tissue. Neocartilage, thus, formed contained collagen type II and chondrocytes in lacunae. More importantly, the compressive stiffness of self-assembled cartilage reached more than one-third of the native tissue values (Hu and Athanasiou 2006b).
Effects of Mechanical Vibration on Bone Tissue
Published in Redha Taiar, Christiano Bittencourt Machado, Xavier Chiementin, Mario Bernardo-Filho, Whole Body Vibrations, 2019
Christiano Bittencourt Machado, Borja Sañudo, Christina Stark, Eckhard Schoenau
Spaces within the bone matrix called lacunae encompass mature osteoblasts named osteocytes, flattened cells responsible for the maintenance of bone tissue, matrix synthesis and resorption to a limited extent. Each osteocyte is incorporated by one lacuna, and the canaliculi are tunnels that make the communication among osteocytes. An interesting finding is that an osteocyte may function like an osteoblast or an osteoclast, depending on the organelles inside them.
Tissue Structure and Function
Published in Joseph W. Freeman, Debabrata Banerjee, Building Tissues, 2018
Joseph W. Freeman, Debabrata Banerjee
Osteocyte lacunae are ellipsoidal-shaped holes within bone that contain osteocytes and extracellular fluid. Their diameters are between 10 and 20 microns. Osteocyte canaliculi are the small tunnels that connect lacunae to one another. Osteocytes have processes that travel through the canaliculi to osteocytes in other lacunae. The processes in these tunnels may allow osteocytes within bone to communicate with one another to coordinate efforts to remodel bone.
The opportunity of using alloplastic bone augmentation materials in the maxillofacial region– Literature review
Published in Particulate Science and Technology, 2019
Simion Bran, Grigore Baciut, Mihaela Baciut, Ileana Mitre, Florin Onisor, Mihaela Hedesiu, Avram Manea
Osteocytes represent 90–95% of the total bone cells, are the most abundant and long-lived cells. They have a lifespan of up to 25 years (Bonewald 2011). Their role was interpreted incorrectly through history, due to different technical errors, but now we have reached the understanding that they serve numerous important functions. They are no longer considered a “placeholder” in the bone, but rather a conductor of osteoclast and osteoblast activity and also an endocrine cell (Bonewald 2007). The osteocytes are placed in interconnected lacunae that are surrounded by a mineralized bone matrix. This way they can act as mechanosensors as their network has the capacity to detect mechanical pressures and loads, which leads to the adaptation of bone to physiological mechanical forces. This explains why the osteocytes act as orchestrators of bone remodeling, by sending orders to osteoblasts and osteoclasts activities. The osteocyte also has the capability to transform mechanical stimuli into biochemical signals, a phenomenon that is called piezoelectric effect (Guo and Yuan 2015). Their capability to secrete growth factors with different functions in the body (e.g., Fibroblast growth factor 23 and its effect on the kidney) contributes to making the bone an endocrine organ (Knothe-Tate 2003; Bonewald 2011; Dallas, Prideaux, and Bonewald 2013; Guo and Yuan 2015).
The application of nanogenerators and piezoelectricity in osteogenesis
Published in Science and Technology of Advanced Materials, 2019
Fu-Cheng Kao, Ping-Yeh Chiu, Tsung-Ting Tsai, Zong-Hong Lin
Bone is a rigid organ that supports and protects various parts of the body. It is highly hierarchical in structure and composed of an extracellular matrix and cellular components: osteoblasts, osteoclasts, osteocytes and bone marrow cells (including hematopoietic cells). The extracellular matrix consists of 65% mineral matrix and 35% organic matrix [4]. Type I collagen makes up about 90% of the organic matrix and possesses a triple helical structure that contributes tensile strength to the extracellular matrix. Inorganic minerals, which are responsible for the compressive strength of bone, are incorporated with the collagen fibrils in the form of calcium hydroxyapatite [5]. Osteoblasts arise from mesenchymal stem cells and are responsible for bone formation. On the other hand, osteoclasts are multinucleated cells deriving from hematopoietic progenitors in the bone marrow and are responsible for bone resorption. Osteocytes are thought to be mechanosensor cells that control the activity of osteoblasts and osteoclasts. They are embedded in lacunae with long processes located in small channels called canaliculi. Canaliculi are considered the lifelines that permit nutrients, oxygen, and waste products to be exchanged with the blood vessels within the Haversian canal, Volkmann canal, and osteocytes. When a bone is loaded, the interstitial fluid within the lacuna and canaliculi is squeezed through a thin layer of non-mineralized matrix surrounding the cell bodies and cell processes toward the Haversian or Volkmann channels. This flow of fluid mobilizes the cell surface glycocalyx and initiates biochemical processes promoting osteogenesis [6].
Multi-scale numerical simulation on mechano-transduction of osteocytes in different gravity fields
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Chaohui Zhao, Haiying Liu, Congbiao Tian, Chunqiu Zhang, Wei Wang
Human skeleton supports and protects the body and movement, and bone is a type of porous tissue full of fluid, which is typically comprised of dense bone, cancellous bone and tissue fluid. The mass and structure of bone are always changing to adapt the continuous change of the mechanical environment, and the daily activities in the gravity field of the Earth can effectively maintain human bone mass. The mechanical environment a human body lives in is quite complex (Weiner et al. 1999). The forces outside the human body (such as gravity), the interaction forces between internal bone tissues, cells (such as tension, fluid shear force and hydrostatic pressure) produced by human movement, and the intracellular tension interaction produced during the formation and change of cytoskeleton, constitute a mechanical system (Mullender et al. 2004). Osteocytes buried in the bone matrix lacunae are the main mechanical signal receptors in bone tissue, which can convert mechanical signals into biological signals that regulate bone remodeling. The activity of effector cells (such as osteoblasts and osteoclasts) and bone remodeling is consequently regulated, and only when mechanical stimulation reaches a certain threshold can the biological function of osteocytes be activated (Bakker et al. 2002; Bacabac et al. 2004). In microgravity, the human body is released from the restraint of gravity and the hydrostatic pressure on the body disappears. This results in the distribution of blood and tissue fluid to the head, which significantly changes the mechanical microenvironment of osteocytes in load-bearing bone of the lower extremities, and affects the mechanical signal perception and conduction of osteocytes. According to aeromedical research, the adaptive changes of bone tissue of astronauts during long-term space flight lead to irreversible disuse osteoporosis, which has become one of the major reasons restricting long-term stay in space. Therefore, mechano-transduction of osteocytes under a variety of gravity fields is critical for bone formation, development and functional maintenance. The cell processes and primary cilium are thought as the main mechanical signal receptors of osteocytes (Singla and Reiter 2006; Satir et al. 2010), capable of transmitting complex mechanical signals for osteocytes.