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Tissue Engineering: overview of biochemical data and mechanical modeling
Published in Benjamin Loret, Fernando M. F. Simões, Biomechanical Aspects of Soft Tissues, 2017
Benjamin Loret, Fernando M. F. Simões
It might be important to precise the terminology and distinguish the modes, growth, atrophy and structuration, through which biological processes like development, maintenance, aging and healing occur. In particular, growth is defined as the creation of mass, also referred to as mass deposition, and atrophy as the loss of mass. Growth may occur by change of the number of cells (hyperplasia), by change of the size of the cells (hypertrophy), or by change of the mass of the extracellular matrix. Structuration or re-structuration is usually understood to involve changes in microstructure and material properties in order to adapt to a new environment. Morphogenesis refers to the molding and shaping of tissues and organs, and concerns the relations between forms and biological functions.
Engineering Biomimetic Scaffolds
Published in Claudio Migliaresi, Antonella Motta, Scaffolds for Tissue Engineering, 2014
Nasim Annabi, Nihal Engin Vrana, Pinar Zorlutuna, Fariba Dehghani, Ali Khademhosseini
cannot in adulthood. Morphogenesis, the path of development in which a given organism assumes its shape, is strongly affected by the presence of physical and biochemical cues. Scaffolding can be viewed as a radical approach to morphogenesis, as it is used as a template for seeded cells to regenerate the final structure via its initial architecture and with the aid of bioactive agents. However, the distinct difference between the embryo where 3D cell aggregates turn into well-structured organs and the remodeling process of an artificial scaffold of cells to create a semblance of their in vivo environment should be taken into consideration.109 Thus, it can be argued that instead of engineering the cellular compositions and the scaffold, it may be useful to engineer the actual process of the cellular remodeling of fabricated structure. Each step of scaffold remodeling then matches a developmental stage and biochemical signal plays a critical role in this process.110 Growth factors both in liquid and solid phase have a direct control on the outcomes of biological events. Stem cell differentiation, phenotype changes, cell proliferation, angiogenesis, apoptosis, and many other cellular activities are directly controlled by biochemical signals. One approach to mimic this process is to use gradients of growth factors or other bioactive agents within tissue engineering scaffolds. Gradients of bioactive agents can be achieved by direct printing techniques such as inkjet printing,111 inclusion in the certain parts of the scaffolds by micro-and nanopatterning techniques,112 or by microfluidics methods.113 A common method is the covalent conjugation of growth factors into the scaffold to mimic the actual structure that exists in vivo (i.e., bound to the ECM) (Fig. 7.6). This approach can be coupled to patterned surfaces to control the cellular differentiation by the gradients of different growth factors in microscale distances.114 Compared to supplying growth factor exogenously, the approach of using covalent bonding and production of gradients of growth factors is beneficial as it prolongs their effects. This effect is mainly due to the fact that the growth factors in solution can easily diffuse away or can be degraded. The in vivo processing of growth factors is the topic of another line of study, which aims to exert control over temporal presence of bioactive signals. As growth factor stimulation also has a temporal aspect, methods that can mimic the removal of biochemical cues are in development. For example, recently a modified peptide sequence which contained both photo-degradable and photo-crosslinkable moieties, which can be incorporated into
Is order creation through disorder in additive manufacturing possible?
Published in Cogent Engineering, 2021
Frédéric Demoly, Jean-Claude André
Morphogenesis is the set of processes that will give shape to an organism. Perhaps we should examine the movements of a certain number of social insects (e.g., bees, ants, termites), fishes, birds, etc. that know how to move in a complex environment and for some of them build habitats that are themselves complex according to specific forms: “why is the group coherent while each individual seems autonomous? How are the activities of all individuals coordinated without supervision? Ethologists who study the behaviour of social insects observe that cooperation within colonies is self-organized: it often results from interactions between individuals” (Bonabeau et al., 1999; Bonabeau & Théraulaz, 2000). What Nature knows how to do with ants or termites, Man is beginning to understand and do, but the application stage in additive manufacturing is at best only in its infancy. Nevertheless, if we can be satisfied with shapes that are not very precise, it is not impossible to envisage a very flexible process for making intelligent objects …
Directing chemotaxis-based spatial self-organisation via biased, random initial conditions
Published in International Journal of Parallel, Emergent and Distributed Systems, 2019
Sean Grimes, Linge Bai, Andrew W.E. McDonald, David E. Breen
Like Pfeifer et al. [31], we turn to biology and self-organisation for insights into the design of autonomous robots, robotic swarms in our case. Our previous work in self-organising shape formation [2,32] is inspired by developmental biology [33] and morphogenesis [34], and builds upon a chemotaxis-based cell aggregation simulation system [35]. Morphogenesis is the process that forms the shape or structure of an organism through cell shape change, movement, attachment, growth, and death. We have explored chemotaxis as a paradigm for agent system control because the motions induced by chemotaxis (one of the mechanisms of morphogenesis) may produce patterns, structures, or sorting of cells [36].