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Vitro Alzheimer’s Disease Modeling Using Stem Cells
Published in Hyun Jung Kim, Biomimetic Microengineering, 2020
Hyun-Ji Park, Song Ih Ahn, Jeong-Kee Yoon, Hyunjung Lee, YongTae Kim
Obtaining tissue-specific cells from PSCs [e.g., embryonic stem cell (ESC) and iPSC] begins with the replication of embryonic development in a dish. The development of the CNS in embryogenesis starts from a trilaminar embryo with the formation of notochord and somites (Stemple 2005). Both notochord and somites, which are the sources of ectoderm, do not contribute to the nervous system themselves but are associated with the patterning of the initial CNS formation. The central part of the ectoderm forms a neural plate to develop the neural tube further and eventually turns into the entire nervous system (Stemple 2005). The morphogen gradients play essential roles in determining the location, differentiation, and fate of each cell during embryonic development. For example, the ventral identity of the CNS is induced by spatial gradients of sonic hedgehog (SHH) and bone morphogenic protein 7 (BMP 7) (Patten and Placzek 2000, Lupo, Harris, and Lewis 2006). Researchers leverage this idea to develop a variety of cell differentiation protocols to generate in vitro disease model systems for the AD. Protocols for direct stem cell differentiation toward AD neurons have been applied the extrinsic signaling conditions from developmental events.
Articular Cartilage Development
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
Morphogenesis and Morphogens: Morphogenesis is the developmental process of pattern formation and body plan establishment that culminates in the adult form of the whole human body, including component tissues and organs, such as articular cartilage and joints. Morphogens are extracellularly secreted proteins governing morphogenesis during development. They comprise four evolutionarily conserved protein families: bone morphogenetic proteins (BMPs), fibroblast growth factors (FGFs), hedgehog proteins (HHs), and wingless and int-related proteins (Wnts). These morphogen families exhibit redundant and reiterative signaling with distinct spatial and temporal expression during initiation of morphogenesis, including pattern formation, body plan establishment, bilateral symmetry, and attendant cytodifferentiation.
The positional information grid in development and regeneration
Published in David M. Gardiner, Regenerative Engineering and Developmental Biology, 2017
Susan V. Bryant, David M. Gardiner
In earlier years, much attention was focused on the signals that control cell proliferation. With the explosive growth of developmental genetics, the focus shifted to the gene regulatory networks that control differentiation and pattern formation, which has led to the recognition of the function of morphogens. Morphogens are molecules that are critically involved in, and essential for, normal development and regeneration. They are made at a localized source and diffuse away from the source, creating a morphogen gradient across a field of cells (see Gilbert 2013; Wolpert et al. 2015). They earned their name as a result of the effects that experimental changes in morphogen levels (e.g., exposure to exogenous factors) have on developing systems—they alter the morphology of the embryo and cause supernumerary structures to form. Thus, morphogens are obvious candidates for the signaling molecules that function as part of the PI grid.
Bifurcation analysis and spatiotemporal patterns in delayed Schnakenberg reaction-diffusion model
Published in Applicable Analysis, 2023
Taking into consideration of delays in the kinetics of morphogen interactions due to gene expression dynamics, Lee et al. [28] have constructed models of morphogen self-organization on domains due to gene expression based on the typical Schnakenberg model (1). In [28], the possibilities for Turing patterns have been investigated with numerical results. The Schnakenberg kinetics with gene expression time delay is described by: For the delayed reaction-diffusion system, such as predator-prey systems in [29–32] and activator-inhibitor systems in [33], delay-induced Hopf bifurcation has been extensively analyzed. The most relative works investigating delay-induced bifurcation problems in the Schnakenberg model have been presented by Yi et al. [34] and Jiang et al. [35].
Turing instabilities in a glycolysis reaction-diffusion system
Published in Applicable Analysis, 2023
In his seminal paper [2], Turing ‘suggests that a system of chemical substances reacting together and diffusing through a tissue, is adequate to account for the main phenomena of morphogenesis’. He introduces several concepts associated with the chemical basis of morphogenesis (and the name morphogen itself), spatial chemical patterns, and what is now called Diffusion Driven Instability [3].