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Overview of Recent Trends in Stem Cell Bioprocessing
Published in V. Sivasubramanian, Bioprocess Engineering for a Green Environment, 2018
M. Jerold, V. Sivasubramanian, K. Vasantharaj, C. Vigneshwaran
ESCs have the potential to produce all types of cells due to “pluripotency.” They are derived from the embryonic germ layers, that is, the ectoderm, mesoderm, and endoderm (Smith, 2001). However, the ability to use ESCs is undermined due to their innate tumorigenicity, lack of efficient culture system to manage the differentiation, and ethical constraints. Due to these significant disadvantages, there is greater clinical interest in the application of mesenchymal stem cells (MSCs), which are primary candidates in cell therapy and tissue engineering and are being tested in clinical trials to address a wide range of diseases. MSCs possess self-renewal capacity as well as multilineage differentiation into mesoderm lineages, such as chondrocytes, osteocytes, and adipocytes. They are present in almost all tissues. They can be easily isolated from te bone marrow, adipose tissue, the umbilical cord, fetal liver, muscle, and lung and can be successfully expanded in vitro. Although the major source of MSCs in clinic trials is the umbilical cord, recent studies have suggested that the allogenicity of MSCs has no significant adverse impact on the engraftment of MSCs in wound healing (Chen et al., 2009). It is better to use freshly isolated MSCs because it has been shown that five major histocompatibility complex (MHC II) molecules could be increased during in vitro expansion (Tarte et al., 2010).
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
The final arrangement of the embryonic germ layers occurs as a result of the process of gastrulation. The early-cleavage/blastula-stage embryo is a relatively uniform ball of cells, which rearrange during gastrulation through dramatic morphogenetic movements to form the three germ layers. As a consequence, cells from distant positions in the embryo are brought together, and the inner and outer mesodermal layers of cells begin to interact with the adjacent layers of the endoderm and ectoderm, respectively, between which the mesodermal sheet resides. Most of these early-interacting cells are the progenitors of the cells that will build the structures of the embryo and adult. They acquire specialized functions (e.g., nerves, muscles, and blood cells), but they do not have PI (i.e., they are embryonic progenitors of the pattern-following cells). A much smaller subpopulation of cells has PI and is fated to give rise to the pattern-forming cells. It is unclear at what point in development do cells with PI arise; however, as discussed later, differences in cell fates associated with differences in the cell cycle kinetics of subpopulations of cells become evident during early cleavage stages in Drosophila (Foe 1989; see Bryant and Gardiner 2016). In summary, the PI needed to drive the development of embryonic structures in the right place, at the right time, and of the right size resides in the mesodermal grid. Gastrulation puts the PI grid cells where they are needed in order to interact with all the non-grid cells to build tissues and organs (Bryant and Gardiner 2016).
Stem Cells
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Ana-Matea Mikecin, Grdisa Mira
Stem cells (SC) are unique cells present in multicellular organisms that, unlike other cells, have the potential to differentiate into specialized cells as well as to divide via mitosis to produce more SC. Embryonic stem cells (ESC) are present in an embryo which forms from a fertilized egg. ESCs differentiate in three germ layers–ectoderm, endoderm, and mesoderm–which give rise to all the tissues and organs present in an organism. Adult SC (somatic SC) are undifferentiated cells found in differentiated tissue or organ. The maintenance and repair of many adult tissues are ensured by adult SC, which resides at the top of the cellular hierarchy of these tissues. While ESCs are defined by their origin, the origin of adult SC is still under debate.
Stiffness estimation of transversely anisotropic materials using a novel indentation tester with a rectangular hole
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Atsutaka Tamura, Mika Saiki, Jun-ichi Hongu, Takeo Matsumoto
Gastrulation is an essential step in the development of most animals. This process is fundamental to vertebrate animals, and it is the early developmental stage in which a single layer of cells gives rise to multiple germ layers, enabling the differentiation of the internal tissues of the body (Gilbert 2014; Urry et al. 2016); in other words, the body plan of the animal embryo is shaped through the process of gastrulation. In mammals, a cascade of morphogenesis-related molecular events, e.g. polarization, intercalation, and intercellular adhesion, occurs in specific embryonic territories although knowledge about how the territories grow physically and remodel has remained elusive. Thus, characterization of the early developmental process during gastrulation is important to accurately describe the precise timing of cell-type specification.