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Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Stem cell niche is the microenvironment in which a stem cells is situated. During development, the niche may contain various factors and elements that alter gene expression within the stem cell, causing the cell to differentiate and proliferate into various tissues of the fetus. In developed tissue, the niche may help maintain stem cells in a quiescent state, until injury or disease signals them to self-renew and differentiate to replace the damaged tissue. Niche elements may include interactions with other cells, adhesion molecules, growth factors, cytokines and parameters such as pH, ionic strength and gas composition. Scientists study niche characteristics in order to replicate them in vitro, to control and direct the differentiation of stem cells in the laboratory.
Principles and Biological Pathways to Tissue Regeneration: The Tissue Regenerative Niche
Published in Claudio Migliaresi, Antonella Motta, Scaffolds for Tissue Engineering, 2014
Ranieri Cancedda, Claudia Lo Sicco
vide key elements necessary for tissue repair. According to the traditional tissue engineering approach, stem cells are explanted from a patient, expanded in vitro and re-administered to the patient as a cell suspension or in association with a suitable biomaterial. The rapidly developing knowledge about the developmental pathways occurring during the healing process adds fascinating information about the natural response of the body to injury, suggesting a novel approach based on the activation of the endogenous regenerative capacity of the tissue itself. The proper functioning of all tissues of the body depends upon innate regenerative processes that maintain proper cell numbers (homeostasis) and replace damaged cells after injury (repair). This regenerative potential correlates with the presence of a dedicated population of stem/progenitor cells in the tissues, which respond to exogenous signal to produce replacement cells when needed for a physiological turnover or for repair/regeneration of tissues damaged by diseases or injuries. The balance between tissue homeostasis and appropriate responsiveness for cell replacement and repair is accomplished by maintaining stem cells in a specialized microenvironment, or niche, which provides spatial and temporal cues to support and coordinate stem cell activities [Wagers, 2012]. The stem cell niche is originally recognized as a specific anatomic location that regulates stem cell fate decisions, including choices between quiescence or proliferation, self-renewal or differentiation, migration or retention, and cell death or survival [Doetsch, 2003].
Stem Cells
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Ana-Matea Mikecin, Grdisa Mira
SC self-renewal and differentiation are influenced by various signals which are tightly regulated by the stem-cell niche. Stem-cell niche is a microenvironment where the SC is found, and that is responsible for maintaining SCs in pluripotent form with the potential to self-renew. In general, SC fate is regulated by SC’s niche (Morrison and Spradling, 2008). Maintenance of the niche is achieved through environmental cues as well as certain signaling pathways that include Wnt (Nusse, 2008), JAK-STAT (Beebe et al., 2010), Notch (Androutsellis-Theotokis et al., 2006) and Hedgehog (Conia et al., 2013) signaling pathways. These signaling pathways are closely linked to developmental processes and regulation of SC self-renewal. They are also frequently found deregulated in cancer.
The individual and combined effects of spaceflight radiation and microgravity on biologic systems and functional outcomes
Published in Journal of Environmental Science and Health, Part C, 2021
Jeffrey S. Willey, Richard A. Britten, Elizabeth Blaber, Candice G.T. Tahimic, Jeffrey Chancellor, Marie Mortreux, Larry D. Sanford, Angela J. Kubik, Michael D. Delp, Xiao Wen Mao
The role of gravity in maintaining tissue homeostasis has become apparent with expanded study examining the effects of spaceflight on mammalian physiology. Dysfunction in stem cell populations contribute to many Earth-based disease conditions and can be enhanced by aging, oxidative stress, and genetic predisposition.206,207 Adult stem cell populations are found in multiple physiological systems throughout the body and are surrounded by a highly organized and regulated microenvironment consisting of supporting cells and factors, resulting in the formation of a stem cell niche.208 Following injury, damage, or normal cell attrition, stem cells within the niche receive signals resulting in transition to an active state and initiation of the differentiation process.209 Therefore, in order for regeneration of damaged tissues to occur, resident stem cell pools must be activated and induced to differentiate into lineage specific cells.210 Such activation signals may be biochemical or mechanical in nature, and therefore may be affected by exposure to microgravity. Spaceflight exposure may result in premature aging of specific physiological systems, and loss of stem cell functions may contribute to the initial observed tissue degeneration but more importantly, may be linked to regenerative deficits during long-duration spaceflight exposure beyond LEO.
Influence of extracellular cues of hydrogel biomaterials on stem cell fate
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Haley Barnett, Mariya Shevchuk, Nicholas A. Peppas, Mary Caldorera-Moore
One of the major challenges in designing hydrogels for use as tissue engineering scaffolds is reproducibly directing the differentiation of stem cells to the desired fate. This is typically done by mimicking the native ECM of the desired tissue to recapitulate the instructive signals of the stem cell niche. Hydrogels can be modulated in various ways to direct stem cell fate to specific lineages. Four key aspects of hydrogel design to direct cell fate are discussed below (Figure 4), followed by examples of specific applications of hydrogels in tissue engineering.