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Foams in Tissue Engineering
Published in S. T. Lee, Polymeric Foams, 2022
Chenglong Yu, Zhutong Li, Leah K. Gause, Huaguang Yang, Lih-Sheng Turng
Adult stem cells have high renewal and multi-differentiation capabilities, and the 3D microenvironment they are in provides various signals to extremely affect their differentiation, such as cell-cell, cell-ECM interaction, and mechanical forces [128]. Adult stem cells mainly include hematopoietic stem cells, bone marrow stem cells, neural stem cells, adipose stem cells, and skin stem cells [129]. As an intermediate between totipotent cells and differentiated mature cells, adult stem cells possess the most promising potential for clinical applications; however, there are currently some difficulties to overcome. First, it is difficult to separate stem cells just based on cell morphology and growth characteristics due to low content and unclear specific markers of adult stem cells. Second, slow growth and difficulty in expansion of adult stem cells also restrict their clinical applications [124,129].
Gene Therapy in Tissue Engineering: Prospects and Challenges
Published in Rajesh K. Kesharwani, Raj K. Keservani, Anil K. Sharma, Tissue Engineering, 2022
Unlike ESCs, research in adult stem cells does not call for ethical issues as no killing of embryo is involved; rather the cells are obtained from human body. Also known as somatic stem cells, these are undifferentiated cells present in every tissue and organ of the body that helps to maintain homeostasis and replenish damaged and injured tissues. Adult stem cells are multipotent cells that give rise to cell types of one particular tissue and are believed to reside in specific niches. They exhibit tissue-specific characteristics and are defined by expression of specific cell-surface markers and transcription factors (Figure 3.7). These cells mostly remain dormant throughout the lifespan of an individual in certain organs such as brain and heart, till they are triggered by a tissue injury, disease, or other factors to replenish the tissue. While in other tissues such as blood marrow and gut lining, it is continuously being replenished. Though they hold a lot of promise for future therapeutics, many limitations need to be overcome to consider them for clinical application.
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
There are mainly two types of stem cells: pluripotent stem cells (PSCs) and adult stem cells. PSCs include embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). The ESCs produced from the inner cell mass of the blastocyst tend to differentiate into various forms of cell types (Thomson et al., 1998). In various cases, the somatic cells are reprogrammed using pluripotent genes, are allowed to retrieve the properties of pluripotent cells (Takahashi et al., 2007; Yu et al., 2007) and are referred to as iPSCs. Further, the adult stem cells are categorized into three forms: hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), and neural stem cells (NSCs). Adult stem cells are not preferred due to inadequate proliferation and differentiation potential. Somatic cells produced from fetal tissue sources such as amniotic fluid stem cells are widely used in cell therapy, tissue engineering, drug discovery, and disease modelling due to their massive proliferation and differentiation ability (Trohatou et al., 2013).
Down-regulation of pluripotency and expression of SSEA-3 surface marker for mesenchymal Muse cells by in vitro expansion passaging
Published in Egyptian Journal of Basic and Applied Sciences, 2019
Ali M. Fouad, Mahmoud M. Gabr, Elsayed K. Abdelhady, Sahar A. Rashed, Sherry M. Khater, Mahmoud M. Zakaria
Stem cells can be divided as embryonic and non-embryonic stem cells. Embryonic stem cells are the gold standard for pluripotent stem cells which can differentiate into the three germ layers (ectoderm, endoderm and mesoderm). In the developing embryo, pluripotent stem cells are the origin of somatic and germline cells [1]. Adult stem cells as embryonic stem cells are all undifferentiated cells. However, the differentiation capacity of adult stem cells is limited to its origin. Hematopoietic and mesenchymal stem cells are the main identified types of adult stem cells, hematopoietic stem cells can be obtained from bone marrow, umbilical cord blood, and peripheral blood and are capable of generating all cell lineage found in mature blood [2]. While mesenchymal stem cells, in the suitable environment have the ability to differentiate into chondrocytes, adipocytes and osteocytes [3], and can be obtained from bone marrow as a primary source, fat tissue and umbilical cord [4]. In 2006, a scientific breakthrough was performed by Yamanaka and colleagues after generating pluripotent stem cells from somatic cells by genetic manipulation with pluripotent markers, these cells are called induced pluripotent stem cells (iPSCs) [5].
Reconstruction of calvarial bone defects using poly(amino acid)/hydroxyapatite/calcium sulfate composite
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Xiaoxia Fan, Haitao Peng, Hong Li, Yonggang Yan
In recent years, the focus has shifted to bone morphogenetic proteins and adult stem cells, owing to the limited regenerative capability of bone tissue when natural healing capabilities are insufficient or compromised [11]. However, growth factors are expensive, and at high levels they may increase the risk of cancer and other complications [12,13]. Practical issues with adult stem cells include low stem cell yield per harvest, the need for expansion, and the morbidity imposed on the donor. Therefore, there is an urgent need for the development of synthetic scaffolds with better repair properties to repair large calvarial bone defects.