Embryonic stem cells source

Brustle O, Jones KN, Learish RD, Karram K, Choudhary K, Wiestler OD, Duncan ID, McKay RD (1999) Embryonic stem cell-derived glial precursors a source of myelinating transplants. Science 285 754-756... 

Knowledge gained from cell adhesion studies with SAMs has been used to develop culture substrates with the appropriate cell adhesion glycoproteins for different types of cells [7-10], Stem cells, capable of self-renewal and differentiation into multiple cell types, are found in embryonic and adult tissues. Pluripotent stem cells, like embryonic stem cells and induced pluripotent stem cells, have been developed in vitro. These cells are expected to provide cell sources for regenerative medicine. Various culture conditions have been developed to enable expansion of these cells without loss of their multi- and pluripotency and to induce differentiation into viable cells with specific functions. 

Such cells are often classified on the basis of their original source as either embryonic or adult stem cells. As the name suggests, embryonic stem cells are derived from the early embryo, whereas adult stem cells are present in various tissues of the adult species. Much of the earlier work on embryonic stem cells was conducted using mouse embryos. Human embryonic stem cells were first isolated and cultured in the laboratory in 1998. Research on adult stem cells spans some four decades, with the discovery during the 1960s of haematopoietic stem cells in the bone marrow (Chapter 10). However, the exact distribution profile, role and ability to manipulate adult stem cells (particularly those outside of the bone marrow) are subjects of intense current research, and for which more questions remain than are answered. 

In November 2003, the members of the Europe Parliament voted to approve embryonic stem cell research, using techniques similar to that adopted for cloning Dolly the sheep, although severe restrictions were put in place. For US scientists, however, the US legislation meant that they were only allowed to performed research using 12 existing sources of the embryonic stem cells and were not allowed to create any new sources. 

Pouton, C.W and Haynes, J.M. (2007) Embryonic stem cells as a source of models for drug discovery. Nature Reviews. Drug Discovery, 6 (8), 605-616. 

Cell types of various sources and merits, such as cells derived from embryos - embryonic stem cells - from fetuses, or from tissues and organs, have been considered for cellular therapy in the CNS. Because they do not carry ethical and political concerns, and allow rewiring of the CNS, adult NSCs offer of model of choice for cellular therapy. Aside from the ethical and political concerns, NSCs offer a powerful tool for cellular therapy, particularly for cellular transplantation. 

Several sources have reported using stem cells including embryonic stem cells, adult liver progenitors, and transdifferentiated nonhepatic cells in cell-based thera-pies. Hepatocyte lineage in vitro has been reported in murine embryonic stem cells." It is apparent that hematopoietic stem cells can generate hepatocytes directly. This has been shown in rodent models and confirmed in humans by a study of recipients of bone marrow and liver transplants. ... 

The value of cultured stem cells to toxicology is in their promise as a continuous source of cells that can be induced to express a chosen cell-type-specific mature phenotype. This achievement would address two current limitations in safety testing scarcity of metabolically competent human systems and use of experimental animals. Numerous culture additives and conditions have been identified that cause commitment and partial differentiation along specific lineages, such as retinoic-acid-induced neuronal commitment of mouse embryonic stem cells. However, definition of conditions that produce fully differentiated cells with cell-type-specific function quantitatively similar to that of intact tissue remains problematic and is a high-priority research area in toxicology. 

Stem cells. Embryonic and adult stem cells are distinguished. Embryonic stem cells are taken from an early stage of the embryo, such as from blastocytes. They are undifferentiated and totipotent. Their potential to differentiate and to form different cell lines is unlimited. Adult stemcells are taken from the blood forming bone marrow, from epithelial cells from the skin and other sources. They are pluripotent. Both, embryonic totipotent and adult pluripotent stem cells can replace functionally differentiated cells and tissues in the body. Stem cells can divide. After division, they may form again a stem cell or proceed to a final, fully differentiated state. 

Stem cells normally are classified, based on their origin and differentiation capacity, as either embryonic or adult stem cells (1). Embryonic stem cells (ESCs) are derived from the inner cell mass of the blastocyst. ESCs can self-renew indefinitely and are pluripotent—(the ability to differentiate into all cell types in the embryo proper). Adult stem cells are undifferentiated (unspecialized) cells that are found in differentiated, or specialized, tissue. They have limited self-renewal capability and generally can only differentiate into the specialized cell types of the tissue in which they reside. These cells function as the reservoir for cell/tissue renewal during normal homeostasis or tissue regeneration. Sources of adult stem cells have been found in most tissues, including bone marrow, blood stream, cornea... 

Other cell sources have therefore been explored as alternatives. They include olfactory ensheathing cells, embryonic stem cells, mesenchymal stem cells [6,114], and even cell lines such as the immortalized SCTM41 Schwann cells [115]. Genetic modification has been considered for implanting cells as a constant source of growth factors. Most often, fibroblasts have been engineered with this intention, e.g., to produce neurotrophins, CNTF and FGF-2 [116, 117]. 

Mobilis in Mobile - Human Embryonic Stem Cells and Other Sources for Cell Therapy... 

Most of the aforementioned donor cells are derived from different types of stem cells. AU stem cells - whether from adult or embryonic sources - share a number of properties [24]. First, they are capable of self-renewal, which means that they can generate stem cells with similar properties. Second, the stem cells are clonogenic, which means that each cell can form a colony in which all the cells are derived from this single cell and have identical genetic constitution. Third, they are capable of differentiation into one or more mature cell types. The different stem cells can be categorized anatomically, functionally, or by cell surface markers, transcription factors, and the proteins they express. One clear division of the stem cell family is between those in adult somatic tissue (known as adult stem cells) and those isolated from the embryo (known as embryonic stem cells) (see Part I, Chapter 11). 

Several ceU sources have been used for experimental ceU therapy approaches pluripotent stem cells like embryonic stem cells from the blastocyst and embryonic germ cells [47, 48], human cord-blood derived cells [49], but also cultured cell lines. Neural stem cells (stem cells forming neuronal as well as glial cell lineages) isolated from different parts of the brain known to harbor multipotent neural stem cells [50-52] are also an option. In a non-neurode-generative indication, a cultured cell line was used to treat patients after stroke in a pilot clinical trial. The cells were transplanted in the paramedian plane and treatment was reported to be safe, with signs of efficacy [53]. 

Dismore J, Ratliff J, Deacon T, Pakzaban P, Jacoby G, Galpem W, Isacson O. Embryonic stem cells differentiated in vitro as a novel source for transplantation. CeU Transplant 1996, 5, 131-143. 

Organogenesis by Embryonic Renal Progenitors and Additional Stem Cell Sources... 

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