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Mesenchymal stem cells, or MSCs, are multipotent stromal cells that can differentiate into a variety of cell types, including: osteoblasts (bone cells), chondrocytes (cartilage cells), myocytes (muscle cells) and adipocytes (fat cells). This phenomenon has been documented in specific cells and tissues in living animals and their counterparts growing in tissue culture. ==Definition== While the terms ''mesenchymal stem cell'' and ''marrow stromal cell'' have been used interchangeably, neither term is sufficiently descriptive: * Mesenchyme is embryonic connective tissue that is derived from the mesoderm and that differentiates into hematopoietic and connective tissue, whereas MSCs do not differentiate into hematopoietic cells. * Stromal cells are connective tissue cells that form the supportive structure in which the functional cells of the tissue reside. While this is an accurate description for one function of MSCs, the term fails to convey the relatively recently discovered roles of MSCs in the repair of tissue. * Because the cells, called MSCs by many labs today, can encompass multipotent cells derived from other non-marrow tissues, such as placenta, umbilical cord blood, adipose tissue, adult muscle, corneal stroma or the dental pulp of deciduous baby teeth, yet do not have the capacity to reconstitute an entire organ, the term multipotent stromal cell has been proposed as a better replacement. The youngest, most primitive MSCs can be obtained from the umbilical cord tissue, namely Wharton's jelly and the umbilical cord blood. However the MSCs are found in much higher concentration in the Wharton’s jelly compared to the umbilical cord blood, which is a rich source of hematopoietic stem cells. The umbilical cord is easily obtained after the birth of the newborn, is normally thrown away, and poses no risk for collection. The umbilical cord MSCs have more primitive properties than other adult MSCs obtained later in life, which might make them a useful source of MSCs for clinical applications. An extremely rich source for mesenchymal stem cells is the developing tooth bud of the mandibular third molar. While considered multipotent, they may prove to be pluripotent. The stem cells eventually form enamel, dentin, blood vessels, dental pulp, and nervous tissues, including a minimum of 29 different unique end organs. Because of extreme ease in collection at 8–10 years of age before calcification, and minimal to no morbidity, they will probably constitute a major source for personal banking, research, and multiple therapies. These stem cells have been shown capable of producing hepatocytes. Additionally, amniotic fluid has been shown to be a rich source of stem cells. As many as 1 in 100 cells collected during amniocentesis has been shown to be a pluripotent mesenchymal stem cell.〔(【引用サイトリンク】url=http://cordadvantage.com/cord-tissue-banking.html )〕 Adipose tissue is one of the richest sources of MSCs. There are more than 500 times more stem cells in 1 gram of fat than in 1 gram of aspirated bone marrow. Adipose stem cells are actively being researched in clinical trials for treatment of a variety of diseases. The presence of MSCs in peripheral blood has been controversial. However, a few groups have successfully isolated MSCs from human peripheral blood and been able to expand them in culture. Australian company Cynata also claims the ability to mass-produce MSCs from induced pluripotent stem cells obtained from blood cells using the method of K. Hu et al. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「mesenchymal stem cell」の詳細全文を読む スポンサード リンク
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