After Asia. Embryonic Totipotent Cell Biological Characteristics And Differentiation Of Hematopoietic Cells

Recent studies have suggested that there are multipotent stem cells in adult tissues. Stem cell plasticity, i.e., tissue-derived stem cells had the capacity of exhibiting a phenotypic potential that extends beyond the differentiated cell phenotypes of their resident tissue. But the mechanism underlying plasticity remains a matter of debate. We suppose that there is a presently undefined subfraction of stem cell population that exists in a number of tissues beyond embryonic development. We term them postembryonic pluripotent stem cells. They differ from embryonic stem (ES) cells in that they gradually lose some differentiation potentials during development and adopt some special phenotypes once within a certain tissue. They can give rise to different kinds of stem cells; therefore, help to maintain balance during development and metabolism. They provide cells not only for the damaged tissues they reside, but also for damaged tissues different from them by migration triggered by proinflammatory cytokines or growth factors. This will be of great importance when stem cells in damaged tissues are destroyed or not enough in number. In fact, results from other laboratories have also suggested that subpopulations of stem cells within specific tissues might remain unrestricted and pluripotent potential that is reminiscent of embryonic stem cells. So the ability to purify, culture, and manipulate these postembryonic stem cells would provide investigators with an invaluable cell source to study cell and organ development. Besides, such cells can be used as an ideal source of stem cells in the development of replacement tissues for genetic or degenerative disorders.The purpose of the first part of this paper is to investigate whether there are postembryonic pluripotent stem cells in diverse fetal tissues and organs as well as in bone marrow (BM). Firstly, we used MACS CD45, GlyA and CD34 micromagnetic beads and limiting dilution to obtain a cell population from human fetal BM, and the...