Multipotential stem cells

A large number of cells are involved in the immune response and all are derived fiom the multipotential stem cells of the bone marrow. The predominant cell is the lymphocyte but monocytes-macrophages, endothelial cells, eosinophils and mast cells are also involved with certain immune responses. The two types of immunity (humoral and cell-mediated) are dependent on two distinct populations of lymphocytes, the B cells and the T cells respectively. Both the humoral and the cell-mediated systems interact to achieve an effective immune response. 

The FGFs stimulate the proliferation of mesodermally and ectodermally-derived cells and play central roles in mammalian development. Members of the FGF family are expressed in the embryonic period and are required for several critical events in neural development and specifically for neural induction. FGF-8 is necessary for positional identity required for axial specification and patterning of limb development. FGF-2 stimulates the proliferation of multipotential stem cells that subsequently give rise to neurons of the cortex and other brain regions. 

The development of mature neutrophils in the bone marrow occurs via the differentiation of multipotential stem cells into progenitor cells that are committed to neutrophilic lineages. As this process proceeds the ability of... 

Gritti, A., Parati, E.A., Cova, L., Frolichsthal, P., Galli, R., Wanke, E., Faravelli, L., Morassutti, D.J., Roisen, F., Nickel, D.D., Vescovi, A.L. (1996). Multipotential stem cells from the adult mouse brain proliferate and self-renew in response to basic fibroblast growth factor. JNeurosci, 16, 1091-100. 

Every second of life a human must produce about 2.5 million red blood cells, about 2 million granulocytes, and many lymphocytes as well as other less numerous leukocytes. All of these arise from multipotential stem cells found in the bone marrow.376-379 Each of these stem cells divides to form one daughter stem cell and one progenitor cell.380 The progenitor cells are also stem cells but have differentiated into myeloid,381 erythroid, and lymphoid382 383 cells. 

A number of cytokines (see p. 280) stimulate the growth, differentiation and functional activity of myeloid progenitor cells. As the name implies the function of these polypeptides was defined by in-vitro colony assays of bone marrow progenitors. They have effects on all myeloid cells including the multipotential stem cells (but probably not the more immature pluripotentiai cells), intermediate progenitors and circulating mature cells. Those in clinical use are described below. 

Enhances survival, proliferation and differentiation of multipotential stem cells and committed precursors of the granulocyte, macrophage, erythroid, eosinophil, neutrophil, megakaryocyte, mast cell and basophil lineages Enhances effector functions of myeloid end cells such as phagocytosis and cytotoxicity... 

Eosinophil differentiation and proliferation, production of IgM and IgA, increased IL-2 receptors, increased IgA secretion Synthesis of acute-phase proteins by hepatocytes, synergistic with IL-3 on multipotential stem cells, growth and differentiation of T cells, dilferentiation to antibody secretion... 

Our further studies demonstrated that a preponderance of sensory-like neurons could be generated from FGF treated cultures if they were subsequently treated with leukemia inhibitory factor (LIF) (Murphy et al., 1994 see also below Section 3.6.2.). This does not necessarily indicate that FGF was specifically stimulating the proliferation of a pool of sensory precursor cells, as it has been shown that the majority of sensory neurons are derived from multipotential stem cells (Sieber-Blum, 1989). Thus FGF may be acting to expand a multipotential stem cell pool. Previous results with subcloning of neuroepithelial cells show that FGF can stimulate proliferation of multipotential cells within this population (Kilpatrick and Bartlett, 1993). 

CI Apbstic anemia is caused by a decrease in the number and function of multipotential stem cells. 

An idea called the looping-out excision theory of erythropoiesis has been formulated by Kabat (1972). This theory takes into account the multipotential stem cells in the erythroidal tissue. These cells are sensitive to erythropoietin and can develop into erythrocytes (Till et al, 1964). The erythropoietin-sensitive cells rapidly... 

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