Potency, stem cells

Iwase T, Nagaya N, Fujii T, et al. Comparison of angiogenic potency between mesenchymal stem cells and mononuclear cells in a rat model of hindlimb ischemia. Cardiovasc Res 2005 66 543-551. 

Within cell lineage differentiation pathways, the inherent potency of the starting material may be restricted based on original source. Bone marrow derived cells have the ability to differentiate into eosinophils, erythrocytes, megakaryocytes, osteoclasts, and lymphoid cells [20]. However, these hematopoietic lineages have limited potential to become a distinct tissue such as liver. Mesenchymal stem cells, on the other hand, can differentiate into a broader array of distinct tissues such osteocytes, chondrocytes, adipocytes, myocytes, and bone marrow stromal cells [20]. This plurality of outcomes requires identification of circumstances under which an aberrant outcome is manifested. 

Based on comparative studies of the relative gonadal toxicity of several antineoplastic agents in experimental models and humans, the vinca alkaloids vinblastine and vincristine have negligible potency for killing stem cells. Permanent recovery of sperm counts and preserved ovarian function, depending on the patient s age at the time of... 

Hu BY et al (2010) Neural differentiation of human induced pluripotent stem cells follows developmental principles but with variable potency. Proc Natl Acad Sci U S A 107(9) 4335 340... 

Thalidomide has been reintroduced to clinical practice as an oral agent for the management of erythema nodosum leprosum (ENL) and in other disease settings, most notably MM. Lenalidomide is a thalidomide derivative with improved potency and safety profile compared to thalidomide. Thalidomide is a nonpolar racemic mixture of cell permeable and rapidly interconverting S(-) and R(+) isomers. The precise mechanisms responsible for thalidomide s clinical activity remain to be elucidated. Multiple distinct, but potentially complementary, mechanisms have been proposed to explain the antitumor activity of thalidomide and its derivatives, including stimulation of T cells and NK cells, inhibition of angiogenesis and tumor cell proliferation, and modulation of hematopoietic stem cell differentiation (Figure 51-6). 

Stem cells are the precursors of all the other cell types. They are undifferentiated cells that have the ability to form any cell type as well as to replicate into more stem cells. Stem cells are often called progenitor cells because of their ability to differentiate into many cell types. A pluripotent stem cell is one that can give rise to all cell types in an embryo or in an adult. Some cells are called multipotent because they can differentiate into more than one cell type, but not into all cell types. The further from a zygote a cell is in the course of development, the less the potency of the cell type. The use of stem cells, especially embryonic stem (ES) cells, has been an exciting field of research for several years. 

PLR elicits rapid, non-cytolytic histamine release with a two-fold greater potency compared with mellitin. PLR is capable of permeabilizing negatively charged unilamellar lipid vesicles, but not neutral vesicles - a result that is consistent with its non-hemolytic action. It inhibits the early development of granulocyte macrophage colonies from bone marrow stem cells [A. 

PDGF receptor p (PDGFRB), and c-kit, a cytokine receptor expressed on the surface of hematopoietic stem cells as well as other cell types. As compared with the two drugs on the market, sorafenib (Nexavar) by Bayer Pharmaceuticals Corp. and Onyx Pharmaceuticals, Inc. and sunitinib (Sutent) by Pfizer, Inc., cediranib inhibits VEGFR targets with improved potency. It is currently in Phase II/III development for advanced non-small cell lung cancer and advanced colorectal cancer. 

Neural differentiation of human induced pluripwtent stem cells follows developmental painciples but with variable potency. PNAS, Vol. 107(9), pp. 4335-4340. 

EMBRYONIC STEM CELLS A fertilized egg divides to form two cells. This binary division process continues till amass of-150 cells is formed. This mass called blastocyst consists of two regions the outer shell and an inner cell mass encapsulated by the outer shell. It is possible to extract this inner cell mass. The extracted mass can be cultured to create stem cells. These stem cells are pluripotent, a term indicative of their multiple potencies for forming any cell type under the proper impulse. 

The term stem cell is used generically and somewhat loosely in this discussion to include true pluripotent stem cells, progenitors of limited potency (monopotent and hipotent) perhaps determined by the tissue they reside in (Tuan et al. 2003). 

N. Sato, L. Meijer, L. Skaltsounis, P Greengard, and A.H. Brivanlou, Maintenance of pluri-potency in human and mouse embryonic stem cells through activation of Wnt signaling by a pharmacological GSK-3-specific inhibitor, Nat. Med., 10 (1) 55-63, Jan. 2004. 

Pietilae, M. Lehtonen, S. Naerhi, M. Hassinen, I. E. Leskelae, H. Aranko, K. Nordstroem, K. Vepsaelaeinen, A. Lehenkari, P. Mitochondrial function determines the viability and osteogenic potency of human mesenchymal stem Cells. Tissue Eng., Part C Methods 2010,16,435-445. 

Hansen K, Stem RM. 1984. Toxicity and transformation potency of nickel compounds in BHK cells in vitro. In Sunderman FW Jr, Aitio A, Berlin A, eds. Nickel in the human environment. lARC scientific publication no. 53. Lyon, France International Agency for Research on Cancer 193-200. 

Farmers in Asia sometimes bend the stem of the plant near the base or cut it and insert a small stone or a piece of opium a few days before harvest. They believe that this will increase its potency, but there are no reliable data on this point, and there is no apparent mechanism by which potency increase could occur. After harvesting, it is common practice to hang the cut plants upside down for curing. These and other methods may rest on the mistaken belief that cannabinoids are synthesized in the roots and translocated to the top of the plant. This is not true. Actually, the specialized cells which synthesize cannabinoids happen to be more numerous and perhaps more active in the flowering tops than elsewhere. 

Inhalation anesthetics do not appear to work through a receptor mechanism and the mechanism of action remains a mystery. Theories suggesting that anesthetics work by altering the lipids in cell membranes stem from the observation that the potency of anesthetics correlates extremely closely with the solubility of the drug in oil. 

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