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Thread: Iacovitti, et al. (2001): Three articles reporting factors stimulating differentiation of stem cells to dopaminergic neurons

  1. #1

    Iacovitti, et al. (2001): Three articles reporting factors stimulating differentiation of stem cells to dopaminergic neurons

    • Iacovitti L, Stull ND and Jin H (2001). Differentiation of human dopamine neurons from an embryonic carcinomal stem cell line. Brain Res. 912 (1): 99-104. Summary: Previous studies from this laboratory have demonstrated that fibroblast growth factor 1 together with a number of co-activator molecules (dopamine, TPA, IBMX/forskolin), will induce the expression of the catecholamine biosynthetic enzyme tyrosine hydroxylase (TH) in 10% of human neurons (hNTs) derived from the NT2 cell line [10]. In the present study, we found that TH induction was increased to nearly 75% in hNTs when cells were permitted to age 2 weeks in culture prior to treatment with the differentiation cocktail. This high level of TH expression was sustained 7 days after removal of the differentiating agents from the media. Moreover, the induced TH present in these cells was enzymatically active, resulting in the production of low levels of dopamine (DA) and its metabolite DOPAC. These findings suggest that hNTs may provide an important tissue culture model for the study of factors regulating TH gene expression in human neurons. Moreover, hNTs may serve, in vivo, as a source of human DA neurons for use in transplantation therapies. <http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&li st_uids=11520498> Department of Neurology, Thomas Jefferson University Medical College, 1025 Walnut Street, 19107, Philadelphia, PA, USA


    • Stull ND and Iacovitti L (2001). Sonic hedgehog and FGF8: inadequate signals for the differentiation of a dopamine phenotype in mouse and human neurons in culture. Exp Neurol. 169 (1): 36-43. Summary: Embryonic mouse striatal neurons and human neurons derived from the NT2/hNT stem cell line can be induced, in culture, to express the dopaminergic (DA) biosynthetic enzyme tyrosine hydroxylase (TH). The novel expression of TH in these cells is signaled by the synergistic interaction of factors present in the media, such as fibroblast growth factor 1 (FGF1) and one of several possible coactivators [DA, phorbol 12-myristate 13-acetate (TPA), isobutylmethylxanthine (IBMX), or forskolin]. Similarly, in vivo, it has recently been reported that the expression of TH in the developing midbrain is mediated by the synergy of FGF8 and the patterning molecule sonic hedgehog (Shh). In the present study, we examined whether the putative in vivo DA differentiation factors can similarly signal TH in our in vitro cell systems. We found that FGF8 and Shh induced TH expression in fewer than 2% of NT2/hNT cells and less than 5% of striatal neurons. The latter could be amplified to as much as 30% by increasing the concentration of growth factor 10-fold or by the addition of other competent coactivators (IBMX/forskolin, TPA, and DA). Additivity/inhibitor experiments indicated that FGF8 worked through traditional tyrosine kinase-initiated MAP/MEK signaling pathways. However, the Shh signal transduction cascade remained unclear. These data suggest that cues effective in vivo may be less successful in promoting the differentiation of a DA phenotype in mouse and human neurons in culture. Thus, our ability to generate DA neurons from different cell lines, for use in the treatment of Parkinson's disease, will depend on the identification of appropriate differentiation signals for each cell type under investigation. Copyright 2001 Academic Press. <http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&li st_uids=11312556> Department of Neurology, Thomas Jefferson University Medical College, 1025 Walnut Street, Philadelphia, Pennsylvania, 19107, USA.

    • Stull ND, Jung JW and Iacovitti L (2001). Induction of a dopaminergic phenotype in cultured striatal neurons by bone morphogenetic proteins. Brain Res Dev Brain Res. 130 (1): 91-8. Summary: In the present study, we examined whether the bone morphogenetic proteins (BMPs), which are important in the developmental specification of transmitter type in certain classes of neurons, might also play a role in signaling the differentiation of a dopaminergic (DA) phenotype. We found that BMP-2, -4 and -6 were each capable of inducing, in a dose and time dependent manner, moderate levels of the DA enzyme tyrosine hydroxylase (TH) in cultured neurons from the mouse embryonic striatum. In contradistinction to other TH-inducing agents, BMPs initiated de novo TH expression without the required synergy of exogenous growth factors or co-activating substances and in neurons presumably aged (E16) beyond the critical period for induction. However, the appearance of TH in induced cells was short-lived (24 h) and could not be prolonged by repeated supplementation with the BMPs. Inhibitors of the mitogen-activated protein kinase (MAPK/ERK) signaling pathway, PD98059 and apigenin, did not prevent TH induction by BMP-4, as they did other TH inducing agents, indicating that the MAPK/ERK pathway does not mediate BMPs effects on TH expression. We conclude that BMP-2, -4 and -6 can be added to the expanding inventory of agents capable of inducing TH, making them potentially important in the specification of a DA phenotype in stem/precursor cells for the treatment of Parkinson's disease. <http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&li st_uids=11557097> Department of Neurology, Thomas Jefferson University Medical College, 1025 Walnut Street, 19107, Philadelphia, PA, USA

  2. #2

    Researchers Find Evidence That Bone Marrow Stem Cells Can Become Brain Cells

    http://www.stemcellresearchnews.com/new2581.html

    Using a potion of growth factors and other nutrients, scientists at Jefferson Medical College have shown in the laboratory they are able to convert adult human bone marrow stem cells into adult brain cells.
    While itÃ*s early in the research, the results suggest such stem cells may have potential use in someday treating neurodegenerative diseases such as ParkinsonÃ*s disease.
    ìThe goal [of the work] is to find stem cells that we can differentiate into dopamine neurons to replace those lost in ParkinsonÃ*s disease,î says developmental biologist Lorraine Iacovitti, Ph.D., professor of neurology at Jefferson Medical College of Thomas Jefferson University in Philadelphia, who leads the research.
    She reports her teamÃ*s findings November 11 at the annual meeting of the Society for Neuroscience in San Diego.
    Human adult bone marrow stem cells - also known as pluripotent stem cells - normally give rise to human bone, muscle, cartilage and fat cells. Embryonic stem cells, in contrast, can become any type of cell.
    Other scientists have shown previously that at least a portion of mouse bone marrow stem cells treated with various growth factors and other agents will go on to resemble neurons in cell culture.
    Dr. IacovittiÃ*s team used the previous groupÃ*s cocktail of growth factors and nutrients on human bone marrow stem cells and found that only some cells converted to neurons - that is, they looked like neurons in that they developed ìcellular processes.î
    But by experimenting with different combinations of growth factors and nutrients, they eventually found a cocktail of reagents that converted 100 percent of cells within an hour - a stunning development that had never been shown before.
    ìIt flew in the face of everything I knew from developmental biology,î Dr. Iacovitti says. ìWeÃ*ve identified factors that get 100 percent of adult human bone marrow stem cells converted to neurons very quickly.î Not only do the converted cells look like neurons, she says, they contain neuronal proteins.
    The converted stem cells have neuronal markers and markers that are identified with subclasses of neurons. ìThatÃ*s important because weÃ*ve shown they can convert to specific classes of neurons. We have seen serotonin and GABA enzyme neurons. We want to get them to convert to dopamine neurons, which we havenÃ*t seen yet.î Adult human bone marrow stem cells have advantages as sources of cells.
    ìThe major advantage of using adult human bone marrow stem cells is that each person can be his own donor, meaning they can have an autologous graft of cells without rejection,î Dr. Iacovitti says. ìThe hope is that we wonÃ*t have to use embryonic stem cells and aborted fetuses for stem cell lines.î

    One Drawback

    There is one caveat, she notes. To date, the new neurons revert back to their original undifferentiated state in two to three days. ìThe bigger problem to solve is how to keep them differentiated,î she says. A key, she says, may lie in understanding what occurs in the growth media in which the stem cells incubate for several days and into which they release certain growth factors.
    If the ìconditionedî growth media plays a role in the conversion to neurons, the researchers ìhope to find ways to remove the stem cells from the culture - which is difficult - and differentiate them into what we want.î The next step, she says, will be for her team to both better understand the stem cell conversion in the laboratory and to study the process in animals.
    Â*Â*Â*Contact: Lorraine Iacovitti, Ph.D., 215-955-9427, http://www.tju.edu/jmc/home/index.cfm

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