| 1. |
- Aldskogius, Håkan, 1943-, et al.
(författare)
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Regulation of boundary cap neural crest stem cell differentiation after transplantation
- 2009
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 27:7, s. 1592-1603
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Tidskriftsartikel (refereegranskat)abstract
- Success of cell replacement therapies for neurological disorders will dependlargely on the optimization of strategies to enhance viability and control thedevelopmental fate of stem cells after transplantation. Once transplanted,stem/progenitor cells display a tendency to maintain an undifferentiatedphenotype or differentiate into inappropriate cell types. Gain and loss offunction experiments have revealed key transcription factors which drivedifferentiation of immature stem/progenitor cells toward more mature stages andeventually to full differentiation. An attractive course of action to promotesurvival and direct the differentiation of transplanted stem cells to a specific cell type would therefore be to force expression of regulatory differentiationmolecules in already transplanted stem cells, using inducible gene expressionsystems which can be controlled from the outside. Here, we explore thishypothesis by employing a tetracycline gene regulating system (Tet-On) to drivethe differentiation of boundary cap neural crest stem cells (bNCSCs) toward asensory neuron fate after transplantation. We induced the expression of the keytranscription factor Runx1 in Sox10-expressing bNCSCs. Forced expression of Runx1strongly increased transplant survival in the enriched neurotrophic environmentof the dorsal root ganglion cavity, and was sufficient to guide differentiationof bNCSCs toward a nonpeptidergic nociceptive sensory neuron phenotype both invitro and in vivo after transplantation. These findings suggest that exogenousactivation of transcription factors expression after transplantation instem/progenitor cell grafts can be a constructive approach to control theirsurvival as well as their differentiation to the desired type of cell and thatthe Tet-system is a useful tool to achieve this.
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| 2. |
- Kozlova, Elena, 1956-, et al.
(författare)
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Guiding differentiation of stem cells in vivo by tetracycline-controlled expression of key transcription factors
- 2012
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 21, s. 2537-2554
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Forskningsöversikt (refereegranskat)abstract
- Transplantation of stem or progenitor cells is an attractive strategy for cell replacement therapy. However, poor long-term survival and insufficiently reproducible differentiation to functionally appropriate cells in vivo still present major obstacles for translation of this methodology to clinical applications. Numerous experimental studies have revealed that the expression of just a few transcription factors can be sufficient to drive stem cell differentiation towards a specific cell type, to transdifferentiate cells from one fate to another, or to dedifferentiate mature cells to pluripotent stem/progenitor cells (iPSCs). We thus propose here to apply the strategy of expressing the relevant key transcription factors to guide the differentiation of transplanted cells to the desired cell fate in vivo. To achieve this requires tools allowing us to control the expression of these genes in the transplant. Here, we describe drug-inducible systems that allow us to sequentially and timely activate gene expression from the outside, with a particular emphasis on the Tet system which has been widely and successfully used in stem cells. These regulatory systems offer a tool for strictly limiting gene expression to the respective optimal stage after transplantation. This approach will direct the differentiation of the immature stem/progenitor cells in vivo to the desired cell type.
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| 3. |
- König, Niclas, et al.
(författare)
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Forced Runx1 expression in human neural stem/progenitor cells transplanted to the rat dorsal root ganglion cavity results in extensive axonal growth specifically from spinal cord-derived neurospheres
- 2011
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Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 20:11, s. 1847-1857
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Tidskriftsartikel (refereegranskat)abstract
- Cell replacement therapy holds great promise for treating a wide range of human disorders. However, ensuring the predictable differentiation of transplanted stem cells, eliminating their risk of tumor formation, and generating fully functional cells after transplantation remain major challenges in regenerative medicine. Here, we explore the potential of human neural stem/progenitor cells isolated from the embryonic forebrain (hfNSPCs) or the spinal cord (hscNSPCs) to differentiate to projection neurons when transplanted into the dorsal root ganglion cavity of adult recipient rats. To stimulate axonal growth, we transfected hfNSPC- and hscNSPC-derived neurospheres, prior to their transplantation, with a Tet-Off Runx1-overexpressing plasmid to maintain Runx1 expression in vivo after transplantation. Although pronounced cell differentiation was found in the Runx1-expressing transplants from both cell sources, we observed extensive, long-distance growth of axons exclusively from hscNSPC-derived transplants. These axons ultimately reached the dorsal root transitional zone, the boundary separating peripheral and central nervous systems. Our data show that hscNSPCs have the potential to differentiate to projection neurons with long-distance axonal outgrowth and that Runx1 overexpression is a useful approach to induce such outgrowth in specific sources of NSPCs.
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| 4. |
- Venkatesan, Meera, et al.
(författare)
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Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes : parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.
- 2014
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Ingår i: The American journal of tropical medicine and hygiene. - : American Society of Tropical Medicine and Hygiene. - 1476-1645 .- 0002-9637. ; 91:4, s. 833-43
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Tidskriftsartikel (refereegranskat)abstract
- Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine.
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