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  • Adler, Andrew, et al. (författare)
  • Transsynaptic tracing and its emerging use to assess graftreconstructed neural circuits
  • ????
  • Ingår i: Stem Cells. - AlphaMed Press. - 1549-4918.
  • Tidskriftsartikel (refereegranskat)abstract
    • Fetal neural progenitor grafts have been evaluated in preclinical animal models of spinal cord injury and Parkinson’s disease for decades, but the initial reliance on primary tissue as a cell source limited the scale of their clinical translatability. With the development of robust methods to differentiate human pluripotent stem cells to specific neural subtypes, cell replacement therapy holds renewed promise to treat a variety of neurodegenerative diseases and injuries at scale. As these cell sources are evaluated in preclinical models, new transsynaptic tracing methods are making it possible to study the connectivity between host and graft neurons with greater speed and detail than was previously possible. To date, these studies have revealed that widespread, long-lasting, and anatomically-appropriate synaptic contacts are established between host and graft neurons, as well as new aspects of host-graft connectivity which may be relevant to clinical cell replacement therapy. It is not yet clear, however, whether the synaptic connectivity between graft and host neurons is as celltype specific as it is in the endogenous nervous system, or whether that connectivity is responsible for the functional efficacy of cell replacement therapy. Here, we review evidence suggesting that the new contacts established between host and graft neuronsmay indeed be cell-type specific, and how transsynaptic tracing can be used inthe future to further elucidate the mechanisms of graft-mediated functional recovery in spinal cord injury and Parkinson’s disease.
  • Aldskogius, Håkan, 1943-, et al. (författare)
  • Regulation of boundary cap neural crest stem cell differentiation after transplantation
  • 2009
  • Ingår i: Stem Cells. - 1066-5099 .- 1549-4918. ; 27:7, s. 1592-1603
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>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.</p>
  • Ameri, Jacqueline, et al. (författare)
  • FGF2 Specifies hESC-Derived Definitive Endoderm into Foregut/Midgut Cell Lineages in a Concentration-Dependent Manner.
  • 2010
  • Ingår i: Stem Cells. - AlphaMed Press. - 1549-4918. ; 28, s. 45-56
  • Tidskriftsartikel (refereegranskat)abstract
    • Fibroblast growth factor (FGF) signaling controls axis formation during endoderm development. Studies in lower vertebrates have demonstrated that FGF2 primarily patterns the ventral foregut endoderm into liver and lung, whereas FGF4 exhibits broad anterior-posterior and left-right patterning activities. Furthermore, an inductive role of FGF2 during dorsal pancreas formation has been shown. However, whether FGF2 plays a similar role during human endoderm development remains unknown. Here, we show that FGF2 specifies hESC-derived definitive endoderm (DE) into different foregut lineages in a dosage-dependent manner. Specifically, increasing concentrations of FGF2 inhibits hepatocyte differentiation, whereas intermediate concentration of FGF2 promotes differentiation towards a pancreatic cell fate. At high FGF2 levels specification of midgut endoderm into small intestinal progenitors is increased at the expense of PDX1+ pancreatic progenitors. High FGF2 concentrations also promote differentiation towards an anterior foregut pulmonary cell fate. Finally, by dissecting the FGF receptor intracellular pathway that regulates pancreas specification, we demonstrate for the first time to our knowledge that induction of PDX1+ pancreatic progenitors relies on FGF2-mediated activation of the MAPK signaling pathway. Altogether, these observations suggest a broader gut endodermal patterning activity of FGF2 that corresponds to what has previously been advocated for FGF4, implying a functional switch from FGF4 to FGF2 during evolution. Thus, our results provide new knowledge of how cell fate specification of human DE is controlled - facts that will be of great value for future regenerative cell therapies.
  • Avaliani, Natalia, et al. (författare)
  • Optogenetics reveal delayed afferent synaptogenesis on grafted human induced pluripotent stem cell-derived neural progenitors.
  • 2014
  • Ingår i: Stem Cells. - AlphaMed Press. - 1549-4918. ; 32:12, s. 3088-3098
  • Tidskriftsartikel (refereegranskat)abstract
    • Reprogramming of somatic cells into pluripotency stem cell state have opened new opportunities in cell replacement therapy and disease modeling in a number of neurological disorders. It still remains unknown, however, to what degree the grafted human induced pluripotent stem cells (hiPSCs) differentiate into a functional neuronal phenotype and if they integrate into the host circuitry. Here we present a detailed characterization of the functional properties and synaptic integration of hiPSC-derived neurons grafted in an in vitro model of hyperexcitable epileptic tissue, namely organotypic hippocampal slice cultures (OHSC), and in adult rats in vivo. The hiPSCs were first differentiated into long-term self-renewing neuroepithelial stem (lt-NES) cells, which are known to form primarily GABAergic neurons. When differentiated in OHSCs for six weeks, lt-NES cell-derived neurons displayed neuronal properties such as TTX-sensitive sodium currents and action potentials (APs), as well as both spontaneous and evoked postsynaptic currents, indicating functional afferent synaptic inputs. The grafted cells had a distinct electrophysiological profile compared to host cells in the OHSCs with higher input resistance, lower resting membrane potential and APs with lower amplitude and longer duration. To investigate the origin of synaptic afferents to the grafted lt-NES cell-derived neurons, the host neurons were transduced with Channelrhodopsin-2 (ChR2) and optogenetically activated by blue light. Simultaneous recordings of synaptic currents in grafted lt-NES cell-derived neurons using whole-cell patch-clamp technique at 6 weeks after grafting revealed limited synaptic connections from host neurons. Longer differentiation times, up to 24 weeks after grafting in vivo, revealed more mature intrinsic properties and extensive synaptic afferents from host neurons to the It-NES cell-derived neurons, suggesting that these cells require extended time for differentiation/maturation and synaptogenesis. However, even at this later time-point, the grafted cells maintained a higher input resistance. These data indicate that grafted lt-NES cell-derived neurons receive ample afferent input from the host brain. Since the lt-NES cells used in this study show a strong propensity for GABAergic differentiation, the host-to-graft synaptic afferents may facilitate inhibitory neurotransmitter release, and normalize hyperexcitable neuronal networks in brain diseases, e.g. such as epilepsy. Stem Cells 2014.
  • Azim, Kasum, et al. (författare)
  • Persistent Wnt/β‐Catenin Signaling Determines Dorsalization of the Postnatal Subventricular Zone and Neural Stem Cell Specification into Oligodendrocytes and Glutamatergic Neurons
  • 2014
  • Ingår i: Stem Cells. - Durham, United States : AlphaMed Press, Inc.. - 1066-5099 .- 1549-4918. ; 32:5, s. 1301-1312
  • Tidskriftsartikel (refereegranskat)abstract
    • <p data-select-like-a-boss="1">In the postnatal and adult central nervous system (CNS), the subventricular zone (SVZ) of the forebrain is the main source of neural stem cells (NSCs) that generate olfactory neurons and oligodendrocytes (OLs), the myelinating cells of the CNS. Here, we provide evidence of a primary role for canonical Wnt/β-catenin signaling in regulating NSC fate along neuronal and oligodendroglial lineages in the postnatal SVZ. Our findings demonstrate that glutamatergic neuronal precursors (NPs) and oligodendrocyte precursors (OPs) are derived strictly from the dorsal SVZ (dSVZ) microdomain under the control of Wnt/β-catenin, whereas GABAergic NPs are derived mainly from the lateral SVZ (lSVZ) microdomain independent of Wnt/β-catenin. Transcript analysis of microdissected SVZ microdomains revealed that canonical Wnt/β-catenin signaling was more pronounced in the dSVZ microdomain. This was confirmed using the β-catenin-activated Wnt-reporter mouse and by pharmacological stimulation of Wnt/β-catenin by infusion of the specific glycogen synthase kinase 3β inhibitor, AR-A014418, which profoundly increased the generation of cycling cells. In vivo genetic/pharmacological stimulation or inhibition of Wnt/β-catenin, respectively, increased and decreased the differentiation of dSVZ-NSCs into glutamatergic NPs, and had a converse effect on GABAergic NPs. Activation of Wnt/β-catenin dramatically stimulated the generation of OPs, but its inhibition had no effect, indicating other factors act in concert with Wnt/β-catenin to fine tune oligodendrogliogenesis in the postnatal dSVZ. These results demonstrate a role for Wnt/β-catenin signaling within the dorsal microdomain of the postnatal SVZ, in regulating the genesis of glutamatergic neurons and OLs.</p>
  • Behnan, Jinan, et al. (författare)
  • Recruited brain tumor-derived mesenchymal stem cells contribute to brain tumor progression.
  • 2014
  • Ingår i: Stem Cells. - AlphaMed Press. - 1549-4918. ; 32:5, s. 1110-1123
  • Tidskriftsartikel (refereegranskat)abstract
    • The identity of the cells that contribute to brain tumor structure and progression remains unclear. Mesenchymal stem cells (MSCs) have recently been isolated from normal mouse brain. Here, we report the infiltration of MSC-like cells into the GL261 murine glioma model. These Brain Tumor derived Mesenchymal Stem Cells (BT-MSCs) are defined with the phenotype (Lin-Sca-1+CD9+CD44+CD166+/-) and have multipotent differentiation capacity. We show that the infiltration of BT-MSCs correlates to tumor progression; furthermore, BT-MSCs increased the proliferation rate of GL261 cells in vitro. For the first time, we report that the majority of GL261 cells expressed mesenchymal phenotype under both adherent and sphere culture conditions in vitro, and that the non-MSC population is non-tumorigenic in vivo. Although the GL261 cell line expressed mesenchymal phenotype markers in vitro, most BT-MSCs are recruited cells from host origin in both wild type GL261 inoculated into GFP-transgenic mice and GL261-GFP cells inoculated into wild type mice. We show the expression of chemokine receptors CXCR4 and CXCR6 on different recruited cell populations. In vivo, the GL261 cells change marker profile, and acquire a phenotype that is more similar to cells growing in sphere culture conditions. Finally, we identify a BT-MSC population in human glioblastoma that is CD44+CD9+CD166+ both in freshly isolated and culture-expanded cells. Our data indicate that cells with MSC-like phenotype infiltrate into the tumor stroma and play an important role in tumor cell growth in vitro and in vivo. Thus we suggest that targeting BT-MSCs could be a possible strategy for treating glioblastoma patients. Stem Cells 2013.
  • Berglin-Enquist, Ida, et al. (författare)
  • Successful Low-Risk Hematopoietic Cell Therapy in a Mouse Model of Type 1 Gaucher Disease
  • 2009
  • Ingår i: Stem Cells. - AlphaMed Press. - 1549-4918. ; 27:3, s. 744-752
  • Tidskriftsartikel (refereegranskat)abstract
    • Hematopoietic stem cell-based gene therapy offers the possibility of permanent correction for genetic disorders of the hematopoietic system. However, optimization of present protocols is required before gene therapy can be safely applied as general treatment of genetic diseases. In this study we have used a mouse model of type 1 Gaucher disease (GD) to demonstrate the feasibility of a low-risk conditioning regimen instead of standard radiation, which is associated with severe adverse effects. We first wanted to establish what level of engraftment and glucosylceramidase (GCase) activity is required to correct the pathology of the type 1 GD mouse. Our results demonstrate that a median wild-type (WT) cell engraftment of 7%, corresponding to GCase activity levels above 10 nmoles/hour and mg protein, was sufficient to reverse pathology in bone marrow and spleen in the GD mouse. Moreover, we applied nonmyeloablative doses of busulfan as a pretransplant conditioning regimen and show that even WT cell engraftment in the range of 1%-10% can confer a beneficial therapeutical outcome in this disease model. Taken together, our data provide encouraging evidence for the possibility of developing safe and efficient conditioning protocols for diseases that require only a low level of normal or gene-corrected cells for a permanent and beneficial therapeutic outcome. STEM CELLS 2009; 27: 744-752
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