9 research outputs found
An ependymal cell quest : identification and functional role of spinal cord neural stem cells
Few injuries have as profound and long-lasting consequences as spinal cord injury. The
primary areas of impaired function typically include sensation, mobility, bladder, bowel
and sexual function. The economic, social and personal effects can also be devastating.
Today there is no cure available but the discovery of neural stem cells in the adult
spinal cord has raised the hope for a treatment. It has, however, proven difficult to
identify these stem cells and several different cell types including ependymal cells,
astrocytes and oligodendrocyte progenitors have been proposed to function as neural
stem or progenitor cells in the adult spinal cord. We assessed the generation of new
cells from these cell populations under physiological conditions and after spinal cord
injury.
In Paper I, we identify ependymal cells as latent neural stem cells. They have in
vitro stem cell potential and are multipotent in vivo after injury, giving rise to scarforming
astrocytes and remyelinating oligodendrocytes. We also show thatoligodendrocyte progenitors
and astrocytes are lineage restricted progenitors in theadult spinal cord. We offer an
integrated view of how several different endogenous cell populations generate new cells
under physiological and pathological conditions.
Scar formation has traditionally been seen as an impediment to functional recovery
after spinal cord injury. However, in Paper II, we show that scarring by ependymal
cell-derived astrocytes is required to reinforce the tissue to prevent expansion of the
lesion and further damage. We also identify ependymal cell progeny as a major source
of neurotrophic support, and find substantial neuronal loss in the absence of this
component of the scar tissue.
In order to modify the endogenous stem cell response following an injury it is
important to understand if all spinal cord ependymal cells have stem cell properties, or
if this feature is limited to a subpopulation. In Paper III, we show that ependymal cells
are functionally heterogeneous with proliferating progenitors and quiescent stem cells.
The latent neural stem cell population in the adult spinal cord is made up of a small
subpopulation of ependymal cells that are activated, proliferate and give rise to a large
number of cells both in vitro and in response to injury. This thesis is an ependymal cell
quest that provides new insights to the identity and function of a latent neural stem cell
population residing in the center of the spinal cord
Enhancing protective microglial activities with a dual function TREM2 antibody to the stalk region
Triggering receptor expressed on myeloid cells 2 (TREM2) is essential for the transition of homeostatic microglia to a diseaseâassociated microglial state. To enhance TREM2 activity, we sought to selectively increase the fullâlength protein on the cell surface via reducing its proteolytic shedding by A Disintegrin And Metalloproteinase (i.e., αâsecretase) 10/17. We screened a panel of monoclonal antibodies against TREM2, with the aim to selectively compete for αâsecretaseâmediated shedding. Monoclonal antibody 4D9, which has a stalk region epitope close to the cleavage site, demonstrated dual mechanisms of action by stabilizing TREM2 on the cell surface and reducing its shedding, and concomitantly activating phosphoâSYK signaling. 4D9 stimulated survival of macrophages and increased microglial uptake of myelin debris and amyloid ÎČâpeptide in vitro. In vivo target engagement was demonstrated in cerebrospinal fluid, where nearly all oluble TREM2 was 4D9âbound. Moreover, in a mouse model for Alzheimer's diseaseârelated pathology, 4D9 reduced amyloidogenesis, enhanced microglial TREM2 expression, and reduced a homeostatic marker, suggesting a protective function by driving microglia toward a diseaseâassociated state
Dopamine neuron precursors within the developing human mesencephalon show radial glial characteristics.
Specification and differentiation of neural precursors into dopaminergic neurons within the ventral mesencephalon has been subject to much attention due to the implication of dopaminergic neurons in Parkinson's disease and the perspective of generating sources of therapeutically active cells to be used for cell replacement therapy for the disease. However, despite intensive research efforts, little is known about the characteristics of the dopamine neuron progenitors in human. We show that the dopamine neuron determinant LMX1a is expressed in the diencephalic and mesencephalic dopaminergic neuron domains during human development. Within the mesencephalon, LMX1a is expressed in the dopaminergic neurons and their progenitors located in the ventricular zone of the floor plate region. Furthermore, the neural progenitors in the developing human ventral mesencephalon have a radial morphology and express the radial glial markers Vimentin and BLBP. These radial glia are mitotic and act as precursors for the dopaminergic neurons. Finally, we show that progenitors isolated from the human ventral mesencephalon maintain their radial glial characteristics and neurogenic capacity after expansion in vitro, making them a promising future source of cells to be used in cell replacement therapy for Parkinson's disease. (c) 2009 Wiley-Liss, Inc
Identification of a discrete subpopulation of spinal cord ependymal cells with neural stem cell properties
Spinal cord ependymal cells display neural stem cell properties in vitro and generate scar-forming astrocytes and remyelinating oligodendrocytes after injury. We report that ependymal cells are functionally heterogeneous and identify a small subpopulation (8% of ependymal cells and 0.1% of all cells in a spinal cord segment), which we denote ependymal A (EpA) cells, that accounts for the in vitro stem cell potential in the adult spinal cord. After spinal cord injury, EpA cells undergo self-renewing cell division as they give rise to differentiated progeny. Single-cell transcriptome analysis revealed a loss of ependymal cell gene expression programs as EpA cells gained signaling entropy and dedifferentiated to a stem-cell-like transcriptional state after an injury. We conclude that EpA cells are highly differentiated cells that can revert to a stem cell state and constitute a therapeutic target for spinal cord repair
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Antisecretory Factor-Mediated Inhibition of Cell Volume Dynamics Produces Antitumor Activity in Glioblastoma.
Interstitial fluid pressure (IFP) presents a barrier to drug uptake in solid tumors, including the aggressive primary brain tumor glioblastoma (GBM). It remains unclear how fluid dynamics impacts tumor progression and can be targeted therapeutically. To address this issue, a novel telemetry-based approach was developed to measure changes in IFP during progression of GBM xenografts. Antisecretory factor (AF) is an endogenous protein that displays antisecretory effects in animals and patients. Here, endogenous induction of AF protein or exogenous administration of AF peptide reduced IFP and increased drug uptake in GBM xenografts. AF inhibited cell volume regulation of GBM cells, an effect that was phenocopied in vitro by the sodium-potassium-chloride cotransporter 1 (SLC12A2/NKCC1) inhibitor bumetanide. As a result, AF induced apoptosis and increased survival in GBM models. In vitro, the ability of AF to reduce GBM cell proliferation was phenocopied by bumetanide and NKCC1 knockdown. Next, AF's ability to sensitize GBM cells to the alkylating agent temozolomide, standard of care in GBM patients, was evaluated. Importantly, combination of AF induction and temozolomide treatment blocked regrowth in GBM xenografts. Thus, AF-mediated inhibition of cell volume regulation represents a novel strategy to increase drug uptake and improve outcome in GBM. Mol Cancer Res; 16(5); 777-90. ©2018 AACR