Neurosphere

About: Neurosphere is a research topic. Over the lifetime, 5145 publications have been published within this topic receiving 321088 citations.

Neural Stem Cell– and Schwann Cell–Loaded Biodegradable Polymer Scaffolds Support Axonal Regeneration in the Transected Spinal Cord

Abstract: Biodegradable polymer scaffolds provide an excellent approach to quantifying critical factors necessary for restoration of function after a transection spinal cord injury. Neural stem cells (NSCs) and Schwann cells (SCs) support axonal regeneration. This study examines the compatibility of NSCs and SCs with the poly-lactic-co-glycolic acid polymer scaffold and quantitatively assesses their potential to promote regeneration after a spinal cord transection injury in rats. NSCs were cultured as neurospheres and characterized by immunostaining for nestin (NSCs), glial fibrillary acidic protein (GFAP) (astrocytes), betaIII-tubulin (immature neurons), oligodendrocyte-4 (immature oligodendrocytes), and myelin oligodendrocyte (mature oligodendrocytes), while SCs were characterized by immunostaining for S-100. Rats with transection injuries received scaffold implants containing NSCs (n=17), SCs (n=17), and no cells (control) (n=8). The degree of axonal regeneration was determined by counting neurofilament-stained axons through the scaffold channels 1 month after transplantation. Serial sectioning through the scaffold channels in NSC- and SC-treated groups revealed the presence of nestin, neurofilament, S-100, and betaIII tubulin-positive cells. GFAP-positive cells were only seen at the spinal cord-scaffold border. There were significantly more axons in the NSC- and SC- treated groups compared to the control group. In conclusion, biodegradable scaffolds with aligned columns seeded with NSCs or SCs facilitate regeneration across the transected spinal cord. Further, these multichannel biodegradable polymer scaffolds effectively serve as platforms for quantitative analysis of axonal regeneration.

Identification of self-replicating multipotent progenitors in the embryonic nervous system by high Notch activity and Hes5 expression.

Abstract: Discrimination of neural stem cells from other progenitors in the developing mammalian brain has been hampered by the lack of specific markers. Identifying the progenitor pools and signalling pathways that guide mammalian neurogenesis are central to understanding the complex mechanisms that govern development of the nervous system. Notch signalling plays a pivotal role in the development of the mammalian nervous system by maintaining multipotent neural stem cells and regulating their fate. In order to identify putative neural stem cells in situ, we generated transgenic mice that express Green Fluorescent Protein (GFP) and report Notch signalling activity in the developing CNS. Here we show the subdivision of progenitors within the neural tube of these mice. We purify progenitors from the neural tube and show that cells with the highest levels of Notch-reporter activity have self-renewal capability and multipotency, whereas those lacking Hes5 expression do not form neurospheres in vitro. Using marker protein co-expression and cell sorting, we show that both neuroepithelial cells as well as some radial glia at all axial levels of the embryonic neural tube display active Notch signalling. However, Tbr2-positive basal progenitors of the developing telencephalon and differentiating Islet1/2- and Lim1-positive motor neurons outside the ventricular zone do not express Hes5-GFP. Quantitative analysis showed that Hes5 expression correlates better with neural stem cell potential than expression of the related gene Hes1. Thus, Notch activity through Hes5 identifies multipotent progenitors with stem cell properties and subdivides the different progenitors into defined pools.

Cell number and timing of transplantation determine survival of human neural stem cell grafts in stroke-damaged rat brain.

Abstract: Neural stem cells (NSCs) derived from human fetal striatum and transplanted as neurospheres survive in stroke-damaged striatum, migrate from the implantation site, and differentiate into mature neurons. Here, we investigated how various steps of neurogenesis are affected by intrastriatal transplantation of human NSCs at different time points after stroke and with different numbers of cells in each implant. Rats were subjected to middle cerebral artery occlusion and then received intrastriatal transplants of NSCs. Transplantation shortly after stroke (48 hours) resulted in better cell survival than did transplantation 6 weeks after stroke, but the delayed transplantation did not influence the magnitude of migration, neuronal differentiation, and cell proliferation in the grafts. Transplanting greater numbers of grafted NSCs did not result in a greater number of surviving cells or increased neuronal differentiation. A substantial number of activated microglia was observed at 48 hours after the insult in the injured striatum, but reached maximum levels 1 to 6 weeks after stroke. Our findings show that the best survival of grafted human NSCs in stroke-damaged brain requires optimum numbers of cells to be transplanted in the early poststroke phase, before the inflammatory response is established. These findings, therefore, have direct clinical implications.

Extensive tissue-regenerative capacity of neonatal human keratinocyte stem cells and their progeny

Abstract: Given our recent discovery that it is possible to separate human epidermal stem cells of the skin from their more committed progeny (ie, transit-amplifying cells and early differentiating cells) using FACS techniques, we sought to determine the comparative tissue regeneration ability of these keratinocyte progenitors We demonstrate that the ability to regenerate a fully stratified epidermis with appropriate spatial and temporal expression of differentiation markers in a short-term in vitro organotypic culture system is an intrinsic characteristic of both epidermal stem and transit-amplifying cells, although the stem cell fraction is most capable of achieving homeostasis Early differentiating keratinocytes exhibited limited short-term tissue regeneration under specific experimental conditions in this assay, although significant improvement was obtained by manipulating microenvironmental factors, that is, coculture with minimally passaged dermal cells or exogenous supply of the ECM protein laminin-10/11 Importantly, transplantation of all classes of keratinocyte progenitors into an in vivo setting demonstrated that tissue regeneration can be elicited from stem, transit-amplifying, and early differentiating keratinocytes for up to 10 weeks These data illustrate that significant proliferative and tissue-regenerative capacity resides not only in keratinocyte stem cells as expected, but also in their more committed progeny, including early differentiating cells