Neurosphere

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

N-Cadherin is expressed by putative stem/progenitor cells and melanocytes in the human limbal epithelial stem cell niche.

Abstract: Corneal epithelial stem cells are known to be localized to the basal layer of the limbal epithelium, providing a model system for epithelial stem cell biology; however, the mechanisms regarding the maintenance of these stem cells in their specialized niche remain poorly understood. N-cadherin is a member of the classic cadherin family and has previously been demonstrated to be expressed by hematopoietic stem cells. In the present study, we demonstrate that N-cadherin is expressed by putative stem/progenitor cells, as well as melanocytes, in the human limbal epithelial stem cell niche. In addition, we demonstrate that upon in vitro culture using 3T3 feeder layers, loss of N-cadherin expression occurs with cell proliferation. These results indicate that N-cadherin may be a critical cell-to-cell adhesion molecule between corneal epithelial stem/progenitor cells and their corresponding niche cells in the limbal epithelium.

Dependence of corneal stem/progenitor cells on ocular surface innervation

Abstract: Corneolimbal epithelial stem/progenitor cells are a small subpopulation of oligopotent cells located primarily in the basal epithelial layer of the limbus. They produce undifferentiated progeny with limited proliferative potential that migrate centripetally from the periphery of the cornea to replace cells desquamating during normal life.1–7 Corneal limbal stem cells reside primarily in the palisades of Vogt in a niche which maintains their “stemness” by producing a unique anatomic and functional milieu.8,9 Although the exact anatomic location of the niche is thought to be the limbus in humans, it has recently been proposed that epithelial stem/progenitor cells of equal potency are distributed throughout the entire ocular surface in other mammals.10 Detection of corneal epithelial stem cells is the object of controversy between many groups, as there is still no universal consensus over which marker(s) should be used. Side population (SP) cell detection is a commonly used method to quantify these cells. Stem cells express the SP phenotype based on the ability to efflux the DNA-binding dye Hoechst 33342.11–13 SP cells have also been identified in the hematopoietic compartments of different species, and have been isolated from various other adult tissues.12,13 These findings suggest that the SP phenotype represents a common feature of adult tissue-specific stem cells, and the same method has been used to isolate stem cells from human, rabbit, rat, and mouse limbi.14–17 The cornea is the most densely innervated tissue in the body, being 400 times more sensitive than the skin.18 Corneal nerves, in addition to their well known sensory function, help maintain the integrity of the ocular surface by releasing epitheliotrophic substances that promote corneal surface health.19 The limbus, where stem cells reside, is densely innervated; however, the role of these nerves is poorly understood.20 It has been suggested that various nerve-secreted factors and neuropeptides such as nerve growth factor (NGF), substance P, acetylcholine, and brain-derived neurotrophic factor (BDNF) could influence corneal stem cells, and play a role in maintaining epithelial integrity, and promote epithelial proliferation.19 It has also been shown that human corneal stem cells express TrkA which is a high affinity receptor for NGF.21–23 Moreover, corneal limbal stem cells grown in the presence of both epidermal growth factor (EGF) and nerve-secreted factors show the highest rate of colony expansion in vitro compared with EGF alone.24 However, the influence of corneal denervation on epithelial stem/progenitor cells has not yet been studied in vivo. The purpose of the present study was to elucidate the relationship between corneal stem/progenitor cells and trigeminal nerves in vivo using a mouse model of denervated cornea. Herein, we hypothesize that corneal stem/progenitor cell survival and/or function is dependent on intact corneal innervation. Our data demonstrate that sensory nerve deprivation of cornea affects stem cell homeostasis and lead to a significant decrease in both the frequency and the function of corneolimbal stem/progenitor cells.

Exercise increases neural stem cell number in a growth hormone-dependent manner, augmenting the regenerative response in aged mice.

Abstract: The exercise-induced enhancement of learning and memory, and its ability to slow age-related cognitive decline in humans led us to investigate whether running stimulates periventricular (PVR) neural stem cells (NSCs) in aging mice, thereby augmenting the regenerative capacity of the brain. To establish a benchmark of normal aging on endogenous NSCs, we harvested the PVR from serial vibratome sections through the lateral ventricles of juvenile (6-8 weeks), 6-, 12-, 18-, and 24-month-old mice, culturing the cells in the neural colony-forming cell assay. A significant decline in NSC frequency was apparent by 6 months ( approximately 40%), ultimately resulting in a approximately 90% reduction by 24 months. Concurrent with this decline was a progressive loss in regenerative capacity, as reflected by an incomplete repopulation of neurosphere-forming cells following gamma cell irradiation-induced depletion of the PVR. However, voluntary exercise (i.e., 21 days of running) significantly increased NSC frequency in mice > or = 18 months of age, augmenting the regeneration of irradiation-ablated periventricular cells and restoring NSC numbers to youthful levels. Importantly, and consistent with the demonstrated ability of growth hormone (GH) to increase NSC proliferation, and the elevated secretion of GH during exercise, exercise failed to stimulate NSCs in GH receptor-null mice. These findings now provide a novel basis for understanding the ability of exercise to delay the onset and rate of decline in neurodegenerative conditions not typically associated with the hippocampus and suggest that the GH-dependent activation of endogenous NSCs may be effective in reversing or preventing age-related neurodegeneration in humans.

2-DE proteome analysis of a proliferating and differentiating human neuronal stem cell line (ReNcell VM)

Abstract: The proteome of a proliferating human stem cell line was analyzed and then utilized to detect stem cell differentiation-associated changes in the protein profile. The analysis was conducted with a stable human fetal midbrain stem cell line (ReNcell VM) that displays the properties of a neural stem cell. Therefore, acquisition of proteomic data should be representative of cultured human neural stem cells (hNSCs) in general. Here we present a 2-DE protein-map of this cell line with annotations of 402 spots representing 318 unique proteins identified by MS. The subsequent proteome profiling of differentiating cells of this stem cell line at days 0, 4 and 7 of differentiation revealed changes in the expression of 49 identified spots that could be annotated to 45 distinct proteins. This differentiation-associated expression pattern was validated by Western blot analysis for transgelin-2, proliferating cell nuclear antigen, as well as peroxiredoxin 1 and 4. The group of regulated proteins also included NudC, ubiquilin-1, STRAP, stress-70 protein, creatine kinase B, glial fibrillary acidic protein and vimentin. Our results reflect the large rearrangement of the proteome during the differentiation process of the stem cells to terminally differentiated neurons and offer the possibility for further characterization of specific targets driving the stem cell differentiation.