Adult Spinal Cord Radial Glia Display a Unique Progenitor Phenotype

Radial glia (RG) are primarily embryonic neuroglial progenitors that express Brain Lipid Binding Protein (Blbp a.k.a. Fabp7) and Glial Fibrillary Acidic Protein (Gfap). We used these transcripts to demarcate the distribution of spinal cord radial glia (SCRG) and screen for SCRG gene expression in the Allen Spinal Cord Atlas (ASCA). We reveal that neonatal and adult SCRG are anchored in a non-ventricular niche at the spinal cord (SC) pial boundary, and express a “signature” subset of 122 genes, many of which are shared with “classic” neural stem cells (NSCs) of the subventricular zone (SVZ) and SC central canal (CC). A core expressed gene set shared between SCRG and progenitors of the SVZ and CC is particularly enriched in genes associated with human disease. Visualizing SCRG in a Fabp7-EGFP reporter mouse reveals an extensive population of SCRG that extend processes around the SC boundary and inwardly (through) the SC white matter (WM), whose abundance increases in a gradient from cervical to lumbar SC. Confocal analysis of multiple NSC-enriched proteins reveals that postnatal SCRG are a discrete and heterogeneous potential progenitor population that become activated by multiple SC lesions, and that CC progenitors are also more heterogeneous than previously appreciated. Gene ontology analysis highlights potentially unique regulatory pathways that may be further manipulated in SCRG to enhance repair in the context of injury and SC disease

Olfactory ensheathing cells: isolation and culture from the neonatal olfactory bulb

Olfactory ensheathing cells (OECs), which are glia from the olfactory system, have evolved as attractive candidates for transplant-mediated repair based on long-standing knowledge that the olfactory system is one of the only central nervous system tissues that can support neurogenesis throughout life. After injury and during normal cell turnover, the olfactory receptor neurons (ORNs) die, and new nerves are generated from putative stem cells in the olfactory epithelium. OECs, which reside throughout the olfactory system, guide the ORN axons as they travel through the olfactory mucosa (olfactory epithelium and lamina propria) and the cribriform plate, terminating in synapse formation in the usually nonpermissive environment of the olfactory bulb. It is this ability to support axonal outgrowth throughout life that has made olfactory tissue such a promising focus for repair strategies. Here, we provide a method to purify OECs—from the rat olfactory bulb and in Chapter 9, from the turbinates of the mouse olfactory epithelium

Olfactory ensheathing cells: isolation and culture from the rat olfactory bulb

The ability to produce highly purified populations of individual cell types is crucial for examining the molecular regulation of cell growth, differentiation, and function. Olfactory ensheathing cells (OECs) are also known as olfactory ensheathing glia (OEG) and olfactory nerve ensheathing cells (ONECs). These glia do not fit the classic description of stem cells, but have a number of intriguing developmental characteristics that have recently piqued the interest of the developmental neurobiology community. Their ability to support neuronal regeneration, both within the olfactory system and elsewhere in the central nervous system (CNS) has made them an attractive cellular model for transplantation paradigms. Their ability to switch, in vitro, from a nonmyelinating to a myelinating state, has enabled investigators to examine OECs for events leading to the onset of myelination

SPARC expression by cerebral microvascular endothelial cells in vitro and its influence on blood-brain barrier properties

Background: SPARC (secreted protein acidic and rich in cysteine) is a nonstructural, cell-matrix modulating protein involved in angiogenesis and endothelial barrier function, yet its potential role in cerebrovascular development, inflammation, and repair in the central nervous system (CNS) remains undetermined. Methods This study examines SPARC expression in cultured human cerebral microvascular endothelial cells (hCMEC/D3)—an in vitro model of the blood-brain barrier (BBB)—as they transition between proliferative and barrier phenotypes and encounter pro-inflammatory stimuli. SPARC protein levels were quantified by Western blotting and immunocytochemistry and messenger RNA (mRNA) by RT-PCR. Results Constitutive SPARC expression by proliferating hCMEC/D3s is reduced as cells mature and establish a confluent monolayer. SPARC expression positively correlated with the proliferation marker Ki-67 suggesting a role for SPARC in cerebrovascular development. The pro-inflammatory molecules tumor necrosis factor-α (TNF-α) and endotoxin lipopolysaccharide (LPS) increased SPARC expression in cerebral endothelia. Interferon gamma (IFN-γ) abrogated SPARC induction observed with TNF-α alone. Barrier function assays show recombinant human (rh)-SPARC increased paracellular permeability and decreased transendothelial electrical resistance (TEER). This was paralleled by reduced zonula occludens-1 (ZO-1) and occludin expression in hCMEC/D3s exposed to rh-SPARC (1–10 μg/ml) compared with cells in media containing a physiological dose of SPARC. Conclusions Together, these findings define a role for SPARC in influencing cerebral microvascular properties and function during development and inflammation at the BBB such that it may mediate processes of CNS inflammation and repair.Medicine, Faculty ofScience, Faculty ofNon UBCMedicine, Department ofPathology and Laboratory Medicine, Department ofZoology, Department ofReviewedFacult