Subtractive hybridization identifies genes differentially expressed by olfactory ensheathing cells and neural stem cells

Transplantation of Predegenerated Peripheral Nerves after Complete Spinal Cord Transection in Rats: Effect of Neural Precursor Cells and Pharmacological Treatment with the Sulfoglycolipid Tol-51

Following spinal cord injury (SCI), the regenerative capacity of the central nervous system (CNS) is severely limited by the failure of axonal regeneration. The regeneration of CNS axons has been shown to occur by grafting predegenerated peripheral nerves (PPNs) and to be promoted by the transplantation of neural precursor cells (NPCs). The introduction of a combinatorial treatment of PPNs and NPCs after SCI has to address the additional problem of glial scar formation, which prevents regenerating axons from leaving the implant and making functional connections. Previously, we discovered that the synthetic sulfoglycolipid Tol-51 inhibits astrogliosis. The objective was to evaluate axonal regeneration and locomotor function improvement after SCI in rats treated with a combination of PPN, NPC, and Tol-51. One month after SCI, the scar tissue was removed and replaced with segments of PPN or PPN+Tol-51; PPN+NPC+Tol-51. The transplantation of a PPN segment favors regenerative axonal growth; in combination with Tol-51 and NPC, 30% of the labeled descending corticospinal axons were able to grow through the PPN and penetrate the caudal spinal cord. The animals treated with PPN showed significantly better motor function. Our data demonstrate that PPN implants plus NPC and Tol-51 allow successful axonal regeneration in the CNS.

Ensheathing cell-conditioned medium directs the differentiation of human umbilical cord blood cells into aldynoglial phenotype cells

Despite their similarities to bone marrow precursor cells (PC), human umbilical cord blood (HUCB) PCs are more immature and, thus, they exhibit greater plasticity. This plasticity is evident by their ability to proliferate and spontaneously differentiate into almost any cell type, depending on their environment. Moreover, HUCB-PCs yield an accessible cell population that can be grown in culture and differentiated into glial, neuronal and other cell phenotypes. HUCB-PCs offer many potential therapeutic benefits, particularly in the area of neural replacement. We sought to induce the differentiation of HUCB-PCs into glial cells, known as aldynoglia. These cells can promote neuronal regeneration after lesion and they can be transplanted into areas affected by several pathologies, which represents an important therapeutic strategy to treat central nervous system damage. To induce differentiation to the aldynoglia phenotype, HUCB-PCs were exposed to different culture media. Mononuclear cells from HUCB were isolated and purified by identification of CD34 and CD133 antigens, and after 12 days in culture, differentiation of CD34+ HUCB-PCs to an aldynoglia phenotypic, but not that of CD133+ cells, was induced in ensheathing cell (EC)-conditioned medium. Thus, we demonstrate that the differentiation of HUCB-PCs into aldynoglia cells in EC-conditioned medium can provide a new source of aldynoglial cells for use in transplants to treat injuries or neurodegenerative diseases.

Defining the morphological phenotype: 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) is a novel marker for in situ detection of canine but not rat olfactory ensheathing cells

Olfactory ensheathing cells (OECs) are the non-myelinating glial cells of the olfactory nerves and bulb. The fragmentary characterization of OECs in situ during normal development may be due to their small size requiring intricate ultrastructural analysis and to the fact that available markers for in situ detection are either expressed only by OEC subpopulations or lost during development. In the present study, we searched for markers with stable expression in OECs and investigated the spatiotemporal distribution of CNPase, an early oligodendrocyte/Schwann cell marker, in comparison with the prototype marker p75(NTR). Anti-CNPase antibodies labeled canine but not rat OECs in situ, while Schwann cells and oligodendrocytes were positive in both species. CNPase immunoreactivity in the dog was confined to all OECs throughout the postnatal development and associated with the entire cell body, including its finest processes, while p75(NTR) was mainly detected in perineural cells and only in some neonatal OECs. Adult olfactory bulb slices displayed CNPase expression after 4 and 10 days, while p75(NTR) was detectable only after 10 days in vitro. Finally, treatment of purified adult canine OECs with fibroblast growth factor-2 significantly reduced CNPase expression at the protein and mRNA level. Taken together, we conclude that CNPase but not p75(NTR) is a stable marker suitable for in situ visualization of OECs that will facilitate their light-microscopic characterization and challenge our general view of OEC marker expression in situ. The fact that canine but not rat OECs expressed CNPase supports the idea that glia from large animals differs substantially from rodents.

A meta-analysis of microarray-based gene expression studies of olfactory bulb-derived olfactory ensheathing cells

Genome wide transcriptional profiling and large scale proteomics have emerged as two powerful methods to dissect the molecular properties of specific neural tissues or cell types on a global scale. Several genome-wide transcriptional profiling and proteomics studies have been published on cultured olfactory ensheathing cells (OEC). In this article we present a meta-analysis of all five published and publicly available micro-array gene expression datasets of cultured early-passage-OB-OEC with other cell types (Schwann cells, late-passage-OB-OEC, mucosa-OEC, an OEC cell line, and acutely dissected OEC). The aim of this meta-analysis is to identify genes and molecular pathways that are found in multiple instead of one isolated study. 454 Genes were detected in at least three out of five microarray datasets. In this "Top-list", genes involved in the biological processes "growth of neurites", "blood vessel development", "migration of cells" and "immune response" were strongly overrepresented. By applying network analysis tools, molecular networks were constructed and Hub-genes were identified that may function as key genes in the above mentioned interrelated processes. We also identified 7 genes (ENTPD2, MATN2, CTSC, PTHLH, GLRX1, COL27A1 and ID2) with uniformly higher or lower expression in early-passage-OB-OEC in all five microarray comparisons. These genes have diverse but intriguing roles in neuroprotection, neurite extension and/or tissue repair. Our meta-analysis provides novel insights into the molecular basis of OB-OEC-mediated neural repair and can serve as a repository for investigators interested in the molecular biology of OEC. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

Olfactory ensheathing cells moderate nuclear factor kappaB translocation in astrocytes

Nuclear factor kappaB (NFκB) is a key transcriptional regulator of inflammatory genes. We investigated the modulatory effects of olfactory ensheathing cells (OECs), microglia and meningeal fibroblasts on translocation of NFκB to astrocyte nuclei. The percentage of activated astrocytes in co-cultures with OECs was significantly less than for co-cultures with microglia (p<0.001) and fibroblasts (p<0.05). Phorbol myristate acetate (PMA) and calcium ionophore stimulation of p65 NFκB translocation to nuclei provided an in vitro model of astrocyte inflammatory activation. Soluble factors released by OECs significantly moderated the astrocytic NFκB translocation induced by either PMA/calcium ionophore or microglia-derived factors (p<0.001). Insulin-like growth factor-1 may contribute to these effects, since it is expressed by OECs and also significantly moderated the astrocytic NFκB translocation (p<0.05), albeit insufficiently to fully account for the OEC-induced moderation (p<0.01). Olfactory ensheathing cells significantly moderated the increased transcription of the pro-inflammatory cytokine, granulocyte macrophage-colony stimulating factor in the activated astrocytes (p<0.01). These results suggest that transplanted OECs could improve neural repair after CNS injury by moderating astrocyte activation.