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Abstract

Although olfactory ensheathing cells (OECs) are used to promote repair in the injured
spinal cord, little is known of their phenotype in this environment. This study examined the
effect of the injured spinal cord on OEC morphology and gene expression. For in situ
experiments OECs were encapsulated in porous polymer tubes and implanted into the lesioned
rat spinal cord. Adult male hooded Wistar rats (300-350g) were anaesthetised with isoflurane
maintained at 2.5% with 100% 02 (0.5L/min). Lesions were made to the corticospinal tract at the
level of T7-T8 and OEC-filled capsules were inserted under the dura above the lesion. After one
week animals were sacrificed and the capsules retrieved. Procedures were performed in
accordance with NHMRC guidelines approved by the University of Tasmania Animal Ethics
Committee. Morphological characteristics were examined using scanning electron microscopy
(SEM) for which implanted and un-implanted capsules were cut into halves so as the inner
surfaces could be viewed. Implanted capsules were filled with rounded OECs and extracellular
matrix (ECM)-like matter. Although no cells with the morphology of cultured OECs were
observed these may have been obscured by the abundant ECM. In the un-implanted capsules
cells with morphology typical of cultured OECs were predominant and although some rounded
cells were detected. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was
used to analyse expression of Neuregulin-1 (Nrg-1) and Nogo in cultured OECs and
encapsulated OECs both in culture and after implantation. Neuregulins are known mitogens and
survival factors for central nervous system (CNS) cells whilst Nogo is an axonal growth
regulator. For comparison transcripts were also examined in a number of other glial cell types.
Similar to astrocytes (ASTs) and fibroblasts (FBs), OECs expressed various Nrg-1 subtypes
including neu Differentiation Factor (NDF), Glial Growth Factor (GGF) and Sensory and
Motomeuron-derived Factor (SMDF) along with other splice variants including those containing
the epidermal growth factor (EGF), a-EGF, ß-EGF and secreted domains. After implantation,
OECs increased expression of NDF and secreted Neuregulin and decreased expression of the
other variants. Olfactory ensheathing cells, oligodendrocytes (OLGs) Schwann cells (SCs) and
ASTs all expressed Nogo-A, -B and -ABC. OECs and OLGs were also immunopositive for
Nogo-A protein. Unlike OLGs, OECs, SCs and ASTs expressed mRNA for the Nogo-66
receptor (NgR) although the protein could not be detected by immunocytochemistry in OECs.
Implantation of OECs resulted in an increase in Nogo-A and -B and a decrease in Nogo-ABC
and the NgR. Taken together these results show that OEC phenotype in the lesion environment is
different from their characteristic profile in culture.

Item Type:	Thesis - PhD
Authors/Creators:	Woodhall, Emma
Keywords:	Cellular therapy, Spinal cord, Spinal cord
Copyright Holders:	The Author
Copyright Information:	Copyright 2004 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (Ph.D.)--University of Tasmania, 2004. Includes bibliographical references
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