Implantation of cultured olfactory ensheathing cells into the damaged spinal cord of adult rats has been reported to remyelinate central axons. This observation is curious because olfactory ensheathing cells do not myelinate axons in their native environment. We have recently determined that calponin is the first definitive phenotypic marker for olfactory ensheathing cells. Primary cultures of adult rat olfactory mucosa and olfactory bulb were immunostained for p75 neurotrophin receptor and calponin. Our results reveal that two populations of p75 neurotrophin receptor-positive cells exist in primary cultures of the olfactory mucosa and bulb: calponin-positive olfactory ensheathing cells and calponin-negative Schwann cells. As olfactory tissues likely yield a mixed glial population, the idea that olfactory ensheathing cells are capable of de novo myelin synthesis after intraspinal implantation should be re-evaluated.
"However, an increased mitotic rate and migratory ability of LP in vitro was observed in vivo due to their migration within the SC, reduced cavity formation and lesion size, and stimulated outgrowth of axonal subpopulation when compared with OB. For otherwise, there is an important aspect concerning remyelination, that is, olfactory ensheathing cells (OEC) do not myelinate axons in their native environment. Therefore, it is not clear how the myelination happens. "
[Show abstract][Hide abstract] ABSTRACT: Glial scar (GS) is the most important inhibitor factor to neuroregeneration after spinal cord injury (SCI) and behaves as a tertiary lesion. The present review of the literature searched for representative studies concerning GS and therapeutic strategies to neuroregeneration.
The author used the PubMed database and Google scholar to search articles published in the last 20 years. Key words used were SCI, spinal cord (SC) inflammation, GS, and SCI treatment.
Both inflammation and GS are considered important events after SCI. Despite the fact that firstly they seem to cause benefit, in the end they cause more harm than good to neuroregeneration. Each stage has its own aspects under the influence of the immune system causing inflammation, from the primary to secondary lesion and from those to GS (tertiary lesion).
Future studies should stress the key points where and when GS presents itself as an inhibitory factor to neuroregeneration. Considering GS as an important event after SCI, the author defends GS as being a tertiary lesion. Current strategies are presented with emphasis on stem cells and drug therapy. A better understanding will permit the development of a therapeutic basis in the treatment of the SCI patients considering each stage of the lesion, with emphasis on GS and neuroregeneration.
Surgical Neurology International 08/2011; 2(1):112. DOI:10.4103/2152-7806.83732 · 1.18 Impact Factor
"This medium is selective for OECs because it does not support long-term culture of Schwann cells beyond 24 hrs (Cheng et al., 1998, Levi et al., 1994, Lobsiger et al., 2000). In many laboratories the culture medium contains either fetal calf serum or one of the neuregulins which will support both OECs and Schwann cells (Bock et al., 2007, Rizek and Kawaja, 2006). "
[Show abstract][Hide abstract] ABSTRACT: Olfactory mucosa, the sense organ of smell, is an adult tissue that is regenerated and repaired throughout life to maintain the integrity of the sense of smell. When the sensory neurons of the olfactory epithelium die they are replaced by proliferation of stem cells and their axons grow from the nose to brain assisted by olfactory ensheathing cells located in the lamina propria beneath the sensory epithelium. When transplanted into the site of traumatic spinal cord injury in rat, olfactory lamina propria or purified olfactory ensheathing cells promote behavioural recovery and assist regrowth of some nerves in the spinal cord. A Phase I clinical trial demonstrated that autologous olfactory ensheathing cell transplantation is safe, with no adverse outcomes recorded for three years following transplantation. Autologous olfactory mucosa transplantation is also being investigated in traumatic spinal cord injury although this whole tissue contains many cells in addition to olfactory ensheathing cells, including stem cells. If olfactory ensheathing cells are proven therapeutic for human spinal cord injury there are several important practical issues that will need to be solved before they reach general clinical application. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.
"It has been argued that OECs are not the myelinating cell in the above studies and that contaminating SCs may be responsible for the remyelination (Rizek and Kawaja, 2006). These investigators suggest that OECs, but not SCs, express the muscle fiber actin binding protein calponin (Boyd et al., 2006), and that most cells in OEC culture preparations are p75 + and calponin -, thus suggesting a contamination in OEC cultures of Schwann cells. "
[Show abstract][Hide abstract] ABSTRACT: Olfactory ensheathing cells (OECs) are specialized glial cells that guide olfactory receptor axons from the nasal mucosa into the brain where they make synaptic contacts in the olfactory bulb. While a number of studies have demonstrated that in vivo transplantation of OECs into injured spinal cord results in improved functional outcome, precise cellular mechanisms underlying this improvement are not fully understood. Current thinking is that OECs can encourage axonal regeneration, provide trophic support for injured neurons and for angiogenesis, and remyelinate axons. However, Schwann cell (SC) transplantation also results in significant functional improvement in animal models of spinal cord injury. In culture SCs and OECs share a number of phenotypic properties such as expression of the low affinity NGF receptor (p75). An important area of research has been to distinguish potential differences in the in vivo behavior of OECs and SCs to determine if one cell type may offer greater advantage as a cellular therapeutic candidate. In this review we focus on several unique features of OECs when they are transplanted into the spinal cord.
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