Olfactory ensheathing cells enhance Schwann cell-mediated anatomical and functional repair after sciatic nerve injury in adult rats.

Sciatic nerve injury results in axon damage, muscle degeneration, and loss of function. We compared the potential of Schwann cell (SC), olfactory ensheathing cell (OEC), or mixed SC/OEC transplants for anatomical and functional restoration after adult rat sciatic nerve transection. The cells were seeded into a 20mm long macroporous poly(dl-lactide-co-glycolide) acid conduit and grafted between the sciatic nerve stumps. Some rats received a conduit without cells (controls) or an autologous nerve graft, the clinical standard of care. Compared with SC transplants, axon regeneration was 25% less with OEC transplants but 28% more with SC/OEC transplants. Gastrocnemius muscle restoration was similar with a SC or OEC transplant and 35% better with a SC/OEC transplant. With SC transplants, motor and sensory function recovery and electrophysiological outcomes were similar as with OEC transplants and 33% better with SC/OEC transplants. Compared with the mixed SC/OEC transplants, axon regeneration was 21% better and gastrocnemius muscle restoration was 18% better with autologous peripheral nerve transplants, but these improvements did not translate into increased function and electrophysiological outcomes. Our results revealed that OEC synergistically improve SC mediated sciatic nerve repair. The data emphasized the promise of SC/OEC transplants as artificial nerves for peripheral nerve repair. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

You H ，Wei L ，Liu Y ，Oudega M ，Jiao SS ，Feng SN ，Chen Y ，Chen JM ，Li BC ... -  《-》

Transplantation of olfactory ensheathing cells promotes axonal regeneration and functional recovery of peripheral nerve lesion in rats.

Olfactory ensheathing cells (OECs) hold promise for cell therapy because they may promote regeneration of the central nervous system. However, OECs have been less studied after peripheral nerve injury (PNI). The purpose of this investigation was to determine the effect of OEC transplantation on a severe sciatic nerve (SN) lesion. OECs were injected in rats after section and 2-cm resection of the SN. Three months after therapy, muscle strength and morphometric studies showed complete restoration of the contractile properties of the gastrocnemius and complete repair of the SN. Immunohistochemistry and RT-PCR studies indicated an increase in the presence of neurotrophic factors. Interestingly, tracking of green fluorescent protein (GFP)-positive OECs showed that no OECs were present in the SN. Our results demonstrate that, after severe PNI, OECs have remarkable potential for nerve regeneration by creating a favorable microenvironment.

Guérout N ，Duclos C ，Drouot L ，Abramovici O ，Bon-Mardion N ，Lacoume Y ，Jean L ，Boyer O ，Marie JP ... -  《-》

Acute transplantation of olfactory ensheathing cells or Schwann cells promotes recovery after spinal cord injury in the rat.

We compared the neurological and electrophysiological outcome, glial reactivity, and spared spinal cord connectivity promoted by acute transplantation of olfactory ensheathing cells (group OEC) or Schwann cells (group SC) after a mild injury to the rat spinal cord. Animals were subjected to a photochemical injury of 2.5 min irradiation at the T8 spinal cord segment. After lesion, a suspension containing 180,000 OECs or SCs was injected. A control group (group DM) received the vehicle alone. During 3 months postsurgery, behavioral skills were assessed with open field-BBB scale, inclined plane, and thermal algesimetry tests. Motor (MEPs) and somatosensory evoked potentials (SSEPs) were performed to evaluate the integrity of spinal cord pathways, whereas lumbar spinal reflexes were evaluated by the H reflex responses. Glial fibrillary acidic protein and proteoglycan expressions were quantified immunohistochemically at the injured spinal segments, and the preservation of corticospinal and raphespinal tracts caudal to the lesion was evaluated. Both OEC- and SC-transplanted groups showed significantly better results in all the behavioral tests than the DM group. Furthermore, the OEC group had higher MEP amplitudes and lower H responses than the other two groups. At the injury site, the area of spared parenchyma was greater in transplanted than in control injured rats. OEC-transplanted animals had reduced astrocytic reactivity and proteoglycan expression in comparison with SC-transplanted and DM rats. Taken together, these results indicate that transplantation of both OEC and SC has potential for restoration of injured spinal cords. OEC grafts showed superior ability to reduce glial reactivity and to improve functional recovery.

García-Alías G ，López-Vales R ，Forés J ，Navarro X ，Verdú E ... -  《JOURNAL OF NEUROSCIENCE RESEARCH》

Juvenile and adult olfactory ensheathing cells bundle and myelinate dorsal root ganglion axons in culture.

Olfactory ensheathing cells (OEC), which normally associate closely with but do not myelinate axons in situ, myelinate axons in the adult mammalian spinal cord. They are of clinical interest as candidate cells for autologous transplantation but the ability of OEC to myelinate axons in vitro has been controversial. To clarify this issue, we isolated OEC from olfactory bulbs (OB) of juvenile and adult rats expressing GFP and analyzed their ability to myelinate axons. Using a well-defined assay for myelination of dorsal root ganglia (DRG) axons in culture, we found that OEC from juvenile pups associated with and then myelinated DRG axons. OEC assembled into bundles with the axons by 1week and required more than a week before myelination on axons was detected. In contrast, rat Schwann cells did not bundle axons and they formed P0(+) and MBP(+) myelin segments after as little as 1week. Most of the OEC in culture exhibited staining for calponin, a marker that was not found on Schwann cells in culture, whereas in both OEC and Schwann cell populations nearly all cells were positive for p75NTR and GFAP. These results confirm previous reports showing only subtle immunological differences between Schwann cells and OEC. Besides differences in the rate of myelination, we detected two additional functional differences in the interactions of OEC and Schwann cells with DRG axons. First, the diameter of OEC generated myelin was greater than for Schwann cell myelin on DRG axons. Second, OEC but not Schwann cells myelinated DRG axons in the absence of vitamin C. OEC isolated from adult OB were also found to bundle and myelinate DRG axons but the latter occurred only after incubation times of at least 3weeks. The results indicate that adult OEC require longer incubation times than juvenile OEC to myelinate axons and suggest that patterns of myelination by OEC and Schwann cells are distinguishable at least on axons in vitro. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

Babiarz J ，Kane-Goldsmith N ，Basak S ，Liu K ，Young W ，Grumet M ... -  《-》

Efficacy of olfactory ensheathing cells to support regeneration after spinal cord injury is influenced by method of culture preparation.

Olfactory ensheathing cells (OEC) have been shown to stimulate regeneration, myelination and functional recovery in different spinal cord injury models. However, recent reports from several laboratories have challenged this treatment strategy. The discrepancy in results could be attributed to many factors including variations in culture protocols. The present study investigates whether the differences in culture preparation could influence neuroprotective and growth-promoting effects of OEC after transplantation into the injured spinal cord. Primary OEC cultures were purified using method of differential cell adhesion (a-OEC) or separated with immunomagnetic beads (b-OEC). After cervical C4 hemisection in adult rats, short-term (3 weeks) or long-term (7 weeks) cultured OEC were transplanted into the lateral funiculus at 1mm rostral and caudal to the transection site. At 3-8 weeks after transplantation, labeled OEC were mainly found in the injection sites and in the trauma zone. Short-term cultured a-OEC supported regrowth of rubrospinal, raphaespinal and CGRP-positive fibers, and attenuated retrograde degeneration in the red nucleus. Short-term cultured b-OEC failed to promote axonal regrowth but increased the density of rubrospinal axons within the dorsolateral funiculus and provided significant neuroprotection for axotomized rubrospinal neurons. In addition, short-term cultured OEC attenuated sprouting of rubrospinal terminals. In contrast, long-term cultured OEC neither enhanced axonal growth nor prevented retrograde cell death. The results suggest that the age of OEC in culture and the method of cell purification could affect the efficacy of OEC to support neuronal survival and regeneration after spinal cord injury. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

Novikova LN ，Lobov S ，Wiberg M ，Novikov LN ... -  《-》