Autologous olfactory ensheathing cell transplantation in human spinal cord injury

Protection and repair of the injured spinal cord: a review of completed, ongoing, and planned clinical trials for acute spinal cord injury

Over the past 2 decades, advances in understanding the pathophysiology of spinal cord injury (SCI) have stimulated the recent emergence of several therapeutic strategies that are being examined in Phase I/II clinical trials. Ten randomized controlled trials examining methylprednisolone sodium succinate, tirilizad mesylate, monosialotetrahexosylganglioside, thyrotropin releasing hormone, gacyclidine, naloxone, and nimodipine have been completed. Although the primary outcomes in these trials were laregely negative, a secondary analysis of the North American Spinal Cord Injury Study II demonstrated that when administered within 8 hours of injury, methylprednisolone sodium succinate was associated with modest clinical benefits, which need to be weighed against potential complications. Thyrotropin releasing hormone (Phase II trial) and monosialotetrahexosylganglioside (Phase II and III trials) also showed some promise, but we are unaware of plans for future trials with these agents. These studies have, however, yielded many insights into the conduct of clinical trials for SCI. Several current or planned clinical trials are exploring interventions such as early surgical decompression (Surgical Treatment of Acute Spinal Cord Injury Study) and electrical field stimulation, neuroprotective strategies such as riluzole and minocycline, the inactivation of myelin inhibition by blocking Nogo and Rho, and the transplantation of various cellular substrates into the injured cord. Unfortunately, some experimental and poorly characterized SCI therapies are being offered outside a formal investigational structure, which will yield findings of limited scientific value and risk harm to patients with SCI who are understandably desperate for any intervention that might improve their function. Taken together, recent advances suggest that optimism for patients and clinicians alike is justified, as there is real hope that several safe and effective therapies for SCI may become available over the next decade.

Translating basic research into clinical practice or what else do we have to learn about olfactory ensheathing cells?

Olfactory ensheathing cells (OECs) are Schwann cell-like glial cells of the olfactory system that have been shown to promote axonal regeneration and remyelination in a variety of different lesion paradigms. It is still a matter of debate in how far OECs differ from Schwann cells regarding their regenerative potential and molecular setup. The fact that OECs have been already used for transplantation in humans may imply that the need of the hour is the fine-tuning of clinical application details rather than to cross the bridge between laboratory animal and man. Considering the therapeutic transplantation of OECs, however, the basic question to date is not 'how' to translate but rather 'what' to translate into clinical practice. The aim of the present article is to provide a summary of the current literature and to define the open issues relevant for translating basic research on OECs into clinical practice.

New perspectives for the treatment options in spinal cord injury

Spinal cord injury (SCI) is a serious clinical disorder that leads to lifetime disability for which no suitable therapeutic agents are available so far. Further research is needed to understand the basic mechanisms of spinal cord pathology that results in permanent disability and poses a heavy burden on our society. In the past, a lot of effort was placed on improving functional outcome with the help of various therapeutic agents, however less attention has been paid on the development and propagation of spinal cord pathology over time. Thus, it is still unclear whether improvement of functional outcome is related to spinal cord pathology or vice versa. Few drugs are able to influence functional outcome without having any improvement on cord pathology. Some drugs, however, can lessen cord pathology but fail to influence the functional outcome. The goal of future treatment options for SCI is therefore to find suitable new drugs or a combination of existing drugs and to use various cellular transplants, neurotrophic factors, myelin-inhibiting factors, tissue engineering and nano-drug delivery to improve both the functional and the pathological outcome in the inured patient. This review deals with the key aspects of the latest treatments for SCI and suggests some possible future therapeutic measures to enhance healthcare in clinical situations.

Transplantation of olfactory ensheathing cells enhances peripheral nerve regeneration after microsurgical nerve repair

While axonal regeneration is more successful in peripheral nerve than in the central nervous system, it is by no means complete and research to enhance peripheral nerve regeneration is clinically important. Olfactory ensheathing cells (OECs) are known to enhance axonal regeneration and to produce myelin after transplantation. In contrast to Schwann cells their migratory potential and ability to penetrate glial scars is higher. This study evaluated the effect of OEC transplantation on microsurgically repaired sciatic nerves. Rat sciatic nerves were transected followed by microsurgical repair and transplantation of OECs or injection of medium without cells. Twenty-one days later the nerves were removed and prepared for either histology or electrophysiological analysis. Footprint analysis was carried out at 7, 14 and 21 days. The OECs survived and integrated into the repaired nerves as indicated by eGFP-expressing cells aligned with neurofilament identified axons bridging the repair site. Moreover, regenerated axons were myelinated by the transplanted OECs and nodes of Ranvier were formed. Conduction velocity in the OEC transplant group was increased in comparison to the microsurgical repair alone, and improved stepping was observed in the transplant group. These results suggest that presentation of OECs at the time of nerve injury enhances regeneration and improves functional outcome. Even a modest improvement in nerve regeneration could have significant clinical implications for reconstructive nerve surgery.

Neurosurgery, “neurospine,” and neuroscience: a vital synergy?

A fundamental dilemma that faces both neurosurgery in general and the subspecialty field of spine surgery is the question of whether those who trained in the former and now work in the latter should maintain their links with their origins and remain under the broader umbrella of neurosurgery, or whether they should develop their own organizational structure and identity separate from organized neurosurgery. This challenge raises many questions with respect to future potential for growth and development, professional identity, and collegiality.

This paper is an edited version of an invited speech to the 2007 Annual Meeting of the Joint Section on Disorders of the Spine and Peripheral Nerves. It uses the concept of synergy to review relevant history and explore possible future options for neurosurgery, neurospine, and neuroscience. An example from medical politics is used to illustrate the importance of perspective in approaching these questions, and examples of current therapeutic cutting-edge endeavors highlight the need for team-based behavior that takes a broad view.

The premise of the paper is that while individual and specialty aspirations need to be acknowledged, considered, and managed, the results from truly working together will be greater than the sum of the individual efforts—synergy.

Control of demyelination for recovery of spinal cord injury

Since loss of oligodendrocytes and consequent demyelination of spared axons severely impair the functional recovery of injured spinal cord, it is reasonably expected that the reduction of oligodendroglial death and enhanced remyelination of demyelinated axons will have a therapeutic potential to treat spinal cord injury. Amelioration of axonal myelination in the injured spinal cord is valuable for recovery of the neural function of incompletely injured patients. Here, this article presents an overview about the pathophysiology and mechanism of axonal demyelination in spinal cord injury and discusses its therapeutic significance in the treatment of spinal cord injury. Moreover, it further introduces the recent strategies to improve the axonal myeliantion to facilitate functional recovery of spinal cord injury.

Autologous olfactory ensheathing cell transplantation in human paraplegia: a 3-year clinical trial

Olfactory ensheathing cells show promise in preclinical animal models as a cell transplantation therapy for repair of the injured spinal cord. This is a report of a clinical trial of autologous transplantation of olfactory ensheathing cells into the spinal cord in six patients with complete, thoracic paraplegia. We previously reported on the methods of surgery and transplantation and the safety aspects of the trial 1 year after transplantation. Here we address the overall design of the trial and the safety of the procedure, assessed during a period of 3 years following the transplantation surgery. All patients were assessed at entry into the trial and regularly during the period of the trial. Clinical assessments included medical, psychosocial, radiological and neurological, as well as specialized tests of neurological and functional deficits (standard American Spinal Injury Association and Functional Independence Measure assessments). Quantitative test included neurophysiological tests of sensory and motor function below the level of injury. The trial was a Phase I/IIa design whose main aim was to test the feasibility and safety of transplantation of autologous olfactory ensheathing cells into the injured spinal cord in human paraplegia. The design included a control group who did not receive surgery, otherwise closely matched to the transplant recipient group. This group acted as a control for the assessors, who were blind to the treatment status of the patients. The control group also provided the opportunity for preliminary assessment of the efficacy of the transplantation. There were no adverse findings 3 years after autologous transplantation of olfactory ensheathing cells into spinal cords injured at least 2 years prior to transplantation. The magnetic resonance images (MRIs) at 3 years showed no change from preoperative MRIs or intervening MRIs at 1 and 2 years, with no evidence of any tumour of introduced cells and no development of post-traumatic syringomyelia or other adverse radiological findings. There were no significant functional changes in any patients and no neuropathic pain. In one transplant recipient, there was an improvement over 3 segments in light touch and pin prick sensitivity bilaterally, anteriorly and posteriorly. We conclude that transplantation of autologous olfactory ensheathing cells into the injured spinal cord is feasible and is safe up to 3 years of post-implantation, however, this conclusion should be considered preliminary because of the small number of trial patients.

The strong financial case for regenerative medicine and the regen industry

Although the therapeutic promise of regenerative medicine is immensely exciting, the cost of product development, and particularly of clinical trials, for the more demanding applications will be high. For this reason it is vital for scientists and start-ups who wish to see their ideas implemented to be able to convince established major pharmaceutical or device companies with the necessary 'deep pockets' that the expenditure can yield an appropriate return. It also means that governments and health insurance companies must see a gain in funding regenerative medicine for patients. To address this issue the costs of five major medical conditions that could benefit from regenerative medicine have been defined for the USA as an illustration. This choice of country was made as potentially the largest initial market and one where the billing system for healthcare allows access to individual direct and some indirect costs. The data are complemented by a number of relevant examples of costs per quality-adjusted life year to indicate where current treatment methods are weak or strong. Finally, the relationship of the nascent regen* industry to the pharma and medical device sectors is summarized to assess the challenge of encouraging their involvement.

A novel cell transplantation protocol and its application to an ALS mouse model

Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease, which selectively affects motor neurons throughout the central nervous system. The extensive distribution of motor neurons is an obstacle to applying cell transplantation therapy for the treatment of ALS. To overcome this problem, we developed a cell transplantation method via the fourth cerebral ventricle in mice. We used mouse olfactory ensheathing cells (OECs) and rat mesenchymal stem cells (MSCs) as donor cells. OECs are reported to promote regeneration and remyelination in the spinal cord, while MSCs have a capability to differentiate into several types of specific cells including neural cells. Furthermore both types of cells can be relatively easily obtained by biopsy in human. Initially, we confirmed the safety of the operative procedure and broad distribution of grafted cells in the spinal cord using wild-type mice. After transplantation, OECs distributed widely and survived as long as 100 days after transplantation, with a time-dependent depletion of cell number. In ALS model mice, OEC transplantation revealed no adverse effects but no significant differences in clinical evaluation were found between OEC-treated and non-transplanted animals. After MSC transplantation into the ALS model mice, females, but not males, showed a statistically longer disease duration than the non-transplanted controls. We conclude that intrathecal transplantation could be a promising way to deliver donor cells to the central nervous system. Further experiments to elucidate relevant conditions for optimal outcomes are required.

Treatment of chronic thoracic spinal cord injury patients with autologous Schwann cell transplantation: an interim report on safety considerations and possible outcomes

Several experimental studies have introduced Schwann cell transplantation as a means of recovery in animal models of spinal cord injury (SCI). The reported promising results together with the availability of autologous sources for Schwann cells indicate Schwann cell transplantation as a possible treatment for SCI. To address the safety and feasibility concerns we report 1-year follow-up of four patients aged between 22 and 43 years who had stable chronic (28-80 months) spinal cord injury at mid-thoracic level and treated with autologous Schwann cell transplantation. Purified Schwann cells used for transplantation were acquired from autologous sural nerve and cultured without the use of any specific mitogenic or growth factors. The patients were evaluated by means of American Spinal Injury Association (ASIA) criteria, sphincter, sexual function and Magnetic Resonance Imaging assessments for 1 year after transplantation. None of the patients were found to have any adverse effects indicating transfer of infection, neurological deterioration or other related clinical problems. Of the four patients, only one patient with incomplete SCI showed motor and sensory improvement 1 year after transplantation with extensive and continuous rehabilitation. All the four patients experienced transient paresthesia or increased muscle spasm after transplantation. Magnetic Resonance (MR) images of the patients did not show any visible changes or pathological findings after 1 year. This preliminary report shows that autologous Schwann cell transplantation is generally safe for the selected number of SCI patients but it does not prove beneficial effects. Further safety and outcome studies are recommended.

Clinical studies in spinal cord injury: moving towards successful trials

Spinal cord injury is a devastating condition for which there is still no cure. Many new therapies have emerged in the past few decades that have attempted to improve the outcome after injury, with varying levels of supporting experimental and clinical data. Most studies have been preliminary and have lacked control groups, but positive results can often be embraced by clinicians and patients who are faced without an alternative, despite the poor design and bias of many studies. This article is a review of clinical studies in spinal cord injury and discusses guidelines for future clinical trial design.

[Immunoablation and autologous hematopoietic stem cell transplantation (AHSCT) in multiple sclerosis]

Numerous pathophysiological arguments supporting immunosuppression for multiple sclerosis have been collected during recent years. The relevance of intense immunosuppression, in terms of clinical benefit and early or late risk, remains a matter of discussion. Immunoablation followed by autologous hematopoietic stem cell transplantation (AHSCT) in multiple sclerosis uses intense immunosuppression, followed by reinjection of AHSC, a rescue procedure for the induced aplasia. This method targets disappearance of the immune disorder, and thus, in theory, the interruption of the disease course. Use of AHSCT to treat several types of autoimmune diseases has been performed with contrasted results. In multiple sclerosis, the experience has been gained over the past 10 years through short series of patients treated at a late stage of their disease. This article highlights the recent data of this particular treatment option in multiple sclerosis as well as the therapeutic aims that should be investigated in further trials.

Neural stem cells in the mammalian brain

New fundamental results on stem cell biology have been obtained in the past 15 years. These results allow us to reinterpret the functioning of the cerebral tissue in health and disease. Proliferating stem cells have been found in the adult brain, which can be involved in postinjury repair and can replace dead cells under specific conditions. Numerous genomic mechanisms controlling stem cell proliferation and differentiation have been identified. The involvement of stem cells in the genesis of malignant tumors has been demonstrated. Neural stem cell tropism toward tumors has been shown. These findings suggest new lines of research on brain functioning and development. Stem cells can be used to develop radically new treatments of neurodegenerative and cancer diseases of the brain.

Stem cells and neurological diseases

Cells of the central nervous system were once thought to be incapable of regeneration. This dogma has been challenged in the last decade with studies showing new, migrating stem cells in the brain in many rodent injury models and findings of new neurones in the human hippocampus in adults. Moreover, there are reports of bone marrow-derived cells developing neuronal and vascular phenotypes and aiding in repair of injured brain. These findings have fuelled excitement and interest in regenerative medicine for neurological diseases, arguably the most difficult diseases to treat. There are numerous proposed regenerative approaches to neurological diseases. These include cell therapy approaches in which cells are delivered intracerebrally or are infused by an intravenous or intra-arterial route; stem cell mobilization approaches in which endogenous stem and progenitor cells are mobilized by cytokines such as granulocyte colony stimulatory factor (GCSF) or chemokines such as SDF-1; trophic and growth factor support, such as delivering brain-derived neurotrophic factor (BDNF) or glial-derived neurotrophic factor (GDNF) into the brain to support injured neurones; these approaches may be used together to maximize recovery. While initially, it was thought that cell therapy might work by a 'cell replacement' mechanism, a large body of evidence is emerging that cell therapy works by providing trophic or 'chaperone' support to the injured tissue and brain. Angiogenesis and neurogenesis are coupled in the brain. Increasing angiogenesis with adult stem cell approaches in rodent models of stroke leads to preservation of neurones and improved functional outcome. A number of stem and progenitor cell types has been proposed as therapy for neurological disease ranging from neural stem cells to bone marrow derived stem cells to embryonic stem cells. Any cell therapy approach to neurological disease will have to be scalable and easily commercialized if it will have the necessary impact on public health. Currently, bone marrow-derived cell populations such as the marrow stromal cell, multipotential progenitor cells, umbilical cord stem cells and neural stem cells meet these criteria the best. Of great clinical significance, initial evidence suggests these cell types may be delivered by an allogeneic approach, so strict tissue matching may not be necessary. The most immediate impact on patients will be achieved by making use of the trophic support capability of cell therapy and not by a cell replacement mechanism.

Stem cells and genetic disease

Stem cell research is now a very broad field encompassing cells derived from all stages of life from the embryonic stem cells of the early blastocyst through to the adult stem cells of many tissues of the body. Adult stem cells from a variety of tissues are proving to be pluripotent and can differentiate into cell types different from the tissues from which they derive. Pre-clinical animal models indicate that adult stem cells do not cause tumours, not even, teratomas when transplanted. These properties, combined with the possibility of autologous transplantation, indicate significant advantages over embryonic stem cells in many proposed clinical applications.

Treatments for spinal cord injury: is there hope in neurosteroids?

In this review, we describe the current therapeutic strategies to find a cure for paralysis. We use the example of DHEA, a neurosteroid normally produced in the developing neural tube, to raise the hypothesis that such a class of molecules, capable of modulating proliferation of committed neural precursors, could serve as an environmental cue in the adult injured spinal cord to promote re-population of CNS lesion with endogenous dormant precursor cells. Such mechanism may be a part of the natural response to heal the injured CNS and promote recovery of function, suggesting that neurosteroid-treatment could be a promising and novel therapeutic avenue for SCI. We will review pertinent biological activities of DHEA supporting this hypothesis, demonstrate that such activities, dependent on an intact sonic-hedgehog pathway, are responsible for the motor and bladder functional recovery observed after DHEA-treatment in the adult injured spinal cord. We will also raise the current limitations to further development of DHEA- or other neurosteroid-treatments as drug candidates, including the urgent need to further document DHEA long-term safety in CNS indications.

Xenografts of expanded primate olfactory ensheathing glia support transient behavioral recovery that is independent of serotonergic or corticospinal axonal regeneration in nude rats following spinal cord transection

Transplantation of olfactory ensheathing glial cells (OEG) may improve the outcome from spinal cord injury. Proof-of-principle studies in primates are desirable and the feasibility and efficacy of using in vitro expanded OEG should be tested. An intermediate step between the validation of rodent studies and human clinical trials is to study expanded primate OEG (POEG) xenografts in immunotolerant rodents. In this study the time course to generate purified POEG was evaluated as well as their survival, effect on damaged axons of the corticospinal and serotonergic systems, tissue sparing, and chronic locomotor recovery following transplantation. Fifty-seven nude rats underwent T9/10 spinal cord transection. Thirty-eight rats received POEG, 19 controls were injected with cell medium, and 10 received lentivirally-GFP-transfected POEG. Histological evaluation was conducted at 6 weeks, 8 weeks, 14 weeks and 23-24 weeks. Of these 57 rats, 18 were studied with 5-HT immunostaining, 16 with BDA anterograde CST labeling, and six were used for transmission electron microscopy. In grafted animals, behavioral recovery, sprouting and limited regeneration of 5-HT fibers, and increased numbers of proximal collateral processes but not regeneration of CST fibers was observed. Grafted animals had less cavitation in the spinal cord stumps than controls. Behavioral recovery peaked at three months and then declined. Five POEG-transplanted animals that had shown behavioral recovery underwent retransection and behavioral scores did not change significantly, suggesting that long tract axonal regeneration did not account for the locomotor improvement. At the ultrastructural level presumptive POEG were found to have direct contacts with astrocytes forming the glia limitans, distinct from those formed by Schwann cells. At 6 weeks GFP expression was detected in cells within the lesion site and within nerve roots but did not match the pattern of Hoechst nuclear labeling. At 3.5 months only GFP-positive debris in macrophages could be detected. Transplanted POEG support behavioral recovery via mechanisms that appear to be independent of long tract regeneration.

Myelin repair: the role of stem and precursor cells in multiple sclerosis

Multiple sclerosis is the most common potential cause of neurological disability in young adults. The disease has two distinct clinical phases, each reflecting a dominant role for separate pathological processes: inflammation drives activity during the relapsing-remitting stage and axon degeneration represents the principal substrate of progressive disability. Recent advances in disease-modifying treatments target only the inflammatory process. They are ineffective in the progressive stage, leaving the science of disease progression unsolved. Here, the requirement is for strategies that promote remyelination and prevent axonal loss. Pathological and experimental studies suggest that these processes are tightly linked, and that remyelination or myelin repair will both restore structure and protect axons. This review considers the basic and clinical biology of remyelination and the potential contribution of stem and precursor cells to enhance and supplement spontaneous remyelination.

Differential expression of HNK-1 and p75(NTR) in adult canine Schwann cells and olfactory ensheathing cells in situ but not in vitro

Olfactory ensheathing cells (OECs) are promising candidates for autologous cell transplantation therapies of nervous system injury and disease. Large animal models are relevant for transferring experimental data into clinical practice. In vivo studies have suggested that adult canine OECs may display similar regenerating capacities as their rodent counterpart. However, data on their molecular phenotype required for generating pure cell preparations are still scarce. In the present study, we comparatively analyzed expression of the carbohydrate HNK-1 epitope and the neurotrophin receptor p75(NTR) in adult canine Schwann cells and olfactory ensheathing cells in situ and in vitro. Myelinating and nonmyelinating Schwann cells in situ exclusively expressed HNK-1 and p75(NTR), respectively, whereas OECs were negative for both markers. In vitro, OECs and Schwann cells shared cell surface expression of p75(NTR) but not of HNK-1, which could be detected transiently in intracellular vesicles. This suggests that Schwann cells and OECs in vitro phagozytose HNK-1+ cellular debris. The cultivation-induced downregulation of HNK-1 expression in Schwann cells and upregulation of p75(NTR) in OECs argues for the possibility that axonal signals control the expression of both markers in situ. Whereas HNK-1 expression in Schwann cells is most likely controlled by signals inducing myelination, e.g., neuregulin, the mechanisms that may suppress p75(NTR) expression in OECs in situ remain to be elucidated. Interestingly, HNK-1 expression in the adult dog was found in both sensory and motor nerve myelinating Schwann cells. This is reminiscent of humans and differs from rodents; it also underscores the importance of large animal models for translational research.

Repair in the central nervous system

The subject of central nervous system damage includes a wide variety of problems, from the slow selective 'picking off' of characteristic sub-populations of neurons typical of neurodegenerative diseases, to the wholesale destruction of areas of brain and spinal cord seen in traumatic injury and stroke. Experimental repair strategies are diverse and the type of pathology dictates which approach will be appropriate. Damage may be to grey matter (loss of neurons), white matter (cutting of axons, leaving neurons otherwise intact, at least initially) or both. This review will consider four possible forms of treatment for repair of the human central nervous system.

Evaluation of olfactory ensheathing and schwann cells after implantation into a dorsal injury of adult rat spinal cord

Olfactory ensheathing cells (OECs) and Schwann cells (SCs) obtained from adult transgenic rats expressing alkaline phosphatase (AP) were studied following implantation into intact spinal cord and after dorsal column crush (DCC) injury, either within the lesion or near the lesion borders. We observed no evidence of migration of AP OECs or AP SCs after lesion site injections, with most cells remaining in or nearby the injection/lesion site. Acute injection of either cell type outside of the lesion site resulted in the presence of cells in the lesion even two hours after injection. However, after a 2-week delay between DCC injury and cell injection, only OECs injected 2.5-mm outside of a DCC lesion entered the lesion, while SCs did not pass a region of increased astroglial immunoreactivity. GFAP-immunoreactivity also revealed differences in the astroglial scar at the lesion border with openings apparent in this region only in the OEC group. SCs induced greater ingrowth of CGRP-positive axons within the lesion, two weeks post-injury. Equivalent numbers of GAP-43-positive axons grew within the lesion after SC or OEC implantation. These findings show that, although there is no active migration for either cell type, both OECs and SCs are able to support axonal regrowth and/or sprouting into the lesion. The openings in the astroglial boundary at the lesion site may give OECs a potential advantage over SCs in promoting axonal growth through the astroglial scar.

Cell therapy for spinal cord regeneration

This review presents a summary of the various types of cellular therapy used to treat spinal cord injury. The inhibitory environment and loss of axonal connections after spinal cord injury pose many obstacles to regenerating the lost tissue. Cellular therapy provides a means of restoring the cells lost to the injury and could potentially promote functional recovery after such injuries. A wide range of cell types have been investigated for such uses and the advantages and disadvantages of each cell type are discussed along with the research studying each cell type. Additionally, methods of delivering cells to the injury site are evaluated. Based on the current research, suggestions are given for future investigation of cellular therapies for spinal cord regeneration.

Olfactory ensheathing glia: Their contribution to primary olfactory nervous system regeneration and their regenerative potential following transplantation into the injured spinal cord

Olfactory ensheathing glia (OEG) are a specialized type of glia that guide primary olfactory axons from the neuroepithelium in the nasal cavity to the brain. The primary olfactory system is able to regenerate after a lesion and OEG contribute to this process by providing a growth-supportive environment for newly formed axons. In the spinal cord, axons are not able to restore connections after an injury. The effects of OEG transplants on the regeneration of the injured spinal cord have been studied for over a decade. To date, of all the studies using only OEG as a transplant, 41 showed positive effects, while 13 studies showed limited or no effects. There are several contradictory reports on the migratory and axon growth-supporting properties of transplanted OEG. Hence, the regenerative potential of OEG has become the subject of intense discussion. In this review, we first provide an overview of the molecular and cellular characteristics of OEG in their natural environment, the primary olfactory nervous system. Second, their potential to stimulate regeneration in the injured spinal cord is discussed. OEG influence scar formation by their ability to interact with astrocytes, they are able to remyelinate axons and promote angiogenesis. The ability of OEG to interact with scar tissue cells is an important difference with Schwann cells and may be a unique characteristic of OEG. Because of these effects after transplantation and because of their role in primary olfactory system regeneration, the OEG can be considered as a source of neuroregeneration-promoting molecules. To identify these molecules, more insight into the molecular biology of OEG is required. We believe that genome-wide gene expression studies of OEG in their native environment, in culture and after transplantation will ultimately reveal unique combinations of molecules involved in the regeneration-promoting potential of OEG.

Curiosity and cure: translational research strategies for neural repair-mediated rehabilitation

Clinicians who seek interventions for neural repair in patients with paralysis and other impairments may extrapolate the results of cell culture and rodent experiments into the framework of a preclinical study. These experiments, however, must be interpreted within the context of the model and the highly constrained hypothesis and manipulation being tested. Rodent models of repair for stroke and spinal cord injury offer examples of potential pitfalls in the interpretation of results from developmental gene activation, transgenic mice, endogeneous neurogenesis, cellular transplantation, axon regeneration and remyelination, dendritic proliferation, activity-dependent adaptations, skills learning, and behavioral testing. Preclinical experiments that inform the design of human trials ideally include a lesion of etiology, volume and location that reflects the human disease; examine changes induced by injury and by repair procedures both near and remote from the lesion; distinguish between reactive molecular and histologic changes versus changes critical to repair cascades; employ explicit training paradigms for the reacquisition of testable skills; correlate morphologic and physiologic measures of repair with behavioral measures of task reacquisition; reproduce key results in more than one laboratory, in different strains or species of rodent, and in a larger mammal; and generalize the results across several disease models, such as axonal regeneration in a stroke and spinal cord injury platform. Collaborations between basic and clinical scientists in the development of translational animal models of injury and repair can propel experiments for ethical bench-to-bedside therapies to augment the rehabilitation of disabled patients.

Human stem cells for CNS repair

Although most peripheral tissues have at least a limited ability for self-repair, the central nervous system (CNS) has long been known to be relatively resistant to regeneration. Small numbers of stem cells have been found in the adult brain but do not appear to be able to affect any significant recovery following disease or insult. In the last few decades, the idea of being able to repair the brain by introducing new cells to repair damaged areas has become an accepted potential treatment for neurodegenerative diseases. This review focuses on the suitability of various human stem cell sources for such treatments of both slowly progressing conditions, such as Parkinson's disease, Huntington's disease and multiple sclerosis, and acute insult, such as stroke and spinal cord injury. Despite stem cell transplantation having now moved a step closer to the clinic with the first trials of autologous mesenchymal stem cells, the effects shown are moderate and are not yet at the stage of development that can fulfil the hopes that have been placed on stem cells as a means to replace degenerating cells in the CNS. Success will depend on careful investigation in experimental models to enable us to understand not just the practicalities of stem cell use, but also the underlying biological principles.

Development of a universal measure of quadrupedal forelimb-hindlimb coordination using digital motion capture and computerised analysis

Background

Clinical spinal cord injury in domestic dogs provides a model population in which to test the efficacy of putative therapeutic interventions for human spinal cord injury. To achieve this potential a robust method of functional analysis is required so that statistical comparison of numerical data derived from treated and control animals can be achieved.

Results

In this study we describe the use of digital motion capture equipment combined with mathematical analysis to derive a simple quantitative parameter – 'the mean diagonal coupling interval' – to describe coordination between forelimb and hindlimb movement. In normal dogs this parameter is independent of size, conformation, speed of walking or gait pattern. We show here that mean diagonal coupling interval is highly sensitive to alterations in forelimb-hindlimb coordination in dogs that have suffered spinal cord injury, and can be accurately quantified, but is unaffected by orthopaedic perturbations of gait.

Conclusion

Mean diagonal coupling interval is an easily derived, highly robust measurement that provides an ideal method to compare the functional effect of therapeutic interventions after spinal cord injury in quadrupeds.

Bacteria and PAMPs activate nuclear factor kappaB and Gro production in a subset of olfactory ensheathing cells and astrocytes but not in Schwann cells

The primary olfactory nerves provide uninterrupted conduits for neurotropic pathogens to access the brain from the nasal cavity, yet infection via this route is uncommon. It is conceivable that olfactory ensheathing cells (OECs), which envelope the olfactory nerves along their entire length, provide a degree of immunological protection against such infections. We hypothesized that cultured OECs would be able to mount a biologically significant response to bacteria and pathogen-associated molecular patterns (PAMPs). The response of OECs to Escherichia coli (E. coli) and various PAMPs was compared to that of Schwann cells (SCs), astrocytes (ACs), and microglia (MG). A subset of OECs displayed nuclear localization of nuclear factor kappaB), an inflammatory transcription factor, after treatment with E. coli (20% +/- 5%), lipopolysacchride (33% +/- 9%), and Poly I:C (25% +/- 5%), but not with peptidoglycan or CpG oligonucleotides. ACs displayed a similar level of activation to these treatments, and in addition responded to peptidoglycan. The activation of OECs and ACs was enhanced by coculture with MG (56% +/- 16% and 85% +/- 13%, respectively). In contrast, SCs did not respond to any treatment or to costimulation by MG. Immunostaining for the chemokine Gro demonstrated a functional response that was consistent with NF kappaB activation. OECs expressed mRNA for Toll-like receptors (TLRs) 2 and 4, but only TLR4 protein was detected by Western blotting and immunohistochemistry. The results demonstrate that OECs possess the cellular machinery that permits them to respond to certain bacterial ligands, and may have an innate immune function in protecting the CNS against infection.

Multipotent stem and progenitor cells of the olfactory epithelium

In recent decades, a wide spectrum of fetal and embryonic stem and progenitor cells were used for cell therapy of diseases of the central nervous system, but the olfactory glial ensheathing cells exhibited certain advantages due to their biological properties and capacity to stimulate regeneratory processes in spinal injury. The therapeutic effect of a heterogeneous complex of olfactory epithelial cells is more pronounced; apart from glial ensheathing cells, this complex includes fibroblasts, Schwann cells, stem and progenitor cells of this structure. The use of minimally invasive methods for isolation of human olfactory epithelial tissue is important for clinical practice, because they provide cells for autologous transplantation and rule out graft rejection immune reaction and the risk of transmission viral infection and transfer of genetic defects, which can be associated with allotransplantation.

An overview of tissue engineering approaches for management of spinal cord injuries

Severe spinal cord injury (SCI) leads to devastating neurological deficits and disabilities, which necessitates spending a great deal of health budget for psychological and healthcare problems of these patients and their relatives. This justifies the cost of research into the new modalities for treatment of spinal cord injuries, even in developing countries. Apart from surgical management and nerve grafting, several other approaches have been adopted for management of this condition including pharmacologic and gene therapy, cell therapy, and use of different cell-free or cell-seeded bioscaffolds. In current paper, the recent developments for therapeutic delivery of stem and non-stem cells to the site of injury, and application of cell-free and cell-seeded natural and synthetic scaffolds have been reviewed.

Spinal cord injury medicine. 5. Long-term medical issues and health maintenance

This self-directed learning module highlights long-term care issues in patients with spinal cord injury (SCI). It is part of the study guide on SCI in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. The most common secondary medical complications include pressure ulcers, pneumonia, and genitourinary issues. Health care maintenance is important to prevent medical complications, for general health as well as for issues specific to SCI. Women with SCI have gender-specific issues regarding amenorrhea, sexuality, fertility, and menopause. Options exist to assist disabled men with sexuality and fertility complications. Pain is a common complication after SCI. Many new areas of research in the field of SCI are discussed.

OVERALL ARTICLE OBJECTIVE

To discuss long-term care issues in patients with spinal cord injury, including health maintenance, secondary conditions, women's health, sexual function, pain, and spinal cord regeneration and recovery.

Complete spinal cord injury treatment using autologous bone marrow cell transplantation and bone marrow stimulation with granulocyte macrophage-colony stimulating factor: Phase I/II clinical trial

To assess the safety and therapeutic efficacy of autologous human bone marrow cell (BMC) transplantation and the administration of granulocyte macrophage-colony stimulating factor (GM-CSF), a phase I/II open-label and nonrandomized study was conducted on 35 complete spinal cord injury patients. The BMCs were transplanted by injection into the surrounding area of the spinal cord injury site within 14 injury days (n = 17), between 14 days and 8 weeks (n = 6), and at more than 8 weeks (n = 12) after injury. In the control group, all patients (n = 13) were treated only with conventional decompression and fusion surgery without BMC transplantation. The patients underwent preoperative and follow-up neurological assessment using the American Spinal Injury Association Impairment Scale (AIS), electrophysiological monitoring, and magnetic resonance imaging (MRI). The mean follow-up period was 10.4 months after injury. At 4 months, the MRI analysis showed the enlargement of spinal cords and the small enhancement of the cell implantation sites, which were not any adverse lesions such as malignant transformation, hemorrhage, new cysts, or infections. Furthermore, the BMC transplantation and GM-CSF administration were not associated with any serious adverse clinical events increasing morbidities. The AIS grade increased in 30.4% of the acute and subacute treated patients (AIS A to B or C), whereas no significant improvement was observed in the chronic treatment group. Increasing neuropathic pain during the treatment and tumor formation at the site of transplantation are still remaining to be investigated. Long-term and large scale multicenter clinical study is required to determine its precise therapeutic effect. Disclosure of potential conflicts of interest is found at the end of this article.

Repair of neural pathways by olfactory ensheathing cells

Damage to nerve fibre pathways results in a devastating loss of function, due to the disconnection of nerve fibres from their targets. However, some recovery does occur and this has been correlated with the formation of new (albeit abnormal) connections. The view that an untapped growth potential resides in the adult CNS has led to various attempts to stimulate the repair of disconnectional injuries. A key factor in the failure of axonal regeneration in the CNS after injury is the loss of the aligned glial pathways that nerve fibres require for their elongation. Transplantation of cultured adult olfactory ensheathing cells into lesions is being investigated as a procedure to re-establish glial pathways permissive for the regeneration of severed axons.

AN EXPERIMENTAL MODEL OF VENTRAL ROOT REPAIR SHOWING THE BENEFICIAL EFFECT OF TRANSPLANTING OLFACTORY ENSHEATHING CELLS

OBJECTIVE

A series of published cases show that repair of brachial plexus injuries by reimplantation of avulsed spinal roots can restore a degree of recovery, particularly to the more proximal shoulder and arm musculature in a proportion of patients. There remains, however, some disagreement regarding how far the benefits outweigh the risks of causing further spinal cord damage. Improving the number of motor fibers regenerating into the reimplanted ventral roots may enhance the muscular recovery, possibly extending it to the more useful distal musculature that would restore a degree of wrist and finger functions.

METHODS

This study was based on our previous rat model showing regeneration of severed fibers and resumption of function after transplantation of cultured adult olfactory ensheathing cells into spinal cord injuries and reimplanted dorsal roots.

RESULTS

We now report that olfactory ensheathing cells transplanted at the spinal cord interface of reimplanted S1 ventral roots survive and migrate selectively into the ventral root where they associate intimately with regenerating ventral root fibers. Whereas only approximately 20% of the normal complement of fibers enter roots reimplanted without olfactory ensheathing cells, this increases to 80% in the presence of olfactory ensheathing cell transplants.

CONCLUSION

These observations suggest that transplants of olfactory ensheathing cells could improve the outcome of ventral root repair.