Variability in Early Surgery for Acute Cervical Spinal Cord Injury Patients: An Opportunity for Enhanced Care Delivery.

Data supporting the benefits of early surgical intervention in acute spinal cord injury (SCI) is growing. For early surgery to be accomplished, understanding the causes of variabilities that effect the timing of surgery is needed to achieve this goal. The purpose of this analysis is to determine factors that affect the timing of surgery for acute cervical SCI within the North American Clinical Trials Network (NACTN) for SCI registry. Patients in the NACTN SCI registry from 2005 to 2019 with a cervical SCI, excluding acute traumatic central cord syndrome, were analyzed for time elapsed from injury to arrival to the hospital, and time to surgery. Two categories were defined: 1) Early Arrival with Early Surgery (EAES) commenced within 24 h of injury, and 2) Early Arrival but Delayed Surgery (EADS), with surgery occurring between 24 to 72 h post-injury. Patients' demographic features, initial clinical evaluation, medical comorbidities, neurological status, surgical intervention, complications, and outcome data were correlated with respect to the two arrival groups. Of the 222 acute cervical SCI patients undergoing surgery, 163 (73.4%) were EAES, and 59 (26.6%) were EADS. There was no statistical difference in arrival time between the EAES and EADS groups. There was a statistical difference in the median arrival time to surgery between the EAES group (9 h) compared with the EADS group (31 h; p < 0.05). There was no statistical difference in race, sex, age, mechanism of injury, Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II scores, or medical comorbidities between the two groups, but the EAES group did present with a significantly lower systolic blood pressure (p < 0.05). EADS patients were more likely to present as an American Spinal Injury Association Impairment Scale (AIS) D than EAES (p < 0.05). Early surgery was statistically more likely to occur if the injury occurred over the weekend (p < 0.05). There were variations in the rates of early surgery between the eight NACTN sites within the study, ranging from 57 to 100%. Of the 114 patients with 6-month outcome data, there was no significant change between the two groups regarding AIS grade change and motor/pin prick/light touch score recovery. A trend towards improved motor scores with early surgery was not statistically significant (p = 0.21). Although there is data that surgery within 24 h of injury improves outcomes and can be performed safely, there remain variations in care outside of clinical trials. In the present study of cervical SCI, NACTN achieved its goal of early surgery in 73.4% of patients from 2005-2019 who arrived within 24 h of their injury. Variability in achieving this goal was related to severity of neurological injury, the day of the week, and the treating NACTN center. Evaluating variations within our network improves understanding of potential systemic limitations and our decision-making process to accomplish the goal of early surgery.

Interhospital Transfer Delays Care for Spinal Cord Injury Patients: A Report from the North American Clinical Trials Network for Spinal Cord Injury.

Abstract The North America Clinical Trials Network (NACTN) for Spinal Cord Injury (SCI) is a consortium of tertiary medical centers that has maintained a prospective SCI registry since 2004, and it has espoused that early surgical intervention is associated with improved outcome. It has previously been shown that initial presentation to a lower acuity center and necessity of transfer to a higher acuity center reduce rates of early surgery. The NACTN database was evaluated to examine the association between interhospital transfer (IHT), early surgery, and outcome, taking into account distance traveled and site of origin for the patient. Data from a 15-year period of the NACTN SCI Registry were analyzed (years 2005-2019). Patients were stratified into transfers directly from the scene to a Level 1 trauma center (NACTN site) versus IHT from a Level 2 or 3 trauma facility. The main outcome was surgery within 24 hours of injury (yes/no), whereas secondary outcomes were length of stay, death, discharge disposition, and 6-month American Spinal Injury Association Impairment Scale (AIS) grade conversion. For the IHT patients, distance traveled for transfer was calculated by measuring the shortest distance between origin and NACTN hospital. Analysis was performed with Brown-Mood test and chi-square tests. Of 724 patients with transfer data, 295 (40%) underwent IHT and 429 (60%) were admitted directly from the scene of injury. Patients who underwent IHT were more likely to have a less severe SCI (AIS D; p = 0.002), have a central cord injury (p = 0.004), and have a fall as their mechanism of injury (p < 0.0001) than those directly admitted to an NACTN center. Of the 634 patients who had surgery, direct admission to an NACTN site was more likely to result in surgery within 24 hours compared with IHT patients (52% vs. 38%) (p < 0.0003). Median IHT distance was 28 miles (interquartile range [IQR] = 13-62 miles). There was no significant difference in death, length of stay, discharge to a rehab facility versus home, or 6-month AIS grade conversion rates between the two groups. Patients who underwent IHT to an NACTN site were less likely to have surgery within 24 hours of injury, compared with those directly admitted to the Level 1 trauma facility. Although there was no difference in mortality rates, length of stay, or 6-month AIS conversion between groups, patients with IHT were more likely be older with a less severe level of injury (AIS D). This study suggests there are barriers to timely recognition of SCI in the field, appropriate admission to a higher level of care after recognition, and challenges related to the management of individuals with less severe SCI.

Bulbocavernosus Reflex Has No Prognostic Features During the Acute Evaluation of Spinal Cord Injuries.

The bulbocavernosus reflex (BCR) has been used during the initial evaluation of a spinal cord injury patient as a metric to determine prognosis and whether the patient is in "spinal shock." This reflex has been less utilized over the last decade, and therefore a review was performed to assess the value of BCR in patient prognosis. The North American Clinical Trials Network (NACTN) for Spinal Cord Injury (SCI) is a consortium of tertiary medical centers that includes a prospective SCI registry. The NACTN registry data was analyzed to evaluate the prognostic implication of the BCR during the initial evaluation of a spinal cord injury patient. SCI patients were divided into those with an intact or absent BCR during their initial evaluation. Associations of participants' descriptors and neurological status on follow-up were performed, followed by associations with the presence of a BCR. A total of 769 registry patients with recorded BCRs were included in the study. The median age was 49 years (32-61 years), and the majority were male (n = 566, 77%) and white (n = 519, 73%). Among included patients, high blood pressure was the most common comorbidity (n = 230, 31%). Cervical spinal cord injury was the most common (n = 470, 76%) with fall (n = 320, 43%) being the most frequent mechanism of injury. BCR was present in 311 patients (40.4%), while 458 (59.6%) had a negative BCR within 7 days of injury or before surgery. At 6 months post-injury, 230 patients (29.9%) followed up, of which 145 had a positive BCR, while 85 had a negative BCR. The presence/absence of BCR was significantly different in patients with cervical (p = 0.0015) or thoracic SCI (p = 0.0089), or conus medullaris syndrome (p = 0.0035), and in those who were American Spinal Injury Association Impairment Scale grade A (p = 0.0313). No significant relationship was observed between BCR results and demographics, AIS grade conversion, motor score changes (p = 0.1669), and changes in pin prick (p = 0.3795) and light touch scores (p = 0.8178). In addition, cohorts were not different in surgery decision (p = 0.7762) and injury to surgery time (p = 0.0681). In our review of the NACTN spinal cord registry, the BCR did not provide prognostic utility in the acute evaluation of spinal cord injury patients. Therefore, it should not be used as a reliable marker for predicting neurological outcomes post-injury.

Evolving Profile of Acute Spinal Cord Injury Demographics, Outcomes, and Surgical Treatment in North America: Analysis of a Prospective Multi-Center Dataset of 989 Patients.

Changes in demography and injury patterns have altered the profile and outcome of acute spinal cord injury (SCI) over time. This study sought to describe recent trends in epidemiology and early clinical outcomes using the multi-center North American Clinical Trial Network (NACTN) for Spinal Cord Injury Registry. All participants with blunt acute traumatic SCI (n = 782) were grouped into three five-year time intervals from 2005 to 2019 (2005-2009, 2010-2014, and 2015-2019). Baseline demographics, clinical scores, medical co-morbidities, as well as early clinical outcomes were extracted. Categorical and continuous variables were analyzed to determine between-group differences. Subgroup analysis was performed for participants <50 and ≥50 years of age. Over the duration of the study period, there was an increase in age at presentation (p = 0.0077) as well as a greater incidence of falls as the mechanism of injury. Participants who were ≥50 years of age were more likely to sustain incomplete SCI (<0.0003) and central cord syndrome (< 0.0001). In the most recent period (2015-2019), a greater proportion of NACTN participants underwent surgery within 24 h of injury (63% vs. 41% vs. 41%, p = 0.0001). There was a statistically significant increase in cardiac complications (p < 0.0001) and decrease in pulmonary complications (p < 0.0001) during the study period. Data from the NACTN registry shows that the age of participants with acute SCI is increasing, falls have become the major mechanism of injury, and central cord injury is becoming increasingly prevalent. While early surgical intervention for acute SCI is more common in recent years, cardiac complications are more prevalent while pulmonary complications are less prevalent.

History and Accomplishments of the North American Clinical Trials Network for Spinal Cord Injury, 2004-2022.

This is a historical account of the origin and accomplishments of the North American Clinical Trials Network (NACTN) for traumatic spinal cord injury (SCI), which was established in 2004 by Christopher Reeve and Robert Grossman. Christopher Reeve was an actor who became quadriplegic and started the Christopher & Dana Reeve Foundation (CDRF), and Robert Grossman was a neurosurgeon experienced in neurotrauma and a university professor in Houston. NACTN has member investigators at university and military centers in North America and has contributed greatly to the improvement of care, primarily acute care, of patients sustaining traumatic SCI. Its accomplishments are a clinical registry database of >1000 acute SCI patients documenting the care pathways, including complications. NACTN has assessed the effectiveness of treatment, including pharmacotherapy and the role and timing of surgery, and has also identified barriers to early surgery. The principal focus has been on improving neurological recovery. NACTN has trained many SCI practitioners and has collaborated with other SCI networks and organizations internationally to promote the care of SCI patients.

Management of peripheral nerve sheath tumors: 17 years of experience at Toronto Western Hospital.

OBJECTIVE A surgical series of 201 benign and malignant peripheral nerve sheath tumors (PNSTs) was assessed to characterize the anatomical and clinical presentation of tumors and identify predictors of neurological outcome, recurrence, and extent of resection. METHODS All surgically treated PNSTs from the Division of Neurosurgery at Toronto Western Hospital from 1993 to 2010 were reviewed retrospectively. Data were collected on patient demographics, clinical presentation, surgical technique, extent of resection, postoperative neurological outcomes, and recurrence. RESULTS One hundred seventy-five patients with 201 tumors had adequate follow-up for analysis. There were 182 benign and 19 malignant PNSTs. Of the benign lesions, 133 were schwannomas, 21 of which were associated with a diagnosis of schwannomatosis. There were 49 neurofibromas, and 26 were associated with neurofibromatosis Type 1 (NF1). Patients presenting with schwannomas were significantly older than those with neurofibromas. Schwannomas were more readily resected than neurofibromas, with the extent of resection of the former influenced by tumor location. Patients with benign PNSTs typically presented with a painful mass and less frequently with motor deficits. The likelihood of worsened postoperative motor function was decreased in patients with fully resected tumors or preoperative deficits. Recurrence of schwannomas and neurofibromas were seen more frequently in patients diagnosed with NF3 and NF1, respectively. Subtotal resection was associated with the increased recurrence of all benign lesions. CONCLUSIONS Outcomes following resection of benign PNSTs depend on tumor histopathology, tumor location, and genetic predisposition syndrome. Gross-total resection should be attempted for benign lesions where possible. The management of malignant PNSTs remains challenging, requiring a multimodal approach.

Positive Modulation of AMPA Receptors Promotes Survival and Proliferation of Neural Stem/Progenitor Cells from the Adult Rat Spinal Cord.

Transplantation of neural stem/progenitor cells (NSPCs) following spinal cord injury (SCI) is a promising strategy to enhance regeneration but is limited by poor survival of grafted cells. Determining methods to enhance survival of NSPCs is therefore essential. Positive modulation of AMPA receptors has been shown to enhance neurogenesis in various models of brain injury. Here we examined the effect of selective AMPA receptor modulation in adult rat spinal cord-derived NSPCs using a class of allosteric AMPA receptor modulators known as ampakines. NSPCs from the periventricular region of the adult rat spinal cord were treated with ampakines CX614 and CX546 for 72 h either alone or in the presence of low-dose glutamate (50 µM). Treatment with either agent in the presence of glutamate significantly increased cell survival and proliferation and reduced cell death. Moreover, ampakine/glutamate treatment reduced cell death in the setting of oxidative stress. Treatment with ampakines did not significantly alter cell phenotype. These findings offer important insight into a potential therapeutic strategy to positively regulate transplanted and endogenous adult spinal cord-derived NSPCs after SCI.

Glutamate Increases In Vitro Survival and Proliferation and Attenuates Oxidative Stress-Induced Cell Death in Adult Spinal Cord-Derived Neural Stem/Progenitor Cells via Non-NMDA Ionotropic Glutamate Receptors.

Traumatic spinal cord injury (SCI) leads to a cascade of secondary chemical insults, including oxidative stress and glutamate excitotoxicity, which damage host neurons and glia. Transplantation of exogenous neural stem/progenitor cells (NSPCs) has shown promise in enhancing regeneration after SCI, although survival of transplanted cells remains poor. Understanding the response of NSPCs to the chemical mediators of secondary injury is essential in finding therapies to enhance survival. We examined the in vitro effects of glutamate and glutamate receptor agonists on adult rat spinal cord-derived NSPCs. NSPCs isolated from the periventricular region of the adult rat spinal cord were exposed to various concentrations of glutamate for 96 h. We found that glutamate treatment (500 µM) for 96 h significantly increased live cell numbers, reduced cell death, and increased proliferation, but did not significantly alter cell phenotype. Concurrent glutamate treatment (500 µM) in the setting of H2O2 exposure (500 µM) for 10 h increased NSPC survival compared to H2O2 exposure alone. The effects of glutamate on NSPCs were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)/kainate receptor antagonist GYKI-52466, but not by the N-methyl-D-aspartic acid receptor antagonist MK-801 or DL-AP5, or the mGluR3 antagonist LY-341495. Furthermore, treatment of NSPCs with AMPA, kainic acid, or the kainate receptor-specific agonist (RS)-2-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl)propanoic acid mimicked the responses seen with glutamate both alone and in the setting of oxidative stress. These findings offer important insights into potential mechanisms to enhance NSPC survival and implicate a potential role for glutamate in promoting NSPC survival and proliferation after traumatic SCI.

Postconcussion syndrome: demographics and predictors in 221 patients.

OBJECTIVE The objective of this study was to determine the demographics and predictors of postconcussion syndrome (PCS) in a large series of patients using a novel definition of PCS. METHODS The authors conducted a retrospective cohort study of 284 consecutive concussed patients, 221 of whom had PCS on the basis of at least 3 symptoms persisting at least 1 month. This definition of PCS was uniformly employed and is unique in accepting an expanded list of symptoms, in shortening the postconcussion interval to 1 month from 3 months, and in excluding those with focal injuries such as hemorrhages and contusions. RESULTS The 221 cases showed considerable heterogeneity in clinical features of PCS. They averaged 3.3 concussions, with a range of 0 to 12 or more concussions, and 62.4% occurred during sports and recreation. The median duration of PCS was 7 months at the time of examination, with 11.8% lasting more than 2 years, and 23.1% with PCS had only 1 concussion. The average patient age was 27 years (range 10-74 years). The average number of persistent symptoms was 8.1; 26.2% had a previous psychiatric condition, attention-deficit disorder/attention-deficit hyperactivity disorder, a learning disability, or previous migraine headaches. The prevalence of arachnoid cysts and Chiari malformation in PCS exceeded the general population. Additionally, involvement in litigation, presence of extracranial injuries, amnesia and/or loss of consciousness, and female sex were predictive of reporting a high number of symptoms. A prior history of psychiatric conditions or migraines, cause of injury, number of previous concussions, and age did not significantly predict symptom number. Only the number of symptoms reported predicted the duration of PCS. To predict the number of symptoms for those who fulfilled PCS criteria according to the International Classification of Diseases, 10th Revision (ICD-10), and the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV), the number of previous concussions was significant. CONCLUSIONS PCS is commonly associated with multiple concussions, but 23.1% in the present series occurred after only 1 concussion. Most patients with PCS had multiple symptoms persisting for months or years. The median duration of PCS was 7 months, with a range up to 26 years. In only 11.3%, the PCS had ended at the time of consultation. Not all predictors commonly cited in the literature align with the findings in this study. This is likely due to differences in the definitions of PCS used in research. These results suggest that the use of ICD-10 and DSM-IV to diagnose PCS may be biased toward those who are vulnerable to concussions or with more severe forms of PCS. It is thus important to redefine PCS based on evidence-based medicine.

Effect of BDNF and Other Potential Survival Factors in Models of In Vitro Oxidative Stress on Adult Spinal Cord-Derived Neural Stem/Progenitor Cells.

Transplantation of neural stem/progenitor cells (NSPCs) is a promising strategy in spinal cord injury (SCI). However, poor survival of transplanted stem cells remains a major limitation of this therapy due to the hostile environment of the injured cord. Oxidative stress is a hallmark in the pathogenesis of SCI; however, its effects on NSPCs from the adult spinal cord have yet to be examined. We therefore developed in vitro models of mild and severe oxidative stress of adult spinal cord-derived NSPCs and used these models to examine potential cell survival factors. NSPCs harvested from the adult rat spinal cord were treated with hydrogen peroxide (H2O2) in vitro to induce oxidative stress. A mild 4 h exposure to H2O2 (500 µM) significantly increased the level of intracellular reactive oxygen species with minimal effect on viability. In contrast, 24 h of oxidative stress led to a marked reduction in cell survival. Pretreatment with brain-derived neurotrophic factor (BDNF) for 48 h attenuated the increase in intracellular reactive oxygen species and enhanced survival. This survival effect was associated with a significant reduction in the number of apoptotic cells and a significant increase in the activity of the antioxidant enzymes glutathione reductase and superoxide dismutase. BDNF treatment had no effect on NSPC differentiation or proliferation. In contrast, cyclosporin A and thyrotropin-releasing hormone had minimal or no effect on NSPC survival. Thus, these models of in vitro oxidative stress may be useful for screening neuroprotective factors administered prior to transplantation to enhance survival of stem cell transplants.

Review of transplantation of neural stem/progenitor cells for spinal cord injury.

Spinal cord injury (SCI) is a debilitating condition often resulting in paralysis, yet currently there is no effective treatment. Stem cell transplantation is a promising therapeutic strategy for promoting tissue repair after SCI. Stem cells offer a renewable source of cells with inherent plasticity for tissue regeneration. Neural stem/progenitor cells (NSPCs) are multipotent cells that self-renew and are committed to the neural lineage, and thus, they are especially suited to SCI repair. NSPCs may differentiate into neural cells after transplantation into the injured spinal cord, replacing lost or damaged cells, providing trophic support, restoring connectivity, and facilitating regeneration. Here, we review experimental studies and considerations for clinical translation of NSPC transplantation for SCI.

Absence of chronic traumatic encephalopathy in retired football players with multiple concussions and neurological symptomatology.

BACKGROUND: Chronic traumatic encephalopathy (CTE) is the term coined for the neurodegenerative disease often suspected in athletes with histories of repeated concussion and progressive dementia. Histologically, CTE is defined as a tauopathy with a distribution of tau-positive neurofibrillary tangles (NFTs) that is distinct from other tauopathies, and usually shows an absence of beta-amyloid deposits, in contrast to Alzheimer's disease (AD). Although the connection between repeated concussions and CTE-type neurodegeneration has been recently proposed, this causal relationship has not yet been firmly established. Also, the prevalence of CTE among athletes with multiple concussions is unknown. METHODS: We performed a consecutive case series brain autopsy study on six retired professional football players from the Canadian Football League (CFL) with histories of multiple concussions and significant neurological decline. RESULTS: All participants had progressive neurocognitive decline prior to death; however, only 3 cases had post-mortem neuropathological findings consistent with CTE. The other 3 participants had pathological diagnoses of AD, amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD). Moreover, the CTE cases showed co-morbid pathology of cancer, vascular disease, and AD. DISCUSSION: Our case studies highlight that not all athletes with history of repeated concussions and neurological symptomology present neuropathological changes of CTE. These preliminary findings support the need for further research into the link between concussion and CTE as well as the need to expand the research to other possible causes of taupathy in athletes. They point to a critical need for prospective studies with good sampling methods to allow us to understand the relationship between multiple concussions and the development of CTE.

Repair of the injured spinal cord by transplantation of neural stem cells in a hyaluronan-based hydrogel.

Traumatic injury to the spinal cord causes cell death, demyelination, axonal degeneration, and cavitation resulting in functional motor and sensory loss. Stem cell therapy is a promising approach for spinal cord injury (SCI); however, this strategy is currently limited by the poor survival and uncontrolled differentiation of transplanted stem cells. In an attempt to achieve greater survival and integration with the host tissue, we examined the survival and efficacy of adult brain-derived neural stem/progenitor cells (NSPCs) injected within a hydrogel blend of hyaluronan and methyl cellulose (HAMC) into a subacute, clinically relevant model of rat SCI. Prior to use, HAMC was covalently modified with recombinant rat platelet-derived growth factor-A (rPDGF-A) to promote oligodendrocytic differentiation. SCI rats transplanted with NSPCs in HAMC-rPDGF-A showed improved behavioral recovery compared to rats transplanted with NSPCs in media. Rats with NSPC/HAMC-rPDGF-A transplants had a significant reduction in cavitation, improved graft survival, increased oligodendrocytic differentiation, and sparing of perilesional host oligodendrocytes and neurons. These data suggest that HAMC-rPDGF-A is a promising vehicle for cell delivery to the injured spinal cord.

Localized and sustained delivery of fibroblast growth factor-2 from a nanoparticle-hydrogel composite for treatment of spinal cord injury.

After traumatic spinal cord injury, grossly injured blood vessels leak blood and fluid into the parenchyma, leading to a large cystic cavity. Fibroblast growth factor-2 (FGF2) can reduce immediate vasoconstriction of vessels in the tissue surrounding the primary injury and promote angiogenesis. A localized delivery system would both achieve restricted delivery of FGF2 to the spinal cord and limit possible systemic effects such as mitogenesis. To enhance the endogenous angiogenic response after spinal cord injury, FGF2 was encapsulated in poly(lactide-co-glycolide) (PLGA) nanoparticles which were embedded in a biopolymer blend of hyaluronan and methylcellulose (HAMC) and then injected into the intrathecal space. Treatment began immediately after a 26 g clip compression spinal cord injury in rats and consisted of intrathecal delivery of FGF2 from the HAMC/PLGA/FGF2 composite. Control animals received intrathecal HAMC loaded with blank nanoparticles, intrathecal HAMC alone or intrathecal artificial cerebrospinal fluid alone. Sustained and localized delivery of FGF2 from composite HAMC/PLGA/FGF2 achieved higher blood vessel density in the dorsal horns 28 days post-injury, due to either greater angiogenesis near the epicenter of the injury or vasoprotection acutely after spinal cord injury. Importantly, delivery of FGF2 from composite HAMC/PLGA/FGF2 did not produce proliferative lesions that had been previously reported for FGF2 delivered locally using a minipump/catheter. These results suggest that localized and sustained delivery with composite HAMC/PLGA/FGF2 is an excellent system to deliver biomolecules directly to the spinal cord, thereby circumventing the blood spinal cord barrier and avoiding systemic side effects.

Ephrin-B3 decreases the survival of adult rat spinal cord-derived neural stem/progenitor cells in vitro and after transplantation into the injured rat spinal cord.

Although transplantation of neural stem/progenitor cells (NSPC) encourages regeneration and repair after spinal cord injury (SCI), the survival of transplanted NSPC is limited. Ephrin-B3 has been shown to reduce the death of endogenous NSPC in the subventricular zone of the mouse brain without inducing uncontrolled proliferation. Due to similarities in the environment of the brain and spinal cord, we hypothesized that ephrin-B3 might reduce the death of both transplanted and endogenous spinal cord-derived NSPC. Both normal and injured (26 g clip compression) spinal cords were examined. Ephrin-B3-Fc was tested, and Fc fragments and phosphate-buffered saline (PBS) were used as controls. We found that EphA4 receptors were expressed by spinal cord-derived NSPC and expressed in the normal and injured rat spinal cord (higher expression in the latter). In vitro, ephrin-B3-Fc did not significantly reduce the survival of NSPC except at 1 µg/mL (P<0.05), but Fc fragments alone reduced NSPC survival at all doses in a dose-dependent fashion. In vivo, intrathecal infusion of ephrin-B3-Fc increased the proliferation of endogenous ependymal cells and the proportion of proliferating cells that expressed the glial fibrillary acidic protein astrocytic marker in the injured spinal cord compared with the infusion of PBS (P<0.05). However, in the injured spinal cord, the infusion of either ephrin-B3-Fc or Fc fragments alone caused a 20-fold reduction in the survival of transplanted NSPC (P<0.001). Thus, after SCI, ephrin-B3-Fc and Fc fragments are toxic to transplanted NSPC.

Advances in stem cell therapy for spinal cord injury.

Spinal cord injury (SCI) is a devastating condition producing great personal and societal costs and for which there is no effective treatment. Stem cell transplantation is a promising therapeutic strategy, though much preclinical and clinical research work remains. Here, we briefly describe SCI epidemiology, pathophysiology, and experimental and clinical stem cell strategies. Research in stem cell biology and cell reprogramming is rapidly advancing, with the hope of moving stem cell therapy closer to helping people with SCI. We examine issues important for clinical translation and provide a commentary on recent developments, including termination of the first human embryonic stem cell transplantation trial in human SCI.

Evaluation of clinical experience using cell-based therapies in patients with spinal cord injury: a systematic review.

OBJECT: Using a systematic approach, the authors evaluated the current utilization, safety, and effectiveness of cellular therapies for traumatic spinal cord injuries (SCIs) in humans. METHODS: A systematic search and critical review of the literature published through mid-January 2012 was performed. Articles included in the search were restricted to the English language, studies with at least 10 patients, and those analyzing cellular therapies for traumatic SCI. Citations were evaluated for relevance using a priori criteria, and those that met the inclusion criteria were critically reviewed. Each article was then designated a level of evidence that was developed by the Oxford Centre for Evidence-Based Medicine. RESULTS: The initial literature search identified 651 relevant articles, which decreased to 350 after excluding case reports and reviews. Evaluation of articles at the title/abstract level, and later at the full-text level, limited the final article set to 12 papers. The following cellular therapies employed in humans with SCI are reviewed: bone marrow mesenchymal and hematopoietic stem cells (8 studies), olfactory ensheathing cells (2 studies), Schwann cells (1 study), and fetal neurogenic tissue (1 study). Overall the quality of the literature was very low, with 3 Grade III levels of evidence and 9 Grade IV studies. CONCLUSIONS: Several different cellular-mediated strategies for adult SCI have been reported to be relatively safe with varying degrees of neurological recovery. However, the literature is of low quality and there is a need for improved preclinical studies and prospective, controlled clinical trials.

The effect of growth factors and soluble Nogo-66 receptor protein on transplanted neural stem/progenitor survival and axonal regeneration after complete transection of rat spinal cord.

Adult central mammalian axons show minimal regeneration after spinal cord injury due to loss of oligodendrocytes, demyelination of surviving axons, absence of growth-promoting molecules, and inhibitors of axonal outgrowth. In the present study, we attempted to address these impediments to regeneration by using a combinatory strategy to enhance cell survival and regeneration after complete spinal cord transection (SCT) in adult rats. The strategy comprised: 1) adult rat brain-derived neural stem/progenitor cells (NSPCs) preseeded on laminin-coated chitosan channels; 2) extramedullary chitosan channels to promote axonal regrowth and reduce the barrier caused by scarring; 3) local delivery of a novel rat soluble Nogo-66 receptor protein [NgR(310)ecto-Fc, referred to as NgR] to block the inhibitory effect of myelin-based inhibitors; and 4) local delivery of basic fibroblast growth factor, epidermal growth factor, and platelet-derived growth factor to enhance survival and promote differentiation of transplanted cells. Compared with our previous studies where brain-derived NSPCs preseeded in extramedullary chitosan channels were implanted in the same SCT model but without growth factors and NgR, the present channel-growth factor combination produced greater numbers of surviving NSPCs after SCT. Also, the growth factors promoted preferential differentiation of NSPCs toward oligodendrocytes, while NgR significantly decreased astrocytic differentiation of NSPCs. NgR alone or in combination with NSPCs significantly enhanced the total number of myelinated fibers in the bridge and increased the area of the bridging tissue between the cord stumps. The combination of NgR, growth factors, and NSPCs had synergistic effect on bridge formation. However, only a small number of descending corticospinal tract axons grew into the central portions of the bridges as shown by anterograde tracing of the corticospinal tract with BDA. The majority of the regenerated axons in the channels originated from local host neurons adjacent to the tissue bridges. In conclusion, we showed that growth factors increased survival of transplanted NSPCs whereas NgR enhanced axonal regeneration, but the combination did not have additive effects on functional recovery or regeneration.

Neural stem/progenitor cells from the adult human spinal cord are multipotent and self-renewing and differentiate after transplantation.

Neural stem/progenitor cell (NSPC) transplantation is a promising therapy for spinal cord injury (SCI). However, little is known about NSPC from the adult human spinal cord as a donor source. We demonstrate for the first time that multipotent and self-renewing NSPC can be cultured, passaged and transplanted from the adult human spinal cord of organ transplant donors. Adult human spinal cord NSPC require an adherent substrate for selection and expansion in EGF (epidermal growth factor) and FGF2 (fibroblast growth factor) enriched medium. NSPC as an adherent monolayer can be passaged for at least 9 months and form neurospheres when plated in suspension culture. In EGF/FGF2 culture, NSPC proliferate and primarily express nestin and Sox2, and low levels of markers for differentiating cells. Leukemia inhibitory factor (LIF) promotes NSPC proliferation and significantly enhances GFAP expression in hypoxia. In differentiating conditions in the presence of serum, these NSPC show multipotentiality, expressing markers of neurons, astrocytes, and oligodendrocytes. Dibutyryl cyclic AMP (dbcAMP) significantly enhances neuronal differentiation. We transplanted the multipotent NSPC into SCI rats and show that the xenografts survive, are post-mitotic, and retain the capacity to differentiate into neurons and glia.Together, these findings reveal that multipotent self-renewing NSPC cultured and passaged from adult human spinal cords of organ transplant donors, respond to exogenous factors that promote selective differentiation, and survive and differentiate after transplantation into the injured spinal cord.

Effects of dibutyryl cyclic-AMP on survival and neuronal differentiation of neural stem/progenitor cells transplanted into spinal cord injured rats.

Neural stem/progenitor cells (NSPCs) have great potential as a cell replacement therapy for spinal cord injury. However, poor control over transplant cell differentiation and survival remain major obstacles. In this study, we asked whether dibutyryl cyclic-AMP (dbcAMP), which was shown to induce up to 85% in vitro differentiation of NSPCs into neurons would enhance survival of transplanted NSPCs through prolonged exposure either in vitro or in vivo through the controlled release of dbcAMP encapsulated within poly(lactic-co-glycolic acid) (PLGA) microspheres and embedded within chitosan guidance channels. NSPCs, seeded in fibrin scaffolds within the channels, differentiated in vitro to betaIII-tubulin positive neurons by immunostaining and mRNA expression, in response to dbcAMP released from PLGA microspheres. After transplantation in spinal cord injured rats, the survival and differentiation of NSPCs was evaluated. Untreated NSPCs, NSPCs transplanted with dbcAMP-releasing microspheres, and NSPCs pre-differentiated with dbcAMP for 4 days in vitro were transplanted after rat spinal cord transection and assessed 2 and 6 weeks later. Interestingly, NSPC survival was highest in the dbcAMP pre-treated group, having approximately 80% survival at both time points, which is remarkable given that stem cell transplantation often results in less than 1% survival at similar times. Importantly, dbcAMP pre-treatment also resulted in the greatest number of in vivo NSPCs differentiated into neurons (37±4%), followed by dbcAMP-microsphere treated NSPCs (27±14%) and untreated NSPCs (15±7%). The reverse trend was observed for NSPC-derived oligodendrocytes and astrocytes, with these populations being highest in untreated NSPCs. This combination strategy of stem cell-loaded chitosan channels implanted in a fully transected spinal cord resulted in extensive axonal regeneration into the injury site, with improved functional recovery after 6 weeks in animals implanted with pre-differentiated stem cells in chitosan channels.