Fighting for recovery on multiple fronts: The past, present, and future of clinical trials for spinal cord injury

Reanalysis of Published Histological Data Can Help to Characterize Neuronal Death After Spinal Cord Injury

Neuronal death is a central event in spinal cord injury (SCI) pathophysiology. Despite its importance, we have a fragmentary vision of the process. In our opinion, the research community has accumulated enough information to provide a more detailed, integrated vision of neuronal death after SCI. This work embeds this vision by creating an open repository to store and share data and results from their analysis. We have employed this repository to upload raw images of spinal cord sections from a mouse model of contusive SCI and used this information to compare manual-, threshold-, and neural network-based neuron identifications and to explore neuronal death at the injury penumbra 21 days after injury and the effects of the anti-apoptotic drug ucf-101. Results indicate that, whereas the three identification methods assayed yield coherent estimates of the total number of neurons per section, neural network (NN) outperforms the other two methods. Combining NN identification and image registration has allowed us to characterize neuron distribution among Rexed laminae in the mice T11, revealing spatial patterns in the neuronal death that follows injury and in their survival following ucf-101 treatment.

Combinatorial approaches increasing neuronal activity accelerate recovery after spinal cord injury

Combinatorial approaches targeting multiple aspects of spinal cord injury (SCI) pathophysiology are needed to maximize functional recovery. We hypothesized that strengthening corticospinal synapses via Hebbian stimulation and increasing neuronal transmission with 4-aminopyridine (4-AP, a potassium blocker) could accelerate locomotor recovery in individuals with chronic SCI. Participants were randomly assigned to receive 10 mg of 4-AP or placebo, where both groups followed with 60-min of Hebbian stimulation targeting corticospinal-motoneuronal synapses supplying leg muscles involved in locomotion and 60-min of standard exercise rehabilitation for 40 sessions over 8-14 weeks. During Hebbian stimulation, 720 paired pulses were delivered to elicit corticospinal action potentials via electrical stimulation of the thoracic spine, ensuring volleys reached the spinal cord 1-2 milliseconds before motoneurons were retrogradely activated through bilateral electrical stimulation of the femoral, common peroneal, and posterior tibial nerves (targeting the quadriceps femoris, tibialis anterior, and soleus muscles, respectively). Results showed that participants who received 4-AP exhibited significantly greater improvements in walking speed and endurance, corticospinal transmission, and light touch sensation compared to those who received the placebo. The minimal clinically important difference in walking speed and endurance was achieved after 20 sessions in the 4-AP group, but was not consistently reached in the placebo group. Although walking continued to improve in both groups over the course of 40 sessions, the 4-AP group demonstrated significantly greater progress. Improvement in the 4-AP group was still present twelve months later. These findings suggest that 4-AP represents a strategy to potentiate and accelerate Hebbian stimulation effects on motor recovery in individuals with chronic SCI.

John J, Haag-Molkenteller C, Freund P, Guest J, Mikol DD, Harkema S, Trumbower RD, Fehlings MG, Weidner N, Hogge GS, Field-Fote EC, Baptista MA, Curt A, Hsieh J, Jones L. Lessons Learned and Recommendations from a SCOPE Spinal Cord Injury Neurorestorative Clinical Trials Update

The Spinal Cord Outcomes Partnership Endeavors presented a clinical trials update (CTU) in collaboration with the International Spinal Research Trust as a precourse to their annual meeting. Selected trials adhered to a priori considerations, prioritizing novelty and a focus on neurorestorative approaches. The sessions featured 13 speakers, covering 4 in-preparation, 4 in-progress, and 4 recently completed trials. In addition to in-person attendance, individuals worldwide viewed a live stream of the presentations. Approximately 1600 participants, comprising clinicians, researchers, industry stakeholders, foundations, and individuals with lived experiences, engaged in the CTU through both in-person and virtual channels. Presentations represented a variety of approaches, including drug, biological, and device-based therapeutics. This summary provides high-level summaries of the trials presented and the resulting discussions including lessons learned. Rather than recapitulating published data, the presentations and discussions emphasized the novelty and strengths of each trial, practical aspects of translation, and lessons learned. Throughout the day, several discussion themes surfaced. These included reflections on the suitability of outcome measures and the distinction between statistically or clinically meaningful effects and meaningful changes in quality of life. Additional topics included novel trial designs, selection of inclusion criteria, recognizing the indispensable role of rehabilitation, tailoring approaches to individual needs, the importance of integrating lived experience, and emphasizing the importance of establishing robust pre-clinical data packages before venturing into clinical translation. Importantly, strategic directives are summarized to address these challenges, focusing resources and efforts to steer forthcoming trials effectively.

Making the Invisible Visible: Understanding Autonomic Dysfunctions Following Spinal Cord Injury

Autonomic dysfunctions are a major challenge to individuals following spinal cord injury. Despite this, these consequences receive far less attention compared with motor recovery. This review will highlight the major autonomic dysfunctions following SCI predominantly based on our present understanding of the anatomy and physiology of autonomic control and available clinical data.

An Update on Spinal Cord Injury and Current Management

» Spinal cord injury is associated with increased lifelong cost and decreased life expectancy.» Current treatment guidelines have been limited to studies of small effect sizes and limited availability of randomized control trials.» Recovery is best correlated with the initial American Spinal Injury Association impairment scale grade with A and B less likely to recover regarding ambulation as compared with C and D grades.» Surgical intervention within less than 24 hours, especially in the cervical spine, has been associated with some motor improvement.» The use of mean arterial pressure goals and steroids to maintain perfusion and decrease secondary injury requires further study to elucidate clearer evidence-based results.

Unravelling the Road to Recovery: Mechanisms of Wnt Signalling in Spinal Cord Injury

Spinal cord injury (SCI) is a complex neurodegenerative pathology that consistently harbours a poor prognostic outcome. At present, there are few therapeutic strategies that can halt neuronal cell death and facilitate functional motor recovery. However, recent studies have highlighted the Wnt pathway as a key promoter of axon regeneration following central nervous system (CNS) injuries. Emerging evidence also suggests that the temporal dysregulation of Wnt may drive cell death post-SCI. A major challenge in SCI treatment resides in developing therapeutics that can effectively target inflammation and facilitate glial scar repair. Before Wnt signalling is exploited for SCI therapy, further research is needed to clarify the implications of Wnt on neuroinflammation during chronic stages of injury. In this review, an attempt is made to dissect the impact of canonical and non-canonical Wnt pathways in relation to individual aspects of glial and fibrotic scar formation. Furthermore, it is also highlighted how modulating Wnt activity at chronic time points may aid in limiting lesion expansion and promoting axonal repair.

Ethics and accountability for clinical trials

In May 2023, a disclaimer posted on ClinicalTrials.gov dismisses accountability for the accuracy of registered information. For spinal cord injury, inconsistencies in intervention classification, phase designation, and lack of study protocols and results threaten the integrity of the database and put users at risk. An investment in what the resource should be rather than what it is not will give it the authority commensurate with the requirements for its regulatory use and informed decision-making for prospective trial participants.

Combinatorial strategies for cell transplantation in traumatic spinal cord injury

Spinal cord injury (SCI) substantially reduces the quality of life of affected individuals. Recovery of function is therefore a primary concern of the patient population and a primary goal for therapeutic interventions. Currently, even with growing numbers of clinical trials, there are still no effective treatments that can improve neurological outcomes after SCI. A large body of work has demonstrated that transplantation of neural stem/progenitor cells (NSPCs) can promote regeneration of the injured spinal cord by providing new neurons that can integrate into injured host neural circuitry. Despite these promising findings, the degree of functional recovery observed after NSPC transplantation remains modest. It is evident that treatment of such a complex injury cannot be addressed with a single therapeutic approach. In this mini-review, we discuss combinatorial strategies that can be used along with NSPC transplantation to promote spinal cord regeneration. We begin by introducing bioengineering and neuromodulatory approaches, and highlight promising work using these strategies in integration with NSPCs transplantation. The future of NSPC transplantation will likely include a multi-factorial approach, combining stem cells with biomaterials and/or neuromodulation as a promising treatment for SCI.

Traumatic spinal cord and spinal column injuries: A bibliometric analysis of the 200 most cited articles

Study Design

Bibliometric analysis.

Objectives

This study aimed to highlight the 200 most influential articles related to traumatic spinal cord and spinal column injuries and provide an insight of past and current global trends in spinal trauma research.

Methods

The Web of Science database was used to identify the top 200 most cited articles on the topic of traumatic spinal cord injury (SCI) and spinal column injuries between using a prespecified algorithm. The articles were manually reviewed; bibliometrics were collected on title, first and corresponding authors' country, institution, journal, publication year, and citation data.

Results

The search string yielded 30,551 articles during 1977-2019. The average time from the publication was 19.5 years. A total of 1356 authors contributed to 67 different journals, the top 200 most cited articles amassing a total of 88,115 citations and an average 440.6 citations. The United States of America (USA) contributed the most with 110 articles; the top institution was the University of Toronto with 34 publications. Most studies focused on basic science research on SCI. Keyword analysis revealed the most commonly used keywords: SCI, inflammation, apoptosis, incidence/prevalence, and regeneration; four word-clusters were identified. Institutions from the USA and Canada collaborated the most and two major and two minor institutional collaboration subnetworks were identified. Co-citation analysis detected three main clusters of authors.

Conclusion

This overview of the most cited articles on traumatic spinal cord and spinal column injuries provides insight into the international spinal trauma community and the terrain in this field, potentially acting as a springboard for further collaboration development.

Moving CNS axon growth and regeneration research into human model systems

Axon regeneration is limited in the adult mammalian central nervous system (CNS) due to both intrinsic and extrinsic factors. Rodent studies have shown that developmental age can drive differences in intrinsic axon growth ability, such that embryonic rodent CNS neurons extend long axons while postnatal and adult CNS neurons do not. In recent decades, scientists have identified several intrinsic developmental regulators in rodents that modulate growth. However, whether this developmentally programmed decline in CNS axon growth is conserved in humans is not yet known. Until recently, there have been limited human neuronal model systems, and even fewer age-specific human models. Human in vitro models range from pluripotent stem cell-derived neurons to directly reprogrammed (transdifferentiated) neurons derived from human somatic cells. In this review, we discuss the advantages and disadvantages of each system, and how studying axon growth in human neurons can provide species-specific knowledge in the field of CNS axon regeneration with the goal of bridging basic science studies to clinical trials. Additionally, with the increased availability and quality of 'omics datasets of human cortical tissue across development and lifespan, scientists can mine these datasets for developmentally regulated pathways and genes. As there has been little research performed in human neurons to study modulators of axon growth, here we provide a summary of approaches to begin to shift the field of CNS axon growth and regeneration into human model systems to uncover novel drivers of axon growth.

Advances in molecular therapies for targeting pathophysiology in spinal cord injury

INTRODUCTION

Spinal cord injury (SCI) affects 25,000-50,000 people around the world each year and there is no cure for SCI patients currently. The primary injury damages spinal cord tissues and secondary injury mechanisms, including ischemia, apoptosis, inflammation, and astrogliosis, further exacerbate the lesions to the spinal cord. Recently, researchers have designed various therapeutic approaches for SCI by targeting its major cellular or molecular pathophysiology.

AREAS COVERED

Some strategies have shown promise in repairing injured spinal cord for functional recoveries, such as administering neuroprotective reagents, targeting specific genes to promote robust axon regeneration of disconnected spinal fiber tracts, targeting epigenetic factors to enhance cell survival and neural repair, and facilitating neuronal relay pathways and neuroplasticity for restoration of function after SCI. This review focuses on the major advances in preclinical molecular therapies for SCI reported in recent years.

EXPERT OPINION

Recent progress in developing novel and effective repairing strategies for SCI is encouraging, but many challenges remain for future design of effective treatments, including developing highly effective neuroprotectants for early interventions, stimulating robust neuronal regeneration with functional synaptic reconnections among disconnected neurons, maximizing the recovery of lost neural functions with combination strategies, and translating the most promising therapies into human use.