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We describe here the meningeal sheath that encloses the spinal cord, and the sheath that develops when the cord regenerates after a total transection. This description is derived from electron and light microscopy. The sheath of the uninjured cord was found to be a single structure of two parts: an outer, thin melanocyte layer and an inner, thicker layer of 2 to 10 rows of fibroblasts, closely associated with collagen and elastic fibers. Soon after cord transection, the injured axons re-grow and, together with the reforming central canal, create a bridge that links the transected cord within 8 days of injury. This bridge is covered at first by a rudimentary meningeal sheath, formed of fibroblasts and macrophages, that later progressively thickens and becomes more compact. By about day 20, the fibroblasts are arranged as 16 to 20 loose rows that include bundles of collagen, oriented along the rostro-caudal axis of the cord. Even after 144 days, the meninx, although substantially thicker than normal because of the numerous fibroblast rows (20 to 30), still lacks the melanocyte layer. In cases in which the meninx at the transection site was mechanically and pharmacologically (6-hydroxydopamine) disrupted, bridge formation was essentially unchanged, and axonal regrowth continued; some regrowing axons, however, extruded from the denuded cord. Accordingly, our findings indicate that although the meningeal sheath is not essential for cord regeneration to take place, it may well facilitate recovery by providing mechanical guidance and support to the regrowing axons.

After transection, the spinal cord of the eel Anguilla quickly regrows and reconnects, and function recovers. We describe here the changes in the central canal region that accompany this regeneration by using serial semithin plastic sections and immunohistochemistry. The progress of axonal regrowth was followed in material labeled with DiI. The canal of the uninjured cord is surrounded by four cell types: S-100-immunopositive ependymocytes, S-100- and glial fibrillary acidic protein (GFAP)-immunopositive tanycytes, vimentin-immunopositive dorsally located cells, and lateral and ventral liquor-contacting neurons, which label for either gamma-aminobutyric acid (GABA) or tyrosine hydroxylase (TH). After cord transection, a new central canal forms rapidly as small groups of cells at the leading edges of the transection create flat "plates" that serve as templates for subsequent formation of the lateral and dorsal walls. Profile counts and 5-bromo-2'-deoxyuridine immunohistochemistry indicate that these cells are dividing rapidly during the first 20 days of the repair process. The newly formed canal, which bridges the transection by day 10 but is not complete until about day 20, is greatly enlarged (

Background: Patient and public involvement in research (PPI) has many benefits including increasing relevance and impact. While using PPI in clinical research is now an established practice, the involvement of patients and the public in pre-clinical research, which takes place in a laboratory setting, has been less frequently described and presents specific challenges. This study aimed to explore the perspectives of seriously injured rugby players' who live with a spinal cord injury on PPI in pre-clinical research. Methods: Semi-structured interviews were conducted via telephone with 11 seriously injured rugby players living with spinal cord injury on the island of Ireland. A purposive sampling approach was used to identify participants. Selected individuals were invited to take part via gatekeeper in a charitable organisation that supports seriously injured rugby players. Interviews were transcribed verbatim and analysed thematically. Findings: Six themes were identified during analysis: 'appreciating potential benefits of PPI despite limited knowledge', 'the informed perspectives of people living with spinal cord injury can improve pre-clinical research relevance', 'making pre-clinical research more accessible reduces the potential for misunderstandings to occur', 'barriers to involvement include disinterest, accessibility issues, and fear of losing hope if results are negative', 'personal contact and dialogue helps people feel valued in pre-clinical research, and 'PPI can facilitate effective dissemination of pre-clinical research as desired by people living with spinal cord injury.' Conclusion: People affected by spinal cord injury in this study desire further involvement in pre-clinical spinal cord injury research through dialogue and contact with researchers. Sharing experiences of spinal cord injury can form the basis of PPI for pre-clinical spinal cord injury research. [ABSTRACT FROM AUTHOR]

Introduction: Patient and public involvement (PPI) in research is an embedded practice in clinical research, however, its role in preclinical or laboratory‐based research is less well established and presents specific challenges. This study aimed to explore the perspectives of two key stakeholder groups, preclinical researchers and clinicians on PPI in preclinical research, using spinal cord research as a case study. Methods: Semi‐structured interviews were conducted online with 11 clinicians and 11 preclinical researchers all working in the area of spinal cord injury (SCI). Interviews were transcribed verbatim and analysed thematically. Findings: Nine themes were developed through analysis. Participants' perspectives included that people living with SCI had a right to be involved, that PPI can improve the relevance of preclinical research, and that PPI can positively impact the experiences of researchers. They identified the distance between lab‐based research and the daily experiences of living with SCI to be a barrier and proactive management of accessibility and the motivated and networked SCI community as key facilitators. To develop strong partnerships, participants suggested setting clear expectations, ensuring good communication, and demonstrating respect for the time of PPI contributors involved in the research. Conclusions: While traditionally PPI has been more commonly associated with clinical research, participants identified several potential benefits of PPI in preclinical spinal cord research that have applicability to preclinical researchers more broadly. Preclinical spinal researchers should explore how to include PPI in their work. Patient or Public Contribution: This study was conducted as part of a broader project aiming to develop an evidence base for preclinical PPI that draws on a 5‐year preclinical research programme focused on the development of advanced biomaterials for spinal cord repair as a case study. A PPI Advisory Panel comprising seriously injured rugby players, clinicians, preclinical researchers, and PPI facilitators collaborated as co‐authors on the conceptualisation, design of the interview protocol, data analysis and writing of this manuscript. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) is a devastating traumatic injury often causing permanent loss of function. The challenge of treating SCI stems from the development of a complex pathophysiology at the site of injury, involving multiple biochemical cascades, widespread inflammation, blood supply interruption, inhibitory scar formation, and poor regrowth of injured axons. Clinical options are limited to surgical stabilization and attempt to ameliorate secondary damage following injury. Gene therapy has significant potential to tackle multiple aspects of SCI and improve functional outcomes. The emergence of a diverse array of biomaterial‐based nonviral nanoparticle vectors capable of delivering gene‐modifying nucleic acids offers the potential to improve the efficiency and specificity of genetic cargos for spinal cord regeneration. In this review, the progress that has been made in the field of SCI repair and the different types of nanoparticles and nucleic acid cargoes that have been used are outlined, placing a particular focus on the different cell types and pathways targeted. While many challenges remain, a perspective on the future of the field of nanoparticle‐mediated gene delivery for SCI is provided, including using biomaterial scaffolds engineered specifically for SCI to deliver gene therapeutics and the exciting opportunities that exist in the post‐COVID landscape. [ABSTRACT FROM AUTHOR]

Aim: Recently, the zebrafish (Danio rerio) has been shown to be an excellent model for human paediatric research. Advantages over other models include its small size, externally visually accessible development and ease of experimental manipulation. The enteric nervous system (ENS) consists of neurons and enteric glia. Glial cells permit cell bodies and processes of neurons to be arranged and maintained in a proper spatial arrangement, and are essential in the maintenance of basic physiological functions of neurons. Glial fibrillary acidic protein (GFAP) is expressed in astrocytes, but also expressed outside of the central nervous system. The aim of this study was to investigate the spatio-temporal pattern of GFAP expression in developing zebrafish ENS from 24 h post-fertilization (hpf), using transgenic fish that express green fluorescent protein (GFP).Methods: Zebrafish embryos were collected from transgenic GFP Tg(GFAP:GFP)(mi2001) adult zebrafish from 24 to 120 hpf, fixed and processed for whole mount immunohistochemistry. Antibodies to Phox2b were used to identify enteric neurons. Specimens were mounted on slides and imaging was performed using a fluorescent laser confocal microscope.Results: GFAP:GFP labelling outside the spinal cord was identified in embryos from 48 hpf. The patterning was intracellular and consisted of elongated profiles that appeared to migrate away from the spinal cord into the periphery. At 72 and 96 hpf, GFAP:GFP was expressed dorsally and ventrally to the intestinal tract. At 120 hpf, GFAP:GFP was expressed throughout the intestinal wall, and clusters of enteric neurons were identified using Phox2b immunofluorescence along the pathway of GFAP:GFP positive processes, indicative of a migratory pathway of ENS precursors from the spinal cord into the intestine.Conclusion: The pattern of migration of GFAP:GFP expressing cells outside the spinal cord suggests an organized, early developing migratory pathway to the ENS. This shows for the first time that Tg(GFAP:GFP)(mi2001) zebrafish model is an ideal one to study spatio-temporal patterning of early ENS development. [ABSTRACT FROM AUTHOR]