The Development of Principles for Patient and Public Involvement (PPI) in Preclinical Spinal Cord Research: A Modified Delphi Study.

INTRODUCTION: There is currently limited guidance for researchers on Patient and Public Involvement (PPI) for preclinical spinal cord research, leading to uncertainty about design and implementation. This study aimed to develop evidence-informed principles to support preclinical spinal cord researchers to incorporate PPI into their research. METHODS: This study used a modified Delphi method with the aim of establishing consensus on a set of principles for PPI in spinal cord research. Thirty-eight stakeholders including researchers, clinicians and people living with spinal cord injury took part in the expert panel. Participants were asked to rate their agreement with a series of statements relating to PPI in preclinical spinal cord research over two rounds. As part of Round 2, they were also asked to rate statements as essential or desirable. RESULTS: Thirty-eight statements were included in Round 1, after which five statements were amended and two additional statements were added. After Round 2, consensus (> 75% agreement) was reached for a total of 27 principles, with 13 rated as essential and 14 rated as desirable. The principles with highest agreement related to diversity in representation among PPI contributors, clarity of the purpose of PPI and effective communication. CONCLUSION: This research developed a previously unavailable set of evidence-informed principles to inform PPI in preclinical spinal cord research. These principles provide guidance for researchers seeking to conduct PPI in preclinical spinal cord research and may also inform PPI in other preclinical disciplines. PATIENT AND PUBLIC INVOLVEMENT STATEMENT: This study was conducted as part of a project aiming to develop PPI in preclinical spinal cord injury research associated with an ongoing research collaboration funded by the Irish Rugby Football Union Charitable Trust (IRFU CT) and the Science Foundation Ireland Centre for Advanced Materials and BioEngineering Research (SFI AMBER), with research conducted by the Tissue Engineering Research Group (TERG) at the RCSI University of Medicine and Health Sciences. The project aims to develop an advanced biomaterials platform for spinal cord repair and includes a PPI Advisory Panel comprising researchers, clinicians and seriously injured rugby players to oversee the work of the project. PPI is included in this study through the involvement of members of the PPI Advisory Panel in the conceptualisation of this research, review of findings, identification of key points for discussion and preparation of the study manuscript as co-authors.

The role of Patient and public involvement (PPI) in pre-clinical spinal cord research: An interview study.

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.

The Manufacture and Characterization of Biomimetic, Biomaterial-Based Scaffolds for Studying Physicochemical Interactions of Neural Cells in 3D Environments.

A particular challenge to the field of neuroscience involves translating findings from 2D in vitro systems to 3D in vivo environments. Standardized cell culture environments that adequately reflect the properties of the central nervous system (CNS) such as the stiffness, protein composition, and microarchitecture in which to study 3D cell-cell and cell-matrix interactions are generally lacking for in vitro culture systems. In particular, there remains an unmet need for reproducible, low-cost, high-throughput, and physiologically relevant environments comprised of tissue-native matrix proteins for the study of CNS microenvironments in 3D. Advances in the field of biofabrication over the past number of years have facilitated the production and characterization of biomaterial-based scaffolds. Typically developed for tissue engineering applications, they also provide sophisticated environments in which to study cell-cell and cell-matrix interactions and have been used for 3D modeling for a range of tissues. Here, we describe a simple and scalable protocol for the production of biomimetic, highly porous freeze-dried hyaluronic acid scaffolds with tunable microarchitecture, stiffness, and protein composition. Furthermore, we describe several different approaches that can be used to characterize a range of physicochemical properties and how to employ the scaffolds for the 3D culture of sensitive CNS cells in vitro. Finally, we detail several approaches for the study of key cell responses within the 3D scaffold environments. Overall, this protocol describes the manufacture and testing of a biomimetic and tunable macroporous scaffold system for neuronal cell culture applications. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Scaffold manufacture Basic Protocol 2: Scaffold characterization Basic Protocol 3: Cell culture and analysis of neurons in scaffolds.

Applying Patient and Public Involvement in preclinical research: A co-created scoping review.

BACKGROUND: Patient and Public Involvement (PPI) in research aims to improve the quality, relevance and appropriateness of research. PPI has an established role in clinical research where there is evidence of benefit, and where policymakers and funders place continued emphasis on its inclusion. However, for preclinical research, PPI has not yet achieved the same level of integration. As more researchers, including our team, aim to include PPI in preclinical research, the development of an evidence-based approach is important. Therefore, this scoping review aimed to identify and map studies where PPI has been used in preclinical research and develop principles that can be applied in other projects. METHODS: A scoping review was conducted to search the literature in Medline (PubMed), EMBASE, CINAHL, PsycInfo and Web of Science Core Collection to identify applied examples of preclinical PPI. Two independent reviewers conducted study selection and data extraction separately. Data were extracted relating to PPI in terms of (i) rationale and aims, (ii) approach used, (iii) benefits and challenges, (iv) impact and evaluation and (v) learning opportunities for preclinical PPI. Findings were reviewed collaboratively by PPI contributors and the research team to identify principles that could be applied to other projects. RESULTS: Nine studies were included in the final review with the majority of included studies reporting PPI to improve the relevance of their research, using approaches such as PPI advisory panels and workshops. Researchers report several benefits and challenges, although evidence of formal evaluation is limited. CONCLUSION: Although currently there are few examples of preclinical research studies reporting empirical PPI activity, their findings may support those aiming to use PPI in preclinical research. Through collaborative analysis of the scoping review findings, several principles were developed that may be useful for other preclinical researchers. 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 conceptualization, execution and writing of this review, including refining the findings into the set of principles reported here.

Multi-factorial nerve guidance conduit engineering improves outcomes in inflammation, angiogenesis and large defect nerve repair.

Nerve guidance conduits (NGCs) are sub-optimal for long-distance injuries with inflammation and poor vascularization related to poor axonal repair. This study used a multi-factorial approach to create an optimized biomaterial NGC to address each of these issues. Through stepwise optimization, a collagen-chondroitin-6-sulfate (Coll-CS) biomaterial was functionalized with extracellular matrix (ECM) components; fibronectin, laminin 1 and laminin 2 (FibL1L2) in specific ratios. A snap-cooled freeze-drying process was then developed with optimal pore architecture and alignment to guide axonal bridging. Culture of adult rat dorsal root ganglia on NGCs demonstrated significant improvements in inflammation, neurogenesis and angiogenesis in the specific Fib:L1:L2 ratio of 1:4:1. In clinically relevant, large 15 mm rat sciatic nerve defects, FibL1L2-NGCs demonstrated significant improvements in axonal density and angiogenesis compared to unmodified NGCs with functional equivalence to autografts. Therefore, a multiparameter ECM-driven strategy can significantly improve axonal repair across large defects, without exogenous cells or growth factors.

Biomimetic Scaffolds for Spinal Cord Applications Exhibit Stiffness-Dependent Immunomodulatory and Neurotrophic Characteristics.

After spinal cord injury (SCI), tissue engineering scaffolds offer a potential bridge for regeneration across the lesion and support repair through proregenerative signaling. Ideal biomaterial scaffolds that mimic the physicochemical properties of native tissue have the potential to provide innate trophic signaling while also minimizing damaging inflammation. To address this challenge, taking cues from the spinal cord's structure, the proregenerative signaling capabilities of native cord components are compared in vitro. A synergistic mix of collagen-IV and fibronectin (Coll-IV/Fn) is found to optimally enhance axonal extension from neuronal cell lines (SHSY-5Y and NSC-34) and induce morphological features typical of quiescent astrocytes. This optimal composition is incorporated into hyaluronic acid scaffolds with aligned pore architectures but varying stiffnesses (0.8-3 kPa). Scaffolds with biomimetic mechanical properties (<1 kPa), functionalized with Coll-IV/Fn, not only modulate primary astrocyte behavior but also stimulate the production of anti-inflammatory cytokine IL-10 in a stiffness-dependent manner. Seeded SHSY-5Y neurons generate distributed neuronal networks, while softer biomimetic scaffolds promote axonal outgrowth in an ex vivo model of axonal regrowth. These results indicate that the interaction of stiffness and biomaterial composition plays an essential role in vitro in generating repair-critical cellular responses and demonstrates the potential of biomimetic scaffold design.

Biomaterial and Therapeutic Approaches for the Manipulation of Macrophage Phenotype in Peripheral and Central Nerve Repair.

Injury to the peripheral or central nervous systems often results in extensive loss of motor and sensory function that can greatly diminish quality of life. In both cases, macrophage infiltration into the injury site plays an integral role in the host tissue inflammatory response. In particular, the temporally related transition of macrophage phenotype between the M1/M2 inflammatory/repair states is critical for successful tissue repair. In recent years, biomaterial implants have emerged as a novel approach to bridge lesion sites and provide a growth-inductive environment for regenerating axons. This has more recently seen these two areas of research increasingly intersecting in the creation of 'immune-modulatory' biomaterials. These synthetic or naturally derived materials are fabricated to drive macrophages towards a pro-repair phenotype. This review considers the macrophage-mediated inflammatory events that occur following nervous tissue injury and outlines the latest developments in biomaterial-based strategies to influence macrophage phenotype and enhance repair.

Patient and Public Involvement (PPI) in preclinical research: A scoping review protocol.

Introduction: Patient and public involvement (PPI) aims to improve the quality, relevance, and appropriateness of research and ensure that it meets the needs and expectations of those affected by particular conditions to the greatest possible degree. The evidence base for the positive impact of PPI on clinical research continues to grow, but the role of PPI in preclinical research (an umbrella term encompassing 'basic', 'fundamental', 'translational' or 'lab-based' research) remains limited. As funding bodies and policymakers continue to increase emphasis on the relevance of PPI to preclinical research, it is timely to map the PPI literature to support preclinical researchers involving the public, patients, or other service users in their research. Therefore, the aim of this scoping review is to explore the literature on patient and public involvement in preclinical research from any discipline. Methods: This scoping review will search the literature in Medline (PubMed), Embase, CINAHL, PsycINFO, Web of Science Core Collection, Scopus, and OpenGrey.net to explore the application of PPI in preclinical research. This review will follow the Joanna Briggs Institute (JBI) guidelines for scoping reviews. It will be reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR). Two reviewers will independently review articles for inclusion in the final review. Data extraction will be guided by the research questions. The PPI advisory panel will then collaboratively identify themes in the extracted data. Discussion: This scoping review will provide a map of current evidence surrounding preclinical PPI, and identify the body of literature on this topic, which has not been comprehensively reviewed to date. Findings will inform ongoing work of the research team, support the work of other preclinical researchers aiming to include PPI in their own research, and identify knowledge and practice gaps. Areas for future research will be identified.

FMRP and Ataxin-2 function together in long-term olfactory habituation and neuronal translational control.

Fragile X mental retardation protein (FMRP) and Ataxin-2 (Atx2) are triplet expansion disease- and stress granule-associated proteins implicated in neuronal translational control and microRNA function. We show that Drosophila FMRP (dFMR1) is required for long-term olfactory habituation (LTH), a phenomenon dependent on Atx2-dependent potentiation of inhibitory transmission from local interneurons (LNs) to projection neurons (PNs) in the antennal lobe. dFMR1 is also required for LTH-associated depression of odor-evoked calcium transients in PNs. Strong transdominant genetic interactions among dFMR1, atx2, the deadbox helicase me31B, and argonaute1 (ago1) mutants, as well as coimmunoprecitation of dFMR1 with Atx2, indicate that dFMR1 and Atx2 function together in a microRNA-dependent process necessary for LTH. Consistently, PN or LN knockdown of dFMR1, Atx2, Me31B, or the miRNA-pathway protein GW182 increases expression of a Ca2+/calmodulin-dependent protein kinase II (CaMKII) translational reporter. Moreover, brain immunoprecipitates of dFMR1 and Atx2 proteins include CaMKII mRNA, indicating respective physical interactions with this mRNA. Because CaMKII is necessary for LTH, these data indicate that fragile X mental retardation protein and Atx2 act via at least one common target RNA for memory-associated long-term synaptic plasticity. The observed requirement in LNs and PNs supports an emerging view that both presynaptic and postsynaptic translation are necessary for long-term synaptic plasticity. However, whereas Atx2 is necessary for the integrity of dendritic and somatic Me31B-containing particles, dFmr1 is not. Together, these data indicate that dFmr1 and Atx2 function in long-term but not short-term memory, regulating translation of at least some common presynaptic and postsynaptic target mRNAs in the same cells.

The Ataxin-2 protein is required for microRNA function and synapse-specific long-term olfactory habituation.

Local control of mRNA translation has been proposed as a mechanism for regulating synapse-specific plasticity associated with long-term memory. We show here that glomerulus-selective plasticity of Drosophila multiglomerular local interneurons observed during long-term olfactory habituation (LTH) requires the Ataxin-2 protein (Atx2) to function in uniglomerular projection neurons (PNs) postsynaptic to local interneurons (LNs). PN-selective knockdown of Atx2 selectively blocks LTH to odorants to which the PN responds and in addition selectively blocks LTH-associated structural and functional plasticity in odorant-responsive glomeruli. Atx2 has been shown previously to bind DEAD box helicases of the Me31B family, proteins associated with Argonaute (Ago) and microRNA (miRNA) function. Robust transdominant interactions of atx2 with me31B and ago1 indicate that Atx2 functions with miRNA-pathway components for LTH and associated synaptic plasticity. Further direct experiments show that Atx2 is required for miRNA-mediated repression of several translational reporters in vivo. Together, these observations (i) show that Atx2 and miRNA components regulate synapse-specific long-term plasticity in vivo; (ii) identify Atx2 as a component of the miRNA pathway; and (iii) provide insight into the biological function of Atx2 that is of potential relevance to spinocerebellar ataxia and neurodegenerative disease.

Plasticity of local GABAergic interneurons drives olfactory habituation.

Despite its ubiquity and significance, behavioral habituation is poorly understood in terms of the underlying neural circuit mechanisms. Here, we present evidence that habituation arises from potentiation of inhibitory transmission within a circuit motif commonly repeated in the nervous system. In Drosophila, prior odorant exposure results in a selective reduction of response to this odorant. Both short-term (STH) and long-term (LTH) forms of olfactory habituation require function of the rutabaga-encoded adenylate cyclase in multiglomerular local interneurons (LNs) that mediate GABAergic inhibition in the antennal lobe; LTH additionally requires function of the cAMP response element-binding protein (CREB2) transcription factor in LNs. The odorant selectivity of STH and LTH is mirrored by requirement for NMDA receptors and GABA(A) receptors in odorant-selective, glomerulus-specific projection neurons(PNs). The need for the vesicular glutamate transporter in LNs indicates that a subset of these GABAergic neurons also releases glutamate. LTH is associated with a reduction of odorant-evoked calcium fluxes in PNs as well as growth of the respective odorant-responsive glomeruli. These cellular changes use similar mechanisms to those required for behavioral habituation. Taken together with the observation that enhancement of GABAergic transmission is sufficient to attenuate olfactory behavior, these data indicate that habituation arises from glomerulus-selective potentiation of inhibitory synapses in the antennal lobe. We suggest that similar circuit mechanisms may operate in other species and sensory systems.

Zebrafish: an exciting model for investigating the spatio-temporal pattern of enteric nervous system development.

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.

Retinal ganglion cell death postponed: giving apoptosis a break?

Glaucoma is characterised by the preferential death of retinal ganglion cells (RGCs). However, mammalian models indicate that neurons pass through a period in which they manifest signs of neuronal damage, but have yet to fully commit to death. Mounting evidence suggests that one of the clearest indications of this process is the reduction in RGC dendritic arborisation, resulting in functional compromise. The extent to which this may be reversible is unclear, since the molecular events that precede changes in dendritic structure have received little attention. Furthermore, there are likely to be many factors involved in this process potentially acting in different individual cells at different times. Recent work in Drosophila shows that dendritic reorganisation/remodelling involves local activation and tight regulation of caspase activity. Here, we propose a model in which the balance between caspases and inhibitors of apoptosis (IAPs) contributes towards the regulation of dendritic remodelling. Thus, RGC dendrite reorganisation and cell death represent opposite ends of a spectrum of events regulated by apoptosis signalling pathways. We summarise relevant events in apoptosis, focusing on caspases and IAPs. We also discuss mechanisms of dendrite development, structure and reorganisation and the implications for early diagnosis and treatment of glaucoma and neurodegenerative disease.

Astroglial plasticity and glutamate function in a chronic mouse model of Parkinson's disease.

Astrocytes play a major role in maintaining low levels of synaptically released glutamate, and in many neurodegenerative diseases, astrocytes become reactive and lose their ability to regulate glutamate levels, through a malfunction of the glial glutamate transporter-1. However, in Parkinson's disease, there are few data on these glial cells or their regulation of glutamate transport although glutamate cytotoxicity has been blamed for the morphological and functional decline of striatal neurons. In the present study, we use a chronic mouse model of Parkinson's disease to investigate astrocytes and their relationship to glutamate, its extracellular level, synaptic localization, and transport. C57/bl mice were treated chronically with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p). From 4 to 8 weeks after treatment, these mice show a significant loss of dopaminergic terminals in the striatum and a significant increase in the size and number of GFAP-immunopositive astrocytes. However, no change in extracellular glutamate, its synaptic localization, or transport kinetics was detected. Nevertheless, the density of transporters per astrocyte is significantly reduced in the MPTP/p-treated mice when compared to controls. These results support reactive gliosis as a means of striatal compensation for dopamine loss. The reduction in transporter complement on individual cells, however, suggests that astrocytic function may be compromised. Although reactive astrocytes are important for maintaining homeostasis, changes in their ability to regulate glutamate and its associated synaptic functions could be important for the progressive nature of the pathophysiology associated with Parkinson's disease.

The meningeal sheath of the regenerating spinal cord of the eel, Anguilla.

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.

Reaction of spinal cord central canal cells to cord transection and their contribution to cord regeneration.

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 (