Recommendations for evaluation of neurogenic bladder and bowel dysfunction after spinal cord injury and/or disease.

Objective: To provide an overview of clinical assessments and diagnostic tools, self-report measures (SRMs) and data sets used in neurogenic bladder and bowel (NBB) dysfunction and recommendations for their use with persons with spinal cord injury /disease (SCI/D).Methods: Experts in SCI/D conducted literature reviews, compiled a list of NBB related assessments and measures, reviewed their psychometric properties, discussed their use in SCI/D and issued recommendations for the National Institutes of Health (NIH), National Institute of Neurological Disorders and Stroke (NINDS) Common Data Elements (CDEs) guidelines.Results: Clinical assessments included 15 objective tests and diagnostic tools for neurogenic bladder and 12 for neurogenic bowel. Following a two-phase evaluation, eight SRMs were selected for final review with the Qualiveen and Short-Form (SF) Qualiveen and the Neurogenic Bowel Dysfunction Score (NBDS) being recommended as supplemental, highly-recommended due to their strong psychometrics and extensive use in SCI/D. Two datasets and other SRM measures were recommended as supplemental.Conclusion: There is no one single measure that can be used to assess NBB dysfunction across all clinical research studies. Clinical and diagnostic tools are here recommended based on specific medical needs of the person with SCI/D. Following the CDE for SCI studies guidelines, we recommend both the SF-Qualiveen for bladder and the NBDS for bowel as relatively short measures with strong psychometrics. Other measures are also recommended. A combination of assessment tools (objective and subjective) to be used jointly across the spectrum of care seems critical to best capture changes related to NBB and develop better treatments.

Recommendations for evaluation of bladder and bowel function in pre-clinical spinal cord injury research.

Objective: In order to encourage the inclusion of bladder and bowel outcome measures in preclinical spinal cord injury (SCI) research, this paper identifies and categorizes 1) fundamental, 2) recommended, 3) supplemental and 4) exploratory sets of outcome measures for pre-clinical assessment of bladder and bowel function with broad applicability to animal models of SCI.Methods: Drawing upon the collective research experience of autonomic physiologists and informed in consultation with clinical experts, a critical assessment of currently available bladder and bowel outcome measures (histological, biochemical, in vivo functional, ex vivo physiological and electrophysiological tests) was made to identify the strengths, deficiencies and ease of inclusion for future studies of experimental SCI.Results: Based upon pre-established criteria generated by the Neurogenic Bladder and Bowel Working Group that included history of use in experimental settings, citations in the literature by multiple independent groups, ease of general use, reproducibility and sensitivity to change, three fundamental measures each for bladder and bowel assessments were identified. Briefly defined, these assessments centered upon tissue morphology, voiding efficiency/volume and smooth muscle-mediated pressure studies. Additional assessment measures were categorized as recommended, supplemental or exploratory based upon the balance between technical requirements and potential mechanistic insights to be gained by the study.Conclusion: Several fundamental assessments share reasonable levels of technical and material investment, including some that could assess bladder and bowel function non-invasively and simultaneously. Such measures used more inclusively across SCI studies would advance progress in this high priority area. When complemented with a few additional investigator-selected study-relevant supplemental measures, they are highly recommended for research programs investigating the efficacy of therapeutic interventions in preclinical animal models of SCI that have a bladder and/or bowel focus.

FAIR SCI Ahead: The Evolution of the Open Data Commons for Pre-Clinical Spinal Cord Injury Research.

Over the last 5 years, multiple stakeholders in the field of spinal cord injury (SCI) research have initiated efforts to promote publications standards and enable sharing of experimental data. In 2016, the National Institutes of Health/National Institute of Neurological Disorders and Stroke hosted representatives from the SCI community to streamline these efforts and discuss the future of data sharing in the field according to the FAIR (Findable, Accessible, Interoperable and Reusable) data stewardship principles. As a next step, a multi-stakeholder group hosted a 2017 symposium in Washington, DC entitled "FAIR SCI Ahead: the Evolution of the Open Data Commons for Spinal Cord Injury research." The goal of this meeting was to receive feedback from the community regarding infrastructure, policies, and organization of a community-governed Open Data Commons (ODC) for pre-clinical SCI research. Here, we summarize the policy outcomes of this meeting and report on progress implementing these policies in the form of a digital ecosystem: the Open Data Commons for Spinal Cord Injury (ODC-SCI.org). ODC-SCI enables data management, harmonization, and controlled sharing of data in a manner consistent with the well-established norms of scholarly publication. Specifically, ODC-SCI is organized around virtual "laboratories" with the ability to share data within each of three distinct data-sharing spaces: within the laboratory, across verified laboratories, or publicly under a creative commons license (CC-BY 4.0) with a digital object identifier that enables data citation. The ODC-SCI implements FAIR data sharing and enables pooled data-driven discovery while crediting the generators of valuable SCI data.

Considerations and recommendations for selection and utilization of upper extremity clinical outcome assessments in human spinal cord injury trials.

STUDY DESIGN: This is a focused review article. OBJECTIVES: This review presents important features of clinical outcomes assessments (COAs) in human spinal cord injury research. Considerations for COAs by trial phase and International Classification of Functioning, Disability and Health are presented as well as strengths and recommendations for upper extremity COAs for research. Clinical trial tools and designs to address recruitment challenges are identified. METHODS: The methods include a summary of topics discussed during a two-day workshop, conceptual discussion of upper extremity COAs and additional focused literature review. RESULTS: COAs must be appropriate to trial phase and particularly in mid-late-phase trials, should reflect recovery vs. compensation, as well as being clinically meaningful. The impact and extent of upper vs. lower motoneuron disease should be considered, as this may affect how an individual may respond to a given therapeutic. For trials with broad inclusion criteria, the content of COAs should cover all severities and levels of SCI. Specific measures to assess upper extremity function as well as more comprehensive COAs are under development. In addition to appropriate use of COAs, methods to increase recruitment, such as adaptive trial designs and prognostic modeling to prospectively stratify heterogeneous populations into appropriate cohorts should be considered. CONCLUSIONS: With an increasing number of clinical trials focusing on improving upper extremity function, it is essential to consider a range of factors when choosing a COA. SPONSORS: Craig H. Neilsen Foundation, Spinal Cord Outcomes Partnership Endeavor.

Developing a data sharing community for spinal cord injury research.

The rapid growth in data sharing presents new opportunities across the spectrum of biomedical research. Global efforts are underway to develop practical guidance for implementation of data sharing and open data resources. These include the recent recommendation of 'FAIR Data Principles', which assert that if data is to have broad scientific value, then digital representations of that data should be Findable, Accessible, Interoperable and Reusable (FAIR). The spinal cord injury (SCI) research field has a long history of collaborative initiatives that include sharing of preclinical research models and outcome measures. In addition, new tools and resources are being developed by the SCI research community to enhance opportunities for data sharing and access. With this in mind, the National Institute of Neurological Disorders and Stroke (NINDS) at the National Institutes of Health (NIH) hosted a workshop on October 5-6, 2016 in Bethesda, MD, in collaboration with the Open Data Commons for Spinal Cord Injury (ODC-SCI) titled "Preclinical SCI Data: Creating a FAIR Share Community". Workshop invitees were nominated by the workshop steering committee (co-chairs: ARF and VPL; members: AC, KDA, MSB, KF, LBJ, PGP, JMS), to bring together junior and senior level experts including preclinical and basic SCI researchers from academia and industry, data science and bioinformatics experts, investigators with expertise in other neurological disease fields, clinical researchers, members of the SCI community, and program staff representing federal and private funding agencies. The workshop and ODC-SCI efforts were sponsored by the International Spinal Research Trust (ISRT), the Rick Hansen Institute, Wings for Life, the Craig H. Neilsen Foundation and NINDS. The number of attendees was limited to ensure active participation and feedback in small groups. The goals were to examine the current landscape for data sharing in SCI research and provide a path to its future. Below are highlights from the workshop, including perspectives on the value of data sharing in SCI research, workshop participant perspectives and concerns, descriptions of existing resources and actionable directions for further engaging the SCI research community in a model that may be applicable to many other areas of neuroscience. This manuscript is intended to share these initial findings with the broader research community, and to provide talking points for continued feedback from the SCI field, as it continues to move forward in the age of data sharing.

Epidural Spinal Stimulation to Improve Bladder, Bowel, and Sexual Function in Individuals With Spinal Cord Injuries: A Framework for Clinical Research.

While some recent studies that apply epidural spinal cord stimulation (SCS) have demonstrated a breakthrough in improvement of the health and quality of the life of persons with spinal cord injury (SCI), the numbers of people who have received SCS are small. This is in sharp contrast to the thousands of persons worldwide living with SCI who have no practical recourse or hope of recovery of lost functions. Thus, the vision is to understand the full potential of this new intervention and to determine if it is safe and effective in a larger cohort, and if it is scalable so that it can be made available to all those who might benefit. To achieve this vision, the National Institute of Biomedical Imaging and Bioengineering called for and organized a consortium of multiple stakeholder groups: foundations addressing paralysis, federal and public agencies, industrial partners, academicians, and researchers, all interested in the same goal. Based on input from consortium participants, we have reasoned that a first step is to define a scalable SCS approach that is effective in restoring lost autonomic physiology, specifically bladder, bowel, and sexual function. These functions are most critical for improving the quality of life of persons living with SCI. This report outlines a framework for conducting the research needed to define such an effective SCS procedure that might seek Food and Drug Administration approval and be implemented at the population level.

Harmonization of Databases: A Step for Advancing the Knowledge About Spinal Cord Injury.

The objectives of this article are to (1) provide an overview of existing spinal cord injury (SCI) clinical research databases-their purposes, characteristics, and accessibility to users; and (2) present a vision for future collaborations required for cross-cutting research in SCI. This vision highlights the need for validated and relevant data for longitudinal clinical trials and observational and epidemiologic SCI-related studies. Three existing SCI clinical research databases/registries are reviewed and summarized with regard to current formats, collection methods, and uses, including major strengths and weaknesses. Efforts to provide a uniform approach to data collection are also reviewed. The databases reviewed offer different approaches to capture important clinical information on SCI. They vary on size, purpose, data points, inclusion of standard outcomes, and technical requirements. Each presents with a set of limitations including lack of population data and lack of a common platform for data comparisons and exchanges. It is clear that numerous issues need to be considered when planning to establish common ways of collecting data through data sets or patient registries, ranging from a carefully crafted implementation plan that lists purposes, cost, resources required, and policies to guide such development to establishing a framework for dissemination of data and findings. For the present, taking advantage of the vast but different data already collected over many decades may require a variety of statistical skills and epidemiologic techniques. Ultimately, our ability to speak the same language with regard to variables and assessment tools will facilitate international collaborations and enhance comparability, data pooling, and the ability to generalize findings to a broader population.

Large animal and primate models of spinal cord injury for the testing of novel therapies.

Large animal and primate models of spinal cord injury (SCI) are being increasingly utilized for the testing of novel therapies. While these represent intermediary animal species between rodents and humans and offer the opportunity to pose unique research questions prior to clinical trials, the role that such large animal and primate models should play in the translational pipeline is unclear. In this initiative we engaged members of the SCI research community in a questionnaire and round-table focus group discussion around the use of such models. Forty-one SCI researchers from academia, industry, and granting agencies were asked to complete a questionnaire about their opinion regarding the use of large animal and primate models in the context of testing novel therapeutics. The questions centered around how large animal and primate models of SCI would be best utilized in the spectrum of preclinical testing, and how much testing in rodent models was warranted before employing these models. Further questions were posed at a focus group meeting attended by the respondents. The group generally felt that large animal and primate models of SCI serve a potentially useful role in the translational pipeline for novel therapies, and that the rational use of these models would depend on the type of therapy and specific research question being addressed. While testing within these models should not be mandatory, the detection of beneficial effects using these models lends additional support for translating a therapy to humans. These models provides an opportunity to evaluate and refine surgical procedures prior to use in humans, and safety and bio-distribution in a spinal cord more similar in size and anatomy to that of humans. Our results reveal that while many feel that these models are valuable in the testing of novel therapies, important questions remain unanswered about how they should be used and how data derived from them should be interpreted.

Independent evaluation of the anatomical and behavioral effects of Taxol in rat models of spinal cord injury.

The goal of the current manuscript was to replicate published data that show intrathecal infusions of Taxol® (paclitaxel), an anti-neoplastic microtubule stabilizing agent, reduce fibrogliotic scarring caused by a dorsal spinal hemisection (DHx) injury and increase functional recovery and growth of serotonergic axons after moderate spinal contusion injury. These experiments were completed as part of an NIH-NINDS contract entitled "Facilities of Research Excellence in Spinal Cord Injury (FORE-SCI) - Replication". Here, data are presented that confirm the anti-scarring effects of Taxol after DHx injury; however, Taxol did not confer neuroprotection or promote serotonergic axon growth nor did it improve functional recovery in a model of moderate spinal contusion injury. Thus, only partial replication was achieved. Possible explanations for disparate results in our studies and published data are discussed.

In the presence of danger: The extracellular matrix defensive response to central nervous system injury.

Glial cells in the central nervous system (CNS) contribute to formation of the extracellular matrix, which provides adhesive sites, signaling molecules, and a diffusion barrier to enhance efficient neurotransmission and axon potential propagation. In the normal adult CNS the extracellular matrix (ECM) is relatively stable except in select regions characterized by dynamic remodeling. However, after trauma such as a spinal cord injury or cortical contusion, the lesion epicenter becomes a focus of acute neuroinflammation. The activation of the surrounding glial cells leads to a dramatic change in the composition of the ECM at the edges of the lesion, creating a perilesion environment dominated by growth inhibitory molecules and restoration of the peripheral/central nervous system border. An advantage of this response is to limit the invasion of damaging cells and diffusion of toxic molecules into the spared tissue regions, but this occurs at the cost of inhibiting migration of endogenous repair cells and preventing axonal regrowth. The following review will highlight structural and functional features of the normal adult CNS ECM and then focus on the reactions of glial cells and changes in the perilesion border that occur following spinal cord or contusive brain injury. Current research strategies directed at modifying the inhibitory perilesion microenvironment without eliminating the protective functions of glial cell activation are discussed.

Elevated MMP-9 in the lumbar cord early after thoracic spinal cord injury impedes motor relearning in mice.

Spinal cord injury results in distant pathology around putative locomotor networks that may jeopardize the recovery of locomotion. We previously showed that activated microglia and increased cytokine expression extend at least 10 segments below the injury to influence sensory function. Matrix metalloproteinase-9 (MMP-9) is a potent regulator of acute neuroinflammation. Whether MMP-9 is produced remote to the injury or influences locomotor plasticity remains unexamined. Therefore, we characterized the lumbar enlargement after a T9 spinal cord injury in C57BL/6 (wild-type [WT]) and MMP-9-null (knock-out [KO]) mice. Within 24 h, resident microglia displayed an activated phenotype alongside increased expression of progelatinase MMP-3 in WT mice. By 7 d, increases in active MMP-9 around lumbar vasculature and production of proinflammatory TNF-α were evident. Deletion of MMP-9 attenuated remote microglial activation and restored TNF-α expression to homeostatic levels. To determine whether MMP-9 impedes locomotor plasticity, we delivered lumbar-focused treadmill training in WT and KO mice during early (2-9 d) or late (35-42 d) phases of recovery. Robust behavioral improvements were observed by 7 d, when only trained KO mice stepped in the open field. Locomotor improvements were retained for 4 weeks as identified using state of the art mouse kinematics. Neither training nor MMP-9 depletion alone promoted recovery. The same intervention delivered late was ineffective, suggesting that lesion site sparing is insufficient to facilitate activity-based training and recovery. Our work suggests that by attenuating remote mechanisms of inflammation, acute treadmill training can harness endogenous spinal plasticity to promote robust recovery.

The impact of myelination on axon sparing and locomotor function recovery in spinal cord injury assessed using diffusion tensor imaging.

The dysmyelinated axons of shiverer mice exhibit impaired conduction characteristics, similar to early postnatal axons before myelination, whereas the patterns of neuronal activity and connectivity are relatively comparable with those of wild-type myelinated axons. This unique dysmyelination pattern is exploited in the present study to determine the role of compact myelin in the loss and recovery of function following traumatic spinal cord injury (SCI). We applied in vivo diffusion tensor imaging (DTI) and post-mortem immunohistochemistry analysis to examine changes in myelin and axonal integrity, and evaluated these changes in concert with the analysis of locomotor function from 1 to 4 weeks following a mid-thoracic contusion injury in homozygous shiverer and heterozygous littermate mice. The DTI biomarkers, axial and radial diffusivities, are noninvasive indicators of axon and myelin integrity in response to SCI of both myelinated and dysmyelinated spinal cord. We show that myelin is critical for normal hind limb function in open field locomotion. However, when the functional outcome is limited during chronic SCI, the extent of recovery is associated with residual axonal integrity and independent of the extent of intact myelin at the lesion epicenter.

Alterations in chondroitin sulfate proteoglycan expression occur both at and far from the site of spinal contusion injury.

Chondroitin sulfate proteoglycans (CSPGs) present an inhibitory barrier to axonal growth and plasticity after trauma to the central nervous system. These extracellular and membrane bound molecules are altered after spinal cord injuries, but the magnitude, time course, and patterns of expression following contusion injury have not been fully described. Western blots and immunohistochemistry were combined to assess the expression of four classically inhibitory CSPGs, aggrecan, neurocan, brevican and NG2, at the lesion site and in distal segments of cervical and thoracic spinal cord at 3, 7, 14 and 28 days following a severe mid-thoracic spinal contusion. Total neurocan and the full-length (250 kDa) isoform were strongly upregulated both at the lesion epicenter and in cervical and lumbar segments. In contrast, aggrecan and brevican were sharply reduced at the injury site and were unchanged in distal segments. Total NG2 protein was unchanged across the injury site, while NG2+ profiles were distributed throughout the lesion site by 14 days post-injury (dpi). Far from the lesion, NG2 expression was increased at lumbar, but not cervical spinal cord levels. To determine if the robust increase in neurocan at the distal spinal cord levels corresponded to regions of increased astrogliosis, neurocan and GFAP immunoreactivity were measured in gray and white matter regions of the spinal enlargements. GFAP antibodies revealed a transient increase in reactive astrocyte staining in cervical and lumbar cord, peaking at 14 dpi. In contrast, neurocan immunoreactivity was specifically elevated in the cervical dorsal columns and in the lumbar ventral horn and remained high through 28 dpi. The long lasting increase of neurocan in gray matter regions at distal levels of the spinal cord may contribute to the restriction of plasticity in the chronic phase after SCI. Thus, therapies targeted at altering this CSPG both at and far from the lesion site may represent a reasonable addition to combined strategies to improve recovery after SCI.

A reassessment of a classic neuroprotective combination therapy for spinal cord injured rats: LPS/pregnenolone/indomethacin.

These experiments were completed as part of an NIH-NINDS contract entitled "Facilities of Research Excellence-Spinal Cord Injury (FORE-SCI)-Replication". Our goal was to replicate data from a paper published by Dr. Lloyd Guth and colleagues in which combined injections of lipopolysaccharide, indomethacin and pregnenolone (referred to herein as LIP therapy) conferred marked neuroprotection in a pre-clinical model of spinal cord injury (SCI). Specifically, post-injury injection of the combination LIP therapy was found to significantly reduce tissue damage at/nearby the site of injury and significantly improve recovery of locomotor function. In this report, we confirm the primary observations made by Guth et al., however, the effects of LIP treatment were modest. Specifically, LIP treatment improved myelin and axon sparing, axonal sprouting while reducing lesion cavitation. However, spontaneous recovery of locomotion, as assessed using historical (Tarlov scoring) and more current rating scales (i.e., BBB scoring), was not affected by LIP treatment. Instead, more refined parameters of functional recovery (paw placement accuracy during grid walk) revealed a significant effect of treatment. Possible explanations for the neuroprotective effects of LIP therapy are described along with reasons why the magnitude of neuroprotection may have differed between this study and that of Guth and colleagues.

Transforming growth factor α transforms astrocytes to a growth-supportive phenotype after spinal cord injury.

Astrocytes are both detrimental and beneficial for repair and recovery after spinal cord injury (SCI). These dynamic cells are primary contributors to the growth-inhibitory glial scar, yet they are also neuroprotective and can form growth-supportive bridges on which axons traverse. We have shown that intrathecal administration of transforming growth factor α (TGFα) to the contused mouse spinal cord can enhance astrocyte infiltration and axonal growth within the injury site, but the mechanisms of these effects are not well understood. The present studies demonstrate that the epidermal growth factor receptor (EGFR) is upregulated primarily by astrocytes and glial progenitors early after SCI. TGFα directly activates the EGFR on these cells in vitro, inducing their proliferation, migration, and transformation to a phenotype that supports robust neurite outgrowth. Overexpression of TGFα in vivo by intraparenchymal adeno-associated virus injection adjacent to the injury site enhances cell proliferation, alters astrocyte distribution, and facilitates increased axonal penetration at the rostral lesion border. To determine whether endogenous EGFR activation is required after injury, SCI was also performed on Velvet (C57BL/6J-Egfr(Vel)/J) mice, a mutant strain with defective EGFR activity. The affected mice exhibited malformed glial borders, larger lesions, and impaired recovery of function, indicating that intrinsic EGFR activation is necessary for neuroprotection and normal glial scar formation after SCI. By further stimulating precursor proliferation and modifying glial activation to promote a growth-permissive environment, controlled stimulation of EGFR at the lesion border may be considered in the context of future strategies to enhance endogenous cellular repair after injury.

Injured mice at the gym: review, results and considerations for combining chondroitinase and locomotor exercise to enhance recovery after spinal cord injury.

Exercise provides a number of important benefits after spinal cord injury in clinical studies and animal models. However, the amount of functional improvement in overground locomotion obtained with exercise alone has been limited thus far, for reasons that are still poorly understood. One hypothesis is that the complex network of endogenous extracellular matrix components, including chondroitin sulfate proteoglycans (CSPGs), can inhibit exercise-induced remodeling and limit plasticity of spared circuitry in the adult central nervous system. Recent animal studies have shown that chondroitinase ABC (ChABC) can enhance plasticity in the adult nervous system by cleaving glycosaminoglycan sidechains from CSPGs. In this article we review the current literature on plasticity observed with locomotor training and following degradation of CSPGs with ChABC and then present a rationale for the use of exercise combined with ChABC to promote functional recovery after spinal cord injury. We also present results of a preliminary study that tested the simplest approach for combining these treatments; use of a single intraparenchymal injection of ChABC administered to the lumbar enlargement of mice with voluntary wheel running exercise after a mid-thoracic spinal contusion injury. The results are negative, yet serve to highlight limitations in our understanding of the most effective protocols for combining these approaches. Further work is directed to identify the timing, type, and quantity of exercise and pharmacological interventions that can be used to maximize functional improvements by strengthening appropriate synaptic connections.

Sensory stimulation prior to spinal cord injury induces post-injury dysesthesia in mice.

Chronic pain and dysesthesias are debilitating conditions that can arise following spinal cord injury (SCI). Research studies frequently employ rodent models of SCI to better understand the underlying mechanisms and develop better treatments for these phenomena. While evoked withdrawal tests can assess hypersensitivity in these SCI models, there is little consensus over how to evaluate spontaneous sensory abnormalities that are seen in clinical SCI subjects. Overgrooming (OG) and biting after peripheral nerve injury or spinal cord excitotoxic lesions are thought to be one behavioral demonstration of spontaneous neuropathic pain or dysesthesia. However, reports of OG after contusion SCI are largely anecdotal and conditions causing this response are poorly understood. The present study investigated whether repeated application of sensory stimuli to the trunk prior to mid-thoracic contusion SCI would induce OG after SCI in mice. One week prior to SCI or laminectomy, mice were subjected either to nociceptive and mechanical stimulation, mechanical stimulation only, the testing situation without stimulation, or no treatment. They were then examined for 14 days after surgery and the sizes and locations of OG sites were recorded on anatomical maps. Mice subjected to either stimulus paradigm showed increased OG compared with unstimulated or uninjured mice. Histological analysis showed no difference in spinal cord lesion size due to sensory stimulation, or between mice that overgroomed or did not overgroom. The relationship between prior stimulation and contusion injury in mice that display OG indicates a critical interaction that may underlie one facet of spontaneous neuropathic symptoms after SCI.

Regional heterogeneity in astrocyte responses following contusive spinal cord injury in mice.

Astrocytes and their precursors respond to spinal cord injury (SCI) by proliferating, migrating, and altering phenotype. This contributes to glial scar formation at the lesion border and gliosis in spared gray and white matter. The present study was undertaken to evaluate astrocyte changes over time and determine when and where interventions might be targeted to alter the astrocyte response. Bromodeoxyuridine (BrdU) was administered to mice 3 days after SCI, and cells expressing BrdU and the astrocyte marker, glial fibrillary acidic protein (GFAP), were counted at 3, 7, and 49 days post-injury (DPI). BrdU-labeled cells accumulated at the lesion border by 7 DPI and approximately half of these expressed GFAP. In spared white matter, the total number of BrdU+ cells decreased, while the percentage of BrdU+ cells expressing GFAP increased at 49 DPI. Phenotypic changes were examined using the progenitor marker nestin, the radial glial marker, brain lipid binding protein (BLBP), and GFAP. Nestin was upregulated by 3 DPI and declined between 7 and 49 DPI in all regions, and GFAP increased and remained above naïve levels at all timepoints. BLBP increased early and remained high along the lesion border and spared white matter, but was expressed transiently by cells lining the central canal and in a unique population of small cells found within the lesion and in gray matter rostral and caudal to the border. The results demonstrate that the astrocyte response to SCI is regionally heterogeneous, and suggests astrocyte populations that could be targeted by interventions.

Progranulin expression is upregulated after spinal contusion in mice.

Progranulin (proepithelin) is a pleiotropic growth-factor associated with inflammation and wound repair in peripheral tissues. It also has been implicated in the response to acute traumatic brain injury as well as to chronic neurodegenerative diseases. To determine whether changes in progranulin expression also accompany acute spinal cord injury, C57BL/6 mice were subjected to mid-thoracic (T9 level) contusion spinal cord injury and analyzed by immunohistochemical and biochemical methods. Whereas spinal cord sections prepared from non-injured laminectomy control animals contained low basal levels of progranulin immunoreactivity in gray matter, sections from injured animals contained intense immunoreactivity throughout the injury epicenter that peaked 7-14 days post injury. Progranulin immunoreactivity colocalized with myeloid cell markers CD11b and CD68, indicating that expression increased primarily in activated microglia and macrophages. Immunoblot analysis confirmed that progranulin protein levels rose after injury. On the basis of quantitative polymerase chain reaction analysis, increased protein levels resulted from a tenfold rise in progranulin transcripts. These data demonstrate that progranulin is dramatically induced in myeloid cells after experimental spinal cord injury and is positioned appropriately both spatially and temporally to influence recovery after injury.