Hyperbaric oxygen therapy improves local microenvironment after spinal cord injury

Proteomics in orthopedic research: Recent studies and their translational implications

Proteomics is a growing field that offers insights into various aspects of disease processes and therapy responses. Within the field of orthopedics, there are a variety of diseases that have a poor prognosis due to a lack of targeted curative therapy or disease modifying therapy. Other diseases have been difficult to manage in part due to lack of clinical biomarkers that offer meaningful insight into disease progression or severity. As an emerging technology, proteomics has been increasingly applied in studying bone biology and an assortment of orthopedics related diseases, such as osteoarthritis, osteosarcoma and bone tumors, osteoporosis, traumatic bone injury, spinal cord injury, hip and knee arthroplasty, and fragile healing. These efforts range from mechanistic studies for elucidating novel insights in tissue activity and metabolism to identification of candidate biomarkers for diagnosis, prognosis, and targeted treatment. The knowledge gained from these proteomic and functional studies has provided unique perspectives in studying orthopedic diseases. In this review, we seek to report on the current state of the proteomic study in the field of orthopedics, overview the advances in clinically applicable discoveries, and discuss the opportunities that may guide us for future research.

Oxygen therapy attenuates neuroinflammation after spinal cord injury

Acute hyperbaric O2 (HBO) therapy after spinal cord injury (SCI) can reduce inflammation and increase neuronal survival. To our knowledge, it is unknown if these benefits of HBO require hyperbaric vs. normobaric hyperoxia. We used a C4 lateralized contusion SCI in adult male and female rats to test the hypothesis that the combination of hyperbaria and 100% O2 (i.e. HBO) more effectively mitigates spinal inflammation and neuronal loss, and enhances respiratory recovery, as compared to normobaric 100% O2. Experimental groups included spinal intact, SCI no O2 therapy, and SCI + 100% O2 delivered at normobaric pressure (1 atmosphere, ATA), or at 2- or 3 ATA. O2 treatments lasted 1-h, commenced within 2-h of SCI, and were repeated for 10 days. The spinal inflammatory response was assessed with transcriptomics (RNAseq) and immunohistochemistry. Gene co-expression network analysis showed that the strong inflammatory response to SCI was dramatically diminished by both hyper- and normobaric O2 therapy. Similarly, both HBO and normobaric O2 treatments reduced the prevalence of immunohistological markers for astrocytes (glial fibrillary acidic protein) and microglia (ionized calcium binding adaptor molecule) in the injured spinal cord. However, HBO treatment also had unique impacts not detected in the normobaric group including upregulation of an anti-inflammatory cytokine (interleukin-4) in the plasma, and larger inspiratory tidal volumes at 10-days (whole body-plethysmography measurements). We conclude that normobaric O2 treatment can reduce the spinal inflammatory response after SCI, but pressured O2 (i.e., HBO) provides further benefit.

Anterior Cervical Spine Surgery Complicated With Dysphagia

Anterior cervical spine surgery is a common type of neck surgery in orthopaedics. Swallowing disorder is one of the most common complications after surgery. It is characterized by food entering the esophagus from the mouth through the pharynx. The process of reaching the stomach is hampered and leads to increases in a range of risk factors that affect the health of the patient. This article reviews relevant literature reports from recent years retrieved from various national and international medical databases, aiming to find more economical, effective, and simple perioperative nursing strategies for patients with cervical anterior surgery through evidence-based thinking and methods, with the aim of developing a personalized care model that is easy to implement and has a long-lasting effect and a wide range of rehabilitation benefits to better serve patients.

Advance in hyperbaric oxygen therapy in spinal cord injury

Spinal cord injury (SCI) is a severe lesion comporting various motor, sensory and sphincter dysfunctions, abnormal muscle tone and pathological reflex, resulting in a severe and permanent lifetime disability. The primary injury is the immediate effect of trauma and includes compression, contusion, and shear injury to the spinal cord. A secondary and progressive injury usually follows, beginning within minutes and evolving over several hours after the first ones. Because ischemia is one of the most important mechanisms involved in secondary injury, a treatment to increase the oxygen tension of the injured site, such as hyperbaric oxygen therapy, should theoretically help recovery. Although a meta-analysis concluded that hyperbaric oxygen therapy might be helpful for clinical treatment as a safe, promising and effective choice to limit secondary injury when appropriately started, useful and well-defined protocols/guidelines still need to be created, and its application is influenced by local/national practice. The topic is not a secondary issue because a well-designed randomized controlled trial requires a proper sample size to demonstrate the clinical efficacy of a treatment, and the absence of a common practice guideline represents a limit for results generalization. This narrative review aims to reassemble the evidence on hyperbaric oxygen therapy to treat SCI, focusing on adopted protocols in the studies and underlining the critical issues. Furthermore, we tried to elaborate on a protocol with a flowchart for an evidence-based hyperbaric oxygen therapy treatment. In conclusion, a rationale and shared protocol to standardize as much as possible is needed for the population to be studied, the treatment to be adopted, and the outcomes to be evaluated. Further studies, above all, well-designed randomized controlled trials, are needed to clarify the role of hyperbaric oxygen therapy as a strategic tool to prevent/reduce secondary injury in SCI and evaluate its effectiveness based on an evidence-based treatment protocol. We hope that adopting the proposed protocol can reduce the risk of bias and drive future studies.

Hyperbaric Oxygen Therapy-Induced Molecular and Pathway Changes in a Rat Model of Spinal Cord Injury: A Proteomic Analysis

Hyperbaric Oxygen Therapy (HBOT) has definitive therapeutic effects on spinal cord injury (SCI), but its mechanism of action is still unclear. Here, we've conducted a systemic proteomic analysis to identify differentially expressed proteins (DEPs) between SCI rats and HBOT + SCI rats. The function clustering analysis showed that the top enriched pathways of DEPs include oxygen transport activity, oxygen binding, and regulation of T cell proliferation. The results of functional and signal pathway analyses indicated that metabolic pathways, thermogenesis, LXR/RXR activation, acute phase response signaling, and the intrinsic prothrombin pathway in the SCI + HBOT group was higher than SCI group.

Hyperbaric Oxygen Improves the Survival and Angiogenesis of Fat Grafts after Autologous Fat Transplantation

Objective

Currently, autologous fat transplantation (AFT) still has a low graft survival rate. Elevation of the AFT graft survival rate is a challenge. This study investigated the effect of hyperbaric oxygen (HBO) on AFT.

Methods

Twelve adult male SD rats were randomly divided into two groups after AFT: the control group (n = 6) and the HBO group (n = 6). The rats were killed at 7, 14, and 28 days after transplantation to take the transplanted adipose tissues. The volume and weight of the tissues were detected. The pathological changes in the adipose tissues were observed after H&E staining. Microvessel density and levels of transforming growth factor- (TGF-) β, tumor necrosis factor- (TNF-) α, and malondialdehyde (MDA) in the transplanted adipose tissues were measured with CD31 immunohistochemical stain, ELISA, and biochemical reagents, respectively. Additionally, the protein expression levels of vascular endothelial growth factor- (VEGF-) A and platelet-derived growth factor- (PDGF) A in the adipose tissues were detected by Western blot.

Results

HBO significantly preserved the volume and weight of the transplanted adipose tissue (p < 0.01) and maintained the pathological structure of the transplanted adipose tissue. HBO therapy was effective in reducing inflammatory factor (TGF-β and TNF-α) levels and oxidative stress (MDA) in the transplanted adipose tissue (p < 0.01) and significantly increased the level of CD31 and angiogenesis-related factors including VEGF-A and PDGF-A (p < 0.01) to promote angiogenesis.

Conclusion

HBO therapy regulated the immune response of fat grafts, stimulated their angiogenesis, and ultimately promoted their survival after AFT.

Hyperbaric oxygen therapy after mid-cervical spinal contusion injury

Hyperbaric oxygen (HBO) therapy is frequently used to treat peripheral wounds or decompression sickness. Evidence suggests that HBO therapy can provide neuroprotection and has an anti-inflammatory impact after neurological injury, including spinal cord injury (SCI). Our primary purpose was to conduct a genome-wide screening of mRNA expression changes in the injured spinal cord after HBO therapy. An mRNA gene array was used to evaluate samples taken from the contused region of the spinal cord following a lateralized mid-cervical contusion injury in adult female rats. HBO therapy consisted of daily, 1-h sessions (3.0 ATA, 100% O₂) initiated on the day of SCI and continued for 10 days. Gene set enrichment analyses indicated that HBO upregulated genes in pathways associated with electron transport, mitochondrial function, and oxidative phosphorylation, and downregulated genes in pathways associated with inflammation (including cytokines and nuclear factor kappa B [NF-κB]) and apoptotic signaling. In a separate cohort, spinal cord histology was performed to verify whether the HBO treatment impacted neuronal cell counts or inflammatory markers. Compared with untreated rats, there were increased NeuN positive cells in the spinal cord of HBO-treated rats (p = 0.004). We conclude that HBO therapy, initiated shortly after SCI and continued for 10 days, can alter the molecular signature of the lesioned spinal cord in a manner consistent with a neuroprotective impact.

Protective Effect of Hyperbaric Oxygen Treatment on Axon Degeneration after Acute Motor Axonal Neuropathy

OBJECTIVES

Acute motor axonal neuropathy (AMAN) is a disease that leads to acute flaccid paralysis and may result from the binding of antibody and antigen to the spinal cord. The objective of this study is to evaluate the protective effect of hyperbaric oxygen treatment (HBOT) on axon degeneration of the spinal cord and sciatic nerve of the AMAN model rabbit. Axonal degeneration was assessed by evaluating glutathione (GSH) activity, interleukin-1β (IL-1β) expression, and clinical and histopathological features.

METHODS

Twenty-one New Zealand rabbits were divided into three groups. The treatment group was exposed to 100% oxygen at 2.4 ATA 90 minutes for 10 days at a decompression rate of 2.9 pounds per square inch/minute. GSH level was evaluated using an enzyme-linked immune-sorbent assay. An expression of IL-1β in the spinal cord was determined by immunohistochemistry. Clinical appearances were done by motor scale and body weight. Histological features observed neuronal swelling and inflammatory infiltration in the sagittal lumbar region and the undulation of the longitudinal sciatic nerve.

RESULTS

Rabbits exposed to HBO had high GSH activity levels (p < 0.05) but unexpectedly had high IL1β expression (p > 0.05). In addition, the HBO-exposed rabbits had a better degree of undulation, the size of neuronal swelling was smaller, the number of macrophages was higher, and motor function was better than the AMAN model rabbits (p < 0.05).

CONCLUSIONS

These findings indicate that HBO therapy can decrease axon degeneration by triggering GSH activity, increasing IL-1β level, and restoring tissues and motor status. In conclusion, HBO has a protective effect on axon degeneration of the spinal cord and sciatic nerve of the AMAN model rabbit.

Cytokine expressions of spinal cord injury treated by neurotropin and nafamostat mesylate

Background

Spinal cord injury (SCI) leads to severe physical disability and sensory dysfunction. Neurotropin (NTP) has been used clinically to alleviate neuropathic pain, while nafamostat mesylate (NM) used clinical on pancreatitis patients through inhibiting synthetic serine protease. Our previous studies showed that NTP and NM were able to repair SCI. However, the underlying mechanism has not been fully explored after treatment with these 2 different drugs.

Methods

The drugs NTP and NM were administered on a contusion SCI Wistar rat model. Cytokine array analysis was performed to describe the changes of 67 proteins after acute SCI. Hierarchical clustering and volcano plot analysis were conducted to clarify protein change profiles. The differently expressed proteins related to biological processes were analyzed by functional protein association networks, Gene Ontology and pathway analysis. Flow cytometric analysis was detected to reflect the activation of immune system after drug intervention, while withdrawal threshold and BBB score were detected to evaluated the mechanical allodynia and functional recovery after SCI.

Results

HGF, β-NGF, and activin were the 3 most upregulated proteins, while the receptor for RAGE, IL-1α, and TNF-α were the 3 most downregulated proteins after NTP treatment. Adiponectin, decorin and CTACK were the 3 most upregulated proteins, while RAGE, IL-1α, and IL-1β were the 3 most downregulated proteins in the NM group. Number of lymphocytes was decreased while BBB score was increased both in NTP and NM group. But only NTP could improve mechanical pain threshold after SCI.

Conclusions

The PI3K-Akt, Jak-STAT signaling pathway and apoptosis might participate in SCI restoration by NTP, while the MAPK and NOD-like receptor signaling pathway may participated in repairing SCI with NM. We concluded that NTP regulated the microenvironment via a neuroprotective effect and inhibition of inflammation to repair SCI, while NM healed SCI through an anti-inflammatory effect. Both NTP and NM could down-regulate the activation of immune system and improve the functional recovery while only NTP could improve the pathological neuralgia after SCI. Elucidating the molecular mechanisms of these 2 clinical drugs indicates that they their expected to be effective clinical treatment for SCI.

Effects of oxygen generating scaffolds on cell survival and functional recovery following acute spinal cord injury in rats

Persistent local oxygen delivery is crucial to create a microenvironment for cell survival and nerve regeneration in acute spinal cord injury (SCI). This study aimed to fabricate calcium peroxide-based microspheres incorporated into a 3-D construct scaffold as a novel oxygen release therapy for SCI. The scaffolds were able to generate oxygen over the course of 21 days when incubated under hypoxic conditions. In vitro, GFP-labeled bone marrow-derived mesenchymal stem cells (MSCs) were planted into the scaffolds. We observed that scaffolds could enhance MSC survival under hypoxic conditions for more than 21 days. Oxygen generating scaffolds were transplanted into spinal cord injury sites of rats in vivo. Twelve weeks following transplantation, cavity areas in the injury/graft site were significantly reduced due to tissue regeneration. Additionally, the oxygen generating scaffolds improved revascularization as observed through vWF immunostaining. A striking feature was the occurrence of nerve fiber regeneration in the lesion sites, which eventually led to significant locomotion recovery. The present results indicate that the oxygen generating scaffolds have the property of sustained local oxygen release, thus facilitating regeneration in injured spinal cords.

Hyperbaric Oxygen Treatment Following Mid-Cervical Spinal Cord Injury Preserves Diaphragm Muscle Function

Oxidative damage to the diaphragm as a result of cervical spinal cord injury (SCI) promotes muscle atrophy and weakness. Respiratory insufficiency is the leading cause of morbidity and mortality in cervical spinal cord injury (SCI) patients, emphasizing the need for strategies to maintain diaphragm function. Hyperbaric oxygen (HBO) increases the amount of oxygen dissolved into the blood, elevating the delivery of oxygen to skeletal muscle and reactive oxygen species (ROS) generation. It is proposed that enhanced ROS production due to HBO treatment stimulates adaptations to diaphragm oxidative capacity, resulting in overall reductions in oxidative stress and inflammation. Therefore, we tested the hypothesis that exposure to HBO therapy acutely following SCI would reduce oxidative damage to the diaphragm muscle, preserving muscle fiber size and contractility. Our results demonstrated that lateral contusion injury at C3/4 results in a significant reduction in diaphragm muscle-specific force production and fiber cross-sectional area, which was associated with augmented mitochondrial hydrogen peroxide emission and a reduced mitochondrial respiratory control ratio. In contrast, rats that underwent SCI followed by HBO exposure consisting of 1 h of 100% oxygen at 3 atmospheres absolute (ATA) delivered for 10 consecutive days demonstrated an improvement in diaphragm-specific force production, and an attenuation of fiber atrophy, mitochondrial dysfunction and ROS production. These beneficial adaptations in the diaphragm were related to HBO-induced increases in antioxidant capacity and a reduction in atrogene expression. These findings suggest that HBO therapy may be an effective adjunctive therapy to promote respiratory health following cervical SCI.

The Treatment of Perioperative Spinal Cord Injury With Hyperbaric Oxygen Therapy: A Case Report

STUDY DESIGN

Case report (level IV evidence).

OBJECTIVE

To describe a potential novel application of hyperbaric oxygen therapy (HBOT) in the successful treatment of a postoperative spinal cord injury.

SUMMARY OF BACKGROUND DATA

A 68-year-old man presented with an acute spinal cord injury (ASIA impairment scale D), on the background of degenerative lower thoracic and lumbar canal stenosis. He underwent emergent decompression and instrumented fusion (T9-L5), with an uncomplicated intraoperative course and no electrophysiological changes. Immediate postoperative assessment demonstrated profound bilateral limb weakness (1/5 on the Medical Research Council [MRC] grading scale, ASIA impairment scale B), without radiological abnormality.

METHODS

Conventional medical management (hypertension, level 2 care) was instigated with the addition of Riluzole, with no effect after 30 hours. At 36 hours 100% oxygen at 2.8 atmospheres was applied for 90 minutes, and repeated after 8 hours, with a further three treatments over 48 hours.

RESULTS

The patient demonstrated near-immediate improvement in lower limb function to anti-gravity (MRC grading 3/5) after one treatment. Motor improvement continued over the following treatments, and after 2 weeks the patient was ambulatory. At 4 months, the patient demonstrated normal motor function with no sphincteric disturbance.

CONCLUSION

The application of HBOT contributed to the immediate and sustained improvement (ASIA B to ASIA E) in motor recovery after postoperative spinal cord injury. HBOT may represent a new avenue of therapy for spinal cord injury, and requires further prospective investigation.

LEVEL OF EVIDENCE

4.

Reprogrammed astrocytes display higher neurogenic competence, migration ability and cell death resistance than reprogrammed fibroblasts

The direct reprogramming of somatic cells into induced neural progenitor cells (iNPCs) has been envisioned as a promising approach to overcome ethical and clinical issues of pluripotent stem cell transplantation. We previously reported that astrocyte-derived induced pluripotent stem cells (iPSCs) have more tendencies for neuronal differentiation than fibroblast-derived iPSCs. However, the differences of neurogenic potential between astrocyte-derived iNPCs (AiNPCs) and iNPCs from non-neural origins, such as fibroblast-derived iNPCs (FiNPCs), and the underlying mechanisms remain unclear. Our results suggested that AiNPCs exhibited higher differentiation efficiency, mobility and survival capacities, compared to FiNPCs. The whole transcriptome analysis revealed higher activities of TGFβ signaling in AiNPCs, versus FiNPCs, following a similar trend between astrocytes and fibroblasts. The higher neurogenic competence, migration ability, and cell death resistance of AiNPCs could be abrogated using TGFβ signaling inhibitor LY2157299. Hence, our study demonstrates the difference between iNPCs generated from neural and non-neural cells, together with the underlying mechanisms, which, provides valuable information for donor cell selection in the reprogramming approach.

Melatonin Enhances Autophagy and Reduces Apoptosis to Promote Locomotor Recovery in Spinal Cord Injury via the PI3K/AKT/mTOR Signaling Pathway

Spinal cord injury (SCI) leads to neuronal death resulting in central nervous system (CNS) dysfunction; however, the pathogenesis is still poorly understood. Melatonin (MT), a hormone secreted mainly by the pineal gland, is associated with neuroprotective effects against SCI. Enhanced autophagy can promote the recovery of locomotor function and reduce apoptosis after SCI. Interestingly, MT increases autophagy in SCI in vivo. Nevertheless, the ability of MT to increase autophagy and decrease apoptosis, and the potential effects on the recovery of motor neurons in the anterior horn after SCI remain to be clarified. In this study, we discovered that MT treatment improved motor function recovery in a rat SCI model. Indeed, MT upregulated the expression of the phosphatidylinositol 3-kinase (PI3K), while expression of protein kinase B (AKT) and mammalian target of rapamycin (mTOR) was downregulated after SCI. Additionally, MT increased the expression of autophagy-activating proteins, while the expression of apoptosis-activating proteins in neurons was decreased following SCI. Furthermore, autophagy was inhibited, while apoptosis was induced in SCI model rats and lipopolysaccharide (LPS)-stimulated primary neurons by treatment with MT, the PI3K inhibitor 3-methyladenine (3-MA) and mTOR inhibitor Rapamycin (Rapa). Collectively, our results suggest that MT can improve the recovery of locomotor function by enhancing autophagy as well as reducing apoptosis after SCI in rats, probably via the PI3K/AKT/mTOR signaling pathway.

Evaluation of hyperbaric oxygen therapy for spinal cord injury in rats with different treatment course using diffusion tensor imaging

STUDY DESIGN

Animal study.

OBJECTIVES

To evaluate the efficacy of hyperbaric oxygen (HBO) therapy for spinal cord injury (SCI) in rats with different treatment course using diffusion tensor imaging (DTI).

SETTING

Hospital in Fuzhou, China.

METHODS

Fifty adult Sprague-Dawley rats were grouped as: (A) sham-operated group (n = 10); (B) SCI without HBO therapy group (n = 10); (C) SCI with HBO therapy for 2 weeks (SCI+HBO_2W) group (n = 10); (D) SCI with HBO therapy for 4 weeks (SCI+HBO_4W) group (n = 10); (E) SCI with HBO therapy for 6 weeks (SCI+HBO_6W) group (n = 10). Basso Beattie Bresnahan (BBB) scores and diffusion tensor imaging parameters including fractional anisotropy (FA), mean diffusivity (MD), radial diffusion (RD), and axial diffusion (AD) values in the injury epicenter, as well as 2 mm rostral and caudal to the injury epicenter were collected and analyzed 6 weeks post-injury.

RESULTS

Higher BBB score and FA values were found in the SCI+HBO_4W group than in the SCI and SCI+HBO_2W groups (all P < 0.05), whereas no significant differences of these metrics were observed between the SCI+HBO_4W and SCI+HBO_6W groups. MD and RD values of the SCI+HBO_4W group were significantly lower than those of the SCI group (all P < 0.01). FA values were positively correlated with BBB scores. MD and RD values were negatively correlated with BBB scores.

CONCLUSION

DTI parameters, especially FA, could non-invasively and quantifiably evaluate the efficacy of HBO treatment for rats with SCI and 4 weeks may be the more appropriate treatment course.

Effect of hyperbaric oxygen therapy on HMGB1/NF-κB expression and prognosis of acute spinal cord injury: A randomized clinical trial

Although there are reports of the beneficial effects of hyperbaric oxygen (HBO) therapy in experimental settings, there are few clinical trials of HBO therapy for acute spinal cord injury (SCI). We investigated the effect of HBO in acute SCI by measuring plasma high mobility group box 1 (HMGB1) and nuclear factor kappa-B (NF-κB) levels, and by monitoring changes in electromyogram F-persistence (the percentage of discernible F-waves) and F-chronodispersion (the difference between minimal and maximal latency). We enrolled 79 acute SCI patients and randomly divided them into control (conventional treatment) and the treatment (conventional treatment plus HBO therapy) groups. Plasma was collected before treatment and after treatment on 1st, 3rd, 7th, 10th and 30th day for the measurement of HMGB1 and NF-κB. Electromyogram F-waves were detected before therapy and after therapy on the 10th and 30th days. Clinical profiles and neurological outcomes were evaluated using American Spinal Injury Association (ASIA) and Frankel Grade scores. Compared to the control group, HBO therapy down-regulated HMGB1 and NF-κB expression in patients with acute SCI on days 3, 7, 10 and 30 (p < 0.05). F-wave chronodispersion decreased at days 10 and 30 (p < 0.01) following HBO. ASIA and Frankel Grade motor/pain scores in the treatment group were significantly improved on day 30 (p < 0.01). There was a positive correlation between plasma NF-κB at day 7 and F-wave dispersion at day 30 (r = 0.76, p = 0.00). In summary, HBO therapy regulated the inflammatory reaction in secondary SCI by decreasing plasma HMGB1/NF-κB levels and reducing the dispersion of electromyogram F-waves of the lower limbs, thereby promoting neurological function recovery.

Early Hyperbaric Oxygen Treatment Attenuates Burn-Induced Neuroinflammation by Inhibiting the Galectin-3-Dependent Toll-Like Receptor-4 Pathway in a Rat Model

Hyperbaric oxygen (HBO) treatment has been proven to decrease neuroinflammation in rats. This study aimed to determine the potential mechanism underlying the anti-inflammatory effects of HBO treatment on burn-induced neuroinflammation in rats. Thirty-six adult male Sprague-Dawley (SD) rats were randomly assigned to the following six groups (n = 6 per group): (1) sham burn with sham HBO treatment; (2) sham burn with HBO treatment; (3) burn with one-week sham HBO treatment; (4) burn with two-week sham HBO treatment; (5) burn with one-week HBO treatment; and (6) burn with two-week HBO treatment. SD rats that received third-degree burn injury were used as a full-thickness burn injury model. Subsequently, we analyzed the expression of proteins involved in the galectin-3 (Gal-3)-dependent Toll-like receptor-4 (TLR-4) pathway through enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC) analysis, and Western blotting. A behavior test was also conducted, which revealed that HBO treatment significantly suppressed mechanical hypersensitivity in the burn with HBO treatment group compared to the burn with sham HBO treatment group (p < 0.05). ELISA results showed that tumor necrosis factor α (TNF-α) and interleukin 1 beta (IL-1β) levels in the dorsal horn of the spinal cord and the skin significantly decreased in the burn with HBO treatment group compared with the burn with sham HBO treatment group (p < 0.05). Western blotting results demonstrated that HBO treatment significantly reduced the expression of Gal-3 and TLR-4 in the dorsal horn of the spinal cord in the burn with HBO treatment group compared with the burn with sham HBO treatment group (p < 0.05). IHC analysis showed that the expression of Gal-3, TLR-4, CD68 and CD45 in the dorsal horn of the spinal cord was significantly lower in the burn with HBO treatment group than in the burn with sham HBO treatment group (p < 0.05), and the expression of CD68 and macrophage migration inhibitory factor (MIF) in the right hind paw skin was significantly lower. The expression of vimentin and fibroblast growth factor in the right hind paw skin was significantly higher after HBO treatment (p < 0.05). This study proved that early HBO treatment relieves neuropathic pain, inhibits the Gal-3-dependent TLR-4 pathway, and suppresses microglia and macrophage activation in a rat model.

A Dual Role for Hyperbaric Oxygen in Stroke Neuroprotection: Preconditioning of the Brain and Stem Cells

Stroke continues to be an extremely prevalent disease and poses a great challenge in developing safe and effective therapeutic options. Hyperbaric oxygen therapy (HBOT) has demonstrated significant pre-clinical effectiveness for the treatment of acute ischemic stroke, and limited potential in treating chronic neurological deficits. Reported benefits include reductions in oxidative stress, inflammation, neural apoptosis, and improved physiological metrics such as edema and oxygen perfusion, all of which contribute to improved functional recovery. This pre-clinical evidence has failed to translate into an effective evidence-based therapy, however, due in large part to significant inconsistencies in treatment protocols and design of clinical studies. While the medical community works to standardize clinical protocols in an effort to advance HBOT for acute stroke, pre-clinical investigations continue to probe novel applications of HBOT in an effort to optimize stroke neuroprotection. One such promising strategy is HBOT preconditioning. Based upon the premise of mild oxidative stress priming the brain for tolerating the full-blown oxidative stress inherent in stroke, HBOT preconditioning has displayed extensive efficacy. Here, we first review the pre-clinical and clinical evidence supporting HBOT delivery following ischemic stroke and then discuss the scientific basis for HBOT preconditioning as a neuroprotective strategy. Finally, we propose the innovative concept of stem cell preconditioning, in tandem with brain preconditioning, as a promising regenerative pathway for maximizing the application of HBOT for ischemic stroke treatment.

Worldwide Steroid Prescription for Acute Spinal Cord Injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To continue the line of a previous publication using steroid for acute spinal cord injury (SCI) by spine surgeons from Latin America (LA) and assess the current status of methylprednisolone (MP) prescription in Europe (EU), Asia Pacific (AP), North America (NA), and Middle East (ME) to determine targets for educational activities suitable for each region.

METHODS

The English version of a previously published questionnaire was used to evaluate opinions about MP administration in acute SCI in LA, EU, AP, NA, and ME. This Internet-based survey was conducted by members of AOSpine. The questionnaire asked about demographic features, background with management of spine trauma patients, routine administration of MP in acute SCI, and reasons for MP administration.

RESULTS

A total of 2659 responses were obtained for the electronic questionnaire from LA, EU, AP, NA, and ME. The number of spine surgeons that treat SCI was 2206 (83%). The steroid was used by 1198 (52.9%) surgeons. The uses of MP were based predominantly on the National Acute Spinal Cord Injury Study III study (n = 595, 50%). The answers were most frequently given by spine surgeons from AP, ME, and LA. These regions presented a statistically significant difference from North America (P < .001). The number of SCI patients treated per year inversely influenced the use of MP. The higher the number of patients treated, the lower the administration rates of MP observed.

CONCLUSIONS

The study identified potential targets for educational campaigns, aiming to reduce inappropriate practices of MP administration.

Hyperbaric Oxygen Therapy After Acute Thoracic Spinal Cord Injury: Improvement of Locomotor Recovery in Rats

STUDY DESIGN

A controlled laboratory study.

OBJECTIVE

The aim of this study was to analyze the effectiveness of hyperbaric therapy (HT) using mild and moderate models of spinal cord injury (SCI).

SUMMARY OF BACKGROUND DATA

SCI can cause permanent impairment with socioeconomic consequences. The motor deficit occurs by two mechanisms: destruction of neuronal cells and local inflammatory response, resulting in hypoxia. HT acts by increasing oxygen in the injured area.

METHODS

Thoracic laminectomy was performed in 72 female Wistar rats. The MASCIS impactor was used at 12.5 mm (n = 35) and 25 mm (n = 35) of height to perform, respectively, mild and moderate SCI. Muscle strength was assessed through the Basso, Beattie, and Bresnahan scale (BBB) on days 1, 7, 14, 21, and 28 after SCI. The animals were randomized into five subgroups with seven animals each: (1) control group had SCI without HT; (2) HT 30 minutes after SCI; (3) HT 30 minutes after SCI and daily for 7 days; (4) HT 12 hours after SCI; and (5) HT 12 hours after SCI and daily for 7 days. HT was performed at 2.5 atm for 1 hour.

RESULTS

There was a linear relationship between injury severity and motor deficit until day 21, with similar BBB scores on day 28. A pattern of uniform lesions was observed in the mild SCI, with lower variation of BBB when compared with moderate SCI. All animals that underwent HT had significant improvement in motor function and histology when compared with control group. Regardless of the injury model, animals submitted to 7-day protocols had an early improvement in motor function and a smaller area of histological injury.

CONCLUSION

The present study reported that the sooner HT is begun after mild and moderate SCI and the larger the number of sessions, the greater and earlier is the motor recovery and smaller is the tissue injury.

LEVEL OF EVIDENCE

N/A.

Improving Sperm Viability After Spinal Cord Injury Using Hyperbaric Therapy

BACKGROUND

Infertility is one of many complications of spinal cord injury (SCI) in male patients, who are often at the peak of their reproductive life. This study evaluated effects of hyperbaric therapy (HT) on quality of sperm of rats with SCI and correlated the findings with histologic analysis of the testicles.

METHODS

This experimental study comprised 18 rats that were submitted to SCI with a MASCIS Impactor and randomly allocated to either a HT or a control group. Testicular biopsies were performed on the first and 28th day of the study; 4 parameters were evaluated: concentration of sperm per mL, number of round cells per field, number of inflammatory cells per field (peroxidase [Endtz] test), and sperm viability (hypo-osmotic swelling test).

RESULTS

There was no difference in sperm concentration between the HT group (P = 0.41) and control group (P = 0.74) during 28 days. From day 1 to day 28, sperm viability decreased twice as much in the control group (P = 0.001) compared with the HT group (P = 0.017). There was no difference between the groups in mean sperm concentration and number of round and inflammatory cells. On the first day, there was no difference in sperm viability between groups. There was a significantly higher (P = 0.001) percentage of viable sperm in the HT group (86.8 ± 5.6) compared with the control group (48.8 ± 21.8) on day 28.

CONCLUSIONS

SCI increased the number of round and inflammatory cells and diminished sperm viability in both groups. HT promoted greater sperm viability in rats with SCI.

Hyperbaric oxygenation alleviates chronic constriction injury (CCI)-induced neuropathic pain and inhibits GABAergic neuron apoptosis in the spinal cord

BACKGROUND AND AIMS

Dysfunction of GABAergic inhibitory controls contributes to the development of neuropathic pain. We examined our hypotheses that (1) chronic constriction injury (CCI)-induced neuropathic pain is associated with increased spinal GABAergic neuron apoptosis, and (2) hyperbaric oxygen therapy (HBO) alleviates CCI-induced neuropathic pain by inhibiting GABAergic neuron apoptosis.

METHODS

Male rats were randomized into 3 groups: CCI, CCI+HBO and the control group (SHAM). Mechanical allodynia was tested daily following CCI procedure. HBO rats were treated at 2.4 atmospheres absolute (ATA) for 60min once per day. The rats were euthanized and the spinal cord harvested on day 8 and 14 post-CCI. Detection of GABAergic cells and apoptosis was performed. The percentages of double positive stained cells (NeuN/GABA), cleaved caspase-3 or Cytochrome C in total GABAergic cells or in total NeuN positive cells were calculated.

RESULTS

HBO significantly alleviated mechanical allodynia. CCI-induced neuropathic pain was associated with significantly increased spinal apoptotic GABA-positive neurons. HBO considerably decreased these spinal apoptotic cells. Cytochrome-C-positive neurons and cleaved caspase-3-positive neurons were also significantly higher in CCI rats. HBO significantly decreased these positive cells. Caspase-3 mRNA was also significantly higher in CCI rats. HBO reduced mRNA expression of caspase-3.

CONCLUSIONS

CCI-induced neuropathic pain was associated with increased apoptotic GABAergic neurons induced by activation of key proteins of mitochondrial apoptotic pathways in the dorsal horn of the spinal cord. HBO alleviated CCI-induced neuropathic pain and reduced GABAergic neuron apoptosis. The beneficial effect of HBO may be via its inhibitory role in CCI-induced GABAergic neuron apoptosis by suppressing mitochondrial apoptotic pathways in the spinal cord.

IMPLICATIONS

Increased apoptotic GABAergic neurons induced by activation of key proteins of mitochondrial apoptotic pathways in the dorsal horn of the spinal cord is critical in CCI-induced neuropathic pain. The inhibitory role of HBO in GABAergic neuron apoptosis suppresses ongoing neuropathic pain.

Hyperbaric oxygen therapy of spinal cord injury

Spinal cord injury (SCI) is a complex disease process that involves both primary and secondary mechanisms of injury and can leave patients with devastating functional impairment as well as psychological debilitation. While no curative treatment is available for spinal cord injury, current therapeutic approaches focus on reducing the secondary injury that follows SCI. Hyperbaric oxygen (HBO) therapy has shown promising neuroprotective effects in several experimental studies, but the limited number of clinical reports have shown mixed findings. This review will provide an overview of the potential mechanisms by which HBO therapy may exert neuroprotection, provide a summary of the clinical application of HBO therapy in patients with SCI, and discuss avenues for future studies.

Traumatic Sports-Related Cervical Spine Injuries

Cervical spine trauma in the athlete is not an insignificant occurrence with possibly catastrophic results. Football remains one of the most common and most well studied sporting activities associated with spine injuries. Transient spinal cord and peripheral nerve injuries may manifest as quadriparesis or burners/stingers with symptoms that resolve completely. More severe spinal cord injuries, typically from axial loading on the cervical spine, will cause bilateral symptoms with residual neurological deficit. Acute Trauma Life Support principles must always be applied to the player with a potential spine injury. Recent positional statements by National Athletic Trainers' Association advocate equipment removal on the field by 3 individuals with appropriate training, a shift from previous recommendations. This recommendation is still under debate, but equipment removal in the field is an option depending on staff training. The use of steroids in acute spinal cord injury remains controversial. Moderate systemic hypothermia has theoretical benefits for reducing spinal cord damage in the setting of an acute injury. Although it has been studied in the laboratory, only a few clinical trials have been performed and further research is necessary before routine implementation of hypothermia protocols.

Application of hyperbaric oxygen in liver transplantation

In recent years, hyperbaric oxygen (HBO) has been used in the treatment of a lot of diseases such as decompression sickness, arterial gas embolism, carbon dioxide poisoning, soft tissue infection, refractory osteomyelitis, and problematic wound, but little is known about its application in liver transplantation. Although several studies have been conducted to investigate the protective effects of HBO on liver transplantation and liver preservation, there are still some controversies on this issue, especially its immunomodulatory effect. In this short review, we briefly summarize the findings supporting the application of HBO during liver transplantation (including donors and recipients).

Macrophage polarization: a key event in the secondary phase of acute spinal cord injury

Acute spinal cord injury (SCI) has become epidemic in modern society. Despite advances made in the understanding of the pathogenesis and improvements in early recognition and treatment, it remains a devastating event, often producing severe and permanent disability. SCI has two phases: acute and secondary. Although the acute phase is marked by severe local and systemic events such as tissue contusion, ischaemia, haemorrhage and vascular damage, the outcome of SCI are mainly influenced by the secondary phase. SCI causes inflammatory responses through the activation of innate immune responses that contribute to secondary injury, in which polarization‐based macrophage activation is a hallmarker. Macrophages accumulated within the epicentre and the haematoma of the injured spinal cord play a significant role in this inflammation. Depending on their phenotype and activation status, macrophages may initiate secondary injury mechanisms and/or promote CNS regeneration and repair. When it comes to therapies for SCI, very few can be performed in the acute phase. However, as macrophage activation and polarization switch are exquisitely sensitive to changes in microenvironment, some trials have been conducted to modulate macrophage polarization towards benefiting the recovery of SCI. Given this, it is important to understand how macrophages and SCI interrelate and interact on a molecular pathophysiological level. This review provides a comprehensive overview of the immuno‐pathophysiological features of acute SCI mainly from the following perspectives: (i) the overview of the pathophysiology of acute SCI, (ii) the roles of macrophage, especially its polarization switch in acute SCI, and (iii) newly developed neuroprotective therapies modulating macrophage polarization in acute SCI.

Hyperbaric oxygen preconditioning: a reliable option for neuroprotection

Brain injury is the leading cause of death and disability worldwide and clinically there is no effective therapy for neuroprotection. Hyperbaric oxygen preconditioning (HBO-PC) has been experimentally demonstrated to be neuroprotective in several models and has shown efficiency in patients undergoing on-pump coronary artery bypass graft (CABG) surgery. Compared with other preconditioning stimuli, HBO is benign and has clinically translational potential. In this review, we will summarize the results in experimental brain injury and clinical studies, elaborate the mechanisms of HBO-PC, and discuss regimes and opinions for future interventions in acute brain injury.

Changes in autophagy in rats after spinal cord injury and the effect of hyperbaric oxygen on autophagy

The purpose of this study was to explore the effects of Hyperbaric oxygen (HBO) on the autophagic changes after induction of spinal cord injury (SCI) in rats. A total of 75 rats were randomly divided into the sham-operated group, the spinal cord injury group, and the SCI+HBO group. We found that at 7 d and 14 d after surgery, the BBB scores were higher in the SCI+HBO group in comparison to the SCI group. The expression of Beclin-1 and LC3II was upregulated in the SCI and SCI+HBO groups after SCI. Fluorescently stained Beclin-1 and LC3II proteins were barely detectable in the sham group. In contrast, Beclin-l and LC3II expression was observed in neurons and glial cells from the SCI and SCI+HBO groups. Beclin-1 and LC3II expression appeared at 6h after SCI. At each time point, Beclin-1 and LC3II expression was significantly higher in the SCI+HBO group compared to the SCI group. These results suggest that autophagy is activated in rats after SCI and sustained over a period of time. HBO treatment enhances autophagy expression in rats after SCI and accelerates cell repair rate, which may represent one of the mechanisms of action of HBO in the treatment of SCI.

Hyperbaric oxygen therapy combined with Schwann cell transplantation promotes spinal cord injury recovery

Schwann cell transplantation and hyperbaric oxygen therapy each promote recovery from spinal cord injury, but it remains unclear whether their combination improves therapeutic results more than monotherapy. To investigate this, we used Schwann cell transplantation via the tail vein, hyperbaric oxygen therapy, or their combination, in rat models of spinal cord contusion injury. The combined treatment was more effective in improving hindlimb motor function than either treatment alone; injured spinal tissue showed a greater number of neurite-like structures in the injured spinal tissue, somatosensory and motor evoked potential latencies were notably shorter, and their amplitudes greater, after combination therapy than after monotherapy. These findings indicate that Schwann cell transplantation combined with hyperbaric oxygen therapy is more effective than either treatment alone in promoting the recovery of spinal cord in rats after injury.