Hyperbaric oxygen treatment of spinal cord injury in rat model

Hyperbaric oxygen therapy alleviates intestinal and brain damage in experimental necrotizing enterocolitis

Necrotizing enterocolitis is the most common gastrointestinal emergency in newborns. Its etiology involves bacterial colonization, enteral formula feeding, and hypoxic-ischemic injury. The pathology of necrotizing enterocolitis is characterized by coagulation necrosis and bacterial overgrowth, with limited preventative methods available. In addition to affecting the intestine, this disease has long-term neurological consequences for survivors. Hyperbaric oxygen therapy, a well-established treatment for soft tissue infections and injuries caused by hypoperfusion, may serve as an alternative approach for necrotizing enterocolitis. In this study, a necrotizing enterocolitis model was developed in newborn Sprague-Dawley rat pups through the administration of a hyperosmolar formula, combined with exposure to hypothermia and hypoxia. The rat pups received hyperbaric oxygen therapy sessions at 3 absolute atmospheres for 2 hours each, which were administered over 1 or 2 days. The results demonstrated that hyperbaric oxygen therapy significantly reduced mortality in rats with necrotizing enterocolitis and preserved the number of brain cells in the hippocampus. Additionally, hyperbaric oxygen therapy increased the expression of nitric oxide synthase, intestinal fatty acid-binding protein, and superoxide dismutase 3 in the intestine, and elevated superoxide dismutase 3 levels in the hippocampus. These findings suggest that hyperbaric oxygen therapy not only reduces mortality but also mitigates the severity of intestinal and brain lesions in experimental necrotizing enterocolitis, preserving intestinal cell integrity and enhancing antioxidant mechanisms.

Acute Hyperoxia Improves Spinal Cord Oxygenation and Circulatory Function Following Cervical Spinal Cord Injury in Rats

Spinal cord injury is associated with spinal vascular disruptions that result in spinal ischemia and tissue hypoxia. This study evaluated the therapeutic efficacy of normobaric hyperoxia on spinal cord oxygenation and circulatory function at the acute stage of cervical spinal cord injury. Adult male Sprague Dawley rats underwent dorsal cervical laminectomy or cervical spinal cord contusion. At 1-2 days after spinal surgery, spinal cord oxygenation was monitored in anesthetized and spontaneously breathing rats through optical recording of oxygen sensor foils placed on the cervical spinal cord and pulse oximetry. The arterial blood pressure, heart rate, blood gases, and peripheral oxyhemoglobin saturation were also measured under hyperoxic (50% O2) and normoxic (21% O2) conditions. The results showed that contused animals had significantly lower spinal cord oxygenation levels than uninjured animals during normoxia. Peripheral oxyhemoglobin saturation, arterial oxygen partial pressure, and mean arterial blood pressure are significantly reduced following cervical spinal cord contusion. Notably, spinal oxygenation of contused rats could be improved to a level comparable to uninjured animals under hyperoxia. Furthermore, acute hyperoxia elevated blood pressure, arterial oxygen partial pressure, and peripheral oxyhemoglobin saturation. These results suggest that normobaric hyperoxia can significantly improve spinal cord oxygenation and circulatory function in the acute phase after cervical spinal cord injury. We propose that adjuvant normobaric hyperoxia combined with other hemodynamic optimization strategies may prevent secondary damage after spinal cord injury and improve functional recovery.

Human Placental Mesenchymal Stem Cell-derived Exosomes in Combination with Hyperbaric Oxygen Synergistically Promote Recovery after Spinal Cord Injury in Rats

Spinal cord injury (SCI) is a critical medical condition during which sensorimotor function is lost. Current treatments are still unable to effectively improve these conditions, so it is important to pay attention to other effective approaches. Currently, we investigated the combined effects of human placenta mesenchymal stem cells (hPMSCs)-derived exosomes along with hyperbaric oxygen (HBO) in the recovery of SCI in rats. Ninety male mature Sprague-Dawley (SD) rats were allocated into five equal groups, including; sham group, SCI group, Exo group (underwent SCI and received hPMSCs-derived exosomes), HBO group (underwent SCI and received HBO), and Exo+HBO group (underwent SCI and received hPMSCs-derived exosomes plus HBO). Tissue samples at the lesion site were obtained for the evaluation of stereological, immunohistochemical, biochemical, molecular, and behavioral characteristics. Findings showed a significant increase in stereological parameters, biochemical factors (GSH, SOD, and CAT), IL-10 gene expression and behavioral functions (BBB and EMG Latency) in treatment groups, especially Exo+HBO group, compared to SCI group. In addition, MDA levels, the density of apoptotic cells and gliosis, as well as expression of inflammatory genes (TNF-α and IL-1β) were considerably reduced in treatment groups, especially Exo+HBO group, compared to SCI group. We conclude that co-administration of hPMSCs-derived exosomes and HBO has synergistic neuroprotective effects in animals undergoing SCI.

Synergistic neuroprotective effects of hyperbaric oxygen and methylprednisolone following contusive spinal cord injury in rat

OBJECTIVE

Recent studies revealed the neuroprotective effects of hyperbaric oxygen (HBO) on spinal cord injury (SCI). Meanwhile, the use of methylprednisolone (MP) is one of the current protocols with limited effects in SCI patients. Accordingly, the aim of the present study was to investigate the effect of combined HBO and MP treatment on SCI.

DESIGN

The present study was conducted on five groups of rats each as follows: Sham group (underwent laminectomy alone at T9 level vertebra); SCI group (underwent moderate contusive SCI); MP group (underwent SCI and received MP); HBO group (underwent SCI and received HBO); HBO + MP group (underwent SCI and simultaneously received MP and HBO). Blood serum and Spinal cord tissue samples were taken 48 h after SCI for analysis of serum ferric reducing antioxidant power (FRAP) and tissue malodialdehyde (MDA) levels as well as immunohistochemistry of caspase-3 and tumor necrosis factor-alpha (TNF-α). Neurological function was evaluated by the Basso-Beattie-Bresnehan (BBB) locomotion scores until the end of experiments. Additionally, histopathology was assessed at the end of the study.

SETTING

Mazandaran University of Medical Sciences, Sari, Iran.

RESULTS

Combination therapy with HBO and MP in the HBO + MP group significantly decreased MDA as well as increased FRAP levels compared to other treatment groups. Meanwhile, attenuated TNF-α and Caspase-3 expression could be significantly detected in the HBO + MP group. At the end of treatment, the neurological outcome was significantly improved and the extent of injured spinal tissue was also significantly reduced in the HBO + MP compared to other treatment groups.

CONCLUSION

The results suggest that combined therapy with MP and HBO has synergistic effects on SCI treatment.

Survey of Molecular Mechanisms of Hyperbaric Oxygen in Tissue Repair

For more than six decades, hyperbaric oxygen (HBO) has been used for a variety of indications involving tissue repair. These indications comprise a wide range of diseases ranging from intoxications to ischemia-reperfusion injury, crush syndrome, central nervous injury, radiation-induced tissue damage, burn injury and chronic wounds. In a systematic review, the molecular mechanisms triggered by HBO described within the last two decades were compiled. They cover a wide range of pathways, including transcription, cell-to-cell contacts, structure, adhesion and transmigration, vascular signaling and response to oxidative stress, apoptosis, autophagy and cell death, as well as inflammatory processes. By analyzing 71 predominantly experimental publications, we established an overview of the current concepts regarding the molecular mechanisms underlying the effects of HBO. We considered both the abovementioned pathways and their role in various applications and indications.

Synergistic neuroprotective effects of hyperbaric oxygen and N-acetylcysteine against traumatic spinal cord injury in rat

BACKGROUND

The mitochondrial dysfunction and following oxidative stress, as well as the spread of inflammation plays major roles in the failure to regenerate following severe spinal cord injury (SCI). In this regard, we investigated the neuroprotective effects of hyperbaric oxygen (HBO), as an anti-apoptotic and anti-inflammatory agent, and N-acetylcysteine (NAC), as a mitochondrial enhancer, in SCI.

MATERIAL AND METHODS

Seventy-five female adult Wistar rats divided into five groups (n = 15): laminectomy alone (Sham) group, SCI group, HBO group (underwent SCI and received HBO), NAC group (underwent SCI and received NAC), and HBO+NAC group (underwent SCI and simultaneously received NAC and HBO). At the end of study, spinal cord tissue samples were taken for evaluation of biochemical profiles including malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) levels, immunohistochemistry for caspase-3 as well as gene expressions of interleukin (IL)-10, tumor necrosis factor alpha (TNF-α), and IL-1β. Stereological assessments were performed to determine the total volumes, central cavity volumes and as well as numerical density of the neural and glial cells in traumatic area. Moreover, neurological functions were evaluated by the Basso-Beattie-Bresnehan (BBB) and electromyography (EMG).

RESULTS

Our results showed that the stereological parameters, biochemical profiles (except MDA) and neurological function were significantly higher in each HBO, NAC and HBO+NAC groups compared to the SCI group, and were highest in HBO+NAC ones. The transcript for IL-10 gene was significantly upregulated in all treatment regimens compared to SCI group, and was highest in HBO+NAC ones. While expression of TNF-α and IL-1β, latency, as well as density of apoptosis cells in caspase-3 evaluation significantly more decreased in HBO+NAC group compared to other groups.

CONCLUSION

Overall, using combined therapy with HBO and NAC has synergistic neuroprotective effects in SCI treatment.

Study on the characteristics of microcirculation in the site of pressure ulcer in patients with spinal cord injury

To investigate the characteristics of pressure ulcer microcirculation in SCI patients with pressure ulcer, and to provide evidence for the treatment of pressure ulcer in patients with SCI. Group 1 (n = 12) SCI patients with pressure ulcer, 23 pressure ulcers were included. Group 2 (n = 15) SCI patients without pressure ulcer and the control group (n = 16) healthy adults. The application of laser Doppler perfusion imaging system (Moor FLPI) detector to the microcirculation perfusion of the sacrum area of the control group, the observation group 2 and the pressure ulcer site of the observation group 1, record the microcirculation perfusion (PU), The data of microcirculation perfusion (PU) were compared and analyzed. The correlation between microcirculation perfusion and healing time of pressure ulcer was analyzed. (1) The microcirculation perfusion was highest in the pressure ulcer center. (2) SCI patients and healthy adults had no significant difference of microcirculation perfusion at sacrococcygeal skin. (3) The lower the microcirculation perfusion of the pressure ulcer center, the longer the healing time of pressure ulcer. The healing time and the microcirculation perfusion of pressure ulcer center was negatively correlated. Microcirculation perfusion detection is a noninvasive and effective method for the determination of the scope of pressure ulcer, detection and direction judgment of pressure ulcer sinus tract, monitoring and guidance of pressure ulcer treatment, and prediction of the healing time of pressure ulcer.

A review on the neuroprotective effects of hyperbaric oxygen therapy

Hyperbaric oxygen therapy, intermittent breathing of 100% oxygen at a pressure upper than sea level, has been shown to be some of the neuroprotective effects and used therapeutically in a wide range of neurological disorders. This review summarizes current knowledge about the neuroprotective effects of hyperbaric oxygen therapy with their molecular mechanisms in different models of neurological disorders.

Hyperbaric oxygen therapy for spinal cord injury: A protocol for systematic review and meta-analysis

BACKGROUND

Hyperbaric oxygen (HBO) therapy can prevent further spinal cord injury (SCI) caused by spinal cord ischemia-reperfusion injury to the maximum extent, which has been reported increasingly in recent years. However its security and effectiveness still lack of high-quality medical evidence. In this study, we will perform a systematic review of previously published randomized controlled trials (RCTs) to evaluate the efficacy and safety of HBO therapy for SCI.

METHODS

All potential RCTs on HBO therapy for SCI will be searched from the following electronic databases: PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese Science and Technology Periodical Database, Wanfang database and Chinese Biomedical Literature Database. We will search all electronic databases from their initiation to the September 30, 2020 in spite of language and publication date. Two contributors will independently select studies from all searched literatures, extract data from included trials, and evaluate study quality for all eligible RCTs using Cochrane risk of bias tool, respectively. Any confusion will be resolved by consulting contributor and a consensus will be reached. We will utilize RevMan 5.3 software to pool the data and to conduct the data analysis.

RESULTS

The quality of the assessments will be assessed through Grading of Recommendations Assessment, Development, and Evaluation. Data will be disseminated through publications in peer-reviewed journals.

CONCLUSION

This study will provide evidence to evaluate the efficacy and safety of HBO therapy for SCI at evidence-based medicine level.

TRIAL REGISTRATION NUMBER

INPLASY 2020100084.

An Extra Breath of Fresh Air: Hyperbaric Oxygenation as a Stroke Therapeutic

Stroke serves as a life-threatening disease and continues to face many challenges in the development of safe and effective therapeutic options. The use of hyperbaric oxygen therapy (HBOT) demonstrates pre-clinical effectiveness for the treatment of acute ischemic stroke and reports reductions in oxidative stress, inflammation, and neural apoptosis. These pathophysiological benefits contribute to improved functional recovery. Current pre-clinical and clinical studies are testing the applications of HBOT for stroke neuroprotection, including its use as a preconditioning regimen. Mild oxidative stress may be able to prime the brain to tolerate full extensive oxidative stress that occurs during a stroke, and HBOT preconditioning has displayed efficacy in establishing such ischemic tolerance. In this review, evidence on the use of HBOT following an ischemic stroke is examined, and the potential for HBOT preconditioning as a neuroprotective strategy. Additionally, HBOT as a stem cell preconditioning is also discussed as a promising strategy, thus maximizing the use of HBOT for ischemic stroke.

Utilization, Utility, and Variability in Usage of Adjunctive Hyperbaric Oxygen Therapy in Spinal Management: A Review of the Literature

The objective of this review was to understand the clinical utilization, utility, and variability in the usage of adjunctive hyperbaric oxygen therapy (HBOT). Surgical site infection is associated with high morbidity and mortality, increased health care expenditure, and decreased quality of life. With the increasing prevalence of adult spinal deformity and spinal fusion surgery, it is imperative to understand the potential benefits of adjunctive treatments. HBOT is a safe and common procedure indicated to treat various medical conditions. We conducted a literature search across 3 databases for English articles published between December 1, 2019 and December 1, 2000. Thirteen studies were included. HBOT may lessen the duration of antimicrobial therapy and mitigate instrument removal and revision surgery. The current usage indications for HBOT are supported by level III evidence for chronic osteomyelitis and level IV evidence for osteoradionecrosis. However, the same level of evidence exists to support the beneficial use of adjunctive HBOT for noncomplicated spinal infections within 2 months after surgery. When cultured, the most common organisms were Staphylococcus aureus and other low-virulence organisms. The most common treatment protocol consists of 90-minute sessions of 100% Fio₂ at 2-3 atmosphere absolute with a mean of 35.3 ± 11.6 sessions for 5.2 ± 1.4 weeks. Adjunctive HBOT should be considered in select high-risk patients. Further improvements in diagnosis and categorization of spinal infections are necessary and will indelibly aid the decision making for the initiation of HBOT.

Repeated exposure to hyperbaric hyperoxia affects mitochondrial functions of the lung fibroblasts

Hyperbaric oxygen (HBO) therapy, i.e. breathing pure oxygen under increased environmental pressures serves as a treatment for diverse medical conditions. However, elevated oxygen concentration can be detrimental to central nervous system or lungs. Our study aimed to evaluate the effects of repeated exposure to HBO on mitochondrial respiration assessed by high-resolution respirometry (HRR), cell viability estimated by PrestoBlue® reaction, morphology analyzed by routine phase contrast and fluorescent microscopy, and superoxide dismutase (SOD) and citrate synthase (CS) activities using human lung fibroblasts. The cells were exposed to HBO for 2 h per day for 5 consecutive days. One day after the last exposure, HBO cells displayed significantly smaller area and perimeter, compromised viability and elevated SOD activity. No changes were detected in CS activity or quality of mitochondrial network. HRR revealed impaired mitochondrial oxygen consumption manifested by increased leak respiration, decreased activity of complex II and compromised ATP-related oxygen consumption when fatty acids were oxidized. Our findings document that in conditions mimicking chronic intermittent exposure to HBO, lung fibroblasts suffer from compromised mitochondrial respiration linked to complex II and impaired cellular growth in spite of increased antioxidant defense. Underlying mechanism of this HBO-induced mitochondrial dysfunction should be further explored.

Hyperbaric oxygen therapy reduces astrogliosis and helps to recovery brain damage in hydrocephalic young rats

PURPOSE

We investigated the possible beneficial effects that hyperbaric oxygen therapy could offer in different brain structures affected by ventriculomegaly in pup rats submitted to experimental hydrocephalus.

METHODS

Seven-day-old Wistar rats were submitted to hydrocephalus by intracisternal injection of 10% kaolin into the cisterna magna. The animals were divided into four groups: control (n = 5); control with HBOT (3ATA/2 h/day) (n = 5); untreated hydrocephalic (n = 10); hydrocephalic treated with HBOT (3ATA/2 h/day) (n = 10). The treatment with HBOT was performed daily for 14 days post-induction of hydrocephalus. To evaluate the response to treatment, behavioral tests (open field, Morris water maze, and activity monitor) were performed. After 14 days, the animals were euthanized, and the brain was removed for histological (hematoxylin-eosin and solochrome-cyanine) and immunohistochemical (GFAP and Ki-67) studies.

RESULTS

The hyperbaric treatment, although not causing changes in ventricular enlargement, resulted in a significant improvement in the behavioral performance (p = 0.0001), with greater agility and exploration of the environment, preservation of spatial memory, and greater learning capacity (p = 0.0001). Through the immunohistochemical study, the astrocytic activity (glial fibrillary acidic protein) in the corpus callosum (p = 0.0001) and in the germinative matrix (p = 0.0033) was significantly reduced as compared to that in the H group.

CONCLUSION

The results suggest that hyperbaric treatment bettered the behavioral performance and offered benefits to the structures affected by the ventricular increase helping to recover the brain damages. In this way, the HBOT it can be considered an adjuvant therapy for the treatment of hydrocephalus.

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.