CD34+/CD45-dim stem cell mobilization by hyperbaric oxygen - changes with oxygen dosage

The use of hyperbaric oxygen for veterans with PTSD: basic physiology and current available clinical data

Post-traumatic stress disorder (PTSD) affects up to 30% of veterans returning from the combat zone. Unfortunately, a substantial proportion of them do not remit with the current available treatments and thus continue to experience long-term social, behavioral, and occupational dysfunction. Accumulating data implies that the long-standing unremitting symptoms are related to changes in brain activity and structure, mainly disruption in the frontolimbic circuit. Hence, repair of brain structure and restoration of function could be a potential aim of effective treatment. Hyperbaric oxygen therapy (HBOT) has been effective in treating disruptions of brain structure and functions such as stroke, traumatic brain injury, and fibromyalgia even years after the acute insult. These favorable HBOT brain effects may be related to recent protocols that emphasize frequent fluctuations in oxygen concentrations, which in turn contribute to gene expression alterations and metabolic changes that induce neuronal stem cell proliferation, mitochondrial multiplication, angiogenesis, and regulation of the inflammatory cascade. Recently, clinical findings have also demonstrated the beneficial effect of HBOT on veterans with treatment-resistant PTSD. Moderation of intrusive symptoms, avoidance, mood and cognitive symptoms, and hyperarousal were correlated with improved brain function and with diffusion tensor imaging-defined structural changes. This article reviews the current data on the regenerative biological effects of HBOT, and the ongoing research of its use for veterans with PTSD.

Effect of the Timing of Hyperbaric Oxygen Therapy on the Prognosis of Patients with Idiopathic Sudden Sensorineural Hearing Loss

This study aimed to evaluate the effects of hyperbaric oxygen therapy (HBOT) on the hearing recovery of patients with idiopathic sudden sensorineural hearing loss (ISSNHL). The clinical data of 79 patients diagnosed with ISSNHL and treated with HBOT between January 2017 and December 2019 were retrospectively reviewed. The pure tone audiometry (PTA) scores before and after HBOT were recorded. The associations of HBOT efficacy with demographic and clinical characteristics and the duration from disease onset to HBOT administration were determined. The average PTA score was 80.06 ± 25.94 dB before and 60.75 ± 21.26 dB after HBOT; the difference was significant. HBOT improved the hearing of 55.7% of the patients with ISSNHL (defined as an average PTA ≥ 11dB or a final average PTA score below 29 dB). There was a significant inverse relationship between the duration from symptom onset to HBOT administration and PTA score reduction after HBOT, which was adjusted for factors including age, sex, laterality of hearing loss, initial PTA score, reception of intratympanic steroid injections, tinnitus, dizziness, vertigo, diabetes, hypertension, and coronary artery disease. Commencing HBOT at an earlier stage is closely linked to greater improvements in hearing for patients with ISSNHL.

Hyperbaric Oxygen Therapy for Veterans With Treatment-resistant PTSD: A Longitudinal Follow-up Study

INTRODUCTION

PTSD is common among veteran combatants. PTSD is characterized by brain changes, for which available treatments have shown limited effect. In a short-term study, we showed that hyperbaric oxygen therapy (HBOT) induced neuroplasticity and improved clinical symptoms of veterans with treatment-resistant PTSD. Here, we evaluated the long-term clinical symptoms of the participants of that study.

MATERIALS AND METHODS

Veterans from our short-term study were recruited 1 or more years after completing HBOT. The Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) and self-reported questionnaires were administered at a single site visit. Changes in clinical scores between long-term, short-term, and pretreatment evaluations were analyzed.

RESULTS

Of the 28 participants who received HBOT during or following the short-term study, 22 agreed to participate in the current study. At a mean of 704 ± 230 days after completing the HBOT course, the mean CAPS-5 score (26.6 ± 14.4) was significantly better (lower) than at the pre-HBOT evaluation (47.5 ± 13.1, P < .001) and not statistically different from the short-term evaluation (28.6 ± 16.7, P = .745). However, for the CAPS-5 subcategory D (cognition and mood symptoms), the mean score was significantly better (lower) at long-term than at short-term evaluation (7.6 ± 5.1 vs. 10.0 ± 6.0, P < .001). At the long-term compared to the pretreatment evaluation, higher proportions of the participants were living with life partners (10 (46%) vs. 17 (77%), P = .011) and were working (9 (41%) vs. 16 (73%), P = .033). Decreases were observed between pretreatment and the long-term follow-up, in the number of benzodiazepine users (from 10 (46%) to 4 (18%), P = .07) and in the median (range) cannabis daily dose (from 40.0 g (0-50) to 22.5 g (0-30), P = .046).

CONCLUSIONS

The beneficial clinical effects of HBOT are persistent and were not attenuated at long-term follow-up of about 2 years after completion of HBOT. Additional long-term effects of the treatment were observed in social function and in decreased medication use.

Hyperbaric air mobilizes stem cells in humans; a new perspective on the hormetic dose curve

Introduction

Hyperbaric air (HBA) was first used pharmaceutically in 1662 to treat lung disease. Extensive use in Europe and North America followed throughout the 19th century to treat pulmonary and neurological disorders. HBA reached its zenith in the early 20th century when cyanotic, moribund "Spanish flu pandemic" patients turned normal color and regained consciousness within minutes after HBA treatment. Since that time the 78% Nitrogen fraction in HBA has been completely displaced by 100% oxygen to create the modern pharmaceutical hyperbaric oxygen therapy (HBOT), a powerful treatment that is FDA approved for multiple indications. Current belief purports oxygen as the active element mobilizing stem progenitor cells (SPCs) in HBOT, but hyperbaric air, which increases tensions of both oxygen and nitrogen, has been untested until now. In this study we test HBA for SPC mobilization, cytokine and chemokine expression, and complete blood count.

Methods

Ten 34-35-year-old healthy volunteers were exposed to 1.27ATA (4 psig/965 mmHg) room air for 90 min, M-F, for 10 exposures over 2-weeks. Venous blood samples were taken: (1) prior to the first exposure (served as the control for each subject), (2) directly after the first exposure (to measure the acute effect), (3) immediately prior to the ninth exposure (to measure the chronic effect), and (4) 3 days after the completion of tenth/final exposure (to assess durability). SPCs were gated by blinded scientists using Flow Cytometry.

Results

SPCs (CD45dim/CD34+/CD133-) were mobilized by nearly two-fold following 9 exposures (p = 0.02) increasing to three-fold 72-h post completion of the final (10th) exposure (p = 0.008) confirming durability.

Discussion

This research demonstrates that SPCs are mobilized, and cytokines are modulated by hyperbaric air. HBA likely is a therapeutic treatment. Previously published research using HBA placebos should be re-evaluated to reflect a dose treatment finding rather than finding a placebo effect. Our findings of SPC mobilization by HBA support further investigation into hyperbaric air as a pharmaceutical/therapy.

An overview of hyperbaric oxygen preconditioning against ischemic stroke

Ischemic stroke (IS) has become the second leading cause of morbidity and mortality worldwide, and the prevention of IS should be given high priority. Recent studies have indicated that hyperbaric oxygen preconditioning (HBO-PC) may be a protective nonpharmacological method, but its underlying mechanisms remain poorly defined. This study comprehensively reviewed the pathophysiology of IS and revealed the underlying mechanism of HBO-PC in protection against IS. The preventive effects of HBO-PC against IS may include inducing antioxidant, anti-inflammation, and anti-apoptosis capacity; activating autophagy and immune responses; upregulating heat shock proteins, hypoxia-inducible factor-1, and erythropoietin; and exerting protective effects upon the blood-brain barrier. In addition, HBO-PC may be considered a safe and effective method to prevent IS in combination with stem cell therapy. Although the benefits of HBO-PC on IS have been widely observed in recent research, the implementation of this technique is still controversial due to regimen differences. Transferring the results to clinical application needs to be taken carefully, and screening for the optimal regimen would be a daunting task. In addition, whether we should prescribe an individualized preconditioning regimen to each stroke patient needs further exploration.

Mild Hyperbaric Oxygen Exposure Enhances Peripheral Circulatory Natural Killer Cells in Healthy Young Women

Mild hyperbaric oxygen (HBO) enhances oxygen absorption in blood, relieving fatigue without causing oxidative stress. The benefits of mild HBO have been recognized in the treatment of lifestyle-related diseases and hypertension, but no research has been conducted on its effects on immunity. The aim of the present study is to investigate the effect of mild HBO on natural killer (NK) cells and cytokines in healthy young women. This crossover randomized control trial was conducted with 16 healthy young women. Participants were randomly exposed to normobaric oxygen (NBO; 1.0 atmospheres absolute (ATA), 20.8% oxygen) and mild HBO conditions (1.4 ATA, 35-40% oxygen, injected 18L oxygen per minute) in a hyperbaric oxygen chamber for 70 min. Heart rate, parasympathetic activity, NK cell count, interleukin (IL)-6, IL-12p70 and derivatives of reactive oxygen metabolites (d-ROMs) were measured before and after both exposures. In the NBO condition, parasympathetic activity remained unchanged, whereas after mild HBO exposure, parasympathetic activity was significantly increased. NK cells remained unchanged after NBO exposure, while NK cells were increased after exposure to mild HBO. Exposure to mild HBO did not increase d-ROM values, IL-6 and IL-12p70 protein levels. These findings suggest that exposure to mild HBO can be a useful protocol to increase NK cells by regulating parasympathetic activity via increasing oxygen delivery.

Systematic Review and Dosage Analysis: Hyperbaric Oxygen Therapy Efficacy in Mild Traumatic Brain Injury Persistent Postconcussion Syndrome

Background

Mild traumatic brain injury results in over 15% of patients progressing to Persistent Postconcussion Syndrome, a condition with significant consequences and limited treatment options. Hyperbaric oxygen therapy has been applied to Persistent Postconcussion Syndrome with conflicting results based on its historical understanding/definition as a disease-specific therapy. This is a systematic review of the evidence for hyperbaric oxygen therapy (HBOT) in Persistent Postconcussion Syndrome using a dose-analysis that is based on the scientific definition of hyperbaric oxygen therapy as a dual-component drug composed of increased barometric pressure and hyperoxia.

Methods

In this review, PubMed, CINAHL, and the Cochrane Systematic Review Database were searched from August 8–22, 2021 for all adult clinical studies published in English on hyperbaric oxygen therapy in mild traumatic brain injury Persistent Postconcussion Syndrome (symptoms present at least 3 months). Randomized trials and studies with symptomatic and/or cognitive outcomes were selected for final analysis. Randomized trials included those with no-treatment control groups or control groups defined by either the historical or scientific definition. Studies were analyzed according to the dose of oxygen and barometric pressure and classified as Levels 1–5 based on significant immediate post-treatment symptoms or cognitive outcomes compared to control groups. Levels of evidence classifications were made according to the Centre for Evidence-Based Medicine and a practice recommendation according to the American Society of Plastic Surgeons. Methodologic quality and bias were assessed according to the PEDro Scale.

Results

Eleven studies were included: six randomized trials, one case-controlled study, one case series, and three case reports. Whether analyzed by oxygen, pressure, or composite oxygen and pressure dose of hyperbaric therapy statistically significant symptomatic and cognitive improvements or cognitive improvements alone were achieved for patients treated with 40 HBOTS at 1.5 atmospheres absolute (ATA) (four randomized trials). Symptoms were also improved with 30 treatments at 1.3 ATA air (one study), positive and negative results were obtained at 1.2 ATA air (one positive and one negative study), and negative results in one study at 2.4 ATA oxygen. All studies involved <75 subjects/study. Minimal bias was present in four randomized trials and greater bias in 2.

Conclusion

In multiple randomized and randomized controlled studies HBOT at 1.5 ATA oxygen demonstrated statistically significant symptomatic and cognitive or cognitive improvements alone in patients with mild traumatic brain injury Persistent Postconcussion Syndrome. Positive and negative results occurred at lower and higher doses of oxygen and pressure. Increased pressure within a narrow range appears to be the more important effect than increased oxygen which is effective over a broad range. Improvements were greater when patients had comorbid Post Traumatic Stress Disorder. Despite small sample sizes, the 1.5 ATA HBOT studies meet the Centre for Evidence-Based Medicine Level 1 criteria and an American Society of Plastic Surgeons Class A Recommendation for HBOT treatment of mild traumatic brain injury persistent postconcussion syndrome.

Systemic Administration of G-CSF Accelerates Bone Regeneration and Modulates Mobilization of Progenitor Cells in a Rat Model of Distraction Osteogenesis

Granulocyte colony-stimulating factor (G-CSF) was shown to promote bone regeneration and mobilization of vascular and osteogenic progenitor cells. In this study, we investigated the effects of a systemic low dose of G-CSF on both bone consolidation and mobilization of hematopoietic stem/progenitor cells (HSPCs), endothelial progenitor cells (EPCs) and mesenchymal stromal cells (MSCs) in a rat model of distraction osteogenesis (DO). Neovascularization and mineralization were longitudinally monitored using positron emission tomography and planar scintigraphy. Histological analysis was performed and the number of circulating HSPCs, EPCs and MSCs was studied by flow cytometry. Contrary to control group, in the early phase of consolidation, a bony bridge with lower osteoclast activity and a trend of an increase in osteoblast activity were observed in the distracted callus in the G-CSF group, whereas, at the late phase of consolidation, a significantly lower neovascularization was observed. While no difference was observed in the number of circulating EPCs between control and G-CSF groups, the number of MSCs was significantly lower at the end of the latency phase and that of HSPCs was significantly higher 4 days after the bone lengthening. Our results indicate that G-CSF accelerates bone regeneration and modulates mobilization of progenitor cells during DO.

The Effect of Hyperbaric Oxygen Therapy on Human Adipose-Derived Stem Cells

BACKGROUND

Adipose-derived stem cells are considered as candidate cells for regenerative plastic surgery. Measures to influence cellular properties and thereby direct their regenerative potential remain elusive. Hyperbaric oxygen therapy-the exposure to 100% oxygen at an increased atmospheric pressure-has been propagated as a noninvasive treatment for a multitude of indications and presents a potential option to condition cells for tissue-engineering purposes. The present study evaluates the effect of hyperbaric oxygen therapy on human adipose-derived stem cells.

METHODS

Human adipose-derived stem cells from healthy donors were treated with hyperbaric oxygen therapy at 2 and 3 atm. Viability before and after each hyperbaric oxygen therapy, proliferation, expression of surface markers and protein contents of transforming growth factor (TGF)-β, tumor necrosis factor-α, hepatocyte growth factor, and epithelial growth factor in the supernatants of treated adipose-derived stem cells were measured. Lastly, adipogenic, osteogenic, and chondrogenic differentiation with and without use of differentiation-inducing media (i.e., autodifferentiation) was examined.

RESULTS

Hyperbaric oxygen therapy with 3 atm increased viability, proliferation, and CD34 expression and reduced the CD31/CD34/CD45 adipose-derived stem cell subset and endothelial progenitor cell population. TGF-β levels were significantly decreased after two hyperbaric oxygen therapy sessions in the 2-atm group and decreased after three hyperbaric oxygen therapy sessions in the 3-atm group. Hepatocyte growth factor secretion remained unaltered in all groups. Although the osteogenic and chondrogenic differentiation were not influenced, adipogenic differentiation and autodifferentiation were significantly enhanced, with osteogenic autodifferentiation significantly alleviated by hyperbaric oxygen therapy with 3 atm.

CONCLUSION

Hyperbaric oxygen therapy with 3 atm increases viability and proliferation of adipose-derived stem cells, alters marker expression and subpopulations, decreases TGF-β secretion, and skews adipose-derived stem cells toward adipogenic differentiation.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

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.

The Hyperoxic-Hypoxic Paradox

Effective metabolism is highly dependent on a narrow therapeutic range of oxygen. Accordingly, low levels of oxygen, or hypoxia, are one of the most powerful inducers of gene expression, metabolic changes, and regenerative processes, including angiogenesis and stimulation of stem cell proliferation, migration, and differentiation. The sensing of decreased oxygen levels (hypoxia) or increased oxygen levels (hyperoxia), occurs through specialized chemoreceptor cells and metabolic changes at the cellular level, which regulate the response. Interestingly, fluctuations in the free oxygen concentration rather than the absolute level of oxygen can be interpreted at the cellular level as a lack of oxygen. Thus, repeated intermittent hyperoxia can induce many of the mediators and cellular mechanisms that are usually induced during hypoxia. This is called the hyperoxic-hypoxic paradox (HHP). This article reviews oxygen physiology, the main cellular processes triggered by hypoxia, and the cascade of events triggered by the HHP.

The Hyperoxic-Hypoxic Paradox

Effective metabolism is highly dependent on a narrow therapeutic range of oxygen. Accordingly, low levels of oxygen, or hypoxia, are one of the most powerful inducers of gene expression, metabolic changes, and regenerative processes, including angiogenesis and stimulation of stem cell proliferation, migration, and differentiation. The sensing of decreased oxygen levels (hypoxia) or increased oxygen levels (hyperoxia), occurs through specialized chemoreceptor cells and metabolic changes at the cellular level, which regulate the response. Interestingly, fluctuations in the free oxygen concentration rather than the absolute level of oxygen can be interpreted at the cellular level as a lack of oxygen. Thus, repeated intermittent hyperoxia can induce many of the mediators and cellular mechanisms that are usually induced during hypoxia. This is called the hyperoxic-hypoxic paradox (HHP). This article reviews oxygen physiology, the main cellular processes triggered by hypoxia, and the cascade of events triggered by the HHP.

Effect of intermittent hyperoxia on stem cell mobilization and cytokine expression

The best known form of oxygen therapy is hyperbaric oxygen (HBO) therapy, which increases both concentration and atmospheric pressure. HBO supports tissue regeneration and is indicated in an increasing number of pathologies. Less known but still showing some promising effects is normobaric oxygen (NBO) therapy, which provides some advantages over HBO including eliminating barotrauma risk, increased ease of administration and a significant cost reduction. However, still little is known about differences and similarities in treatment effects between HBO and NBO. Therefore we tested whether NBO induces a biological response comparable to HBO with a focus on stem progenitor cell mobilization and changes in serum cytokine concentration. We randomly assigned Sprague-Dawley rats into an NBO treatment group (n = 6), and a room air control group (n = 6). The NBO treatment group was exposed to 42% oxygen for 2 hours a day for 10 days. The room air group was concurrently kept at 20.9% oxygen. The frequency and number of stem progenitor cells in peripheral blood were analyzed by flow cytometry. Plasma cytokine expression was analyzed by cytokine array enzyme linked immunosorbent assay. All analyses were performed 24 hours after the final exposure to control for transient post treatment effects. The NBO treatment group showed an increase in circulating CD133⁺/CD45⁺ stem progenitor cell frequency and number compared to the room air control group. This rise was largely caused by CD34^- stem progenitor cells (CD133⁺/CD34^-/CD45⁺) without changes in the CD34⁺ population. The plasma cytokine levels tested were mostly unchanged with the exception of tumor necrosis factor-α which showed a decrease 24 hours after the last NBO exposure. These findings support our hypothesis that NBO induces a biological response similar to HBO, affecting serum stem progenitor cell populations and tumor necrosis factor-α concentration. The study was approved by Institutional Animal Care and Use Committee (IACUC) of the University of Wisconsin, Madison, WI, USA (approval No. M005439) on June 28, 2016.

Perioperative Hyperoxyphobia: Justified or Not? Benefits and Harms of Hyperoxia during Surgery

The use of an inspiratory oxygen fraction of 0.80 during surgery is a topic of ongoing debate. Opponents claim that increased oxidative stress, atelectasis, and impaired oxygen delivery due to hyperoxic vasoconstriction are detrimental. Proponents point to the beneficial effects on the incidence of surgical site infections and postoperative nausea and vomiting. Also, hyperoxygenation is thought to extend the safety margin in case of acute intraoperative emergencies. This review provides a comprehensive risk-benefit analysis for the use of perioperative hyperoxia in noncritically ill adults based on clinical evidence and supported by physiological deduction where needed. Data from the field of hyperbaric medicine, as a model of extreme hyperoxygenation, are extrapolated to the perioperative setting. We ultimately conclude that current evidence is in favour of hyperoxia in noncritically ill intubated adult surgical patients.

The effect of hyperbaric oxygenation therapy on myocardial function

Hyperbaric oxygenation therapy is successfully implemented for the treatment of several disorders. Data on the effect of hyperbaric oxygenation on echocardiographic parameters in asymptomatic patients is limited. The current study sought to evaluate the effect of hyperbaric oxygenation therapy on echocardiographic parameters in asymptomatic patients. Thirty-one consecutive patients underwent a 60-sessions course of hyperbaric oxygenation therapy in an attempt to improve cognitive impairment. In all subjects, echocardiography examination was performed before and after a course of hyperbaric oxygenation therapy. Conventional and speckle tracking imaging parameters were calculated and analyzed. The mean age was 70 ± 9.5 years, 28 [90%] were males. History of coronary artery disease was present in 12 [39%]. 94% suffered from hypertension, 42% had diabetes mellitus. Baseline wall motion abnormalities were found in eight patients, however, global ejection fraction was within normal limits. During the study, ejection fraction [EF], increased from 60.71 ± 6.02 to 62.29 ± 5.19%, p = 0.02. Left ventricular end systolic volume [LVESV], decreased from 38.08 ± 13.30 to 35.39 ± 13.32 ml, p = 0.01. Myocardial performance index [MPi] improved, from 0.29 ± 0.07 to 0.26 ± 0.08, p = 0.03. Left ventricular [LV] global longitudinal strain increased from - 19.31 ± 3.17% to - 20.16 ± 3.34%, p = 0.036 due to improvement in regional strain in the apical and antero-septal segments. Twist increased from 18.32 ± 6.61° to 23.12 ± 6.35° p = 0.01, due to improvement in the apical rotation, from 11.76 ± 4.40° to 16.10 ± 5.56°, p = 0.004. Hyperbaric oxygen therapy appears to improve left ventricular function, especially in the apical segments, and is associated with better cardiac performance. If our results are confirmed in further studies, HBOT can be used in many patients with heart failure and systolic dysfunction.

Combination treatment of autologous bone marrow stem cell transplantation and hyperbaric oxygen therapy for type 2 diabetes mellitus: A randomized controlled trial

The objective of this study was to compare standard treatment versus the combination of intrapancreatic autologous stem cell (ASC) infusion and hyperbaric oxygen treatment (HBOT) before and after ASC in the metabolic control of patients with type 2 diabetes mellitus (T2DM). This study was a prospective, randomized controlled trial. The combined intervention consisted of 10 sessions of HBOT before the intrapancreatic infusion of ASC and 10 sessions afterwards. ASCs were infused into the main arterial supply of the pancreas to maximize the presence of the stem cells where the therapeutic effect is most desired. A total of 23 patients were included (control group = 10, intervention group = 13). Age, gender, diabetes duration, number of medications taken, body weight and height, and insulin requirements were recorded at baseline and every three months. Also, body mass index, fasting plasma glucose, C-peptide, and HbA1c, C-peptide/glucose ratio (CPGR) were measured every three months for one year. HbA1c was significantly lower in the intervention group compared with control throughout follow-up. Overall, 77% of patients in the intervention group and 30% of patients in the control group demonstrated a decrease of HbA1c at 180 days (compared with baseline) of at least 1 unit. Glucose levels were significantly lower in the intervention group at all timepoints during follow-up. C-peptide levels were significantly higher in the intervention group during follow-up and at one year: 1.9 ± 1.0 ng/mL versus 0.7 ± 0.4 ng/mL in intervention versus control groups, respectively, p = 0.0021. CPGR was higher in the intervention group at all controls during follow-up. The requirement for insulin was significantly lower in the intervention group at 90, 180, 270, and 365 days. Combined therapy of intrapancreatic ASC infusion and HBOT showed increased metabolic control and reduced insulin requirements in patients with T2DM compared with standard treatment.

Only minor stem cell mobilization in head and neck irradiated patients treated with hyperbaric oxygen

INTRODUCTION

Hyperbaric oxygen, (HBO) is used to treat several conditions including late radiation tissue injury. Previous studies have suggested that HBO mobilizes bone marrow derived stem/progenitor cells (SPC) to the peripheral blood, however possible cumulative effects were highly variable.

METHODS

We have investigated a possible HBO-induced mobilization of SPCs by determining CD34+CD45dim cell numbers, as well as SPCs in general. The latter were characterized by high aldehyde dehydrogenase (ALDH) activity by use of the Aldefluor® assay. We included ten patients admitted for HBO treatment of radiation tissue injury. Six patients completed the 29-30 HBO treatment exposures. We also investigated possible HBO-induced effects on platelet activation as measured by flow cytometry and functional analyses.

RESULTS

We found a weak and insignificant tendency toward mobilization of CD34+CD45dim cells after a single HBO exposure versus before. Additionally, we found an additive effect of 15 HBO exposures on the increase in CD34+CD45dim cells relative to the pre-1st-HBO values. These changes were significantly more than zero but less than a doubling. We could not demonstrate a significant effect of HBO on the content of Aldefluor® positive SPCs in peripheral blood. There was no significant effect on platelet activation overall. However, in patients with increased expression of activation markers at baseline, we found a decrease after one exposure although this was not reflected in functional tests.

CONCLUSION

We found a minor statistically significant mobilizing effect of HBO treatment on the bone marrow derived stem/progenitor cell content in peripheral blood after 15 treatments (n = 10 patients), but no effect after 30 treatments (n = 6 patients). However, because of the low number of patients we cannot confidentially prove or disprove the null hypothesis. The possibility that HBO treatment reduces the number of activated platelets could not be demonstrated nor excluded.

Markers of Pulmonary Oxygen Toxicity in Hyperbaric Oxygen Therapy Using Exhaled Breath Analysis

Introduction

Although hyperbaric oxygen therapy (HBOT) has beneficial effects, some patients experience fatigue and pulmonary complaints after several sessions. The current limits of hyperbaric oxygen exposure to prevent pulmonary oxygen toxicity (POT) are based on pulmonary function tests (PFT), but the limitations of PFT are recognized worldwide. However, no newer modalities to detect POT have been established. Exhaled breath analysis in divers have shown volatile organic compounds (VOCs) of inflammation and methyl alkanes. This study hypothesized that similar VOCs might be detected after HBOT.

Methods

Ten healthy volunteers of the Royal Netherlands Navy underwent six HBOT sessions (95 min at 253 kPa, including three 5-min “air breaks”), i.e., on five consecutive days followed by another session after 2 days of rest. At 30 min before the dive, and at 30 min, 2 and 4 h post-dive, exhaled breath was collected and followed by PFT. Exhaled breath samples were analyzed using gas chromatography-mass spectrometry (GC-MS). After univariate tests and correlation of retention times, ion fragments could be identified using a reference database. Using these fragments VOCs could be reconstructed, which were clustered using principal component analysis. These clusters were tested longitudinally with ANOVA.

Results

After GC-MS analysis, eleven relevant VOCs were identified which could be clustered into two principal components (PC). PC1 consisted of VOCs associated with inflammation and showed no significant change over time. The intensities of PC2, consisting of methyl alkanes, showed a significant decrease (p = 0.001) after the first HBOT session to 50.8%, remained decreased during the subsequent days (mean 82%), and decreased even further after 2 days of rest to 58% (compared to baseline). PFT remained virtually unchanged.

Discussion

Although similar VOCs were found when compared to diving, the decrease of methyl alkanes (PC2) is in contrast to the increase seen in divers. It is unknown why emission of methyl alkanes (which could originate from the phosphatidylcholine membrane in the alveoli) are reduced after HBOT. This suggests that HBOT might not be as damaging to the pulmonary tract as previously assumed. Future research on POT should focus on the identified VOCs (inflammation and methyl alkanes).

Stage III Kienböck's disease treated with hyperbaric oxygen: the role of an unusual approach to a rare condition

Kienböck's disease is a rare condition characterised by avascular necrosis of the lunate bone. Its natural history and aetiopathogenesis have not yet been clarified, nor are its triggering factors identified. We present a case of a 17-year-old male gymnast, without relevant medical/family history, with stage IIIA Kienböck's disease diagnosed in 2016. Initially, submitted to conservative treatment that proved to be insufficient. Consequently, surgical treatment was proposed, but refused. The patient instead underwent experimental treatment with hyperbaric oxygen (120 sessions, 100% oxygen at 2.5 atm, for 70 min periods, once daily, five times per week). In April 2018, a favourable clinical and radiological evolution was observed, with an improvement in the patterns of pain, motion and strength and an almost complete involution of the process of aseptic necrosis of the semilunar. To the best of our knowledge, this is the first report of Kienböck's disease treated with hyperbaric oxygen.

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.

Using advanced wound care and hyperbaric oxygen to manage wound complications following treatment of vulvovaginal carcinoma

Postoperative management of patients with vulvar cancer is associated with a high incidence of poor wound healing and radiation -induced late tissue necrosis. This case series demonstrates the impact on wound healing with the use of hyperbaric oxygen therapy and advanced wound care following radical vulvectomy and/or radiation therapy. A retrospective case series was performed of all patients from 2016 to 2017 with lower genital cancer who underwent radical surgery with or without chemoradiation treatment, experienced wound dehiscence or late tissue radionecrosis, and were treated with advanced wound care, including hyperbaric oxygen therapy (HBO). Five patients were included with a mean age of 63; four had squamous cell carcinoma and one patient had vaginal adenocarcinoma secondary to prior diethylstilbestrol exposure. Three patients underwent radical vulvectomy. All received pelvic radiation therapy, subsequently experienced wound complications, and were managed with advanced wound care and HBO. The mean reduction in wound area at the final wound follow up visit after completion of HBO therapy was found to be 76%, ranging 42-95%, with an average follow up of five months. The mean number of HBO sessions per patient was 58. Complete tissue granulation or significant improvement in tissue radionecrosis was present in all patients. Advanced wound care and hyperbaric oxygen therapy are beneficial in the management of postoperative wound complications. Prospective studies are needed to identify the optimal use of perioperative hyperbaric oxygen and appropriate wound care for patients with gynecologic malignancies.

Topical oxygen therapy & micro/nanobubbles: a new modality for tissue oxygen delivery

Up to 15 billion dollars of US health care expenditure each year is consumed by treatment of poorly healing wounds whose etiologies are often associated with aberrancies in tissue oxygenation. To address this issue, several modes of tissue oxygen delivery systems exist, including Hyperbaric Oxygen Therapy (HBOT) and Topical Oxygen Therapy (TOT), but their efficacies have yet to be fully substantiated. Micro/nanobubbles (MNBs), which range anywhere from 100 μm to <1 μm in diameter and are relatively stable for hours, offer a new mode of oxygen delivery to wounds. The aim of this article is to systematically review literature examining the use of TOT for wound healing and use of MNBs for tissue oxygenation using the MEDLINE database. The search yielded 87 articles (12 MNB articles and 75 TOT articles), of which 52 met the inclusion criteria for this literature review (12 MNB articles and 40 TOT articles). Additionally, we present an analysis on the efficacy of our MNB generating technology and propose its use as a wound healing agent.

Treatment of post-anesthesia dementia with perispinal etanercept injection and hyperbaric oxygen therapy: a case report

Background

We report on the first case of successful treatment for post-anesthesia dementia with perispinal etanercept injection combined with hyperbaric oxygen therapy.

Case presentation

Our patient was a 77-year-old Caucasian man of Mexican ethnicity who presented to our clinic 4.5 years after a knee replacement surgery. Immediately post-surgery, the patient began to show dramatic cognitive, physical, and emotional impairment compared with his presurgical state; these symptoms were still present when he arrived at our clinic. A clinical assessment and brain single-photon emission computer tomography were performed. Diagnoses of dementia with major cognitive deficits and aphasia were established. A 40-session course of hyperbaric oxygen therapy was initiated to address our patient’s impairments. After the first ten hyperbaric oxygen therapy treatments, our patient was administered 25 mg perispinal etanercept injections approximately once weekly for 5 months. Starting after the first perispinal etanercept injection, our patient began showing progressive improvements. By the 5-month follow-up, his cognitive and physical function were substantially restored. A follow-up single-photon emission computer tomography scan showed increased perfusion in several small, localized areas.

Conclusions

In this case of dementia and major cognitive disorder post major surgery and anesthesia, the very beneficial effect of combining hyperbaric oxygen therapy with perispinal etanercept is outlined.

Reactive oxygen species (ROS) and wound healing: the functional role of ROS and emerging ROS-modulating technologies for augmentation of the healing process

Reactive oxygen species (ROS) play a pivotal role in the orchestration of the normal wound-healing response. They act as secondary messengers to many immunocytes and non-lymphoid cells, which are involved in the repair process, and appear to be important in coordinating the recruitment of lymphoid cells to the wound site and effective tissue repair. ROS also possess the ability to regulate the formation of blood vessels (angiogenesis) at the wound site and the optimal perfusion of blood into the wound-healing area. ROS act in the host's defence through phagocytes that induce an ROS burst onto the pathogens present in wounds, leading to their destruction, and during this period, excess ROS leakage into the surrounding environment has further bacteriostatic effects. In light of these important roles of ROS in wound healing and the continued quest for therapeutic strategies to treat wounds in general and chronic wounds, such as diabetic foot ulcers, venous and arterial leg ulcers and pressure ulcers in particular, the manipulation of ROS represents a promising avenue for improving wound-healing responses when they are stalled. This article presents a review of the evidence supporting the critical role of ROS in wound healing and infection control at the wound site, and some of the new emerging concepts associated with ROS modulation and its potential in improving wound healing are discussed.

Hyperbaric Environment: Oxygen and Cellular Damage versus Protection

The elevation of tissue pO2 induced by hyperbaric oxygen (HBO) is a physiological stimulus that elicits a variety of cellular responses. These effects are largely mediated by, or in response to, an increase in the production of reactive oxygen and nitrogen species (RONS). The major consequences of elevated RONS include increased oxidative stress and enhanced antioxidant capacity, and modulation of redox-sensitive cell signaling pathways. Interestingly, these phenomena underlie both the therapeutic and potentially toxic effects of HBO. Emerging evidence indicates that supporting mitochondrial health is a potential method of enhancing the therapeutic efficacy of, and preventing oxygen toxicity during, HBO. This review will focus on the cellular consequences of HBO, and explore how these processes mediate a delicate balance of cellular protection versus damage. © 2017 American Physiological Society. Compr Physiol 7:213-234, 2017.

An Update on the Appropriate Role for Hyperbaric Oxygen: Indications and Evidence

BACKGROUND

Among advanced therapeutic interventions for wounds, hyperbaric oxygen therapy (HBOT) has the unique ability to ameliorate tissue hypoxia, reduce pathologic inflammation, and mitigate ischemia reperfusion injury. Most of the conditions for which it is utilized have few successful alternative treatments, and the morbidity and mortality associated with treatment failure are significant. Data on the efficacy and effectiveness of HBOT were reviewed, comparative effectiveness research of HBOT was explained, and a new paradigm for the appropriate use of HBOT was described.

METHODS

Systematic reviews and randomized controlled trials that have evaluated HBOT were reviewed.

RESULTS

Although numerous small randomized controlled trials provide compelling support for HBOT, the physics of the hyperbaric environment create significant barriers to trial design. The electronic health record infrastructure created to satisfy mandatory quality and registry reporting requirements as part of healthcare reform can be harnessed to facilitate the acquisition of real world data for HBOT comparative effectiveness studies and clinical decision support.

CONCLUSIONS

Predictive models can identify patients unlikely to heal spontaneously and most likely to benefit from HBOT. Although electronic health records can automate the calculation of predictive models making them available at the point of care, using them in clinical decision making is complicated. It is not clear whether stakeholders will support the allocation of healthcare resources using mathematical models, but the current patient selection process mandates a 30-day delay for all patients who might benefit and allows treatment for at least some patients who cannot benefit.

Hyperbaric environment up-regulates CD15s expression on leukocytes, down-regulates CD77 expression on renal cells and up-regulates CD34 expression on pulmonary and cardiac cells in rat

OBJECTIVES

The aim of this study was to estimate effects of hyperbaric (HB) treatment by determination of CD15s and CD11b leukocyte proinflammatory markers expression. In addition, this study describes changes in CD77 and CD34 expression on rat endothelial cells in renal, pulmonary and cardiac tissue following exposure to hyperbaric pressure.

MATERIALS AND METHODS

Expression of CD11b and CD15s on leukocytes, as well as CD77 and CD34 expression on endothelial cells in cell suspensions of renal, pulmonary and cardiac tissue in rats after hyperbaric treatment and in control rats were determined by flow cytometry.

RESULTS

Hyperbaric treatment significantly increased percentage of leukocytes expressing CD15s+CD11b- (from 1.71±1.11 to 23.42±2.85, P<0.05). Hyperbaric treatment significantly decreased sum percentage of CD77+CD34- and CD77+CD34+ renal cells (from 16.35±5.5 to 4.48 ±1.28, P<0.05). Hyperbaric treatment significantly increased percentage of CD34+ pulmonary cells (from 3.27±2.01 to 11.92±6.22, P<0.05). Our study is the first reporting the hyperbaric environment influence on CD34+ heart cells in rats.

CONCLUSION

The current findings of increased percentage of leukocytes expressing endothelial selectin ligand CD15s after hyperbaric treatment, point its role in endothelial damage prevention. We found out a significantly increase in percentage of CD34+ cardiac cells as well as CD34+ pulmonary cells in rats after HB treatment which could be a part of repair mechanism of injured endothelium caused by hyperoxia.

Hyperbaric oxygen therapy in spontaneous brain abscess patients: a population-based comparative cohort study

BACKGROUND

There is a need to improve outcome in patients with brain abscesses and hyperbaric oxygen therapy (HBOT) is a promising treatment modality. The objective of this study was to evaluate HBOT in the treatment of intracranial abscesses.

METHOD

This population-based, comparative cohort study included 40 consecutive adult patients with spontaneous brain abscess treated surgically between January 2003 and May 2014 at our institution. Twenty patients received standard therapy with surgery and antibiotics (non-HBOT group), while the remaining 20 patients also received adjuvant HBOT (HBOT group).

RESULTS

Resolution of brain abscesses and infection was seen in all patients. Two patients had reoperations after HBOT initiation (10 %), while nine patients (45 %) in the non-HBOT group underwent reoperations (p = 0.03). Of the 26 patients who did not receive HBOT after the first surgery, 15 (58 %) had one or several recurrences that lead to a new treatment: surgery (n = 11), surgery + HBO (n = 5) or just HBO (n = 1). In contrast, recurrences occurred in only 2 of 14 (14 %) who did receive HBOT after the first surgery (p < 0.01). A good outcome (Glasgow Outcome Score [GOS] of 5) was achieved in 16 patients (80 %) in the HBOT cohort versus 9 patients (45 %) in the non-HBOT group (p = 0.04).

CONCLUSIONS

HBOT was associated with less treatment failures and need for reoperation and seemingly with improved long-term outcome. Further, HBOT was well tolerated and safe. Prospective studies are warranted to establish the role of HBOT in the treatment of brain abscesses.

Hyperbaric oxygen therapy and osteonecrosis

Osteonecrosis of the jaw may be caused by radiation, medication, or infection. Optimal therapy requires a multimodal approach that combines surgery with adjuvant treatments. This review focuses on the use of adjunctive hyperbaric oxygen therapy for this condition. In addition to evidence regarding the basic and clinical science behind hyperbaric oxygen therapy, controversies in the field and economic implications are discussed.

Measurements of CD34+/CD45-dim Stem Cells Predict Healing of Diabetic Neuropathic Wounds

Management of neuropathic foot ulcers in patients with diabetes (DFUs) has changed little over the past decade, and there is currently no objective method to gauge probability of successful healing. We hypothesized that studies of stem/progenitor cells (SPCs) in the early weeks of standard wound management could predict who will heal within 16 weeks. Blood and debrided wound margins were collected for 8 weeks from 100 patients undergoing weekly evaluations and treatment. SPC number and intracellular content of hypoxia-inducible factors (HIFs) were evaluated by flow cytometry and immunohistochemistry. More SPCs entered the bloodstream in the first 2 weeks of care in patients who healed (n = 37) than in those who did not (n = 63). Logistic regression demonstrated that the number of blood-borne SPCs and the cellular content of HIFs at study entry and the first-week follow-up visit predicted healing. Strong correlations were found among week-to-week assessments of blood-borne SPC HIF factors. We conclude that assays of SPCs during the first weeks of care in patients with DFUs can provide insight into how well wounds will respond and may aid with decisions on the use of adjunctive measures.

Hyperbaric oxygen therapy for acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS), includes acute myocardial infarction and unstable angina, is common and may prove fatal. Hyperbaric oxygen therapy (HBOT) will improve oxygen supply to the threatened heart and may reduce the volume of heart muscle that perishes. The addition of HBOT to standard treatment may reduce death rate and other major adverse outcomes.This an update of a review previously published in May 2004 and June 2010.

OBJECTIVES

The aim of this review was to assess the evidence for the effects of adjunctive HBOT in the treatment of ACS. We compared treatment regimens including adjunctive HBOT against similar regimens excluding HBOT. Where regimens differed significantly between studies this is clearly stated and the implications discussed. All comparisons were made using an intention to treat analysis where this was possible. Efficacy was estimated from randomised trial comparisons but no attempt was made to evaluate the likely effectiveness that might be achieved in routine clinical practice. Specifically, we addressed:Does the adjunctive administration of HBOT to people with acute coronary syndrome (unstable angina or infarction) result in a reduction in the risk of death?Does the adjunctive administration of HBOT to people with acute coronary syndrome result in a reduction in the risk of major adverse cardiac events (MACE), that is: cardiac death, myocardial infarction, and target vessel revascularization by operative or percutaneous intervention?Is the administration of HBOT safe in both the short and long term?

SEARCH METHODS

We updated the search of the following sources in September 2014, but found no additional relevant citations since the previous search in June 2010 (CENTRAL), MEDLINE, EMBASE, CINAHL and DORCTHIM. Relevant journals were handsearched and researchers in the field contacted. We applied no language restrictions.

SELECTION CRITERIA

Randomised studies comparing the effect on ACS of regimens that include HBOT with those that exclude HBOT.

DATA COLLECTION AND ANALYSIS

Three authors independently evaluated the quality of trials using the guidelines of the Cochrane Handbook and extracted data from included trials. Binary outcomes were analysed using risk ratios (RR) and continuous outcomes using the mean difference (MD) and both are presented with 95% confidence intervals. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

No new trials were located in our most recent search in September 2014. Six trials with 665 participants contributed to this review. These trials were small and subject to potential bias. Only two reported randomisation procedures in detail and in only one trial was allocation concealed. While only modest numbers of participants were lost to follow-up, in general there is little information on the longer-term outcome for participants. Patients with acute coronary syndrome allocated to HBOT were associated with a reduction in the risk of death by around 42% (RR: 0.58, (95% CI 0.36 to 0.92), 5 trials, 614 participants; low quality evidence).In general, HBOT was well-tolerated. No patients were reported as suffering neurological oxygen toxicity and only a single patient was reported to have significant barotrauma to the tympanic membrane. One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, 95% CI 1.92 to 521).

AUTHORS' CONCLUSIONS

For people with ACS, there is some evidence from small trials to suggest that HBOT is associated with a reduction in the risk of death, the volume of damaged muscle, the risk of MACE and time to relief from ischaemic pain. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified from this review.

In search of a treatment for radiation-induced optic neuropathy

OPINION STATEMENT

Radiation-induced optic neuropathy (RON) is an iatrogenic complication that causes severe, irreversible vision loss in one or both eyes within the months to years following radiation therapy. Posterior RON is a rare but devastating toxicity of radiation applied to the visual pathways to treat paranasal sinus and skull base tumors. Anterior RON is an unavoidable consequence of proton beam irradiation or ophthalmic plaque treatment of orbital, choroidal, or retinal tumors. Various treatments aimed at stabilizing and ideally reversing vision loss have been investigated but only in small cases series. Systemic corticosteroids and anticoagulants, which are moderately effective when used for cerebral radiation necrosis, have shown no signs of benefit for RON. Hyperbaric oxygen therapy may promote short-term, partial recovery of vision in select patients, especially at partial pressures of at least 2.4 atm and when administered early after symptom onset. Reversal of visual deficits through treatment with systemic bevacizumab has been reported, but until controlled studies are performed, the side effect profile of stroke and myocardial infarction should limit its use in a population with predisposing cardiovascular risk factors. Intravitreal bevacizumab has shown promising results in patients with anterior RON, but repeated, long-term injections are required for sustained effect. As no intervention has been clearly shown to halt or reverse vision loss, larger prospective studies are needed to validate observed benefits for any of the treatments that have been described.