Stem cell mobilization by hyperbaric oxygen

An expert consensus on prevention, diagnosis, and management of hemorrhagic cystitis in pediatric hematopoietic cell transplantation, on behalf of the Infectious Disease and Hematopoietic Cell Transplant Working groups of Italian Pediatric Hematology Oncology Association (AIEOP)

The optimal management of hemorrhagic cystitis (HC) in hematopoietic stem cell transplantation (HCT) is debated, both for early onset HC (EOHC) secondary to chemotherapy toxicity and BK Polyomavirus (BKPyV)-related HC, due to the lack of controlled trials, particularly referred to pediatric setting. Actually, clinical practice is mainly based on guidelines of the European Conference on Infections in Leukemia, 6th edition, which considers both adult and pediatric populations but concludes that, despite much progress in understanding the pathogenesis, epidemiology, and risk factors, this complication still represents a disabling unmet clinical need with limited prophylactic and therapeutic options. Additionally, the Guidelines of the American Society of Clinical Oncology define the management of chemotherapeutic toxicity independently from the patients' population. A panel of experts belonging to the Hematopoietic Cell Transplant and Infectious Disease Working Group (WG) of Associazione Italiana di Emato-Oncologia Pediatrica (AIEOP) developed a consensus to define the best practices in prevention, diagnosis, and management of HC in pediatric HCT setting.

Emerging Indications for Hyperbaric Oxygen Treatment: Registry Cohort Study

BACKGROUND

Hyperbaric oxygen (HBO2) treatment is used across a range of medical specialties for a variety of applications, particularly where hypoxia and inflammation are important contributors. Because of its hypoxia-relieving and anti-inflammatory effects HBO2 may be useful for new indications not currently approved by the Undersea and Hyperbaric Medical Society. Identifying these new applications for HBO2 is difficult because individual centers may only treat a few cases and not track the outcomes consistently. The web-based International Multicenter Registry for Hyperbaric Oxygen Therapy captures prospective outcome data for patients treated with HBO2 therapy. These data can then be used to identify new potential applications for HBO2, which has relevance for a range of medical specialties.

OBJECTIVE

Although hyperbaric medicine has established indications, new ones continue to emerge. One objective of this registry study was to identify cases where HBO2 has been used for conditions falling outside of current Undersea and Hyperbaric Medical Society-approved indications and present outcome data for them.

METHODS

This descriptive study used data from a web-based, multicenter, international registry of patients treated with HBO2. Participating centers agree to collect data on all patients treated using standard outcome measures, and individual centers send deidentified data to the central registry. HBO2 treatment programs in the United States, the United Kingdom, and Australia participate. Demographic, outcome, complication, and treatment data, including pre- and posttreatment quality of life questionnaires (EQ-5D-5L) were collected for individuals referred for HBO2 treatment.

RESULTS

Out of 9726 patient entries, 378 (3.89%) individuals were treated for 45 emerging indications. Post-COVID-19 condition (PCC; also known as postacute sequelae of COVID-19; 149/378, 39.4%), ulcerative colitis (47/378, 12.4%), and Crohn disease (40/378, 10.6%) accounted for 62.4% (n=236) of the total cases. Calciphylaxis (20/378, 5.3%), frostbite (18/378, 4.8%), and peripheral vascular disease-related wounds (12/378, 3.2%) accounted for a further 13.2% (n=50). Patients with PCC reported significant improvement on the Neurobehavioral Symptom Inventory (NSI score: pretreatment=30.6; posttreatment=14.4; P<.001). Patients with Crohn disease reported significantly improved quality of life (EQ-5D score: pretreatment=53.8; posttreatment=68.8), and 5 (13%) reported closing a fistula. Patients with ulcerative colitis and complete pre- and post-HBO2 data reported improved quality of life and lower scores on a bowel questionnaire examining frequency, blood, pain, and urgency. A subset of patients with calciphylaxis and arterial ulcers also reported improvement.

CONCLUSIONS

HBO2 is being used for a wide range of possible applications across various medical specialties for its hypoxia-relieving and anti-inflammatory effects. Results show statistically significant improvements in patient-reported outcomes for inflammatory bowel disease and PCC. HBO2 is also being used for frostbite, pyoderma gangrenosum, pterygium, hypospadias repair, and facial filler procedures. Other indications show evidence for improvement, and the case series for all indications is growing in the registry.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.2196/18857.

Comparison of the effect of hyperbaric oxygen therapy and tadalafil daily use on erectile function: a prospective, double controlled study

PURPOSE

Erectile dysfunction (ED) is a worldwide health problem. Oral phosphodiesterase type 5 inhibitors (PDE5I) are used in its first-line treatment. This study aimed to compare the effects of hyperbaric oxygen (HBO) treatment with PDE5I treatment and determine the patient-dependent factors affecting the efficacy of the HBO treatment and duration of action of HBO treatment.

METHODS

Adult male patients who presented to the HBO unit for HBO treatment with non-urological indications and had ED based on the International Index for Erectile Function (IIEF-5) constituted the target population of this study. Participants were given HBO treatment (Group 1), no treatment (Group 2), or daily oral tadalafil 5 mg treatment (Group 3). The treatment duration was 1 month. Patients were assessed by IIEF-5 both initially and after the completion of 1 month.

RESULTS

There were significant increases in the mean IIEF-5 scores of the patients in Group 1 and Group 3 (p < 0.001, p < 0.001). However, there was no significant improvement in Group 2 (p = 0.496). Also, the post-treatment IIEF-5 scores of Group 1 and Group 3 were significantly higher than Group 2 (p < 0.001). There was no significant difference between the IIEF-5 scores and ∆IIEF-5 values of Group 1 and Group 3 (p = 0.166, p = 0.093). Evaluation regarding comorbidities revealed that patients with the peripheral vascular disease did not improve with HBO treatment (p = 0.285).

CONCLUSION

HBO can improve erectile functions, and it can be a reasonable alternative for patients who cannot use PDE5Is due to comorbidities or treatment side effects.

Hyperoxia: Effective Mechanism of Hyperbaric Treatment at Mild-Pressure

HBOT increases the proportion of dissolved oxygen in the blood, generating hyperoxia. This increased oxygen diffuses into the mitochondria, which consume the majority of inhaled oxygen and constitute the epicenter of HBOT effects. In this way, the oxygen entering the mitochondria can reverse tissue hypoxia, activating the electron transport chain to generate energy. Furthermore, intermittent HBOT is sensed by the cell as relative hypoxia, inducing cellular responses such as the activation of the HIF-1α pathway, which in turn, activates numerous cellular processes, including angiogenesis and inflammation, among others. These effects are harnessed for the treatment of various pathologies. This review summarizes the evidence indicating that the use of medium-pressure HBOT generates hyperoxia and activates cellular pathways capable of producing the mentioned effects. The possibility of using medium-pressure HBOT as a direct or adjunctive treatment in different pathologies may yield benefits, potentially leading to transformative therapeutic advancements in the future.

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.

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.

Structural and biological engineering of 3D hydrogels for wound healing

Chronic wounds have become one of the most important issues for healthcare systems and are a leading cause of death worldwide. Wound dressings are necessary to facilitate wound treatment. Engineering wound dressings may substantially reduce healing time, reduce the risk of recurrent infections, and reduce the disability and costs associated. In the path of engineering of an ideal wound dressing, hydrogels have played a leading role. Hydrogels are 3D hydrophilic polymeric structures that can provide a protective barrier, mimic the native extracellular matrix (ECM), and provide a humid environment. Due to their advantages, hydrogels (with different architectural, physical, mechanical, and biological properties) have been extensively explored as wound dressing platforms. Here we describe recent studies on hydrogels for wound healing applications with a strong focus on the interplay between the fabrication method used and the architectural, mechanical, and biological performance achieved. Moreover, we review different categories of additives which can enhance wound regeneration using 3D hydrogel dressings. Hydrogel engineering for wound healing applications promises the generation of smart solutions to solve this pressing problem, enabling key functionalities such as bacterial growth inhibition, enhanced re-epithelialization, vascularization, improved recovery of the tissue functionality, and overall, accelerated and effective wound healing.

Hyperbaric Oxygen as an Adjunct in the Treatment of Venous Ulcers: A Systematic Review

BACKGROUND

The use of Hyperbaric Oxygen Therapy (HBOT) in diabetic wounds has been studied extensively. Even though venous insufficiency is the most common cause of lower limb ulceration, there is comparatively little evidence regarding the use of HBOT for Venous Leg Ulcers (VLU). We performed a systematic-review to evaluate and synthesise available evidence, to evaluate whether patients with VLU, when treated with HBOT, had greater rates of (i) complete VLU healing or (ii) reduction in VLU area, than controls.

METHODS

In keeping with PRISMA guidelines, database searches of PubMed, Scopus and Embase was performed. After removal of duplicates, titles were screened for relevance by two authors, then abstracts, and in turn full text manuscripts. Data were extracted from relevant sources including one published abstract. Included studies were assessed for risk of bias using the Risk of Bias 2 (RoB-2) and Risk Of Bias In Nonrandomized Studies (ROBINS-I) tools.

RESULTS

Six studies were included. There was significant heterogeneity across the studies, with no standard control intervention, method of outcome reporting, or duration of follow up. Two studies reported 12 week follow up results and pooled analysis of complete ulcer healing showed no statistically significant difference between HBOT and controls for the outcome of complete ulcer healing OR 1.54 (95%CI = .50-4.75) P = .4478. A similar non-signifiacnt result was seen in four studies reporting 5-6 week follow up; OR 5.39 (95%CI = .57-259.57) P = .1136. Change in VLU area was reported in all studies, and pooled standardised mean difference was 1.70 (95%CI = .60 to 2.79) P = .0024, indicating a statistically significant benefit of HBOT in reducing ulcer area.

CONCLUSION

Existing evidence suggests that HBOT does not significantly affect complete healing of VLU. There is a statistically significant benefit in terms of reducing ulcer size, though in the absence of ulcer healing the clinical significance of this is not established. Current evidence does not justify widespread use of HBOT for VLU.

Hyperbaric oxygen therapy for local late radiation toxicity in breast cancer patients: A systematic review

PURPOSE

This systematic review aims to provide an overview of the literature on the effect of hyperbaric oxygen therapy (HBOT) on symptoms of local late radiation toxicity (LRT) in patients treated for breast cancer.

METHODS

A systematic search was performed in September 2021. All studies with a sample size of ≥10 patients reporting the effect of HBOT for symptoms of LRT after radiotherapy of the breast and/or chest wall were included. The ROBINS-I tool was used for critical appraisal of methodological quality. The toxicity outcomes pain, fibrosis, lymphedema, necrosis/skin problems, arm and shoulder mobility, and breast and arm symptoms were evaluated.

RESULTS

Nine studies concerning a total of 1308 patients were included in this review. Except for one study, sample sizes were small. Most studies had inadequate methodology with a substantial risk of bias. Post-HBOT, a significant reduction of pain was observed in 4/5 studies, of fibrosis in 1/2 studies, and of lymphedema of the breast and/or arm in 4/7 studies. Skin problems of the breast were significantly reduced in 1/2 studies, arm- and shoulder mobility significantly improved in 2/2 studies, and breast- and arm symptoms were significantly reduced in one study.

CONCLUSION

This systematic review indicates that HBOT might be useful for reducing symptoms of LRT in breast cancer patients, however evidence is limited. A randomized controlled trial in a larger cohort of patients including a combination of patient- and clinician-reported outcome measures would be valuable to assess the effect of HBOT on symptoms of LRT.

Effectiveness of Hyperbaric Oxygen Therapy in SARS-CoV-2 Pneumonia: The Primary Results of a Randomised Clinical Trial

Mortality in COVID-19 is mainly associated with respiratory failure, cytokine storm, and macrophage activation. Oxygenation and anti-inflammatory effects of Hyperbaric Oxygen Therapy (HBOT) suggest that it is a promising adjunct treatment for COVID-19. Repeated sessions of HBO with standard COVID-19 therapy were used to reduce the inflammation and increase oxygenation. We evaluated the safety and efficacy of HBOT in avoiding the replacement ventilation and/or ECMO and its effect on the inflammatory process. Twenty-eight moderate-to-severe COVID-19 patients were randomized into control or HBOT group. HBOT patients participated in 5 hyperbaric sessions (60 min). Before and after each session blood gas levels and vital parameters were monitored. Blood samples were collected for extended biochemical tests, blood morphology and immunological assays. There were 3 deaths in the control, no deaths in the HBOT group. No adverse events leading to discontinuation of HBOT were observed and patients receiving HBOT required lower oxygen delivery. We observed decrease in CRP, ferritin and LDH and increase in CD3 in HBOT group compared to control. This study confirmed the feasibility and safety of HBOT in patients with COVID-19 and indicated HBOT can lead to alleviation of inflammation and partial restoration of T cell responses.

Debridement of Diabetic Foot Ulcers

Diabetic foot ulcerations have devastating complications, including amputations, poor quality of life, and life-threatening infections. Diabetic wounds can be protracted, take significant time to heal, and can recur after healing. They are costly consuming health care resources. These consequences have serious public health and clinical implications. Debridement is often used as a standard of care. Debridement consists of both nonmechanical (autolytic, enzymatic) and mechanical methods (sharp/surgical, wet to dry debridement, aqueous high-pressure lavage, ultrasound, and biosurgery/maggot debridement therapy). It is used to remove nonviable tissue, to facilitate wound healing, and help prevent these serious outcomes. What are the various forms and rationale behind debridement? This article comprehensively reviews cutting-edge methods and the science behind debridement and diabetic foot ulcers.

Hyperbaric oxygen in children with cerebral palsy: A systematic review of effectiveness and safety

PURPOSE

To report current evidence regarding the effectiveness of hyperbaric oxygen therapy (HBOT) on the impairments presented by children with cerebral palsy (CP), and its safety.

MATERIALS AND METHODS

PUBMED, The Cochrane Library, Google Scholar, and the Undersea and Hyperbaric Medical Society database were searched by two reviewers. Methodological quality was graded independently by 2 reviewers using the Physiotherapy Evidence Database assessment scale for randomized controlled trials (RCTs) and the modified Downs and Black (m-DB) evaluation tool for non RCTs. A meta-analysis was performed where applicable for RCTs.

RESULTS

Five RCTs were identified. Four had a high level of evidence. Seven other studies were observational studies of low quality. All RCTs used 100% O2, 1.5 to 1.75 ATA, as the treatment intervention. Pressurized air was the control intervention in 3 RCTs, and physical therapy in 2. In all but one RCTs, similar improvements were observed regarding motor and/or cognitive functions, in the HBOT and control groups. Adverse events were mostly of mild severity, the most common being middle ear barotrauma (up to 50% of children).

CONCLUSION

There is high-level evidence that HBOT is ineffective in improving motor and cognitive functions, in children with CP. There is moderate-level evidence that HBOT is associated with a higher rate of adverse events than pressurized air in children.

Diagnosis, Prevention, and Treatment of Radiotherapy-Induced Xerostomia: A Review

In patients with head and neck cancer, irradiation (IR)-sensitive salivary gland (SG) tissue is highly prone to damage during radiotherapy (RT). This leads to SG hypofunction and xerostomia. Xerostomia is defined as the subjective complaint of dry mouth, which can cause other symptoms and adversely affect the quality of life. In recent years, diagnostic techniques have constantly improved with the emergence of more reliable and valid questionnaires as well as more accurate equipment for saliva flow rate measurement and imaging methods. Preventive measures such as the antioxidant MitoTEMPO, botulinum toxin (BoNT), and growth factors have been successfully applied in animal experiments, resulting in positive outcomes. Interventions, such as the new delivery methods of pilocarpine, edible saliva substitutes, acupuncture and electrical stimulation, gene transfer, and stem cell transplantation, have shown potential to alleviate or restore xerostomia in patients. The review summarizes the existing and new diagnostic methods for xerostomia, along with current and potential strategies for reducing IR-induced damage to SG function. We also aim to provide guidance on the advantages and disadvantages of the diagnostic methods. Additionally, most prevention and treatment methods remain in the stage of animal experiments, suggesting a need for further clinical research, among which we believe that antioxidants, gene transfer, and stem cell transplantation have broad prospects.

The role of hyperbaric oxygen therapy in the treatment of radiation lesions

INTRODUCTION

Cancer remains one of the leading causes of death worldwide, with 50-60% of patients requiring radiotherapy during the course of treatment. Patients' survival rate has increased significantly, with an inevitable increase in the number of patients experiencing side effects from cancer therapy. One such effect is late radiation injuries in which hyperbaric oxygen therapy appears as complementary treatment. With this work we intend to divulge the results of applying hyperbaric oxygen therapy among patients presenting radiation lesions in our Hyperbaric Medicine Unit.

MATERIALS AND METHODS

Retrospective analysis of clinical records of patients with radiation lesions treated at the Hyperbaric Medicine Unit assessed by the scale Late Effects of Normal Tissues-Subjective, Objective, Management, Analytical (LENT-SOMA) before and after treatment, between October 2014 and September 2019 were included. Demographic characteristics, primary tumor site, subjective assessment of the LENT-SOMA scale before and after treatment were collected and a comparative analysis (Students t test) was done.

RESULTS

88 patients included: 33 with radiation cystitis, 20 with radiation proctitis, 13 with osteoradionecrosis of the mandible and 22 with radiation enteritis. In all groups, there was a significant decrease (p < 0.005) in the subjective parameter of the LENT-SOMA scale.

DISCUSSION

Late radiation lesions have a major influence on patients' quality of life. In our study hyperbaric oxygen therapy presents as an effective therapy after the failure of conventional treatments.

CONCLUSION

Hyperbaric oxygen therapy is an effective complementary therapy in the treatment of refractory radiation lesions.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

Visualization and Bibliometric Analysis of Research Trends on Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy (HBOT) is a professional medical regimen with a wide range of clinical applications in various research fields. In addition to treating diving decompression sickness and air embolism, HBOT is used as an adjuvant in the management of various diseases. A large number of studies have been published to confirm its efficacy. Although HBOT has been clinically applied to the treatment of many diseases, the effectiveness of these treatments remains controversial. Exploring and evaluating HBOT will contribute to the future development of research in this field. Through a quantitative analysis of the literature, this paper explores the citation relevance and collaboration map and their impact on research outcomes. This study used bibliometric and cartographic techniques with VOSviewer to identify the most influential countries and scholars using this treatment, based on syndrome differentiation. It also provides continuous quality evaluation and lean management of the medical expenses associated with HBOT.

Assessment of hyperbaric oxygenation treatment response in parotid glands by T 2 mapping following radiotherapy for head and neck tumours

Background

The study was designed to evaluate the influence of hyperbaric oxygenation therapy (HBOT) on the parotid gland in patients following radiotherapy for head and neck tumours.

Patients and methods

HBOT response was monitored by 3T magnetic resonance imaging (MRI) using T₂ mapping and subsequent measurement of mean T₂ and T₂ variability as well as by salivary tests (salivary flow, buffer capacity, and pH). Eighteen patients previously treated with irradiation doses between 50 and 80 Gy as well as 18 healthy gender and age matched controls were enrolled. MRI was performed prior to HBOT (40.2 ± 20 months after radiotherapy) and after 20 daily HBOT at 2.5 ATA (absolute atmosphere). Each HBOT consisted of breathing 100% oxygen for 90 minutes.

Results

Significant differences in mean T₂ prior to HBOT were observed between the ipsilateral irradiated (121 ± 20 ms), contralateral parotids (107 ± 21) and control group (96 ± 12 ms). A positive correlation in patients between T₂ variability and irradiation dose was detected in contralateral parotids before HBOT (R = 0.489, p = 0.0287). In addition, negative correlations were observed between mean T₂ in the ipsilateral as well as the contralateral gland and salivary flow before and after HBOT. Negative correlations between mean T₂, T₂ variability and pH of unstimulated saliva were also observed in the sides of parotid before and after HBOT.

Conclusions

The study confirmed that T₂ mapping had a potential for monitoring the differences between irradiated and normal parotid glands. It could also be useful in the assessment of the glandular tissue response to HBOT.

Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis

Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.

Hyperbaric oxygen therapy induces transcriptome changes in elderly: a prospective trial

Introduction: Aging is characterized by the progressive loss of physiological capacity. Changes in gene expression can alter activity in defined age-related molecular pathways leading to cellular aging and increased aging disease susceptibility. The aim of the current study was to evaluate whether hyperbaric oxygen therapy (HBOT) affects gene expression in normal, non-pathological, aging adults.

Methods: Thirty-five healthy independently living adults, aged 64 and older, were enrolled to receive 60 daily HBOT exposures. Whole blood samples were collected at baseline, at the 30th and 60th HBOT session, and 1–2 weeks following the last session. Differential gene expression analysis was performed.

Results: Following 60 sessions of HBOT, 1342 genes and 570 genes were differently up- and downregulated (1912 total), respectively (p < 0.01 FDR), compared to baseline. Out of which, five genes were downregulated with a >1.5-fold change: ABCA13 (FC = −2.28), DNAJ6 (FC = −2.16), HBG2 (FC = −1.56), PDXDC1 (FC = −1.53), RANBP17 (FC = −1.75). Two weeks post-HBOT, ABCA13 expression was significantly downregulated with a >1.5fold change (FC = −1.54, p = 0.008).

In conclusion, for the first time in humans, the study provides direct evidence of HBOT is associated with transcriptome changes in whole-blood samples. Our results demonstrate significant changes in gene expression of normal aging population.

Mesenchymal Stem/Stromal Cell Therapy in Blood-Brain Barrier Preservation Following Ischemia: Molecular Mechanisms and Prospects

Ischemic stroke is the leading cause of mortality and long-term disability worldwide. Disruption of the blood-brain barrier (BBB) is a prominent pathophysiological mechanism, responsible for a series of subsequent inflammatory cascades that exacerbate the damage to brain tissue. However, the benefit of recanalization is limited in most patients because of the narrow therapeutic time window. Recently, mesenchymal stem cells (MSCs) have been assessed as excellent candidates for cell-based therapy in cerebral ischemia, including neuroinflammatory alleviation, angiogenesis and neurogenesis promotion through their paracrine actions. In addition, accumulating evidence on how MSC therapy preserves BBB integrity after stroke may open up novel therapeutic targets for treating cerebrovascular diseases. In this review, we focus on the molecular mechanisms of MSC-based therapy in the ischemia-induced prevention of BBB compromise. Currently, therapeutic effects of MSCs for stroke are primarily based on the fundamental pathogenesis of BBB breakdown, such as attenuating leukocyte infiltration, matrix metalloproteinase (MMP) regulation, antioxidant, anti-inflammation, stabilizing morphology and crosstalk between cellular components of the BBB. We also discuss prospective studies to improve the effectiveness of MSC therapy through enhanced migration into defined brain regions of stem cells. Targeted therapy is a promising new direction and is being prioritized for extensive research.

Rationale for hyperbaric oxygen therapy in traumatic injury and wound care in small animal veterinary practice

Hyperbaric oxygen therapy is in wide use in human medicine around the world. Although hyperbaric oxygen therapy is available for veterinary use, it is still significantly underutilised. The physical principles, gas laws and physiologic mechanisms by which hyperbaric oxygen therapy is therapeutic, especially in traumatic injuries and complicated wound care, are discussed. Then, considerations are offered for the implementation of hyperbaric oxygen therapy in veterinary practices. Finally, a review of clinical indications for veterinary practices, including a presentation of select literature, is provided. Applying hyperbaric oxygen therapy in an earlier and more consistent manner could improve short- and long-term outcomes in complicated wounds. The authors also hope this information may stimulate interest in the design of future, prospective studies for the various clinical situations described.

Prolonged oxygen exposure causes the mobilization and functional damage of stem or progenitor cells and exacerbates cardiac ischemia or reperfusion injury in healthy mice

Oxygen is often administered to patients and occasionally to healthy individuals as well; however, the cellular toxicity of oxygen, especially following prolonged exposure, is widely known. To evaluate the potential effect of oxygen exposure on circulating stem/progenitor cells and cardiac ischemia/reperfusion (I/R) injury, we exposed healthy adult mice to 100% oxygen for 20 or 60 min. We then examined the c-kit-positive stem/progenitor cells and colony-forming cells and measured the cytokine/chemokine levels in peripheral blood. We also induced cardiac I/R injury in mice at 3 h after 60 min of oxygen exposure and examined the recruitment of inflammatory cells and the fibrotic area in the heart. The proportion of c-kit-positive stem/progenitor cells significantly increased in peripheral blood at 3 and 24 h after oxygen exposure for either 20 or 60 min (p < .01 vs. control). However, the abundance of colony-forming cells in peripheral blood conversely decreased at 3 and 24 h after oxygen exposure for only 60 min (p < .05 vs. control). Oxygen exposure for either 20 or 60 min resulted in significantly decreased plasma vascular endothelial growth factor levels at 3 h, whereas oxygen exposure for only 60 min reduced plasma insulin-like growth factor 1 levels at 24 h (p < .05 vs. control). Protein array indicated the increase in the levels of some cytokines/chemokines, such as CXCL6 (GCP-2) at 24 h after 60 min of oxygen exposure. Moreover, oxygen exposure for 60 min enhanced the recruitment of Ly6g- and CD11c-positive inflammatory cells at 3 days (p < .05 vs. control) and increased the fibrotic area at 14 days in the heart after I/R injury (p < .05 vs. control). Prolonged oxygen exposure induced the mobilization and functional impairment of stem/progenitor cells and likely enhanced inflammatory responses to exacerbate cardiac I/R injury in healthy mice.

[New Therapeutic Strategies and Future Issues in Hyperbaric Medicine]

Hyperbaric medicine includes two different medical fields: hyperbaric oxygenation (HBO) as emergency and intensive care, and diving medicine. Recent topics in hyperbaric therapy include radiation oncology and regenerative medicine. Of special interest are clinical studies of radiotherapy after HBO that were conducted at some institutes to evaluate its therapeutic effects for cancer patients. A few studies have shown that HBO improves memory disturbance following traumatic brain injury and hypoxic and ischemic events. There is a great possibility that HBO enhances the therapeutic effects of radiotherapy and potentiates regenerative medicine. Randomized controlled trials, however, have indicated the re-examination of its viable treatment effects in some conditions, including decompression illness, carbon monoxide poisoning, and serious soft tissue infection. As recent trends in the treatment of decompression illness have changed on the basis of clinical series, the laws related to diving and caisson work should be amended in the future.

Neovascularization and tissue regeneration by endothelial progenitor cells in ischemic stroke

Endothelial progenitor cells (EPCs) are immature endothelial cells (ECs) capable of proliferating and differentiating into mature ECs. These progenitor cells migrate from bone marrow (BM) after vascular injury to ischemic areas, where they participate in the repair of injured endothelium and new blood vessel formation. EPCs also secrete a series of protective cytokines and growth factors that support cell survival and tissue regeneration. Thus, EPCs provide novel and promising potential therapies to treat vascular disease, including ischemic stroke. However, EPCs are tightly regulated during the process of vascular repair and regeneration by numerous endogenous cytokines that are associated closely with the therapeutic efficacy of the progenitor cells. The regenerative capacity of EPCs also is affected by a range of exogenous factors and drugs as well as vascular risk factors. Understanding the functional properties of EPCs and the factors related to their regenerative capacity will facilitate better use of these progenitor cells in treating vascular disease. Here, we review the current knowledge of EPCs in cerebral neovascularization and tissue regeneration after cerebral ischemia and the factors associated with their regenerative function to better understand the underlying mechanisms and provide more effective strategies for the use of EPCs in treating ischemic stroke.

Hyperbaric hyperoxemia as a risk factor for ventilator-acquired pneumonia?

OBJECTIVES

Ventilator-acquired pneumonia (VAP) is the leading cause of serious associated infections in Intensive Care Units (ICU) and is associated with significant morbidity. The use of hyperbaric oxygen therapy (HBOT) in patients on mechanical ventilation may increase exposure to certain risk factors such as hyperoxemia and the need for multiple transfers. The aim of our study was to assess the relationship between HBOT and VAP.

METHOD

This retrospective observational study was performed from March 2017 to March 2018 in a 10-bed ICU using HBOT. All patients receiving mechanical ventilation (MV) for more than 48 hours were eligible. VAP was defined using clinical and radiological criteria. Data collection was carried out via digital medical records. Risk factors for VAP were determined by univariate and multivariate analysis.

RESULTS

Forty-two (23%) of the 182 patients enrolled developed at least one episode of VAP. One hundred and twenty-four (68%) patients received HBOT. The incidence rate of VAP was 34 per 1000 ventilator days. The occurrence of VAP was significantly associated with immunosuppression (p<0.029), MV duration (5 [3-7] vs 8 [5-11.5] days, p<0.0001), length of stay (8 [5-13] vs 19.5 [13-32] days, p<0.0001), reintubation (p<0.0001), intra-hospital transport (p = 0.001), use of paralytic agents (p = 0.013), tracheotomy (p = 0.003) and prone position (p = 0.003). The use of HBOT was not associated with the occurrence of VAP. Multivariate analysis identified reintubation (OR: 8.3 [2.6-26.6]; p<0.0001), intra-hospital transport (OR: 3.5 [1.3-9.2]; p = 0.011) and the use of paralytic agents (OR: 3.3 [1.3-8.4]; p = 0.014) as independent risk factors for VAP.

CONCLUSION

Known risk factors for VAP are to be found within our ICU population. HBOT, however, is not an extra risk factor for VAP within this group. Further experimental and clinical investigations are needed to understand the impact of HBOT on the occurrence of VAP and on physiological microbiome.

Molecular Biomarkers of Oxygen Therapy in Patients with Diabetic Foot Ulcers

Hyperbaric oxygen therapy (HBOT) and topical oxygen therapy (TOT) including continuous diffuse oxygen therapy (CDOT) are often utilized to enhance wound healing in patients with diabetic foot ulcerations. High pressure pure oxygen assists in the oxygenation of hypoxic wounds to increase perfusion. Although oxygen therapy provides wound healing benefits to some patients with diabetic foot ulcers, it is currently performed from clinical examination and imaging. Data suggest that oxygen therapy promotes wound healing via angiogenesis, the creation of new blood vessels. Molecular biomarkers relating to tissue inflammation, repair, and healing have been identified. Predictive biomarkers can be used to identify patients who will most likely benefit from this specialized treatment. In diabetic foot ulcerations, specifically, certain biomarkers have been linked to factors involving angiogenesis and inflammation, two crucial aspects of wound healing. In this review, the mechanism of how oxygen works in wound healing on a physiological basis, such as cell metabolism and growth factor signaling transduction is detailed. Additionally, observable clinical outcomes such as collagen formation, angiogenesis, respiratory burst and cell proliferation are described. The scientific evidence for the impact of oxygen on biomolecular pathways and its relationship to the outcomes in clinical research is discussed in this narrative review.

Various Therapeutic Methods for the Treatment of Medication-Related Osteonecrosis of the Jaw (MRONJ) and Their Limitations: A Narrative Review on New Molecular and Cellular Therapeutic Approaches

Medication-related osteonecrosis of the jaw (MRONJ) is one of the most interesting diseases in the field of maxillofacial surgery. In addition to bisphosphonates, the use of antiresorptive and antiangiogenic agents is known to be the leading cause. However, the exact pathogenesis of MRONJ has not been established, and various hypotheses have been proposed, such as oxidative stress-related theory. As a result, a definitive treatment protocol for MRONJ has not been identified, while various therapeutic approaches are applied to manage patients with MRONJ. Although the surgical approach to treat osteomyelitis of the jaw has been proven to be most effective, there are limitations, such as recurrence and delayed healing. Many studies and clinical trials are being conducted to develop another effective therapeutic modality. The use of some materials, including platelet concentrates and bone morphogenetic proteins, showed a positive effect on MRONJ. Among them, teriparatide is currently the most promising material, and it has shown encouraging results when applied to patients with MRONJ. Furthermore, cell therapy using mesenchymal stem cells showed promising results, and it can be the new therapeutic approach for the treatment of MRONJ. This review presents various treatment methods for MRONJ and their limitations while investigating newly developed and researched molecular and cellular therapeutic approaches along with a literature review.

Hyperbaric oxygen therapy acts as an alternative method in treating injection-induced nodules

BACKGROUND

Cosmetic injection-induced nodules are tricky to handle in the clinic.

AIMS

We reported a case of injection-induced nodule receiving the experimental treatment of hyperbaric oxygen therapy (HOT).

PATIENT

A woman presented with multiple red solid nodules on the neck after receiving mesotherapy conducted by syringe. Ultrasound examination showed multiple thickened inflammatory skin tissues on the neck. Pathological biopsy results showed epithelioid granulomas in the dermis, within which there were degenerative necrosis and foreign bodies in the center and multinucleated giant cells around. The bacteria tests remained negative. Diagnosed with foreign body granuloma, the patient rejected the resection or steroids, but willingly took the experimental treatment of HOT instead. After one month, the patient's ultrasound examination showed that the lesion's local hardness got significantly reduced, and the local blood flow increased, indicating the condition improved.

RESULTS

Although the patient's nodule has not been eliminated, some improvements have been achieved. So far there has no case report on HOT treating injection-induced nodules in the literature.

CONCLUSION

HOT may be considered as a potential alternative when other treatment options cannot be implemented. More research is needed in this field.

Hyperbaric oxygen therapy for nonhealing wounds: Treatment results of a single center

The present article evaluates the results of the treatment with adjuvant hyperbaric oxygen therapy (HBOT) of patients with nonhealing, chronic wounds. In the period 2013 to 2016, 248 patients were referred from various hospitals because of chronic wounds that were recalcitrant in healing despite standard wound care as described in national and international guidelines. After inclusion, all patients were treated with HBOT and subjected to a weekly standard wound care treatment. During each HBOT session, 100% O2 was administered for 75 minutes under increased pressure of 2.4 ATA. Wounds and quality of life were assessed before and after the total treatment period. A total of 248 patients have been evaluated. Diabetic foot ulcers were present in 134 patients, the remainder (114 patients) showed a variety of wound locations and etiologies. The number of HBOT treatments amounted to an average of 48 (range 20-68) sessions. Before referral to our clinic, 31% of all wounds had existed for at least 18 months (72 patients). After HBOT, 81% of all wounds were near complete healing or completely healed, in 13% of the cases the wound was stable, and in 2% minor or major amputation had to be carried out. The mean treatment time for wounds pre-existing fewer than 6 weeks ("early referrals") was 67 days, and 119 days for wounds pre-existing more than 18 months ("late referrals"). A majority of the patients in our study referred with nonhealing wounds clinically improved when adjuvant HBOT was added to standard wound care protocols. No differences in success rate were seen between diabetic and nondiabetic wounds. It showed that HBOT is a well-tolerated treatment.

Functional MRI (fMRI) Evaluation of Hyperbaric Oxygen Therapy (HBOT) Efficacy in Chronic Cerebral Stroke: A Small Retrospective Consecutive Case Series

Topics: Functional Magnetic Resonance Imaging (fMRI) evaluation of HyberBaric Oxygen Therapy (HBOT) effects on chronic cerebral stroke Patients (Pts). Introduction: Our aim was to evaluate with fMRI, in a 3 Tesla system, the functional effects of HBOT on the Central Nervous System (CNS) in four Pts with established ischaemic and haemorrhagic cerebral strokes (2 Pts each). To our knowledge, no author used this Magnetic Resonance (MR) technique for this purpose, till now. Methods: All four Pts underwent a fMRI study before and after 40 HBOT sessions, with a time window of a few days. They carried out two language (text listening, silent word-verb generation) and two motor (hand and foot movements) tasks (30 s On-Off block paradigms). Results: After HBOT, all Pts reported a clinical improvement, mostly concerning language fluency and motor paresis. fMRI analysis demonstrated an increase in both the extent and the statistical significance of most of the examined eloquent areas. Conclusions: These changes were consistent with the clinical improvement in all Pts, suggesting a possible role of fMRI in revealing neuronal functional correlates of neuronal plasticity and HBOT-related neoangiogenesis. Although only four Pts were examined, fMRI proved to be a sensitive, non-invasive and reliable modality for monitoring neuronal functional changes before and after HBOT.

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.

Ghrelin system is involved in improvements in glucose metabolism mediated by hyperbaric oxygen treatment in a streptozotocin‑induced type 1 diabetes mouse model

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder for which the only effective therapy is insulin replacement. Hyperbaric oxygen (HBO) therapy has demonstrated potential in improving hyperglycemia and as a treatment option for T1DM. Ghrelin and HBO have been previously reported to exert proliferative, anti-apoptotic and anti-inflammatory effects in pancreatic cells. The present study investigated the mechanism underlying HBO- and ghrelin system-mediated regulation of glucose metabolism. Male C57BL/6 mice were intraperitoneally injected with streptozotocin (STZ; 150 mg/kg) to induce T1DM before the diabetic mice were randomly assigned into the T1DM and T1DM + HBO groups. Mice in the T1DM + HBO group received HBO (1 h; 100% oxygen; 2 atmospheres absolute) daily for 2 weeks. Significantly lower blood glucose levels and food intake were observed in mice in the T1DM + HBO group. Following HBO treatment, islet β-cell area were increased whereas those of α-cell were decreased in the pancreas. In addition, greater hepatic glycogen storage in liver was observed, which coincided with higher pancreatic glucose transporter 2 (GLUT2) expression levels and reduced hepatic GLUT2 membrane trafficking. There were also substantially higher total plasma ghrelin concentrations and gastric ghrelin-O-acyl transferase (GOAT) expression levels in mice in the T1DM + HBO group. HBO treatment also abolished reductions in pancreatic GOAT expression levels in T1DM mice. Additionally, hepatic growth hormone secretagogue receptor-1a levels were found to be lower in mice in the T1DM + HBO group compared with those in the T1DM group. These results suggest that HBO administration improved glucose metabolism in a STZ-induced T1DM mouse model. The underlying mechanism involves improved insulin-release, glucose-sensing and regulation of hepatic glycogen storage, an observation that was also likely dependent on the ghrelin signalling system.

Integrin-mediated adhesive properties of neutrophils are reduced by hyperbaric oxygen therapy in patients with chronic non-healing wound

In recent years, several studies suggested that the ability of hyperbaric oxygen therapy (HBOT) to promote healing in patients with diabetic ulcers and chronic wounds is due to the reduction of inflammatory cytokines and to a significant decrease in neutrophils recruitment to the damaged area. α4 and β2 integrins are receptors mediating the neutrophil adhesion to the endothelium and the comprehension of the effects of hyperbaric oxygenation on their expression and functions in neutrophils could be of great importance for the design of novel therapeutic protocols focused on anti-inflammatory agents. In this study, the α4 and β2 integrins' expression and functions have been evaluated in human primary neutrophils obtained from patients with chronic non-healing wounds and undergoing a prolonged HBOT (150 kPa per 90 minutes). The effect of a peptidomimetic α4β1 integrin antagonist has been also analyzed under these conditions. A statistically significant decrease (68%) in β2 integrin expression on neutrophils was observed during the treatment with HBO and maintained one month after the last treatment, while α4 integrin levels remained unchanged. However, cell adhesion function of both neutrophilic integrins α4β1 and β2 was significantly reduced 70 and 67%, respectively), but α4β1 integrin was still sensitive to antagonist inhibition in the presence of fibronectin, suggesting that a combined therapy between HBOT and integrin antagonists could have greater antinflammatory efficacy.

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.

Hyperbaric oxygen therapy for radiation-induced tissue injury following sarcoma treatment: A retrospective analysis of a Dutch cohort

Background and objectives

Sarcomas are commonly managed by surgical resection combined with radiotherapy. Sarcoma treatment is frequently complicated by chronic wounds and late radiation tissue injury (LRTI). This study aims to gain insight in the use and results of hyperbaric oxygen therapy (HBOT) for radiation-induced complications following sarcoma treatment.

Methods

All sarcoma patients treated between 2006 and 2017 in one of the five centers of the Institute for Hyperbaric Oxygen in the Netherlands were included for retrospective analysis.

Results

Thirty patients were included, 18 (60.0%) patients were treated for chronic wounds and 12 (40.0%) for LRTI. Two patients with chronic wounds were excluded from analysis as HBOT was discontinued within five sessions. In 11 of 16 (68.8%) patients treated for chronic wounds, improved wound healing was seen. Nine of 12 (75.0%) patients treated for LRTI reported a decline in pain. Reduction of fibrosis was seen in five of eight patients (62.5%) treated for LRTI.

Conclusions

HBOT is safe and beneficial for treating chronic wounds and LRTI in the sarcoma population. Awaiting further prospective results, we recommend referring to HBOT centers more actively in patients experiencing impaired wound healing or symptoms of delayed radiation-induced tissue injury following multimodality sarcoma treatment.

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.

Identifying the Therapeutic Significance of Mesenchymal Stem Cells

The pleiotropic behavior of mesenchymal stem cells (MSCs) has gained global attention due to their immense potential for immunosuppression and their therapeutic role in immune disorders. MSCs migrate towards inflamed microenvironments, produce anti-inflammatory cytokines and conceal themselves from the innate immune system. These signatures are the reason for the uprising in the sciences of cellular therapy in the last decades. Irrespective of their therapeutic role in immune disorders, some factors limit beneficial effects such as inconsistency of cell characteristics, erratic protocols, deviating dosages, and diverse transfusion patterns. Conclusive protocols for cell culture, differentiation, expansion, and cryopreservation of MSCs are of the utmost importance for a better understanding of MSCs in therapeutic applications. In this review, we address the immunomodulatory properties and immunosuppressive actions of MSCs. Also, we sum up the results of the enhancement, utilization, and therapeutic responses of MSCs in treating inflammatory diseases, metabolic disorders and diabetes.

Altered anxiety and social behaviors in a mouse model of Fragile X syndrome treated with hyperbaric oxygen therapy

Fragile X syndrome (FXS) is a common mental retardation syndrome. Anxiety and abnormal social behaviors are prominent features of FXS in humans. To better understand the effects of hyperbaric oxygen therapy (HBOT) on these behaviors, we analyzed anxiety-related and social behaviors in Fmr1 knockout mice treated by HBOT. In the open field test, HBOT group mice preferred the periphery to central areas and tended to run or walk along the wall. The results suggested that thigmotaxis was significantly increased in the HBOT group compared with the control group. In the elevated plus maze test, the percentage of distance traveled was significantly increased in the open arm and significantly decreased in the closed arm for HBOT group mice compared with control group mice. These results suggested that HBOT group mice displayed enhanced motor activity in the open arm and exhibited fewer anxiety-related behaviors. In the three-chambered social approach test, the HBOT group mice made more approaches to the wire cup containing an acquaintance mouse than control group mice in the sociability test and made more approaches to the wire cup containing a stranger mouse than control group mice in the social novelty preference test. The results suggested that HBOT group mice showed increased levels of social interaction and decreased "social anxiety" than the control group to partner mice in this test. Our findings indicated that HBOT resulted in altered anxiety and social behavior in Fmr1 knockout mice and could possibly be used as a treatment for FXS.

Harnessing the anti-inflammatory properties of stem cells for transplant therapy in hemorrhagic stroke

Hemorrhagic stroke is a global health crisis plagued by neuroinflammation in the acute and chronic phases. Neuroinflammation approximates secondary cell death, which in turn robustly contributes to stroke pathology. Both the physiological and behavioral symptoms of stroke correlate with various inflammatory responses in animal and human studies. That slowing the secondary cell death mediated by this inflammation may attenuate stroke pathology presents a novel treatment strategy. To this end, experimental therapies employing stem cell transplants support their potential for neuroprotection and neuroregeneration after hemorrhagic stroke. In this review, we evaluate experiments using different types of stem cell transplants as treatments for stroke-induced neuroinflammation. We also update this emerging area by examining recent preclinical and clinical trials that have deployed these therapies. While further investigations are warranted to solidify their therapeutic profile, the reviewed studies largely posit stem cells as safe and potent biologics for stroke, specifically owing to their mode of action for sequestering neuroinflammation and promoting neuroregenerative processes.

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.

Effects and mechanism of stem cells from human exfoliated deciduous teeth combined with hyperbaric oxygen therapy in type 2 diabetic rats

OBJECTIVES

Mesenchymal stem cells (MSCs) are potentially ideal for type 2 diabetes treatment, owing to their multidirectional differentiation ability and immunomodulatory properties. Here we investigated whether the stem cells from human exfoliated deciduous teeth (SHED) in combination with hyperbaric oxygen (HBO) could treat type 2 diabetic rats, and explored the underlying mechanism.

METHODS

SD rats were used to generate a type 2 diabetes model, which received stem cell therapy, HBO therapy, or both together. Before and after treatment, body weight, blood glucose, and serum insulin, blood lipid, pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6), and urinary proteins were measured and compared. After 6 weeks, rats were sacrificed and their organs were subjected to hematoxylin and eosin staining and immunofluorescence staining for insulin and glucagon; apoptosis and proliferation were analyzed in islet cells. Structural changes in islets were observed under an electron microscope. Expression levels of Pdx1, Ngn3, and Pax4 mRNAs in the pancreas were assessed by real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

In comparison with diabetic mice, those treated with the combination or SHE therapy showed decreased blood glucose, insulin resistance, serum lipids, and pro-inflammatory cytokines and increased body weight and serum insulin. The morphology and structure of pancreatic islets improved, as evident from an increase in insulin-positive cells and a decrease in glucagon-positive cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining of islet cells revealed the decreased apoptosis index, while Ki67 and proliferating cell nuclear antigen staining showed increased proliferation index. Pancreatic expression of Pdx1, Ngn3, and Pax4 was upregulated.

CONCLUSION

SHED combined with HBO therapy was effective for treating type 2 diabetic rats. The underlying mechanism may involve SHED-mediated increase in the proliferation and trans-differentiation of islet β-cells and decrease in pro-inflammatory cytokines and apoptosis of islets.

The Role of Hyperbaric Oxygen Treatment for COVID-19: A Review

The recent coronavirus disease 2019 (COVID-19) pandemic produced high and excessive demands for hospitalizations and equipment with depletion of critical care resources. The results of these extreme therapeutic efforts have been sobering. Further, we are months away from a robust vaccination effort, and current therapies provide limited clinical relief. Therefore, several empirical oxygenation support initiatives have been initiated with intermittent hyperbaric oxygen (HBO) therapy to overcome the unrelenting and progressive hypoxemia during maximum ventilator support in intubated patients, despite high FiO2. Overall, few patients have been successfully treated in different locations across the globe. More recently, less severe patients at the edge of impending hypoxemia were exposed to HBO preventing intubation and obtaining the rapid resolution of symptoms. The few case descriptions indicate large variability in protocols and exposure frequency. This summary illustrates the biological mechanisms of action of increased O₂ pressure, hoping to clarify more appropriate protocols and more useful application of HBO in COVID-19 treatment.

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.

Is there a role for hyperbaric oxygen therapy in the treatment of refractory wounds of rare etiology?

INTRODUCTION

Delayed wound healing indicates wounds that have failed to respond to more than 4-6 weeks of comprehensive wound care. Wounds with delayed healing are a major source of morbidity and a major cost to hospital and community healthcare providers. Hyperbaric oxygen therapy (HBOT) is a treatment designed to increase the supply of oxygen to wounds and has been applied to a variety of wound types. This article reviews the place of HBOT in the treatment of non-healing vasculitic, calcific uremic arteriolopathy (CUA), livedoid vasculopathy (LV), pyoderma gangrenosum (PG) ulcers.

METHODS

We searched electronic databases for research and review studies focused on HBOT for the treatment of delayed healing ulcers with rare etiologies. We excluded HBOT for ulcers reviewed elsewhere.

RESULTS

We included a total of three case series and four case reports including 63 participants. Most were related to severe, non-healing ulcers in patients with vasculitis, CUA, LV, and PG. There was some evidence that HBOT may improve the healing rate of wounds by increasing nitric oxide (NO) levels and the number of endothelial progenitor cells in the wounds. HBOT may also improve pain in these ulcers.

CONCLUSION

We recommend the establishment of comprehensive and detailed wound care registries to rapidly collect prospective data on the use of HBOT for these problem wounds. There is a strong case for appropriately powered, multi-centre randomized trials to establish the true efficacy and cost-effectiveness of HBOT especially for vasculitis ulcers that have not improved following immunosuppressive therapy.

Wound healing complications in oncological patients: perspectives for cellular therapy

Various types of cancer are nowadays a serious medical and social problem and a great challenge for modern medicine. The majority of anticancer therapy is based on traditional chemotherapy and radiotherapy. Both of these highly non-specific types of treatment have a number of serious side effects including wound healing complications. Radiotherapy and chemotherapy mostly affect rapidly dividing skin cells (e.g. keratinocytes), as well as fibroblasts, melanocytes, endothelial and immune cells. Currently, there are many strategies to improve wound healing in oncological patients, including various types of dressings, biomaterials, growth factors, and cell therapies.