Ozone Activates the Nrf2 Pathway and Improves Preservation of Explanted Adipose Tissue In Vitro

Survival Mechanisms and Retention Strategies in Large-Volume Fat Grafting: A Comprehensive Review and Future Perspectives

INTRODUCTION

Large-volume fat grafting is emerging as a promising technique in plastic and reconstructive surgery. However, the unpredictable graft volume retention rate remains a critical challenge. To address this issue, we need a profound understanding of the survival mechanisms following large-volume fat transplantation. This review summarizes known survival mechanisms and strategies to enhance graft retention.

METHODS

This review comprehensively examines the current literature on the survival mechanisms and retention strategies in large-volume fat grafting. A thorough literature search was conducted using PubMed, Medline and Google Scholar databases, focusing on studies published from 2009 to 2023.

CONCLUSION

In the current research on fat survival mechanisms, few have focused on large-volume fat grafting. This review provides an overview of the survival mechanisms specific to large-volume fat grafting and identifies a survival pattern distinct from that of small-volume fat grafting. Additionally, we have summarized existing strategies to improve graft retention across five stages (harvesting, processing, enrichment, grafting and post-graft care), analyzed their advantages and disadvantages and identified some of the most promising strategies.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors   www.springer.com/00266.

Modifications of Blood Molecular Components after Treatment with Low Ozone Concentrations

The ex vivo treatment of a limited volume of blood with gaseous oxygen-ozone (O2-O3) mixtures and its rapid reinfusion into the patient is a widespread medical procedure. O3 instantly reacts with the blood's antioxidant systems, disappearing before reinfusion, although the molecules formed act as messengers in the organism, inducing multiple antioxidant and anti-inflammatory responses. An appropriate dose of O3 is obviously essential to ensure both safety and therapeutic efficacy, and in recent years, the low-dose O3 concept has led to a significant reduction in the administered O3 concentrations. However, the molecular events triggered by such low concentrations in the blood still need to be fully elucidated. In this basic study, we analysed the molecular modifications induced ex vivo in sheep blood by 5 and 10 µg O3/mL O2 by means of a powerful metabolomics analysis in association with haemogas, light microscopy and bioanalytical assays. This combined approach revealed increased oxygenation and an increased antioxidant capacity in the O3-treated blood, which accorded with the literature. Moreover, original information was obtained on the impact of these low O3 concentrations on the metabolic pathways of amino acids, carbohydrates, lipids and nucleotides, with the modified metabolites being mostly involved in the preservation of the oxidant-antioxidant balance and in energy production.

Ozone and procaine increase secretion of platelet-derived factors in platelet-rich plasma

Platelet-rich plasma (PRP) is gaining more and more attention in regenerative medicine as an innovative and efficient therapeutic approach. The regenerative properties of PRP rely on the numerous bioactive molecules released by the platelets: growth factors are involved in proliferation and differentiation of endothelial cells and fibroblasts, angiogenesis and extracellular matrix formation, while cytokines are mainly involved in immune cell recruitment and inflammation modulation. Attempts are ongoing to improve the therapeutic potential of PRP by combining it with agents able to promote regenerative processes. Two interesting candidates are ozone, administered at low doses as gaseous oxygen-ozone mixtures, and procaine. In the present study, we investigated the effects induced on platelets by the in vitro treatment of PRP with ozone or procaine, or both. We combined transmission electron microscopy to obtain information on platelet modifications and bioanalytical assays to quantify the secreted factors. The results demonstrate that, although platelets were already activated by the procedure to prepare PRP, both ozone and procaine induced differential morpho-functional modifications in platelets resulting in an increased release of factors. In detail, ozone induced an increase in surface protrusions and open canalicular system dilation suggestive of a marked α-granule release, while procaine caused a decrease in surface protrusions and open canalicular system dilation but a remarkable increase in microvesicle release suggestive of high secretory activity. Consistently, nine of the thirteen platelet-derived factors analysed in the PRP serum significantly increased after treatment with ozone and/or procaine. Therefore, ozone and procaine proved to have a remarkable stimulating potential without causing any damage to platelets, probably because they act through physiological, although different, secretory pathways.

Mitochondrial Features of Mouse Myoblasts Are Finely Tuned by Low Doses of Ozone: The Evidence In Vitro

The mild oxidative stress induced by low doses of gaseous ozone (O₃) activates the antioxidant cell response through the nuclear factor erythroid 2-related factor 2 (Nrf2), thus inducing beneficial effects without cell damage. Mitochondria are sensitive to mild oxidative stress and represent a susceptible O₃ target. In this in vitro study, we investigated the mitochondrial response to low O₃ doses in the immortalized, non-tumoral muscle C2C12 cells; a multimodal approach including fluorescence microscopy, transmission electron microscopy and biochemistry was used. Results demonstrated that mitochondrial features are finely tuned by low O₃ doses. The O₃ concentration of 10 μg maintained normal levels of mitochondria-associated Nrf2, promoted the mitochondrial increase of size and cristae extension, reduced cellular reactive oxygen species (ROS) and prevented cell death. Conversely, in 20 μg O₃-treated cells, where the association of Nrf2 with the mitochondria drastically dropped, mitochondria underwent more significant swelling, and ROS and cell death increased. This study, therefore, adds original evidence for the involvement of Nrf2 in the dose-dependent response to low O₃ concentrations not only as an Antioxidant Response Elements (ARE) gene activator but also as a regulatory/protective factor of mitochondrial function.

Ozone at low concentration modulates microglial activity in vitro: A multimodal microscopy and biomolecular study

Oxygen-ozone (O₂ -O₃ ) therapy is an adjuvant/complementary treatment based on the activation of antioxidant and cytoprotective pathways driven by the nuclear factor erythroid 2-related factor 2 (Nrf2). Many drugs, including dimethyl fumarate (DMF), that are used to reduce inflammation in oxidative-stress-related neurodegenerative diseases, act through the Nrf2-pathway. The scope of the present investigation was to get a deeper insight into the mechanisms responsible for the beneficial result of O₂ -O₃ treatment in some neurodegenerative diseases. To do this, we used an integrated approach of multimodal microscopy (bright-field and fluorescence microscopy, transmission and scanning electron microscopy) and biomolecular techniques to investigate the effects of the low O₃ concentrations currently used in clinical practice in lipopolysaccharide (LPS)-activated microglial cells human microglial clone 3 (HMC3) and in DMF-treated LPS-activated (LPS + DMF) HMC3 cells. The results at light and electron microscopy showed that LPS-activation induced morphological modifications of HMC3 cells from elongated/branched to larger roundish shape, cytoplasmic accumulation of lipid droplets, decreased electron density of the cytoplasm and mitochondria, decreased amount of Nrf2 and increased migration rate, while biomolecular data demonstrated that Heme oxygenase 1 gene expression and the secretion of the pro-inflammatory cytokines, Interleukin-6, and tumor necrosis factor-α augmented. O₃ treatment did not affect cell viability, proliferation, and morphological features of both LPS-activated and LPS + DMF cells, whereas the cell motility and the secretion of pro-inflammatory cytokines were significantly decreased. This evidence suggests that modulation of microglia activity may contribute to the beneficial effects of the O₂ -O₃ therapy in patients with neurodegenerative disorders characterized by chronic inflammation. HIGHLIGHTS: Low-dose ozone (O₃ ) does not damage activated microglial cells in vitro Low-dose O₃ decreases cell motility and pro-inflammatory cytokine secretion in activated microglial cells in vitro Low-dose O₃ potentiates the effect of an anti-inflammatory drug on activated microglial cells.

Ozonation of Whole Blood Results in an Increased Release of Microparticles from Blood Cells

Autohemotherapy with ozonated blood is used in the treatment of a broad spectrum of clinical disorders. Ozone demonstrates strong oxidizing properties and causes damage to cell membranes. The impact of whole-blood ozonation on the release of microparticles from blood and endothelial cells and the concentration of selected markers in the hemostatic system (APTT, PT, D-dimer, fibrinogen) were investigated. Venous blood, obtained from 19 healthy men, was split into four equal parts and treated with air, 15 µg/mL ozone, or 30 µg/mL ozone, or left untreated. The number and types of microparticles released were determined using flow cytometry on the basis of surface antigen expression: erythrocyte-derived microparticles (CD235⁺), platelet-derived microparticles (CD42⁺), leukocyte-derived microparticles (CD45⁺), and endothelial-derived microparticles (CD144⁺). The study is the first to demonstrate that ozone induces a statistically significant increase in the number of microparticles derived from blood and endothelial cells. Although statistically significant, the changes in some coagulation factors were somewhat mild and did not exceed normal values.

The Relationship between Ozone and Human Blood in the Course of a Well-Controlled, Mild, and Transitory Oxidative Eustress

In the last twenty years there has been a proliferation of articles on the therapeutic use of ozone. As it is well-known, the term ozone therapy is very broad. It ranges from either systemic or loco-regional administration of unstable gaseous oxygen/ozone mixtures to the topical application of stable ozonated derivatives. Anyway, in relation to the absence of specific receptors and the extreme reactivity with the biological liquids with which it comes into contact, gaseous ozone cannot be classified as either a drug or a pro-drug. When the gaseous ozone impacts a biological matrix, both reactive oxygen species (ROS) and lipid oxidation products (LOPs) are formed. They represent the effector molecules responsible for modulating the therapeutic activity in the body. Apart from the merits of the action mechanisms resulting from the use of ozone, this article seeks to validate the practice of ozone therapy as an adjuvant treatment in full compliance with the physiology of the whole organism.

Low Ozone Concentrations Differentially Affect the Structural and Functional Features of Non-Activated and Activated Fibroblasts In Vitro

Oxygen-ozone (O2-O3) therapy is increasingly applied as a complementary/adjuvant treatment for several diseases; however, the biological mechanisms accounting for the efficacy of low O3 concentrations need further investigations to understand the possibly multiple effects on the different cell types. In this work, we focused our attention on fibroblasts as ubiquitous connective cells playing roles in the body architecture, in the homeostasis of tissue-resident cells, and in many physiological and pathological processes. Using an established human fibroblast cell line as an in vitro model, we adopted a multimodal approach to explore a panel of cell structural and functional features, combining light and electron microscopy, Western blot analysis, real-time quantitative polymerase chain reaction, and multiplex assays for cytokines. The administration of O2-O3 gas mixtures induced multiple effects on fibroblasts, depending on their activation state: in non-activated fibroblasts, O3 stimulated proliferation, formation of cell surface protrusions, antioxidant response, and IL-6 and TGF-β1 secretion, while in LPS-activated fibroblasts, O3 stimulated only antioxidant response and cytokines secretion. Therefore, the low O3 concentrations used in this study induced activation-like responses in non-activated fibroblasts, whereas in already activated fibroblasts, the cell protective capability was potentiated.

Integrated Microscopy and Metabolomics to Test an Innovative Fluid Dynamic System for Skin Explants In Vitro

The in vitro models are receiving growing attention in studies on skin permeation, penetration, and irritancy, especially for the preclinical development of new transcutaneous drugs. However, synthetic membranes or cell cultures are unable to effectively mimic the permeability and absorption features of the cutaneous barrier. The use of explanted skin samples maintained in a fluid dynamic environment would make it possible for an in vitro experimentation closer to in vivo physiological conditions. To this aim, in the present study, we have modified a bioreactor designed for cell culture to host explanted skin samples. The preservation of the skin was evaluated by combining light, transmission, and scanning electron microscopy, for the histo/cytological characterization, with nuclear magnetic resonance spectroscopy, for the identification in the culture medium of metabolites indicative of the functional state of the explants. Our morphological and metabolomics results demonstrated that fluid dynamic conditions ameliorate significantly the structural and functional preservation of skin explants in comparison with conventional culture conditions. Our in vitro system is, therefore, reliable to test novel therapeutic agents intended for transdermal administration in skin samples from biopsies or surgical materials, providing predictive information suitable for focused in vivo research and reducing animal experimentation.

Low Ozone Concentrations Affect the Structural and Functional Features of Jurkat T Cells

Autohemotherapy is the most used method to administer O2-O3 systemically. It consists in exposing a limited amount of blood to a gaseous O2-O3 and reinfusing it, thus activating a cascade of biochemical pathways involving plasma and blood cells that gives rise to antioxidant and anti-inflammatory responses. The therapeutic effects strictly depend on the O3 dose; it is therefore necessary to understand the relationship between the O3 concentration and the effects on blood cells involved in antioxidant and immune response. Here we performed a basic study on the effects of the low O3 concentrations used for autohemotherapy on the structural and functional features of the human T-lymphocyte-derived Jurkat cells. Ultrastructural, biomolecular, and bioanalytic techniques were used. Our findings showed that 10, 20, and 30 µg O3 concentrations were able to trigger Nrf2-induced antioxidant response and increase IL-2 secretion. However, viability and proliferation tests as well as ultrastructural observations revealed stress signs after treatment with 20 and 30 µg O3, thus designating 10 µg O3 as the optimal concentration in combining cell safety and efficient antioxidant and immune response in our in vitro system. These data offer novel evidence of the fine regulatory role played by the oxidative stress level in the hormetic response of T lymphocytes to O2-O3 administration.

Insights on the mechanisms of action of ozone in the medical therapy against COVID-19

An increasing amount of reports in the literature is showing that medical ozone (O₃) is used, with encouraging results, in treating COVID-19 patients, optimizing pain and symptoms relief, respiratory parameters, inflammatory and coagulation markers and the overall health status, so reducing significantly how much time patients underwent hospitalization and intensive care. To date, aside from mechanisms taking into account the ability of O₃ to activate a rapid oxidative stress response, by up-regulating antioxidant and scavenging enzymes, no sound hypothesis was addressed to attempt a synopsis of how O₃ should act on COVID-19. The knowledge on how O₃ works on inflammation and thrombosis mechanisms is of the utmost importance to make physicians endowed with new guns against SARS-CoV2 pandemic. This review tries to address this issue, so to expand the debate in the scientific community.