Development of a Murine Model for the Exploration of the Biological Effects of External Volume Expansion. Sviluppo di un modello murino per l'esplorazione degli effetti biologici dell'espansione volumetrica esterna

Background: External Volume Expansion (EVE) refers to a class of devices that non-invasively stretch and expand tissue compartments by external application of suction. EVE has been suggested to increase compartments volume and stimulate the formation of a more developed vascular network, leading to less stiff and better vascularized tissues. It is proposed to patients as a method to prepare recipient sites, in particular breasts, in view of a fat grafting procedure, basing on the theory that fat grafts will better survive and retain volume if the recipient site is more vascularized and provides less compression. However, the method requires high patient compliance and no experimental validation for it has been attempted. Aims: basing on our group's previous experience in downsizing and testing in animal models clinical devices for wound healing, in particular in settings requiring the application of mechanical forces to soft tissues, we proposed to design an animal model for EVE in which to test the validity of the hypothesis of its being beneficial to fat grafting and explore its mechanisms and potentials. Methods: we designed and built a miniaturized EVE device to be applied to the dorsum of mice. We then designed a series of stepwise incremental studies. We tested the capacity of EVE of inducing angiogenesis and cell proliferation with 28 days long continuous stimulation. We analyzed its effects on tissues in terms of mechanical stretch, hypoxia and ischemia, edema, inflammation, cell proliferation and angiogenesis after a single 2 hours stimulation. We produced a mathematical modeling for the effects of EVE on tissues in relation to fat grafting. We tested if EVE is beneficial to fat grafting and if beneficial effects are maintained also in the setting of chronic radiation damage. We tested if EVE can stimulate adipogenesis and what role inflammation can play in it. Results: in our series of studies, we successfully designed a miniaturized animal model in which to test External Volume Expansion. We demonstrated that the hypotheses of stimulation of cell proliferation, angiogenesis, and expansion of tissue compartments on which it is proposed as a preparatory method to fat grafting is confirmed in experimental settings. We showed how mechanical stretch of tissues, hypoxia and ischemia, edema, and inflammation are all intervening factors that can contribute to these effects. Our results suggest that pre-stimulation with EVE is successful in achieving increased fat graft weight and volume retention, and that its beneficial effects are maintained also in the setting of recipient sites having sustained radiation injury. We also demonstrated that EVE has a potential for direct stimulation of adipogenesis, and gathered supportive results to a role for macrophages in this. Discussion: our results validate the technique for its use in the preparatory phase to fat grafting, and can help moving towards making fat grafting a more effective and reliable procedure with improved outcomes for patients. We gathered evidence that help increasing our understanding of how EVE works and what it implies for tissues. This is the basis for optimizing the technique, make it safer, and increase patients' compliance. For example, stimulation patterns can be improved, duration of treatment can be reduced, and practices such as continuation of EVE after fat grafting should be abandoned as detrimental. Our unexpected observations on adipogenesis also open interesting opportunities, such as that of re-starting EVE after fat grafting when this is at the peak of its remodeling phase. And linking this effect with the understanding of the similarity to other conditions in which adipogenesis is seen and desired, such as tissue engineering, or pathological, such as lymphedema, can expand the potential of our animal model to alternative broader fields

Diffusion and Perfusion: The Keys to Fat Grafting

Background: Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention. Methods: We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention. Results: Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The “Microribbon Model” predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our “Fluid Accommodation Model” predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our “External Volume Expansion Effect Model” predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted. Conclusions: These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories

Hyperspectral Imaging as an Early Biomarker for Radiation Exposure and Microcirculatory Damage

BACKGROUND: Radiation exposure can lead to detrimental effects in skin microcirculation. The precise relationship between radiation dose received and its effect on cutaneous perfusion still remains controversial. Previously, we have shown that hyperspectral imaging (HSI) is able to demonstrate long-term reductions in cutaneous perfusion secondary to chronic microvascular injury. This study characterizes the changes in skin microcirculation in response to varying doses of ionizing radiation and investigates these microcirculatory changes as a possible early non-invasive biomarker that may correlate with the extent of long-term microvascular damage.METHODS: Immunocompetent hairless mice (n=66) were exposed to single fractions of superficial beta-irradiation in doses of 0, 5, 10, 20, 35, or 50 Gy. A HSI device was utilized to measure deoxygenated hemoglobin levels in irradiated and control areas. HSI measurements were performed at baseline before radiation exposure and for the first three days post-irradiation. Maximum macroscopic skin reactions were graded, and histological assessment of cutaneous microvascular densities at four weeks post-irradiation was performed in harvested tissue by CD31 immunohistochemistry.RESULTS: CD31 immunohistochemistry demonstrated a significant correlation (r=0.90, p<0.0001) between dose and vessel density reduction at four weeks. Using HSI analysis, early changes in deoxygenated hemoglobin levels were observed during the first three days post-irradiation in all groups. These deoxygenated hemoglobin changes varied proportionally with dose (r=0.98, p<0.0001) and skin reactions (r=0.98, p<0.0001). There was a highly significant correlation (r= 0.91, p<0.0001) between these early changes in deoxygenated hemoglobin and late vascular injury severity assessed at the end of four weeks.CONCLUSIONS: Radiation dose is directly correlated with cutaneous microvascular injury severity at four weeks in our model. Early post-exposure measurement of cutaneous deoxygenated hemoglobin levels may be a useful biomarker for radiation dose reconstruction and predictor for chronic microvascular injury

Overexpressing IRS1 in Endothelial Cells Enhances Angioblast Differentiation and Wound Healing in Diabetes and Insulin Resistance

The effect of enhancing insulin’s actions in endothelial cells (ECs) to improve angiogenesis and wound healing was studied in obesity and diabetes. Insulin receptor substrate 1 (IRS1) was overexpressed in ECs using the VE-cadherin promoter to create ECIRS1 TG mice, which elevated pAkt activation and expressions of vascular endothelial growth factor (VEGF), Flk1, and VE-cadherin in ECs and granulation tissues (GTs) of full-thickness wounds. Open wound and epithelialization rates and angiogenesis significantly improved in normal mice and high fat (HF) diet–induced diabetic mice with hyperinsulinemia in ECIRS1 TG versus wild type (WT), but not in insulin-deficient diabetic mice. Increased angioblasts and EC numbers in GT of ECIRS1 mice were due to proliferation in situ rather than uptake. GT in HF-fed diabetic mice exhibited parallel decreases in insulin and VEGF-induced pAkt and EC numbers by >50% without changes in angioblasts versus WT mice, which were improved in ECIRS1 TG mice on normal chow or HF diet. Thus, HF-induced diabetes impaired angiogenesis by inhibiting insulin signaling in GT to decrease the differentiation of angioblasts to EC, which was normalized by enhancing insulin’s action targeted to EC, a potential target to improve wound healing in diabetes and obesity

World Society of Emergency Surgery (WSES) guidelines for management of skin and soft tissue infections

Peer reviewe

Development of a Murine Model for the Exploration of the Biological Effects of External Volume Expansion. Sviluppo di un modello murino per l'esplorazione degli effetti biologici dell'espansione volumetrica esterna

Background: External Volume Expansion (EVE) refers to a class of devices that non-invasively stretch and expand tissue compartments by external application of suction. EVE has been suggested to increase compartments volume and stimulate the formation of a more developed vascular network, leading to less stiff and better vascularized tissues. It is proposed to patients as a method to prepare recipient sites, in particular breasts, in view of a fat grafting procedure, basing on the theory that fat grafts will better survive and retain volume if the recipient site is more vascularized and provides less compression. However, the method requires high patient compliance and no experimental validation for it has been attempted. Aims: basing on our group's previous experience in downsizing and testing in animal models clinical devices for wound healing, in particular in settings requiring the application of mechanical forces to soft tissues, we proposed to design an animal model for EVE in which to test the validity of the hypothesis of its being beneficial to fat grafting and explore its mechanisms and potentials. Methods: we designed and built a miniaturized EVE device to be applied to the dorsum of mice. We then designed a series of stepwise incremental studies. We tested the capacity of EVE of inducing angiogenesis and cell proliferation with 28 days long continuous stimulation. We analyzed its effects on tissues in terms of mechanical stretch, hypoxia and ischemia, edema, inflammation, cell proliferation and angiogenesis after a single 2 hours stimulation. We produced a mathematical modeling for the effects of EVE on tissues in relation to fat grafting. We tested if EVE is beneficial to fat grafting and if beneficial effects are maintained also in the setting of chronic radiation damage. We tested if EVE can stimulate adipogenesis and what role inflammation can play in it. Results: in our series of studies, we successfully designed a miniaturized animal model in which to test External Volume Expansion. We demonstrated that the hypotheses of stimulation of cell proliferation, angiogenesis, and expansion of tissue compartments on which it is proposed as a preparatory method to fat grafting is confirmed in experimental settings. We showed how mechanical stretch of tissues, hypoxia and ischemia, edema, and inflammation are all intervening factors that can contribute to these effects. Our results suggest that pre-stimulation with EVE is successful in achieving increased fat graft weight and volume retention, and that its beneficial effects are maintained also in the setting of recipient sites having sustained radiation injury. We also demonstrated that EVE has a potential for direct stimulation of adipogenesis, and gathered supportive results to a role for macrophages in this. Discussion: our results validate the technique for its use in the preparatory phase to fat grafting, and can help moving towards making fat grafting a more effective and reliable procedure with improved outcomes for patients. We gathered evidence that help increasing our understanding of how EVE works and what it implies for tissues. This is the basis for optimizing the technique, make it safer, and increase patients' compliance. For example, stimulation patterns can be improved, duration of treatment can be reduced, and practices such as continuation of EVE after fat grafting should be abandoned as detrimental. Our unexpected observations on adipogenesis also open interesting opportunities, such as that of re-starting EVE after fat grafting when this is at the peak of its remodeling phase. And linking this effect with the understanding of the similarity to other conditions in which adipogenesis is seen and desired, such as tissue engineering, or pathological, such as lymphedema, can expand the potential of our animal model to alternative broader fields.Introduzione: Espansione Volumetrica Esterna (EVE) si riferisce ad una classe di dispositivi che distendono ed espandono compartimenti tissutali in modo non invasivo attraverso l'applicazione dall'esterno di suzione. E' stato suggerito che EVE aumenti il volume dei compartimenti tissutali cui viene applicata e che stimoli un arricchimento della rete vascolare, portando a tessuti meno rigidi e meglio vascolarizzati. Viene proposta a pazienti come metodo per preparare un sito ricevente, soprattutto il seno, in vista di una procedura di innesto di tessuto adiposo con la tecnica del lipofilling, sulla base della teoria che l'innesto sopravvivrà e manterrà il suo volume meglio se il sito ricevente è più vascolarizzato e vi è sottoposto a meno compressione. Tuttavia, il metodo è impegnativo per le pazienti e proposto in assenza di validazione sperimentale delle ipotesi. Scopi: sulla scorta delle precedenti esperienze del nostro gruppo nel realizzare modelli sperimentali animali per dispositivi clinici nel campo della guarigione delle ferite, e in particolare di dispositivi per l'applicazione di forze meccaniche a tessuti molli in vivo, ci siamo proposti di realizzare un modello animale per EVE in cui testare la validità dell'ipotesi che possa offrire benefici all'innesto di tessuto adiposo ed esplorarne i meccanismi e il potenziale. Metodi: abbiamo realizzato un dispositivo per EVE miniaturizzato da applicare al dorso di topi. Abbiamo quindi disegnato una serie di studi con ipotesi e obiettivi incrementali. Abbiamo testato la capacità di EVE di stimolare angiogenesi e proliferazione cellulare applicandola in modo continuo per 28 giorni. Abbiamo analizzato i suoi effetti sui tessuti in termini di stiramento meccanico, ipossia, ischemia, edema, infiammazione, proliferazione cellulare e angiogenesi dopo una singola stimolazione da due ore. Abbiamo elaborato una teorizzazione matematica per gli effetti di EVE sui tessuti in relazione all'innesto di tessuto adiposo. Abbiamo testato se abbia un effetto positivo sull'innesto e se i suoi effetti positivi siano mantenuti nel caso di sito ricevente che abbia sostenuto danno da radiazioni. Abbiamo testato se EVE può timolare l'adipogenesi e che ruolo possano avere in questo i fenomeni infiammatori. Risultati: nella nostra serie di studi, è stato realizzato con successo un modello miniaturizzato con cui testare EVE. Abbiamo confermato sperimentalmente le ipotesi che induca proliferazione cellulare, angiogenesi e espansione dei compartimenti tessutali sulla base delle quali viene proposta come metodo preparatorio all'innesto di tessuto adiposo. Lo stiramento dei tessuti, l'induzione di ipossia e ischemia, edema e infiammazione sono tutti fattori che intervengono e possono contribuire a questi effetti. I nostri risultati suggeriscono che la pre-stimolazione con EVE possa essere efficace nell'ottenere un superiore mantenimento di massa degli innesti di tessuto adiposo, e che gli effetti positivi siano mantenuti anche in tessuti che abbiano subito danno da radiazione. Abbiamo inoltre dimostrato che EVE ha il potenziale di stimolare direttamente fenomeni adipogenici, e raccolto evidenze in favore di un ruolo primario dei macrofagi per questo effetto. Discussione: I nostri risultati offrono supporto sperimentale all'uso di EVE nella fase preparatoria agli innesti di tessuto adiposo, e possono contribuire a rendere l'innesto di tessuto adiposo una procedura più efficiente e prevedibile con maggiori garanzie per i pazienti. Abbiamo raccolto osservazioni che aiutano a comprendere come EVE funzioni e cosa implichi per i tessuti, il che è la base per ottimizzarla, renderla una tecnica più sicura, e aumentare la compliance dei pazienti. Ad esempio, i pattern di stimolazione possono essere migliorati, la durata del trattamento può essere ridotta, e pratiche come quella di riapplicare EVE subito dopo l'innesto di tessuto adiposo dovrebbero essere abbandonate in quanto dannose. La nostra inaspettata osservazione di effetti adipogenici diretti prospetta interessanti alternative, come quella di riapplicare EVE quando un innesto di tessuto adiposo è al picco della sua fase di rimodellamento. E collegare questo effetto con altre condizioni in cui adipogenesi è desiderata, ad esempio in ingegneria tissutale, o patologica, come nel linfedema, può ulteriormente espandere le potenzialità del nostro modello animale ad applicazioni in campi più vasti

PSYCHIATRIC ASPECTS IN BURN PATIENTS

After an epidemiological analysis of psychiatric disorders as a consequence of burns and also psychiatric aspects of burn victims before the accident, this paper discusses the correlation between psychiatric disorders and burns from the epidemiological, etiopathogenetic and clinical-therapeutic aspects. Burn patients often suffer from psychiatric disorders and there is a clear connection between the extent and/or severity of injuries (TBSA) and mental illness, particularly anxiety, mood disorders, and post-traumatic stress disorder. The occurrence of psychiatric disorders (mainly substance or alcohol abuse/dependence, suicidal behaviour, schizophrenia and personality disorders \u2013 antisocial or borderline) is a clear-cut risk factor for those with burn injuries. The occurrence or onset of psychiatric illness during burn hospitalization or recovery is a negative factor for wellbeing and also for the quality of life in the medium-long term. A burn injury is a traumatic experience for patients, not only as regards psychological aspects (no integration of the traumatic experience with self-perception of life) but also personal ones (knowledge of self-vulnerability, difficulty in accepting the new aspect of the body, with its possible deformation and scars) after trauma. All aspects which may refer to primordial and psychoanalytic fear of death must be taken into consideration. It is also necessary to consider the concepts of accident proneness and consequent pre-burn impulsivity, which may anticipate/represent a person's predisposition to a traumatic event. All these concepts have clinical and therapeutic importance for multidisciplinary care. This paper focuses on the relationship between burn injuries and psychiatric illness: post-traumatic stress disorder (acute and chronic), affective disorders, and personality traits. They must all be examined not only as regards their outcomes but also the patient's pre-trauma psychopathology and susceptibility. Also of importance is facing therapy for all these disorders and its correlation with burn care (in terms of length of hospital stay, quality of life, and functional and psychological results)