Risk Factors for Nonunion After Distal Phalangeal Fractures of the Hand.

PURPOSE: This study aimed to evaluate the risk factors for distal phalanx fracture nonunion. METHODS: We retrospectively reviewed all adult patients treated for distal phalanx fractures at our institution between January 2015 and December 2019 with a minimum one-year follow-up period for potential risk factors. The absence of consolidation signs on follow-up radiographs at least 12 months after trauma was defined as nonunion. RESULTS: This study included 124 patients with 143 fractures available for follow-up. Nonunion was diagnosed in 19 patients, 18 of whom initially presented with an open fracture. On the day of the injury, 17 patients with open fractures presented to the hospital. In 16 nonunion cases, the traumatic mechanism was a crush injury. All nonunions occurred in tuft fractures, and none required revision surgery at the follow-up visit. CONCLUSIONS: Our findings suggest that tuft involvement in open fractures is the main risk factor for nonunion of distal phalangeal fractures. However, after a minimum of 1 year of follow-up, none of the tuft nonunions required revision surgery. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Burn Scar Ectropion Correction: Surgical Technique for Functional Outcomes.

BACKGROUND: Eyelid scarring after severe burn injury of the face is a significant complication endangering vision in addition to the burn scar sequelae. Scar contraction leads to asymmetry and malposition of the eyelid axis, resulting in corneal exposure, eyelid retraction, and incomplete eyelid closure. In consequence, dryness and irritation of the cornea can lead to keratitis, corneal opacity, and vision impairment. In this study, we present our surgical technique for lateral canthopexy in combination with full-thickness skin grafting (FTSGing) in patients with eyelid axis distortion after scar contraction of the periorbital region after severe burn injuries of the face. METHODS: In this retrospective, single-center case study, we present 5 consecutive patients who experienced severe burn injuries to the face between 2014 and 2019. Patients were suffering from ectropion and malposition of the eyelid axis. In all cases, we performed lateral transosseous canthopexy and FTSGing. RESULTS: Improved symmetry and complete eyelid closure were restored in all 5 patients. The following ophthalmological examinations showed resolved corneal erosions, as well as reduction of chemosis and epiphora. Further vision impairment was successfully prohibited. Surgical revision with FTSGing was required in 2 patients because of recurrence of unilateral lower eyelid retraction. CONCLUSIONS: Lateral transosseous canthopexy represents a suitable surgical method to durably correct eyelid malposition, ectropion, and incomplete lid closure in patients with severe scarring of the periorbital region after burns of the face. Early detection of patients at risk and timing of surgical intervention are of great importance.

Adipose-derived stromal cell therapy combined with a short course nonmyeloablative conditioning promotes long-term graft tolerance in vascularized composite allotransplantation.

The risks of chronic immunosuppression limit the utility of vascularized composite allotransplantation (VCA) as a reconstructive option in complex tissue defects. We evaluated a novel, clinically translatable, radiation-free conditioning protocol that combines anti-lymphocyte serum (ALS), tacrolimus, and cytotoxic T-lymphocyte-associated protein 4 immunoglobulin (CTLA4-Ig) with adipose-derived stromal cells (ASCs) to allow VCA survival without long-term systemic immunosuppression. Full-mismatched rat hind-limb-transplant recipients received tacrolimus (0.5 mg/kg) for 14 days and were assigned to 4 groups: controls (CTRL) received no conditioning; ASC-group received CTLA4-Ig (10 mg/kg body weight i.p. postoperative day [POD] 2, 4, 7) and donor ASCs (1 × 106 iv, POD 2, 4, 7, 15, 28); the ASC-cyclophosphamide (CYP)-group received CTLA4-Ig, ASC plus cyclophosphamide (50 mg/kg ip, POD 3); the ASC-ALS-group received CTLA4-Ig, ASCs plus ALS (500 µL ip, POD 1, 5). Banff grade III or 120 days were endpoints. ASCs suppressed alloresponse in vitro. Median rejection-free VCA survival was 28 days in CTRL (n = 7), 34 in ASC (n = 6), and 27.5 in ASC-CYP (n = 4). In contrast, ASC-ALS achieved significantly longer, rejection-free VCA survival in 6/7 animals (86%), with persistent mixed donor-cell chimerism, and elevated systemic and allograft skin Tregs , with no signs of acute cellular rejection. Taken together, a regimen comprised of short-course tacrolimus, repeated CTLA4-Ig and ASC administration, combined with ALS, promotes long-term VCA survival without chronic immunosuppression.

Adipose tissue and the vascularization of biomaterials: Stem cells, microvascular fragments and nanofat-a review.

Tissue defects in the human body after trauma and injury require precise reconstruction to regain function. Hence, there is a great demand for clinically translatable approaches with materials that are both biocompatible and biodegradable. They should also be able to adequately integrate within the tissue through sufficient vascularization. Adipose tissue is abundant and easily accessible. It is a valuable tissue source in regenerative medicine and tissue engineering, especially with regard to its angiogenic potential. Derivatives of adipose tissue, such as microfat, nanofat, microvascular fragments, stromal vascular fraction and stem cells, are commonly used in research, but also clinically to enhance the vascularization of implants and grafts at defect sites. In plastic surgery, adipose tissue is harvested via liposuction and can be manipulated in three ways (macro-, micro- and nanofat) in the operating room, depending on its ultimate use. Whereas macro- and microfat are used as a filling material for soft tissue injuries, nanofat is an injectable viscous extract that primarily induces tissue remodeling because it is rich in growth factors and stem cells. In contrast to microfat that adds volume to a defect site, nanofat has the potential to be easily combined with scaffold materials due to its liquid and homogenous consistency and is particularly attractive for blood vessel formation. The same is true for microvascular fragments that are easily isolated from adipose tissue through collagenase digestion. In preclinical animal models, it has been convincingly shown that these vascular fragments inosculate with host vessels and subsequently accelerate scaffold perfusion and host tissue integration. Adipose tissue is also an ideal source of stem cells. It yields larger quantities of cells than any other source and is easier to access for both the patient and doctor compared with other sources such as bone marrow. They are often used for tissue regeneration in combination with biomaterials. Adipose-derived stem cells can be applied unmodified or as single cell suspensions. However, certain pretreatments, such as cultivation under hypoxic conditions or three-dimensional spheroids production, may provide substantial benefit with regard to subsequent vascularization in vivo due to induced growth factor production. In this narrative review, derivatives of adipose tissue and the vascularization of biomaterials are addressed in a comprehensive approach, including several sizes of derivatives, such as whole fat flaps for soft tissue engineering, nanofat or stem cells, their secretome and exosomes. Taken together, it can be concluded that adipose tissue and its fractions down to the molecular level promote, enhance and support vascularization of biomaterials. Therefore, there is a high potential of the individual fat component to be used in regenerative medicine.

Heterotopic Transplantation of Allogeneic Vertical Rectus Abdominis Myocutaneous Flaps in Miniature Swine.

BACKGROUND: Vascularized composite tissue allotransplantation (VCA) opens new possibilities for reconstruction of complex tissue defects, including upper extremity and facial transplantation. The main challenges in VCA transplantation are the side effects of long-term immunosuppression and chronic graft rejection. Translational preclinical animal models are crucial for VCA research to improve clinical outcomes and to study underlying immunologic mechanisms. Herein, we describe a novel, large animal, non-bone-bearing VCA model in inbred, swine leukocyte antigen-typed miniature swine. METHODS: Transplantation of vertical rectus abdominis myocutaneous (VRAM) flaps was performed between fully swine leukocyte antigen-mismatched miniature swine. The flaps were transferred to the posterolateral aspect of the neck of recipients and anastomosed to the common carotid artery and internal jugular vein. Different immunosuppressive drug regimens were used. Clinical graft evaluation was performed daily, and punch biopsies were taken for histology. RESULTS: Ten VRAM transplants were performed. The mean ischemia time was 89.4 min (SD ± 47), mean pedicle length 7.5 cm (SD ± 2), mean venous diameter 2.5 mm (SD ± 0.4), and mean arterial diameter 2.2 mm (SD ± 0.3). Follow-up demonstrated good correlation between clinical appearance and progression of graft rejection confirmed by histologic assessment. Complications were intraoperative cardiac arrest in one recipient and one flap loss due to venous compromise. CONCLUSIONS: VRAM transplantation in miniature swine is an appropriate preclinical VCA model, with the advantage of good clinical and histologic correlation during the course of rejection, as well as easy access to the graft. The availability of inbred, haplotyped animals allows studies across different major histocompatibility complex barriers in a non-bone-bearing VCA.

Pharmacokinetics and Biodistribution of Tacrolimus after Topical Administration: Implications for Vascularized Composite Allotransplantation.

AIM: The high doses of oral tacrolimus (TAC) (1,2) necessary to prevent acute rejection (AR) after vascularized composite allotransplantation (VCA) are associated with systemic adverse effects. The skin is the most antigenic tissue in VCA and the primary target of AR. However, the short-term use of topical TAC (Protopic®), as an off-label adjunct to oral TAC, to treat AR episodes pro re nata (PRN), has yielded inconsistent results. There is lack of data on the pharmacokinetics and tissue distribution of topical TAC in VCA, that hampers our understanding of the reasons for unreliable efficacy. Toward this goal, we evaluated the ability of topical TAC to achieve high local tissue concentrations at the site of application with low systemic concentrations. MATERIALS AND METHODS: We assessed the pharmacokinetics and tissue distribution of topical TAC (Protopic®, 0.03%) after single or repeated topical application in comparison to those after systemic delivery in rats. Animals received a single topical application of TAC ointment (Group 1) or an intravenous (IV) injection of TAC (Group 2) at a dose of 0.5 mg/kg. In another experiment, animals received daily topical application of TAC ointment (Group 3), or daily intraperitoneal (IP) injection of TAC (Group 4) at a dose of 0.5 mg/kg for 7 days. TAC concentrations in blood and tissues were analyzed by Liquid Chromatography-Mass Spectrometry (LC/MS-MS). RESULTS: Following single topical administration, TAC was absorbed slowly with a Tmax of 4 h and an absolute bioavailability of 11%. The concentrations of TAC in skin and muscle were several folds higher than whole blood concentrations. Systemic levels remained subtherapeutic (< 3 ng/ml) with repeated once daily applications. CONCLUSION: Topical application of TAC ointment (Protopic®, 0.03%) at a dose of 0.5 mg/kg/day provided high concentrations in the local tissues with low systemic exposure. Repeated topical administration of TAC is well tolerated with no local or systemic adverse effects. This study confirms the feasibility of topical application of TAC for site specific graft immunosuppression and enables future applications in VCA.

Expression of Pancreatic Stone Protein is Unaffected by Trauma and Subsequent Surgery in Burn Patients.

BACKGROUND: Altered levels of pro-inflammatory markers secondary to trauma or surgery present a major problem to physicians in being prone to interfere with the clinical identification of infectious events. METHODS: Patients admitted to Zurich Burn Center between May 2015 and October 2018 with burns ≥10% total body surface area (TBSA) and without infection. Longitudinal analysis of the time course of PSP and routine inflammatory biomarkers [procalcitonin (PCT), C-reactive protein (CRP) and white blood cells (WBC)] over two days after (a) trauma with initial debridement and (b) subsequent burn surgeries was performed. The influence of TBSA, abbreviated burn severity index (ABSI), age and length of operation was investigated using a linear mixed effect regression model. RESULTS: Sixty-six patients (15 female) were included with a mean age of 45.5 ± 18.3 years, median TBSA of 22% (IQR 17) and mean ABSI score 6.8 ± 2.7. PSP was the only biomarker that showed no association with any of the baseline characteristics. Additionally, PSP serum levels did not change over time neither after the burn trauma (p = 0.832) nor after secondary procedures (p = 0.113), while PCT levels increased significantly after the trauma (p < 0.001). Similarly, CRP serum levels were elevated significantly after both trauma and surgery (p < 0.001), whereas WBC values demonstrated a significant decline after the trauma (p < 0.001). CONCLUSION: Established biomarkers (WBC, CRP and PCT) demonstrate decisive alterations after tissue destruction caused by burn injuries and subsequent surgical interventions. The robustness of PSP serum levels toward these inflammatory insults is a quality criterion for an upcoming sepsis biomarker.

The Significance of Vascular Alterations in Acute and Chronic Rejection for Vascularized Composite Allotransplantation.

Vascularized composite allotransplantation (VCA) has emerged as a useful reconstructive option for patients suffering from major tissue defects and functional deficits. While the technical feasibility has been optimized and more than 130 VCAs have been performed during the last two decades, hurdles such as acute and chronic allograft rejection, graft deterioration, and eventual functional impairment need to be addressed. Recently, chronic graft rejection and progressive failure have been linked to vascular alterations observed in the allografts. Graft vasculopathy (GV) may play a pivotal role in long-term graft deterioration. The understanding of the underlying pathophysiological processes and their initial triggers is of utmost importance in the prevention, attenuation, and therapy of GV. While there are reports on the etiology and development of GV in solid organ transplantation, there are limited data with respect to chronic rejection and GV in the realm of VCA. Nevertheless, recent reports from long-term VCA recipients suggest that GV could truly jeopardize allografts in the follow-up evaluation. Chronic rejection and GV include different entities and might have different pathways in distinct organs. Herein, we reviewed the current literature on vascular changes during both acute and chronic allograft rejection, with a focus on their clinical and translational significance for VCA.

Looking the World in the Face: The Benefits and Challenges of Facial Transplantation for Blind Patients

Total bilateral blindness in the setting of facial transplantation is a controversial matter. Some transplant teams exclude these candidates, while others accept them onto their facial transplant waiting list. Using 3 cases, the clinical and ethical complexity of total bilateral blindness is explored. Guidance (medical, psychological, and social) for total bilateral blindness as both an inclusion and exclusion criterion is provided, with the stipulation that total bilateral blindness should not be an automatic exclusion criterion for facial transplantation. Additionally, guidance for corneal transplant in facial transplant candidates is discussed. Suggestions for posttransplant disability assistance for patients with total bilateral blindness are also provided.

Complications After Cosmetic Surgery Tourism.

Background: Cosmetic surgery tourism characterizes a phenomenon of people traveling abroad for aesthetic surgery treatment. Problems arise when patients return with complications or need of follow-up care. Objectives: To investigate the complications of cosmetic surgery tourism treated at our hospital as well as to analyze arising costs for the health system. Methods: Between 2010 and 2014, we retrospectively included all patients presenting with complications arising from cosmetic surgery abroad. We reviewed medical records for patients' characteristics including performed operations, complications, and treatment. Associated cost expenditure and Diagnose Related Groups (DRG)-related reimbursement were analyzed. Results: In total 109 patients were identified. All patients were female with a mean age of 38.5 ± 11.3 years. Most procedures were performed in South America (43%) and Southeast (29.4%) or central Europe (24.8%), respectively. Favored procedures were breast augmentation (39.4%), abdominoplasty (11%), and breast reduction (7.3%). Median time between the initial procedure abroad and presentation was 15 days (interquartile range [IQR], 9) for early, 81.5 days (IQR, 69.5) for midterm, and 4.9 years (IQR, 9.4) for late complications. Main complications were infections (25.7%), wound breakdown (19.3%), and pain/discomfort (14.7%). The majority of patients (63.3%) were treated conservatively; 34.8% became inpatients with a mean hospital stay of 5.2 ± 3.8 days. Overall DRG-related reimbursement premiums approximately covered the total costs. Conclusions: Despite warnings regarding associated risks, cosmetic surgery tourism has become increasingly popular. Efficient patients' referral to secondary/tertiary care centers with standardized evaluation and treatment can limit arising costs without imposing a too large burden on the social healthcare system. Level of Evidence: 4.

Premise and promise of mesenchymal stem cell-based therapies in clinical vascularized composite allotransplantation.

PURPOSE OF REVIEW: Over the past decade, clinical vascularized composite allotransplantation (VCA) has enabled functional and quality of life restoration in a wide range of indications secondary to devastating tissue loss. However, the spectre of toxicity and long-term complications of chronic immunosuppression has curtailed the momentum of VCA. This study summarizes the literature evidence behind successful mesenchymal stem cell (MSC)-based cell therapies highlighting their multipronged immunomodulatory, restorative and regenerative characteristics with special emphasis towards VCA applications. RECENT FINDINGS: Experimental and clinical studies in solid organs and VCA have confirmed that MSCs facilitate immunosuppression-free allograft survival or tolerance, stimulate peripheral nerve regeneration, attenuate ischaemia-reperfusion injury, and improve tissue healing after surgery. It has been hypothesized that MSC-induced long-term operational tolerance in experimental VCA is mediated by induction of mixed donor-specific chimerism and regulatory T-cell mechanisms. All these characteristics of MSCs could thus help expand the scope and clinical feasibility of VCA. SUMMARY: Cellular therapies, especially those focusing on MSCs, are emerging in solid organ transplantation including VCA. Although some clinical trials have begun to assess the effects of MSCs in solid organ transplantation, much scientific domain remains uncharted, especially for VCA.

Bone marrow-derived mesenchymal stromal cells improve vascular regeneration and reduce leukocyte-endothelium activation in critical ischemic murine skin in a dose-dependent manner.

BACKGROUND AIMS: Stem cells participate in vascular regeneration following critical ischemia. However, their angiogenic and remodeling properties, as well as their role in ischemia-related endothelial leukocyte activation, need to be further elucidated. Herein, we investigated the effect of bone marrow-derived mesenchymal stromal cells (BM-MSCs) in a critically ischemic murine skin flap model. METHODS: Groups received either 1 × 10(5), 5 × 10(5), or 1 × 10(6) BM-MSCs or cell-free conditioned medium (CM). Controls received sodium chloride. Intravital fluorescence microscopy was performed for morphological and quantitative assessment of micro-hemodynamic parameters over 12 days. RESULTS: Tortuosity and diameter of conduit-arterioles were pronounced in the MSC groups (P < 0.01), whereas vasodilation was shifted to the end arteriolar level in the CM group (P < 0.01). These effects were accompanied by angiopoietin-2 expression. Functional capillary density and red blood cell velocity were enhanced in all treatment groups (P < 0.01). Although a significant reduction of rolling and sticking leukocytes was observed in the MSC groups with a reduction of diameter in postcapillary venules (P < 0.01), animals receiving CM exhibited a leukocyte-endothelium interaction similar to controls. This correlated with leukocyte common antigen expression in tissue sections (P < 0.01) and p38 mitogen-activated protein kinase expression from tissue samples. Cytokine analysis from BM-MSC culture medium revealed a 50% reduction of pro-inflammatory cytokines (interleukin [IL]-1ß, IL-6, IL-12, tumor necrosis factor-α, interferon-γ) and chemokines (keratinocyte chemoattractant, granulocyte colony-stimulating factor) under hypoxic conditions. DISCUSSION: We demonstrated positive effects of BM-MSCs on vascular regeneration and modulation of endothelial leukocyte adhesion in critical ischemic skin. The improvements after MSC application were dose-dependent and superior to the use of CM alone.

Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) for the treatment of bladder voiding dysfunction.

PURPOSE: Bladder outflow obstruction (BOO) is common in the elderly and can result in bladder voiding dysfunction (BVD) due to severe bladder muscle damage. The goal of this research was to evaluate the use of adult stem cells for the treatment of BVD due to decreased muscle contractility in a rat model. MATERIALS AND METHODS: Adipose-derived stem cells (ADSCs) and muscle precursor cells (MPCs) were harvested from male Lewis rats and expanded in culture. BOO was induced by tying a suture around the urethra. Six weeks after obstruction, the development of BVD was confirmed by cystometric analysis in conscious rats, histology and molecular investigations. Injection of ADSCs or MPCs into the bladder wall and synchronous deligation was performed 6 weeks after the obstruction. After stem-cell treatment, morphological and functional changes were assessed. Age-matched rats and animals without cellular therapy but deligation-only served as controls. RESULTS: Voiding pressures decreased progressively 6 weeks after obstruction with increased bladder capacities. Structural changes of the detrusor muscle occurred during the time of obstruction with an increased connective tissue-to-smooth muscle ratio and decreased SMA/smoothelin expression. After stem-cell injection, improved voiding pressures and voiding volumes were observed together with recovered tissue architecture. RT-PCR and Western blotting showed an up-regulation of important contractile proteins. CONCLUSIONS: We established a reliable model for BVD and demonstrated that ADSCs and MPCs can prevent pathophysiological remodelling and provide regenerated bladder tissue and function.

Botulinum toxin A and B raise blood flow and increase survival of critically ischemic skin flaps.

BACKGROUND: Botulinum toxin (BTX) A and B are commonly used for aesthetic indications and in neuromuscular disorders. New concepts seek to prove efficacy of BTX for critical tissue perfusion. Our aim was to evaluate BTX A and B in a mouse model of critical flap ischemia for preoperative and intraoperative application. METHODS: BTX A and B were applied on the vascular pedicle of an axial pattern flap in mice preoperatively or intraoperatively. Blood flow, tissue oxygenation, tissue metabolism, flap necrosis rate, apoptosis assay, and RhoA and eNOS expression were endpoints. RESULTS: Blood-flow measurements 1 d after the flap operation revealed a significant reduction to 53% in the control group, while flow was maintained or increased in all BTX groups (103%-129%). Over 5 d all BTX groups showed significant increase in blood flow to 166-187% (P < 0.01). Microdialysis revealed an increase of glucose and reduced lactate/pyruvate ratio and glycerol levels in the flap tissue of all BTX groups. This resulted in significantly improved tissue survival in all BTX groups compared with the control group (62% ± 10%; all P < 0.01): BTX A preconditioning (84% ± 5%), BTX A application intraoperatively (88% ± 4%), BTX B preconditioning (91% ± 4%), and intraoperative BTX B treatment (92% ± 5%). This was confirmed by TUNEL assay. Immunofluorescence demonstrated RhoA and eNOS expression in BTX groups. All BTX applications were similarly effective, despite pharmacologic dissimilarities and different timing. CONCLUSIONS: In conclusion, we were able to show on a vascular, tissue, cell, and molecular level that BTX injection to the feeding arteries supports flap survival through ameliorated blood flow and oxygen delivery.

Site-specific immunosuppression in vascularized composite allotransplantation: prospects and potential.

Skin is the most immunogenic component of a vascularized composite allograft (VCA) and is the primary trigger and target of rejection. The skin is directly accessible for visual monitoring of acute rejection (AR) and for directed biopsy, timely therapeutic intervention, and management of AR. Logically, antirejection drugs, biologics, or other agents delivered locally to the VCA may reduce the need for systemic immunosuppression with its adverse effects. Topical FK 506 (tacrolimus) and steroids have been used in clinical VCA as an adjunct to systemic therapy with unclear beneficial effects. However, there are no commercially available topical formulations for other widely used systemic immunosuppressive drugs such as mycophenolic acid, sirolimus, and everolimus. Investigating the site-specific therapeutic effects and efficacy of systemically active agents may enable optimizing the dosing, frequency, and duration of overall immunosuppression in VCA with minimization or elimination of long-term drug-related toxicity.

Changes in coagulation and temperature management in burn patients - A survey of burn centers in Switzerland, Austria and Germany.

BACKGROUND: Severely burned patients suffer from both coagulopathy and hypothermia, with a lack of international consensus and appropriate treatment guidelines. This study examines recent developments and trends in coagulation and temperature management in European burn centers. METHODS: A survey was sent to burn centers in Switzerland, Austria and Germany in 2016 and again in 2021. The analysis was performed using descriptive statistics, with categorical data reported in absolute numbers (n) and percentages (%) and numerical data reported as mean and standard deviation. RESULTS: The rate of completed questionnaires was 84 % (16 of 19 questionnaires) in 2016 and 91 % (21 of 22 questionnaires) in 2021. The number of global coagulation tests performed has decreased over the observation period in favor of single factor determination and bed-side point-of-care coagulation tests. This has also led to increased administration of single factor concentrates in therapy. Although many centers had a defined treatment protocol for hypothermia in 2016, coverage increased such that in 2021 all centers surveyed had such a protocol. The body temperature was measured more consistently in 2021; thus, hypothermia was more actively sought, detected and treated. CONCLUSION: A point-of-care guided, factor-based coagulation management and the maintenance of normothermia have gained importance in the care of burn patients in recent years.

Serum Selenium-Binding Protein 1 (SELENBP1) in Burn Injury: A Potential Biomarker of Disease Severity and Clinical Course.

Oxidative stress, systemic inflammation, and metabolic derangements are hallmarks of burn pathophysiology. Severely burned patients are highly susceptible to infectious complications. Selenium-binding protein 1 (SELENBP1) modulates intracellular redox homeostasis, and elevated serum concentrations have been associated with adverse clinical outcomes in trauma patients. We hypothesized that serum SELENBP1 at hospital admission and during hospitalization may constitute a meaningful biomarker of disease severity and the clinical course in burn injury, with pulmonary infection as primary endpoint. To this end, we conducted a prospective cohort study that included 90 adult patients admitted to the Burn Center of the University Hospital Zurich, Switzerland. Patients were treated according to the local standard of care, with high-dose selenium supplementation during the first week. Serum SELENBP1 was determined at nine time-points up to six months postburn and the data were correlated to clinical parameters. SELENBP1 was initially elevated and rapidly declined within the first day. Baseline SELENBP1 levels correlated positively with the Abbreviated Burn Severity Index (ABSI) (R = 0.408; p < 0.0001). In multiple logistic regression, a higher ABSI was significantly associated with increased pulmonary infection risk (OR, 14.4; 95% CI, 3.2-88.8; p = 0.001). Similarly, baseline SELENBP1 levels constituted a novel but less accurate predictor of pulmonary infection risk (OR, 2.5; 95% CI, 0.7-8.9; p = 0.164). Further studies are needed to explore the additional value of serum SELENBP1 when stratifying patients with respect to the clinical course following major burns and, potentially, for monitoring therapeutic measures aimed at reducing tissue damage and oxidative stress.

Distinct microhemodynamic efficacy of arteriogenesis and angiogenesis in critically ischemic skin flaps.

Angiogenesis and arteriogenesis are regenerative vascular mechanisms dedicated to cope with critical ischemia after the interruption of the anatomical axial blood supply. The aim of the present study was to visualize, quantify and monitor the orchestration of these mechanisms and their microhemodynamic efficacy. A murine skin flap model was used that allowed for repetitive investigation of identical vascular structures by intravital microscopy. In the conduit arterioles, diameter and relative length increased to 133 ± 20% and 260 ± 80% over 7 days, respectively (both P<0.01), which reduced vascular resistance in this segment to 82 ± 35%. After 1 week, a peak in accumulation of activated leukocytes could be observed in the postcapillary venules (P<0.01) without relevant hemodynamic changes. Thereafter, the arteriolar remodeling was replaced by angiogenesis. Functional capillary density was increased to 141 ± 10% (P<0.01) and capillary diameter to 123 ± 6% (P<0.01) after 14 days. Both mechanisms of vascular regeneration were associated with increases in the capillary perfusion index, to 194 ± 42% (P<0.05) after 7 days and 366 ± 21% after 14 days (P>0.01). Immunohistochemical analysis revealed a correlation of arteriogenesis with eNOS upregulation and of angiogenesis with VEGF upregulation in the corresponding vessels. In conclusion, arteriogenesis was the initial regenerative mechanism leading to arteriolar remodeling, reduction in vascular resistance, and increase in capillary perfusion over the first 7 days. Thereafter, capillary perfusion was improved by angiogenesis in terms of an increase in functional capillary density.

Paracrine effects of mesenchymal stem cells enhance vascular regeneration in ischemic murine skin.

New theories on the regeneration of ischemic vasculature have emerged indicating a pivotal role of adult stem cells. The aim of this study was to investigate homing and hemodynamic effects of circulating bone marrow-derived mesenchymal stem cells (MSCs) in a critically ischemic murine skin flap model. Bone marrow-derived mesenchymal stem cells (Lin(-)CD105(+)) were harvested from GFP(+)-donor mice and transferred to wildtype C57BL/6 mice. Animals receiving GFP(+)-fibroblasts served as a control group. Laser scanning confocal microscopy and intravital fluorescence microscopy were used for morphological analysis, monitoring and quantitative assessment of the stem cell homing and microhemodynamics over two weeks. Immunohistochemical staining was performed for GFP, eNOS, iNOS, VEGF. Tissue viability was analyzed by TUNEL-assay. We were able to visualize perivascular homing of MSCs in vivo. After 4 days, MSCs aligned along the vascular wall without undergoing endothelial or smooth muscle cell differentiation during the observation period. The gradual increase in arterial vascular resistance observed in the control group was abolished after MSC administration (P<0.01). At capillary level, a strong angiogenic response was found from day 7 onwards. Functional capillary density was raised in the MSC group to 197% compared to 132% in the control group (P<0.01). Paracrine expression of VEGF and iNOS, but not eNOS could be shown in the MSC group but not in the controls. In conclusion, we demonstrated that circulating bone marrow-derived MSCs home to perivascular sites in critically ischemic tissue, exhibits paracrine function and augment microhemodynamics. These effects were mediated through arteriogenesis and angiogenesis, which contributed to vascular regeneration.

Evolution of a concept with enzymatic debridement and autologous in situ cell and platelet-rich fibrin therapy (BroKerF).

BACKGROUND: Deep partial-thickness burns are traditionally treated by tangential excision and split thickness skin graft (STSG) coverage. STSGs create donor site morbidity and increase the wound surface in burn patients. Herein, we present a novel concept consisting of enzymatic debridement of deep partial-thickness burns followed by co-delivery of autologous keratinocyte suspension and plated-rich fibrin (PRF) or fibrin glue. MATERIAL AND METHODS: In a retrospective case study, patients with deep partial-thickness burns treated with enzymatic debridement and autologous cell therapy combined with PRF or fibrin glue (BroKerF) between 2017 and 2018 were analysed. BroKerF was applied to up to 15% total body surface area (TBSA); larger injuries were combined with surgical excision and skin grafting. Exclusion criteria were age <18 or >70 years, I°, IIa°-only, III° burns and loss of follow-up. RESULTS: A total of 20 patients with burn injuries of 16.8% ± 10.3% TBSA and mean Abbreviated Burn Severity Score 5.45 ± 1.8 were identified. Of the patients, 65% (n = 13) were treated with PRF, while 35% (n = 7) were treated with fibrin glue. The mean area treated with BroKerF was 7.5% ± 0.05% TBSA, mean time to full epithelialization was 21.06 ± 9.2 days and mean hospitalization time was 24.7 ± 14.4 days. Of the patients, 35% (n = 7) needed additional STSG, 43% (n = 3) of whom had biopsy-proven wound infections. CONCLUSION: BroKerF is an innovative treatment strategy, which, in our opinion, will show its efficacy when higher standardization is achieved. The combination of selective debridement and autologous skin cells in a fibrin matrix combines regenerative measures for burn treatment. LAY SUMMARY: Patients suffering from large burn wounds often require the use of large skin grafts to bring burned areas to heal. Before the application of skin grafts, the burned skin must be removed either by surgery or using enzymatic agents. In this article, we describe a method where small areas of skin are taken and skin cells are extracted and sprayed on wound areas that were treated with an enzymatic agent. The cells are held in place by a substance extracted from patients' blood (PRF) that is sprayed on the wound together with the skin cells. We believe this technique can be helpful to reduce the need of skin grafts in burned patients and improve the healing process.