Altered early immune response after fracture and traumatic brain injury.

Introduction: Clinical and preclinical data suggest accelerated bone fracture healing in subjects with an additional traumatic brain injury (TBI). Mechanistically, altered metabolism and neuro-endocrine regulations have been shown to influence bone formation after combined fracture and TBI, thereby increasing the bone content in the fracture callus. However, the early inflammatory response towards fracture and TBI has not been investigated in detail so far. This is of great importance, since the early inflammatory phase of fracture healing is known to be essential for the initiation of downstream regenerative processes for adequate fracture repair. Methods: Therefore, we analyzed systemic and local inflammatory mediators and immune cells in mice which were exposed to fracture only or fracture + TBI 6h and 24h after injury. Results: We found a dysregulated systemic immune response and significantly fewer neutrophils and mast cells locally in the fracture hematoma. Further, local CXCL10 expression was significantly decreased in the animals with combined trauma, which correlated significantly with the reduced mast cell numbers. Discussion: Since mast cells and mast cell-derived CXCL10 have been shown to increase osteoclastogenesis, the reduced mast cell numbers might contribute to higher bone content in the fracture callus of fracture + TBI mice due to decreased callus remodeling.

Diaphyseal Femur Fractures in Children and Adolescents-Opportunities and Limitations of the ESIN Technique.

Background: Elastic stable intramedullary nailing (ESIN) is the gold standard for non-overweight children aged 6−12 years. However, the complication rate using elastic stable intramedullary nailing is considerably high. Nevertheless, the question arises of whether the indication for elastic stable intramedullary nailing therapy can be extended and which factors must be taken into account when determining the indication. Methods: A retrospective chart review of patients <18 years admitted with diaphyseal femur fracture at a Level I Trauma Center in Germany between 2005 and 2017 was performed. In total, 118 patients were included. For the classification of femur fractures in children, the AO Pediatric Comprehensive Classification of Long-Bone Fractures (AO-PCCF) was applied. Results: Simple oblique fractures (32-D/5.1) occurred in most of the patients. Patients with simple oblique fractures were significantly younger compared to patients with simple transverse (32-D/4.1) or multifragmentary (32-D/5.2) fracture type according to the AO Pediatric Comprehensive Classification of Long-Bone Fractures. Most patients were treated with elastic stable intramedullary nailing (68 patients, 58%). Although children treated with elastic stable intramedullary nailing were older than those treated conservatively (25%, n = 29, mean age 1.5, median age 1.0), the children in the elastic stable intramedullary nailing group were comparatively young (range 1−12 years, mean age 5.4, median age 5). A total of 32 children below the age of 6 years were treated with elastic stable intramedullary nailing. Complications were more frequent in patients with overhead extension (50%) compared to conservative treatment with a spica cast (17%) or elastic stable intramedullary nailing (15%). Conclusions: Elastic stable intramedullary nailing therapy was associated with a low complication rate and was, therefore, a safe and frequently used treatment strategy in diaphyseal femur fractures with satisfactory results, even though the age groups were expanded in favor of younger patients.

Cardiac alterations following experimental hip fracture - inflammaging as independent risk factor.

Background: Cardiac injuries following trauma are associated with a worse clinical outcome. So-called trauma-induced secondary cardiac injuries have been recently described after experimental long bone fracture even in absence of direct heart damage. With the progressive aging of our society, the number of elderly trauma victims rises and therefore the incidence of hip fractures increases. Hip fractures were previously shown to be associated with adverse cardiac events in elderly individuals, which have mainly been attributed to pre-conditioned cardiac diseases. The aim of the present study was to investigate the effect of hip fractures on the heart in healthy young and middle-aged mice. Materials and Methods: Young (12-week-old) and middle-aged (52-week-old) female C57BL/6 mice either received an intramedullary stabilized proximal femur fracture or sham treatment. The observation time points included 6 and 24 h. Systemic levels of pro-inflammatory mediators as well as local inflammation and alterations in myocardial structure, metabolism and calcium homeostasis in left ventricular tissue was analyzed following hip fracture by multiplex analysis, RT-qPCR and immunohistochemistry. Results: After hip fracture young and middle-aged mice showed increased systemic IL-6 and KC levels, which were significantly elevated in the middle-aged animals. Furthermore, the middle-aged mice showed enhanced myocardial expression of HMGB1, TLR2/4, TNF, IL1ß and NLRP3 as well as considerable alterations in the myocardial expression of glucose- and fatty acid transporters (HFABP, GLUT4), calcium homeostasis proteins (SERCA) and cardiac structure proteins (desmin, troponin I) compared to the young animals following hip fracture. Conclusion: Young and middle-aged mice showed local myocardial alterations, which might predispose for the development of secondary cardiac injury following hip fracture. Age and the age-associated phenomenon of 'inflammaging' seemed to be an independent risk factor aggravating and accelerating cardiac alterations following hip fracture.

Olecranon fractures in children: treatment of a rare entity.

BACKGROUND: Olecranon fractures are a rare entity in children. The classification and treatment strategies are still discussed controversially. METHODS: A retrospective chart review of all patients < 17 years admitted with an olecranon fracture at a Level I Trauma Center between 2005 and 2017 has been performed. 46 subjects were included. For classification of olecranon fractures in children the AO Pediatric Comprehensive Classification of Long Bone Fractures (AO-PCCF) was used. Fractures were classified along the fracture line, dislocation, joint involvement and affection of the apophysis. For statistical analysis, a comparison of two groups was performed using Student t test. One-way ANOVA and Tukey's multiple comparison test was used to identify differences between more than two groups. For all analysis p ≤ 0.05 was considered statistically significant. RESULTS: The mean age of the children was 8.5 years (2-16 years). Most children were treated with a conservative therapy (n = 29, 63.0%). 17 patients (36.9%) underwent osteosynthesis (plate or tension band wiring) of which three were initially treated with a conservative therapeutic approach. Children with operative treatment were significantly older compared to children treated conservatively. Interestingly, all patients with luxation were characterized by an oblique fracture line, one of them extraarticular, three intraarticular. CONCLUSION: Taken together, this study analyzed one of the largest selections of pediatric patients with olecranon fracture in regard to fracture type and treatment strategy. Based on the assumption that treatment strategies follow a fracture classification, a consistent classification method is needed which should take into account fracture morphology and localization, as considered by the AO-PCCF, and the dislocation as measured by Braque. Surgical treatment is needed in case of dislocation ≥ 5 mm, intra-articular fractures, instable fracture conditions caused by the fracture line, open fractures and the affection of the apophysis. Otherwise, the conservative treatment shows insufficient results in the elbow mobility. The reliable choice of treatments based on our classification was mirrored by the very low rate of conversion of treatment strategies. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Radial head and neck fractures in children and adolescents.

Background: Radial head and neck fractures are a rare entity in pediatric patients. Due to specific characteristics of the blood supply and remodeling potential, the correct diagnosis and initiation of appropriate therapy are crucial for the outcome. Therefore, the aim of this retrospective observational study was to present the outcome of a series of pediatric patients with radial head and neck fractures. Methods: In total, 67 pediatric and adolescent patients with a fracture of the proximal radius admitted to a Level I Trauma Center (Germany) between 2005 and 2017 were included in this retrospective observational study. Patients were stratified in accordance with the classification of Judet modified by Metaizeau and with the AO Pediatric Comprehensive Classification of Long Bone Fractures (AO-PCCF). Results: AO-PCCF fracture type of proximal radius was age-dependent. Epiphyseal axis angle and displacement angle correlated significantly. Fractures treated with a K-wire or embrochage centromedullaire elastique stable (ECMES) presented higher displacement angles. The duration of callus formation was dependent on both the reduction technique and fracture displacement. The range of motion after complete fracture consolidation was dependent on the Metaizeau type and reduction technique but independent of the duration of immobilization and physical therapy. Conclusion and clinical relevance: Both the epiphyseal axis and displacement angle are suitable for measuring the initial fracture displacement in radiographs. Consolidation is dependent on the initial displacement and reduction technique. The mini-open approach leads to a worse reduction result, later callus formation, and a more restricted range of motion in terms of pronation. Furthermore, the range of motion at follow-up is independent of the duration of immobilization and physiotherapy.

Laboratory Markers in the Management of Pediatric Polytrauma: Current Role and Areas of Future Research.

Severe trauma is the most common cause of mortality in children and is associated with a high socioeconomic burden. The most frequently injured organs in children are the head and thorax, followed by the extremities and by abdominal injuries. The efficient and early assessment and management of these injuries is essential to improve patients' outcome. Physical examination as well as imaging techniques like ultrasound, X-ray and computer tomography are crucial for a valid early diagnosis. Furthermore, laboratory analyses constitute additional helpful tools for the detection and monitoring of pediatric injuries. Specific inflammatory markers correlate with post-traumatic complications, including the development of multiple organ failure. Other laboratory parameters, including lactate concentration, coagulation parameters and markers of organ injury, represent further clinical tools to identify trauma-induced disorders. In this review, we outline and evaluate specific biomarkers for inflammation, acid-base balance, blood coagulation and organ damage following pediatric polytrauma. The early use of relevant laboratory markers may assist decision making on imaging tools, thus contributing to minimize radiation-induced long-term consequences, while improving the outcome of children with multiple trauma.

Increased Presence of Complement Factors and Mast Cells in Alveolar Bone and Tooth Resorption.

Periodontitis is the inflammatory destruction of the tooth-surrounding and -supporting tissue, resulting at worst in tooth loss. Another locally aggressive disease of the oral cavity is tooth resorption (TR). This is associated with the destruction of the dental mineralized tissue. However, the underlying pathomechanisms remain unknown. The complement system, as well as mast cells (MCs), are known to be involved in osteoclastogenesis and bone loss. The complement factors C3 and C5 were previously identified as key players in periodontal disease. Therefore, we hypothesize that complement factors and MCs might play a role in alveolar bone and tooth resorption. To investigate this, we used the cat as a model because of the naturally occurring high prevalence of both these disorders in this species. Teeth, gingiva samples and serum were collected from domestic cats, which had an appointment for dental treatment under anesthesia, as well as from healthy cats. Histological analyses, immunohistochemical staining and the CH-50 and AH-50 assays revealed increased numbers of osteoclasts and MCs, as well as complement activity in cats with TR. Calcifications score in the gingiva was highest in animals that suffer from TR. This indicates that MCs and the complement system are involved in the destruction of the mineralized tissue in this condition.

Early myocardial damage (EMD) and valvular dysfunction after femur fracture in pigs.

Musculoskeletal injuries are the most common reason for surgery in severely injured patients. In addition to direct cardiac damage after physical trauma, there is rising evidence that trauma induces secondary cardiac structural and functional damage. Previous research associates hip fractures with the appearance of coronary heart disease: As 25% of elderly patients developed a major adverse cardiac event after hip fracture. 20 male pigs underwent femur fracture with operative stabilization via nailing (unreamed, reamed, RIA I and a new RIA II; each group n = 5). Blood samples were collected 6 h after trauma and the concentration of troponin I and heart-type fatty acid binding protein (HFABP) as biomarkers for EMD were measured. At baseline and 6 h after trauma, transesophageal ECHO (TOE) was performed; and invasive arterial and left ventricular blood pressure were measured to evaluate the cardiac function after femur fracture. A systemic elevation of troponin I and HFABP indicate an early myocardial damage after femur fracture in pigs. Furthermore, various changes in systolic (ejection fraction and cardiac output) and diastolic (left ventricular end-diastolic pressure, mitral valve deceleration time and E/A ratio) parameters illustrate the functional impairment of the heart. These findings were accompanied by the development of valvular dysfunction (pulmonary and tricuspid valve). To the best of our knowledge, we described for the first time the development of functional impairment of the heart in the context of EMD after long bone fracture in pigs. Next to troponin and HFABP elevation, alterations in the systolic and diastolic function occurred and were accompanied by pulmonary and tricuspid valvular insufficiency. Regarding EMD, none of the fracture stabilization techniques (unreamed nailing, reaming, RIA I and RIA II) was superior.

Systemic and local cardiac inflammation after experimental long bone fracture, traumatic brain injury and combined trauma in mice.

BACKGROUND: Trauma is the leading cause of death and disability worldwide, especially in the young population. Cardiac injuries are an independent predictor for a poor overall outcome after trauma. The aim of the present study was to analyze systemic inflammation as well as local cardiac inflammation after experimental limb-, neuro- and combined trauma in mice. METHODS: Male C57BL/6 mice received either a closed tibia fracture (Fx), isolated traumatic brain injury (TBI) or a combination of both (Fx â€‹+ â€‹TBI). Control animals underwent sham procedure. After 6 and 24 â€‹h, systemic levels of inflammatory mediators were analyzed, respectively. Locally, cardiac inflammation and cardiac structural alterations were investigated in left ventricular tissue of mice 6 and 24 â€‹h after trauma. RESULTS: Mice showed enhanced systemic inflammation after combined trauma, which was manifested by increased levels of KC, MCP-1 and G-CSF. Locally, mice exhibited increased expression of inflammatory cytokines (IL-1ß, TNF) in heart tissue, which was probably mediated via toll-like receptor (TLR) signaling. Furthermore, mice demonstrated a redistribution of connexin 43 in cardiac tissue, which appeared predominantly after combined trauma. Besides inflammation and structural cardiac alterations, expression of glucose transporter 4 (GLUT4) mRNA was increased in the heart early after TBI and after combination of TBI and limb fracture, indicating a modification of energy metabolism. Early after combination of TBI and tibia fracture, nitrosative stress was increased, manifested by elevation of nitrotyrosine in cardiac tissue. Finally, mice showed a trend of increased systemic levels of cardiac troponin I and heart-fatty acid binding protein (HFABP) after combined trauma, which was associated with a significant decrease of troponin I and HFABP mRNA expression in cardiac tissue after TBI and combination of TBI and limb fracture. CONCLUSION: Mice exhibited early cardiac alterations as well as alterations in cardiac glucose transporter expression, indicating a modification of energy metabolism, which might be linked to increased systemic- and local cardiac inflammation after limb-, neuro- and combined trauma. These cardiac alterations might predispose individuals for secondary cardiac damage after trauma that might compromise cardiac function after TBI and long bone fracture. TRANSLATIONAL POTENTIAL STATEMENT: Injuries to the head and extremities frequently occur after severe trauma. In our study, we analyzed the effects of closed tibia fracture, isolated TBI, and the combination of both injuries with regard to the development of post-traumatic secondary cardiac injuries.

Trauma, a Matter of the Heart-Molecular Mechanism of Post-Traumatic Cardiac Dysfunction.

Trauma remains a leading global cause of mortality, particularly in the young population. In the United States, approximately 30,000 patients with blunt cardiac trauma were recorded annually. Cardiac damage is a predictor for poor outcome after multiple trauma, with a poor prognosis and prolonged in-hospitalization. Systemic elevation of cardiac troponins was correlated with survival, injury severity score, and catecholamine consumption of patients after multiple trauma. The clinical features of the so-called "commotio cordis" are dysrhythmias, including ventricular fibrillation and sudden cardiac arrest as well as wall motion disorders. In trauma patients with inappropriate hypotension and inadequate response to fluid resuscitation, cardiac injury should be considered. Therefore, a combination of echocardiography (ECG) measurements, echocardiography, and systemic appearance of cardiomyocyte damage markers such as troponin appears to be an appropriate diagnostic approach to detect cardiac dysfunction after trauma. However, the mechanisms of post-traumatic cardiac dysfunction are still actively being investigated. This review aims to discuss cardiac damage following trauma, focusing on mechanisms of post-traumatic cardiac dysfunction associated with inflammation and complement activation. Herein, a causal relationship of cardiac dysfunction to traumatic brain injury, blunt chest trauma, multiple trauma, burn injury, psychosocial stress, fracture, and hemorrhagic shock are illustrated and therapeutic options are discussed.

Early myocardial damage (EMD) and valvular insufficiency result in impaired cardiac function after multiple trauma in pigs.

One third of multiple trauma patients present abnormal echocardiographic (ECHO) findings. Therefore, ECHO diagnostic after trauma is indicated in case of hemodynamic instability, shock, after chest trauma and after cardiac arrest. 20 male pigs underwent multiple trauma. Blood samples were collected 4 and 6 h after trauma and concentrations of heart-type fatty acid binding protein (HFABP) as a biomarker for EMD were measured. Myocardial damage was evaluated by scoring Hematoxylin-Eosin stained sections. At baseline, 3 and 6 h after trauma, transesophageal ECHO (TOE) was performed, invasive arterial and left ventricular blood pressure were measured to evaluate the cardiac function after multiple trauma. Systemic HFABP concentrations were elevated, furthermore heart injury score in multiple trauma animals was increased determining EMD. A significant decrease of blood pressure in combination with a consecutive rise of heart frequency was observed. Ongoing depression of mean arterial pressure and diastolic blood pressure were accompanied by changes in ECHO-parameters indicating diastolic and systolic dysfunction. Furthermore, a valvular dysfunction was detected. In this study complex myocardial and valvular impairment after multiple trauma in pigs has been observed. Therefore, detection of EMD and progressive valvular dysfunction might be crucial and therapeutically relevant.

Reaming of femoral fractures with different reaming irrigator aspirator systems shows distinct effects on cardiac function after experimental polytrauma.

Cardiac injuries are recorded after multiple trauma and are associated with a poor patient outcome. Reaming prior to locked intramedullary nailing is a frequently used technique to stabilize femoral diaphysis fractures. However, in polytraumatized patients, complications such as fat emboli and acute respiratory distress syndrome have been associated with reaming. The reaming irrigator aspirator (RIA) system provides concomitant irrigation and suction of the intramedullary contents, and should, therefore, reduce reaming-associated complications. The aim of the study was to investigate cardiac function after multiple trauma with regard to two different RIA devices (RIAI vs RIAII). 15 male pigs were included in the study. Pigs received either sham treatment or multiple trauma (chest trauma, femur fracture, liver laceration, and hemorrhagic shock), followed by intramedullary nailing after reaming with either the RIAI or RIAII system (RIAII: reduced diameter of the reamer, improved control of irrigation and suction). Cardiac function was assessed by transesophageal echocardiography and systemic inflammation as well as local cardiac damage examined. Pigs of both treatment groups showed impaired cardiac function, valvular insufficiency, and cardiac damage. Systemic inflammation and local cardiac alterations were observed which might contribute to early myocardial damage in vivo. Multiple trauma including long-bone fracture and subsequent intramedullary reaming induces cardiac dysfunction and valvular insufficiency, which might be linked to both mechanical cardiac injury and increased systemic inflammation. 6 hours after trauma there are less differences between RIAI and RIAII treatment with regard to post-traumatic cardiac consequences in multiple injured pigs, indicating no beneficial effect of RIAII over RIAI.

Structural alterations and inflammation in the heart after multiple trauma followed by reamed versus non-reamed femoral nailing.

BACKGROUND: Approximately 30,000 patients with blunt cardiac trauma are recorded each year in the United States. Blunt cardiac injuries after trauma are associated with a longer hospital stay and a poor overall outcome. Organ damage after trauma is linked to increased systemic release of pro-inflammatory cytokines and damage-associated molecular patterns. However, the interplay between polytrauma and local cardiac injury is unclear. Additionally, the impact of surgical intervention on this process is currently unknown. This study aimed to determine local cardiac immunological and structural alterations after multiple trauma. Furthermore, the impact of the chosen fracture stabilization strategy (reamed versus non-reamed femoral nailing) on cardiac alterations was studied. EXPERIMENTAL APPROACH: 15 male pigs were either exposed to multiple trauma (blunt chest trauma, laparotomy, liver laceration, femur fracture and haemorrhagic shock) or sham conditions. Blood samples as well as cardiac tissue were analysed 4 h and 6 h after trauma. Additionally, murine HL-1 cells were exposed to a defined polytrauma-cocktail, mimicking the pro-inflammatory conditions after multiple trauma in vitro. RESULTS: After multiple trauma, cardiac structural changes were observed in the left ventricle. More specifically, alterations in the alpha-actinin and desmin protein expression were found. Cardiac structural alterations were accompanied by enhanced local nitrosative stress, increased local inflammation and elevated systemic levels of the high-mobility group box 1 protein. Furthermore, cardiac alterations were observed predominantly in pigs that were treated by non-reamed intramedullary reaming. The polytrauma-cocktail impaired the viability of HL-1 cells in vitro, which was accompanied by a release of troponin I and HFABP. DISCUSSION: Multiple trauma induced cardiac structural alterations in vivo, which might contribute to the development of early myocardial damage (EMD). This study also revealed that reamed femoral nailing (reamed) is associated with more prominent immunological cardiac alterations compared to nailing without reaming (non-reamed). This suggests that the choice of the initial fracture treatment strategy might be crucial for the overall outcome as well as for any post-traumatic cardiac consequences.

Effects of Circulating HMGB-1 and Histones on Cardiomyocytes-Hemadsorption of These DAMPs as Therapeutic Strategy after Multiple Trauma.

BACKGROUND AND PURPOSE: The aim of the study was to determine the effects of post-traumatically released High Mobility Group Box-1 protein (HMGB1) and extracellular histones on cardiomyocytes (CM). We also evaluated a therapeutic option to capture circulating histones after trauma, using a hemadsorption filter to treat CM dysfunction. EXPERIMENTAL APPROACH: We evaluated cell viability, calcium handling and mitochondrial respiration of human cardiomyocytes in the presence of HMGB-1 and extracellular histones. In a translational approach, a hemadsorption filter was applied to either directly eliminate extracellular histones or to remove them from blood samples obtained from multiple injured patients. KEY RESULTS: Incubation of human CM with HMGB-1 or histones is associated with changes in calcium handling, a reduction of cell viability and a substantial reduction of the mitochondrial respiratory capacity. Filtrating plasma from injured patients with a hemadsorption filter reduces histone concentration ex vivo and in vitro, depending on dosage. CONCLUSION AND IMPLICATIONS: Danger associated molecular patterns such as HMGB-1 and extracellular histones impair human CM in vitro. A hemadsorption filter could be a therapeutic option to reduce high concentrations of histones.

Toll-Like Receptor-Mediated Cardiac Injury during Experimental Sepsis.

Sepsis is associated with global cardiac dysfunction and with high mortality rate. The development of septic cardiomyopathy is due to complex interactions of damage-associated molecular patters, cytokines, and complement activation products. The aim of this study was to define the effects of sepsis on cardiac structure, gap junction, and tight junction (TJ) proteins. Sepsis was induced by cecal ligation and puncture in male C57BL/6 mice. After a period of 24 h, the expression of cardiac structure, gap junction, and TJ proteins was determined. Murine HL-1 cells were stimulated with LPS, and mRNA expression of cardiac structure and gap junction proteins, intracellular reactive oxygen species, and troponin I release was analyzed. Furthermore, pyrogenic receptor subtype 7 (P2X7) expression and troponin I release of human cardiomyocytes (iPS) were determined after LPS exposure. In vivo, protein expression of connexin43 and α-actinin was decreased after the onset of polymicrobial sepsis, whereas in HL-1 cells, mRNA expression of connexin43, α-actinin, and desmin was increased in the presence of LPS. Expression of TJ proteins was not affected in vivo during sepsis. Although the presence of LPS and nigericin resulted in a significant troponin I release from HL-1 cells. Sepsis affected cardiac structure and gap junction proteins in mice, potentially contributing to compromised cardiac function.

A novel mouse model to study fracture healing of the proximal femur.

The majority of fractures, especially in elderly and osteoporotic patients, occurs in metaphyseal bone. However, only a few experimental models exist to study metaphyseal bone healing in mice. Currently used mouse models of metaphyseal fracture healing are either based on drill hole defects, lacking adequate biomechanical stimulation at the site of fracture and therefore endochondral ossification in the fracture callus, or are introduced into the distal part of the mouse femur stabilized by a locking plate, which is challenging due to the small specimen size. Therefore, the aim of the current study was to develop a new mouse model to study metaphyseal fracture healing of the proximal femur. We chose a combination between an open osteotomy and a closed intramedullary stabilization. A 24 G needle was inserted into the femur in a closed manner, then an osteotomy was made with a 0.4-mm Gigli wire saw between the third and the lesser trochanter of the femur using an open approach. Fractured femurs were analyzed using microcomputed tomography and histology at days 14 and 21 after surgery. No animals were lost due to surgery or anesthesia. All animals displayed normal limb loading and a physiological gait pattern within the first three days after fracture. We found robust endochondral ossification during the fracture healing process with high expression of late chondrocyte and early osteogenic markers at day 14 (d14). By day 21 (d21), all fractures had a bony bridging score of 3 or more, indicating successful healing. Callus volume significantly decreased from d14 to d21, whereas high numbers of osteoclasts appeared at the fracture callus until d21, indicating that callus remodeling had already started at d21. In conclusion, we successfully developed a novel mouse model to study endochondral fracture healing of the proximal femur. This model might be useful for future studies using transgenic animals to unravel molecular mechanisms of osteoporotic metaphyseal fracture healing.

Systemic and Cardiac Alterations After Long Bone Fracture.

The purpose of this study was to reveal possible consequences of long-bone fracture on cardiac tissue and to analyze the role of systemically elevated danger associated molecular patterns, complement anaphylatoxins and cytokines. Blood samples of mice, pigs, and humans after a fracture were analyzed by ELISAs for complement component 5a (C5a), tumor necrosis factor (TNF), and extracellular histones. In vivo results were completed by in vitro experiments with human cardiomyocytes treated with TNF and extracellular histones. The influence of histones and human plasma after fracture on isolated human polymorphonuclear leukocytes (PMNs) was investigated. An elevation of TNF, C5a, and extracellular histones after long bone fracture was measured. Moreover, the appearance of systemic troponin I levels was observed and structural changes in connexin 43 and desmin were detected. Further, the presence of TNF leads to elevation of reactive oxygen species, troponin I release, and histone appearance in supernatant of human cardiomyocytes. Incubation of human PMNs with histones and plasma of patients after fracture lead to formation of neutrophil extracellular traps. Present results suggest that structural alterations in the heart might be consequences of the complement activation, the release of extracellular histones, and the systemic TNF elevation in the context of a long bone fracture.

Complement Activation and Organ Damage After Trauma-Differential Immune Response Based on Surgical Treatment Strategy.

Background: The complement system is part of the innate immunity, is activated immediately after trauma and is associated with adult respiratory distress syndrome, acute lung injury, multiple organ failure, and with death of multiply injured patients. The aim of the study was to investigate the complement activation in multiply injured pigs as well as its effects on the heart in vivo and in vitro. Moreover, the impact of reamed vs. non-reamed intramedullary nailing was examined with regard to the complement activation after multiple trauma in pigs. Materials and Methods: Male pigs received multiple trauma, followed by femoral nailing with/without prior conventional reaming. Systemic complement hemolytic activity (CH-50 and AH-50) as well as the local cardiac expression of C3a receptor, C5a receptors1/2, and the deposition of the fragments C3b/iC3b/C3c was determined in vivo after trauma. Human cardiomyocytes were exposed to C3a or C5a and analyzed regarding calcium signaling and mitochondrial respiration. Results: Systemic complement activation increased within 6 h after trauma and was mediated via the classical and the alternative pathway. Furthermore, complement activation correlated with invasiveness of fracture treatment. The expression of receptors for complement activation were altered locally in vivo in left ventricles. C3a and C5a acted detrimentally on human cardiomyocytes by affecting their functionality and their mitochondrial respiration in vitro. Conclusion: After multiple trauma, an early activation of the complement system is triggered, affecting the heart in vivo as well as in vitro, leading to complement-induced cardiac dysfunction. The intensity of complement activation after multiple trauma might correlate with the invasiveness of fracture treatment. Reaming of the femoral canal might contribute to an enhanced "second hit" response after trauma. Consequently, the choice of fracture treatment might imply the clinical outcome of the critically injured patients and might be therefore crucial for their survival.

Cardiac Glucose and Fatty Acid Transport After Experimental Mono- and Polytrauma.

OBJECTIVE: The aim of this study was to define the influence of trauma on cardiac glucose and fatty acid transport. The effects were investigated in vivo in a porcine mono- and polytrauma model and in vitro in human cardiomyocytes, which were treated simultaneously with different inflammatory substances, mimicking posttraumatic inflammatory conditions. METHODS AND RESULTS: In the porcine fracture- and polytrauma model, blood glucose concentrations were measured by blood gas analysis during an observation period of 72 h. The expression of cardiac glucose and fatty acid transporters in the left ventricle was determined by RT-qPCR and immunofluorescence. Cardiac and hepatic glycogen storage was examined. Furthermore, human cardiomyocytes were exposed to a defined trauma-cocktail and the expression levels of glucose- and fatty acid transporters were determined. Early after polytrauma, hyperglycemia was observed. After 48 and 72 h, pigs with fracture- and polytrauma developed hypoglycemia. The propofol demand significantly increased posttrauma. The hepatic glycogen concentration was reduced 72 h after trauma. Cardiac glucose and fatty acid transporters changed in both trauma models in vivo as well as in vitro in human cardiomyocytes in presence of proinflammatory mediators. CONCLUSIONS: Monotrauma as well as polytrauma changed the cardiac energy transport by altering the expression of glucose and fatty acid transporters. In vitro data suggest that human cardiomyocytes shift to a state alike myocardial hibernation preferring glucose as primary energy source to maintain cardiac function.

Midkine Is Elevated After Multiple Trauma and Acts Directly on Human Cardiomyocytes by Altering Their Functionality and Metabolism.

Background and Purpose: Post-traumatic cardiac dysfunction often occurs in multiply injured patients (ISS ≥ 16). Next to direct cardiac injury, post-traumatic cardiac dysfunction is mostly induced by the release of inflammatory biomarkers. One of these is the heparin-binding factor Midkine, which is elevated in humans after fracture, burn injury and traumatic spinal cord injury. Midkine is associated with cardiac pathologies but the exact role of Midkine in the development of those diseases is ambiguous. The systemic profile of Midkine after multiple trauma, its effects on cardiomyocytes and the association with post-traumatic cardiac dysfunction, remain unknown. Experimental Approach: Midkine levels were investigated in blood plasma of multiply injured humans and pigs. Furthermore, human cardiomyocytes (iPS) were cultured in presence/absence of Midkine and analyzed regarding viability, apoptosis, calcium handling, metabolic alterations, and oxidative stress. Finally, the Midkine filtration capacity of the therapeutic blood absorption column CytoSorb ®300 was tested with recombinant Midkine or plasma from multiply injured patients. Key Results: Midkine levels were significantly increased in blood plasma of multiply injured humans and pigs. Midkine acts on human cardiomyocytes, altering their mitochondrial respiration and calcium handling in vitro. CytoSorb®300 filtration reduced Midkine concentration ex vivo and in vitro depending on the dosage. Conclusion and Implications: Midkine is elevated in human and porcine plasma after multiple trauma, affecting the functionality and metabolism of human cardiomyocytes in vitro. Further examinations are required to determine whether the application of CytoSorb®300 filtration in patients after multiple trauma is a promising therapeutic approach to prevent post-traumatic cardiac disfunction.