Risk Stratification with Sarculator and MSKCC in Patients with Primary and Secondary Angiosarcoma.

BACKGROUND: Sarculator and Memorial Sloan Kettering Cancer Center (MSKCC) nomograms are freely available risk prediction scores for surgically treated patients with primary sarcomas. Due to the rarity of angiosarcomas, these scores have only been tested on small cohorts of angiosarcoma patients. In neither the original patient cohort upon which the Sarculator is based nor in subsequent studies was a distinction made between primary and secondary angiosarcomas, as the app is intended to be applied to primary sarcomas. Therefore, the objective of our investigation was to assess whether the Sarculator reveals a difference in prognosis and whether such differentiation aligns with actual clinical data. PATIENTS AND METHODS: Thirty-one patients with primary or secondary soft tissue angiosarcoma, treated at our Sarcoma Center from 2001 to 2023, were included in the study. Actual survival rates were compared with nomogram-derived data for predicted 5-year survival (Sarculator), as well as 4-, 8- and 12-year sarcoma-specific death probabilities (MSKCC). Harrell's c-index was utilized to assess predictive validity. RESULTS: In total, 31 patients were analyzed. The actual overall 5-year survival was 22.57% with a predicted 5-year survival rate of 25.97%, and the concordance index was 0.726 for the entire cohort. The concordance index results from MSKCC for angiosarcoma patients were below 0.7 indicating limited predictive accuracy in this cohort, particularly when compared to Sarculator. SUMMARY: Nomogram-based predictive models are valuable tools in clinical practice for rapidly assessing prognosis. They can streamline the decision-making process for adjuvant treatments and improve patient counselling especially in the treatment of rare and complicated tumor entities such as angiosarcomas.

Improvement of Predictive Scores in Burn Medicine through Different Machine Learning Approaches.

The mortality of severely burned patients can be predicted by multiple scores which have been created over the last decades. As the treatment of burn injuries and intensive care management have improved immensely over the last years, former prediction scores seem to be losing accuracy in predicting survival. Therefore, various modifications of existing scores have been established and innovative scores have been introduced. In this study, we used data from the German Burn Registry and analyzed them regarding patient mortality using different methods of machine learning. We used Classification and Regression Trees (CARTs), random forests, XGBoost, and logistic regression regarding predictive features for patient mortality. Analyzing the data of 1401 patients via machine learning, the factors of full-thickness burns, patient's age, and total burned surface area could be identified as the most important features regarding the prediction of patient mortality following burn trauma. Although the different methods identified similar aspects, application of machine learning shows that more data are necessary for a valid analysis. In the future, the usage of machine learning can contribute to the development of an innovative and precise predictive score in burn medicine and even to further interpretations of relevant data regarding different forms of outcome from the German Burn registry.

Pharmacological elevation of sphingosine-1-phosphate by S1P lyase inhibition accelerates bone regeneration after post-traumatic osteomyelitis.

Posttraumatic osteomyelitis and the ensuing bone defects are a debilitating complication after open fractures with little therapeutic options. We have recently identified potent osteoanabolic effects of sphingosine-1-phosphate (S1P) signalling and have now tested whether it may beneficially affect bone regeneration after infection. We employed pharmacological S1P lyase inhibition by 4-deoxypyrodoxin (DOP) to raise S1P levels in vivo in an unicortical long bone defect model of posttraumatic osteomyelitis in mice. In a translational approach, human bone specimens of clinical osteomyelitis patients were treated in organ culture in vitro with DOP. Bone regeneration was assessed by µCT, histomorphometry, immunohistology and gene expression analysis. The role of S1P receptors was addressed using S1PR3 deficient mice. Here, we present data that DOP treatment markedly enhanced osteogenesis in posttraumatic osteomyelitis. This was accompanied by greatly improved osteoblastogenesis and enhanced angiogenesis in the callus accompanied by osteoclast-mediated bone remodelling. We also identified the target of increased S1P to be the S1PR3 as S1PR3-/- mice showed no improvement of bone regeneration by DOP. In the human bone explants, bone mass significantly increased along with enhanced osteoblastogenesis and angiogenesis. Our data suggest that enhancement of S1P/S1PR3 signalling may be a promising therapeutic target for bone regeneration in posttraumatic osteomyelitis.

Autologous Reconstruction After Failed Implant-Based Breast Reconstruction: A Comparative Multifactorial Outcome Analysis.

INTRODUCTION: Failure of an implant-based breast reconstruction often requires a change to an autologous procedure (salvage autologous breast reconstruction [Salv-ABR]). The aim of this study was to compare surgical and patient-reported outcomes of Salv-ABR to immediate or delayed-immediate ABR (I/DI-ABR), which has hardly been addressed in the existing literature. METHODS: All patients undergoing Salv- or I/DI-ABR between January 2014 and December 2020 were asked to participate in this study. Complication rates, the aesthetic outcome (5-point Likert scale), and quality of life (EORTC QLQ-C30 and -BR23, Breast-Q, Center for Epidemiology Studies Depression Scale) were compared between both procedures. RESULTS: Seventy patients participated in the study (Salv-ABR: n = 23; mean ± SD age, 53.5 ± 9.1 years; follow-up, 28.6 ± 18.5 month; I/DI-ABR: n = 45, mean ± SD age: 50.2 ± 7.3 years; follow-up, 32.8 ± 18.5 month). Main indication for Salv-ABR was a major capsular contracture (n = 14 [60.1%]). Early unplanned reoperation rates were significantly increased in the Salv-ABR (56.5% vs 14.9%; P < 0.01). Patients with I/DI-ABR showed a significantly improved overall aesthetic outcome (2.7 ± 0.9 vs 3.3 ± 0.7; P < 0.01) and scored significantly higher in several subscales of EORTC QLQ-C30/BR23 (Global Health Status, Role Functioning, Body Image; P < 0.05) and the Breast-Q (Psychosocial Well-being, Satisfaction with Breast; P < 0.05) compared with patients with Salv-ABR. CONCLUSIONS: Salvage ABR is associated with a higher complication rate, compromised aesthetic outcome, and quality of life compared with I/DI-ABR. This should be considered and discussed with the patient when planning any kind of reconstructive breast surgery.

The Partner Perspective on Autologous and Implant-Based Breast Reconstruction.

INTRODUCTION: Partner involvement in the decision-making process concerning breast reconstruction (BR) after a breast cancer diagnosis may be very supportive for the patient. So far, no study evaluates partner satisfaction with the outcome after BR and the relationship to patient satisfaction. The aim of this study was to assess and compare partner satisfaction of BR with autologous tissue (ABR) and prosthetic implants (IBR), respectively, and compare it to patient-reported outcomes. PATIENTS AND METHODS: All patients undergoing ABR and IBR between January 2014 and December 2020 were asked to participate with their partners. Patient and partner satisfaction with breast reconstruction, overall outcome as well as patient's perceived and self-reported psychosocial well-being were evaluated using the Breast-Q and a modified partner questionnaire, respectively. RESULTS: Fifty-three couples participated (IBR: n=30, ABR: n = 23). Patient and partner satisfaction with breast (r = 0.552), outcome (r = 0.465) as well as patient's perceived and self-report psychosocial well-being (r = 0.495) were highly correlated with partners scoring significantly higher (p<0.001). In terms of partner satisfaction, both reconstructive procedures achieved satisfactory results. ABR scored higher in terms of softness of breast and how natural the breast feels to touch whereas IBR was rated superior evaluating the breast size. CONCLUSION: Both reconstructive procedures achieve satisfactory results in terms partner satisfaction whereas patient's psychosocial well-being was highly overestimated by their partners. Hence, partner inclusion in the regular psycho-oncological support might further sensitize them of the high psychological burden of a breast cancer diagnosis and therefore stabilize patients private support system. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Digital Media Play a Key Role in Influencing Female Breast Perception.

The female breast is a symbol of femininity and plays a key role in the female body image. However, factors influencing the preferences for different breast shapes and sizes are still not elucidated. In particular, the role of the emerging social media in breast perception has not been analyzed yet. A representative cohort of 1,049 adults completed a web-based questionnaire containing hyperrealistic 3D models of the female breast in the United States. A machine-learning algorithm (Classification and Regression Tree [CART]) was implemented to identify the most influential factors. The study was able to identify the frequency of pornographic and social media consumption as the most influencing factor for altered breast preferences. Although digital media exposure did not alter satisfaction with the own breast among female participants, the tendency to undergo or history of conducted aesthetic surgery correlated with higher access frequency to digital media. Taken together, the overpowering impact of social media and pornographic consumption on the own body image was shown in preference alterations for different anatomical aspects of the breast in the whole population and distorted self-perception about the breast in female participants.

Standardized Quantitative Sensory Testing to Assess Insufficient Recovery of Touch Discrimination in Free Flap Surgery.

BACKGROUND: With major advances in microsurgical techniques, free tissue transfer has become a widely adopted approach to treat complex soft-tissue defects. However, sensory recovery is poor, leaving the anesthetic skin prone to injuries. METHODS: Twenty-eight patients with 22 anterior lateral thigh flaps and six latissimus dorsi flaps on their extremities participated in the study. Quantitative sensory testing and two-point discrimination was performed in three test areas and one control on the contralateral unaffected extremity. Physical disability, mental health, quality of life, and characteristics of pain were assessed by the painDetect, Disabilities of the Arm, Shoulder, and Hand, Lower Extremity Functional Scale, and 12-Item Short Form questionnaires, respectively. RESULTS: Somatosensory profiles of all flaps were characterized by an overall loss of nerve function. Small-fiber function was mostly recovered, whereas large-fiber function, and thus touch discrimination, was severely impaired. Mechanical detection thresholds improved over time and from center to the periphery. Reported pain was mild to moderate and correlated with decreased physical function. CONCLUSIONS: Standardized quantitative sensory testing provides a useful tool kit to assess the sensory regeneration after surgical treatment of soft-tissue defects. After free tissue transfer, small-fiber function recovers with nerve ingrowth in a centripetal direction from the flap margins to the center, likely by way of collateral axonal sprouting from the undamaged nerves surrounding the flap. Myelinated fibers recover slowly and inefficiently. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Free-flap reconstruction of the lower limb in octogenarians - A comparative analysis of indications, management, and outcomes.

INTRODUCTION: Impaired microcirculation, along with an increase in chronic medical conditions in the geriatric cohort, may favor the development of soft-tissue defects in the lower extremity and equally impair the options for plastic-reconstructive surgery. In particular, outcome analyses in the increasing patient cohort ≥ 80 years (octogenarians) are limited. METHODS: Setting 80 years as the cutoff, we conducted an age-related outcome analysis of all patients undergoing free-flap reconstruction of the lower extremity from 2014 to 2020, comprising the American Society of Anesthesiologists (ASA) score and Charlson Comorbidity Index (CCI) as the possible outcome predicting factors. RESULTS: During the study period, a total of 424 free flaps were performed in 385 patients (∅: 54.7 years ± 16.1; range: 9-89), including 19 octogenarians. Compared with the younger patient cohort, there was a significantly higher rate of early flap revision (p = 0.023) and flap loss (p = 0.028). Furthermore, the mean length of hospital (60.6 ± 37.6 vs. 51.1 ± 37.0) and intensive care unit/intermediate care stay (6.5 ± 15.0 vs. 3.5 ± 8.5) was extended (n.s.). The ASA score presented an independent predictor for major surgical [odds ratio (OR): 1.66; p = 0.041) and medical complications (OR: 3.97; p<0.001). Neither the CCI nor the ASA served as an independent predictor for total flap loss. CONCLUSION: Free-flap reconstruction of the lower extremity in octogenarians is associated with a higher risk of flap revision and flap loss. Considering the prolonged immobilization associated with increased morbidity following limb amputation, it presents still a reasonable option to achieve limb salvage in carefully chosen patients. An adequate tool to predict the success of free-flap survival is still unavailable.

Postoperative Remote Ischemic Conditioning (RIC) significantly improves entire flap microcirculation beyond 4 hours.

OBJECTIVE: Free flap transfer is a safe and reliable technique for soft tissue reconstruction. However, impaired flap perfusion with consecutive microcirculatory failure leading to partial or total flap failure remains a clinically relevant problem. Remote ischemic conditioning (RIC) has been shown to improve microcirculation in adipo-cutaneous tissues in healthy humans as well as in free flaps. Yet, little is known about its effects on different perfusion zones in free flaps and the duration of these effects. METHODS: Twenty-five patients with free perforator-based adipo-cutaneous flap transfer were included in the study. RIC (3 cycles: 10/10 min ischemia/reperfusion) was applied via an inflatable tourniquet placed on the upper arm. Continuous measurement of flaps' microcirculation on postoperative day (POD) 1, 3, and 5 was performed by utilizing an O2C device ("Oxygen-to-see" ©LEA Medizintechnik Germany) during RIC and for the following 4 h. Probes were located both in the flaps' center and on its distal edge. RESULTS: Twenty patients were included in the final analysis. RIC significantly improved flaps' blood flow (BF) by a max. of + 19.6% and oxygen saturation of + 15.7%. Changes affected the entire flap, without significant difference between zones. The increase in flap perfusion could be observed for at least 4 h after the completion of RIC. CONCLUSION: Postoperative application of RIC might serve as an additional treatment to enhance whole flap perfusion and prevent microcirculatory disorders, therefore reducing the risk for potential tissue necrosis, especially in the distal parts of the flaps.

[Analysis of Efficency, Cost Structure and Revenues of ALT Free Flaps in Extremity Reconstruction]. / Analyse der Effizienz, Kostenstruktur und Erlössituation von freien ALT-Lappenplastiken zur Extremitätenrekonstruktion.

Microvascular reconstructions can be lengthy procedures lasting the entire day. As a result of unforeseeable events, the standardization of these procedures can be challenging. Moreover, the length of these procedures varies strongly, which impedes adequate scheduling and, therefore, optimal capacity utilization. Within the years 2018-2020, the duration of ALT free flap extremity reconstructions was correlated with the experience of the microsurgeon (category 1:<50 free flaps life-time experience, category 2: 50-200, category 3:>200) and comorbidities. The resulting costs were compared with the matrix of the German DRG Institute InEK. The surgical experience of the microsurgeon had a significant impact on the duration of surgery in extremity reconstruction. In due consideration of potential complications, category 2 microsurgeons were 45 minutes faster and category 3 microsurgeons were 167 minutes faster than category 1 microsurgeons. Comorbidities, by contrast, did not have a significant impact on procedure duration. Cost analysis revealed deficits for these procedures in relation to the InEK matrix. However, an additional analysis showed that the duration of surgery was within the German average while costs for personnel/OR minute were slightly below the average. According to this calculation, costs for microsurgical training were approximately 1000€/case. The reimbursement for flaps in extremity reconstruction is not entirely mapped in the German DRG system. Given the longer procedure times, microsurgical training is associated with higher costs. Defining the duration of microsurgery based on the level of expertise should result in improved adherence to schedule and more efficient utilization of the valuable operating room time.

Interethnic Influencing Factors Regarding Buttocks Body Image in Women from Nigeria, Germany, USA and Japan.

BACKGROUND: Body image research deals a lot with awareness of the body as an entity. Studies that consider individual anatomical aspects and place them in an intercultural context are rarely present. METHODS: For this purpose, general data, body perception and judgment of body images from 2163 (48% female and 52% male) participants from Germany, Nigeria, the USA and Japan were evaluated as part of a survey. RESULTS: There were clear differences in the personal body image of the participants' own buttocks, the buttocks as a beauty ideal and the way in which dissatisfaction was dealt with in different countries. In addition to sexual well-being (importance score: 0.405 a.u.), the country of origin (0.353), media consumption (0.042) and one's own weight (0.069) were also identified as influencing factors for satisfaction with one's own buttocks. A clear evolution could be derived regarding a WHR (waist-to-hip ratio) of well below 0.7, which was consistently favored by the participants but also propagated by influencers through images (p < 0.001). In this context, participants who indicated celebrities as role models for the buttocks showed a correspondingly high level of dissatisfaction with their own buttocks (R = -0.207, p < 0.001, ρ = -0.218). CONCLUSION: Overall, a highly significant correlation was shown between the consumption frequency of Instagram, TikTok and pornography with the negative perception of women's own buttocks.

Autologous vs. implant-based breast reconstruction after skin- and nipple-sparing mastectomy-A deeper insight considering surgical and patient-reported outcomes.

Introduction: Autologous (ABR) and implant-based breast reconstruction (IBR) represent the most common procedures after skin- and nipple-sparing mastectomy. This cross-sectional study is a comprehensive analysis of ABR and IBR considering surgical and patient-reported outcomes. Patients and methods: Eligible patients underwent breast reconstruction (ABR and IBR) after skin- and nipple-sparing mastectomy between January 2014 and December 2020. Outcome parameters included quality of life (European Organisation for Research and Treatment of Cancer - EORTC - QLQ30, BR23, Breast-Q, CES-D), complication rates, aesthetic result, and breast sensitivity. Results: 108 patients participated in the study (IBR: n = 72, age 48.9 ± 9.9 years; ABR: n = 36, age: 46.6 ± 7.3 years). Mean follow-up was 27.1 ± 9.3 (IBR) and 34.9 ± 20.5 (ABR), respectively. IBR patients suffered significantly more often from major complications (30.6% vs. 8.3%; p = 0.01), while ABR patients underwent secondary procedures significantly more often to improve the aesthetic result (55.6% vs. 29.2%, p = 0.004). Unilateral reconstructions revealed superior aesthetic results in ABR (n.s.), while in bilateral reconstruction IBR tended to score higher (n.s.). Scar evaluation resulted in a better result of IBR in both categories (p < 0.01). Breast sensitivity was severely impaired in both groups. The Breast-Q revealed a significantly higher "patient satisfaction with breast" after ABR (p = 0.033), while the other QoL-tests and subscales showed no significant differences between the two procedures. Conclusion: ABR is associated with a higher patient satisfaction despite the high probability of secondary procedures to improve the aesthetic outcome, whereas IBR-patients suffer more often from major complications. Furthermore, the laterality of reconstruction should be included in the individual decision-making process.

A Machine Learning Approach to Identify Previously Unconsidered Causes for Complications in Aesthetic Breast Augmentation.

INTRODUCTION: Primary breast augmentation is one of the most commonly requested aesthetic procedures. Considering the large number of procedures performed in connection with a high demand, it is crucial to prevent complications. For this reason, finding and avoiding possible sources of complications is decisive. METHODS: Between January 2010 and December 2021, 1625 female patients underwent an aesthetic breast augmentation performed by a single surgeon. The data collected were analyzed through a machine learning technique for binary recursive partitioning. This made it possible to detect unknown sources of a complication and determine a vertex for the various features. RESULTS: When analyzing the data, for most features a high importance score with low entropy was achieved, concluding a high significance. In addition, reproducibility was demonstrated through detailed testing and training accuracies in the algorithm. With this procedure, in addition to known risks such as a high BMI and round implant shape, a larger than A preoperative bra-cup size (OR: 2.7) and a taller body could also be identified as most significant influencing factors for complications. DISCUSSION: Preoperative breast size plays an exceptionally important role in the occurrence of complications and should be a factor held in a surgeon's considerations. In addition, this study shows ways to transfer artificial intelligence into plastic surgery to increase medical quality. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Superior Enhancement of Cutaneous Microcirculation Due to "Cyclic" Application of a Negative Pressure Wound Therapy Device in Humans - Local and Remote Effects.

Objectives: Despite a common utilization of "Negative Pressure Wound Therapy" (NPWT) Devices in a wide range of specialties, some of the basic mechanisms of action of the techniques are still on debate. Conflicting results from prior studies demonstrate our lack of understanding how wound-bed perfusion or cutaneous microcirculation is affected by NPWT. Methods: We conducted a prospective randomized study which included 45 healthy subjects to further investigate the acute effects of NPWT on cutaneous microcirculation underneath the applied dressing. Three modes of application, namely, continuous, intermittent, cyclic, were tested. Amongst others, measurements of elicited surface pressure and a comprehensive microcirculatory analysis were carried out by utilizing an O2C-device. For the detection of (systemic) remote effects, perfusion changes of the contra-lateral thigh were evaluated. Results: All three tested modes of application led to a significant (p < 0.05) improvement in local tissue perfusion with an increased blood flow of max +151% and tissue oxygen saturation of +28.2% compared to baseline values. Surface pressure under the dressing significantly increased up to 29.29 mmHg due to the activation of the NPWT device. Continuous, intermittent, and cyclic application of negative pressure were accurately sensed by participants, resulting in reported pain values that mirrored the different levels of applied suction. Although the cyclic application mode showed the most pronounced effects regarding microcirculatory changes, no statistical significance between groups was observed. Conclusion: We could demonstrate a significant improvement of cutaneous microcirculation under an applied NPWT dressing with favorable effects due to cyclic mode of application. An increased surface pressure leads to a better venous drainage of the tissue, which was shown to increase arterial inflow with a consecutive improvement of oxygen supply. Further research is warranted to evaluate our findings regarding wound bed perfusion in the clinical field with respect to formation of granulation tissue and wound healing.

Closed-Incision Negative-Pressure Wound Therapy after Resection of Soft-Tissue Tumors Reduces Wound Complications: Results of a Randomized Trial.

BACKGROUND: Wound healing after resection of large soft-tissue tumors is often impaired by large dead space and fluid collection. Recently, the authors were able to show an association of wound complications with worse oncologic outcome in soft-tissue sarcomas. The aim of the study was to examine the value of closed-incision negative pressure wound therapy on postoperative wound drainage and wound complications after soft-tissue tumor resection. METHODS: Patients for whom resection is planned of a soft-tissue tumor larger than 10 cm in diameter of the extremities or the trunk were allocated randomly to one of two groups. After wound closure, patients in the study group received closed-incision negative-pressure wound therapy for a duration of 5 days, whereas those in the control group received regular dressings. The amount of drainage fluid, course of wound healing, length of hospital stay, and wound edge perfusion at postoperative day 5 measured by white-light infrared spectroscopy were compared. RESULTS: Sixty patients could be included in the study with even distribution to both study arms, meeting the goal. The postoperative course of wound drainage volume was significantly lower in the study group, and hospital stay was significantly shorter, with 9.1 ± 3.8 days versus 13.9 ± 11.8 days. The occurrence of wound complications was significantly lower in the study group on time-to-event analysis (one versus six). Tissue spectroscopy revealed a significantly higher oxygen saturation increase in the wound edge for the study group versus the control group. CONCLUSION: Closed-incision negative-pressure wound therapy should be considered for patients undergoing resection of large soft-tissue tumors. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Risk Factors for Occurrence and Relapse of Soft Tissue Sarcoma.

The diagnosis and prognostic outcome of STS pose a therapeutic challenge in an interdisciplinary setting. The treatment protocols are still discussed controversially. This systematic meta-analysis aimed to determine prognostic factors leading to the development and recurrence of STS. Eligible studies that investigated potential risk factors such as smoking, genetic dispositions, toxins, chronic inflammation as well as prognostic relapse factors including radiation, chemotherapy and margins of resection were identified. Data from 24 studies published between 1993 and 2019 that comprised 6452 patients were pooled. A statistically significant effect developing STS was found in overall studies stating a causality between risk factors and the development of STS (p < 0.01). Although subgroup analysis did not meet statistical significances, it revealed a greater magnitude with smoking (p = 0.23), genetic predisposition (p = 0.13) chronic inflammation, (p = 0.20), and toxins (p = 0.14). Secondly, pooled analyses demonstrated a higher risk of relapse for margin of resection (p = 0.78), chemotherapy (p = 0.20) and radiation (p = 0.16); after 3 years of follow-up. Therefore, we were able to identify risk and relapse prognostic factors for STS, helping to diagnose and treat this low incidental cancer properly.

Inhibition of Pathological Increased Matrix Metalloproteinase (MMP) Activity for Improvement of Bone Regeneration in Diabetes.

Patients with diabetes suffer from poor fracture healing. Molecular reasons are not fully understood and our previous gene expression microarray analyses of regenerating bones from mice with type 2 diabetes (db-/db-) revealed accelerated activation of pathways concerning matrix metalloproteases (MMPs). Thus, we picked out the pathological MMP acceleration as a target for profound gene expression analyses and additional therapeutic intervention in the present study. In the first part, gene expression of ECM degrading proteinases and inhibitors was investigated three and seven days postoperatively. Mmp3, Mmp9, Mmp13 and gene expression of MMP inhibitor Timp2 was significantly higher in regenerating bone fractures of db-/db- compared to wild type animals. Timp1 and metalloproteinase AdamTS4 showed no differences. In the second part, we locally applied a single dose (1 µL of 5 µM solution) of the broad-spectrum molecular MMP inhibitor Marimastat on tibial defects in db-/db-. We performed immunohistochemical and histological stainings seven days post operation. Impaired bone healing, collagen content, angiogenesis, and osteoclast invasion in db-/db- were restored significantly by application of Marimastat compared to PBS controls (n = 7/group). Hence, local intervention of bone defects by the molecular MMP inhibitor Marimastat might be an alternative therapeutic intervention for bone healing in diabetes.

Maggot Extract Interrupts Bacterial Biofilm Formation and Maturation in Combination with Antibiotics by Reducing the Expression of Virulence Genes.

Biofilms are aggregates of bacteria encased in an extracellular polymer matrix that acts as a diffusion barrier protecting the microbial community. Bacterial communication occurs by small signaling molecules called quorum sensing (QS) factors, which are involved in the activation of virulence genes and formation of biofilms. Larvae of the green bottle blowfly Lucilia sericata remove necrotic tissue by mechanical action (debridement) and proteolytic digestion. We produced a freeze-dried storable powder from larval extract and investigated its therapeutic effect on biofilms. Larval extract in concentrations of 6 and 12 mg/mL in combination with 0.5% antibiotics (≙50 U/mL penicillin and 50 µg/mL streptomycin) diminished free-floating (planktonic) Pseudomonas aeruginosa maintenance, while it showed no effect on Staphylococcus aureus and was not toxic to dermal cells. We established an ex vivo human dermal wound model. Larval extract in concentrations of 24 and 75 mg/mL in the presence of antibiotics (0.5%) significantly destroyed the biofilm stability of both P. aeruginosa and S. aureus biofilms. Furthermore, SEM analyses revealed crack and gap formations on P. aeruginosa. biofilm surface and decreased expression of P. aeruginosa biofilm maturation and virulence genes (lasR, rhlR and rhlA) was observed after treatment by larval extract in combination with antibiotics.

Role of Autonomous Neuropathy in Diabetic Bone Regeneration.

Diabetes mellitus has multiple negative effects on regenerative processes, especially on wound and fracture healing. Despite the well-known negative effects of diabetes on the autonomous nervous system, only little is known about the role in bone regeneration within this context. Subsequently, we investigated diabetic bone regeneration in db-/db- mice with a special emphasis on the sympathetic nervous system of the bone in a monocortical tibia defect model. Moreover, the effect of pharmacological sympathectomy via administration of 6-OHDA was evaluated in C57Bl6 wildtype mice. Diabetic animals as well as wildtype mice received a treatment of BRL37344, a ß3-adrenergic agonist. Bones of animals were examined via µCT, aniline-blue and Masson-Goldner staining for new bone formation, TRAP staining for bone turnover and immunoflourescence staining against tyrosinhydroxylase and stromal cell-derived factor 1 (SDF-1). Sympathectomized wildtype mice showed a significantly decreased bone regeneration, just comparable to db-/db- mice. New bone formation of BRL37344 treated db-/db- and sympathectomized wildtype mice was markedly improved in histology and µCT. Immunoflourescence stainings revealed significantly increased SDF-1 due to BRL37344 treatment in diabetic animals and sympathectomized wildtypes. This study depicts the important role of the sympathetic nervous system for bone regenerative processes using the clinical example of diabetes mellitus type 2. In order to improve and gain further insights into diabetic fracture healing, ß3-agonist BRL37344 proved to be a potent treatment option, restoring impaired diabetic bone regeneration.