Evaluation of a Novel Thiol-Norbornene-Functionalized Gelatin Hydrogel for Bioprinting of Mesenchymal Stem Cells.

Introduction: Three-dimensional bioprinting can be considered as an advancement of the classical tissue engineering concept. For bioprinting, cells have to be dispersed in hydrogels. Recently, a novel semi-synthetic thiolene hydrogel system based on norbornene-functionalized gelatin (GelNB) and thiolated gelatin (GelS) was described that resulted in the photoclick hydrogel GelNB/GelS. In this study, we evaluated the printability and biocompatibility of this hydrogel system towards adipose-tissue-derived mesenchymal stem cells (ASCs). Methods: GelNB/GelS was synthesized with three different crosslinking densities (low, medium and high), resulting in different mechanical properties with moduli of elasticity between 206 Pa and 1383 Pa. These hydrogels were tested for their biocompatibility towards ASCs in terms of their viability, proliferation and differentiation. The extrusion-based bioprinting of ASCs in GelNB/GelS-high was performed to manufacture three-dimensional cubic constructs. Results: All three hydrogels supported the viability, proliferation and chondrogenic differentiation of ASCs to a similar extent. The adipogenic differentiation of ASCs was better supported by the softer hydrogel (GelNB/GelS-low), whereas the osteogenic differentiation was more pronounced in the harder hydrogel (GelNB/GelS-high), indicating that the differentiation fate of ASCs can be influenced via the adaption of the mechanical properties of the GelNB/GelS system. After the ex vivo chondrogenic differentiation and subcutaneous implantation of the bioprinted construct into immunocompromised mice, the production of negatively charged sulfated proteoglycans could be observed with only minimal inflammatory signs in the implanted material. Conclusions: Our results indicate that the GelNB/GelS hydrogels are very well suited for the bioprinting of ASCs and may represent attractive hydrogels for subsequent in vivo tissue engineering applications.

Direct comparison of the immunogenicity of major histocompatibility complex-I and -II deficient mesenchymal stem cells in vivo.

Mesenchymal stem cells (MSCs) play an important role in tissue engineering applications aiming at the regeneration or substitution of damaged tissues. In this context, off-the-shelf allogeneic MSCs would represent an attractive universal cell source. However, immune rejection is a major limitation for the clinical use of allogeneic MSCs. Immune rejection is mediated by the expression of major histocompatibility complexes (MHC)-I and -II on the donor cells. In this study, we eliminated MHC-I and/or MHC-II expression in human MSCs by using the CRISPR/Cas9 technology and investigated the effect of the individual or combined knockout of MHC-I and MHC-II on MSC survival after transplantation into immunocompetent mice. Elimination of MHC-I and/or MHC-II expression did not affect mesenchymal marker gene expression, viability, proliferation and the differentiation potential of MSCs in vitro. However, cell survival of transplanted MSCs was significantly elevated in MHC-I and MHC-II deficient MSCs. A direct side-by-side comparison does not reveal any significant difference in the immunogenicity of MHC-I and MHC-II knockout MSCs. Moreover, double knockout of MHC-I and MHC-II did not further increase in vivo cell survival of transplanted MSCs. Our results demonstrate that knockout of MHC-I and/or MHC-II represents an effective strategy to prevent immune rejection of allogeneic MSCs.

The Edmonton Obesity Staging System Predicts Postoperative Complications After Abdominoplasty.

BACKGROUND: This study investigates the relationship between Edmonton Obesity Staging System (EOSS) and the occurrence of postoperative complications after abdominoplasty in massive weight loss patients. METHODS: A single-institution retrospective review of patients undergoing abdominoplasty between 2009 and 2019 after massive weight loss. Demographic data, laboratory findings, known risk factors for postoperative complications, as well as data on major and minor complications were extracted from the patient charts. Logistic regression models were used to investigate the relationship between the variables. RESULTS: Four hundred and five patients were included in the study. The prevalence of EOSS stages was: 0 (no comorbidities, N = 151, 37%), 1 (mild conditions, N = 40, 10%), 2 (moderate conditions, N = 149, 36%) and 3 (severe conditions, N = 70, 17%). Regression analysis showed that, controlling for body mass index (BMI), BMI Δ (maximal BMI - BMI at presentation), bariatric surgery, volume of resected tissue, and duration of surgery, EOSS stage significantly associated with the occurrence of postoperative complications. Compared with EOSS stage 0, EOSS stages 2 and 3 patients were associated with significantly more minor and major complications, respectively. The volume of resected tissue, BMI Δ, and age were associated with the occurrence of major complications. A regression model of comorbidities comprising the EOSS revealed a significant association of variables diabetes mellitus and hypertension with the occurrence of postoperative complications. CONCLUSIONS: Edmonton Obesity Staging System is a robust predictor of postoperative complications in abdominoplasty.

Comparison of symmetry after smile reconstruction for flaccid facial paralysis with combined fascia lata grafts and functional gracilis transfer for static suspension or gracilis transfer alone.

PURPOSE: Facial paralysis has a profound impact on functionality and esthetics of the oral region. In patients with strong skin laxity and soft tissue ptosis, functional smile reconstruction is challenging due to the accentuated asymmetry at rest. Thus, the purpose of the study was to analyze facial symmetry in this patient clientele following a combination of dynamic reanimation with fascial strips for static suspension compared to functional gracilis transfer alone. METHODS: In 2014, we altered the single-stage approach for microsurgical smile reconstruction in patients with significant soft tissue ptosis by adding fascia lata grafts for static support. We evaluated 6 patients (mean age 57.8 ± 5.2, group A) who underwent the combined procedure, and compared their results to 6 patients with flaccid facial paralysis who were treated before 2014 and received a functional gracilis transfer alone (mean age 52.5 ± 7.5, group B). To test the efficacy of the technique, we retrospectively analyzed the correction of the oral asymmetry as well as nasal and philtral deviation by computer-assisted photograph analysis 6 months postoperatively. RESULTS: The comparative analysis revealed a significant postoperative improvement of the oral asymmetry (A: 90.0 ± 5.0% relative correction at rest vs. B: 62.6 ± 17.2%, P < .05), nasal (A: 0.4 ± 0.2 vs. B: 0.7 ± 0.4 mm, P < .05), and philtral deviation (A: 0.5 ± 0.6 vs. B: 2.8 ± 1.8 mm, P < .05) in group A. CONCLUSIONS: The combined procedure for dynamic facial reanimation allows for immediate correction of the oral asymmetry and improves overall outcome in patients with advanced soft tissue ptosis and oral asymmetry at rest.

Transcriptomic Changes in Osteoblasts Following Endothelial Cell-Cocultivation Suggest a Role of Extracellular Matrix in Cellular Interaction.

Vascularization is important for bone development, fracture healing and engineering of artificial bone tissue. In the context of bone tissue engineering, it was shown that coimplantation of human primary umbilical vein endothelial cells (HUVECs) and human osteoblasts (hOBs) results in the formation of functional blood vessels and enhanced bone regeneration. Implanted endothelial cells do not only contribute to blood vessel formation, but also support proliferation, cell survival and osteogenic differentiation of coimplanted hOBs. These effects are partially mediated by direct heterotypic cell contacts. In a previous report we could show that cocultivated hOBs strongly increase the expression of genes involved in extracellular matrix (ECM) formation in HUVECs, suggesting that ECM may be involved in the intercellular communication between hOBs and HUVECs. The present study aimed at investigating whether comparable changes occur in hOBs. We therefore performed a microarray analysis of hOBs cultivated in direct contact with HUVECs, revealing 1,004 differentially expressed genes. The differentially expressed genes could be assigned to the functional clusters ECM, proliferation, apoptosis and osteogenic differentiation. The microarray data could be confirmed by performing quantitative real time RT-PCR on selected genes. Furthermore, we could show that the ECM produced by HUVECs increased the expression of the osteogenic differentiation marker alkaline phosphatase (ALP) in hOBs. In summary, our data demonstrate that HUVECs provoke complex changes in gene expression patterns in cocultivated hOBs and that ECM plays and important role in this interaction. J. Cell. Biochem. 117: 1869-1879, 2016. © 2016 Wiley Periodicals, Inc.

Overexpression of hypoxia-inducible factor-1 alpha improves vasculogenesis-related functions of endothelial progenitor cells.

Postnatal vasculogenesis is mediated by mobilization of endothelial progenitor cells (EPCs) from bone marrow and homing to ischemic tissues. This feature emphasizes this cell type for cell-based therapies aiming at the improvement of neovascularization in tissue engineering applications and regenerative medicine. In animal models, it was demonstrated that implantation of EPCs from cord blood (cbEPCs) led to the formation of a complex functional neovasculature, whereas EPCs isolated from adult peripheral blood (pbEPCs) showed a limited vasculogenic potential, which may be attributed to age-related dysfunction. Recently, it was demonstrated that activation of hypoxia-inducible factor-1α (Hif-1α) improves cell functions of progenitor cells of mesenchymal and endothelial origin. Thus, we hypothesized that overexpression of Hif-1α may improve the vasculogenesis-related phenotype of pbEPCs. In the present study, we overexpressed Hif-1α in pbEPCs and cbEPCs by using recombinant adenoviruses and investigated effects on stem cell- and vasculogenesis-related cell parameters. Overexpression of Hif-1α enhanced proliferation, invasion, cell survival and in vitro capillary sprout formation of both EPC populations. Migration was increased in cbEPCs upon Hif-1α overexpression, but not in pbEPCs. Cellular senescence was decreased in pbEPCs, while remained in cbEPCs, which showed, as expected, intrinsically a dramatically lower senescent phenotype in relation to pbEPCs. Similarly, the colony-formation capacity was much higher in cbEPCs in comparison to pbEPCs and was further increased by Hif-1α overexpression, whereas Hif-1α transduction exerted no significant influence on colony formation of pbEPCs. In summary, our experiments illustrated multifarious effects of Hif-1α overexpression on stem cell and vasculogenic parameters. Therefore, Hif-1α overexpression may represent a therapeutic option to improve cellular functions of adult as well as postnatal EPCs.

Identification of a blood-borne miRNA signature of synovial sarcoma.

BACKGROUND: Synovial sarcoma account for approximately 10 % of all soft-tissue tumors and occur most frequently in young adults. A specific translocation in this sarcoma induces fusion of the SYT gene on chromosome 18 to the SSX genes on chromosome X, leading to proliferation of the tumor cells. The need for non-invasive biomarkers indicating recurrence and activity of this disease has sparked research into short non-coding RNA known as microRNA (miRNA). METHODS: Blood samples of patients with active synovial sarcoma and of synovial sarcoma patients in complete remission as well as of healthy donors and patients with active leiomyosarcoma, MPNST, Ewing sarcoma and liposarcoma were collected. Whole blood RNA was extracted and samples of patients with active synovial sarcoma and of healthy donors were analyzed using an Affymetrix GeneChip miRNA Array v. 4.0. qRT-PCR was carried out to confirm a panel of miRNAs which where differentially expressed in the miRNA array. This miRNA-panel was further evaluated in patients with synovial sarcoma in complete remission and patients with active leiomyosarcoma, MPNST, Ewing sarcoma and liposarcoma as well as in an independent cohort of synovial sarcoma patients. RESULTS: Unsupervised hierarchical clustering of the miRNA arrays separated patients with active synovial sarcoma from healthy controls. A panel of seven miRNAs (miR-99a-5p, miR-146b-5p, miR-148b-3p, miR-195-5p, miR-223-3p, miR-500b-3p and miR-505-3p) was further validated by qRT-PCR to be significantly upregulated in synovial sarcoma patients. Moreover, most of the analyzed miRNAs were shown to be significantly upregulated in synovial sarcoma patients compared to leiomyosarcoma, MPNST, Ewing sarcoma and liposarcoma patients. Validation of the miRNA panel in an independent cohort of synovial sarcoma patients confirmed higher expression levels compared to healthy controls and patients in complete remission. CONCLUSION: Our results have identified a specific whole blood miRNA signature that may serve as an independent biomarker for the diagnosis of local recurrence or distant metastasis of synovial sarcoma. It even distinguishes synovial sarcoma from other sarcoma subtypes, thus potentially serving as a specific biomarker for synovial sarcoma.

miR-126 regulates platelet-derived growth factor receptor-α expression and migration of primary human osteoblasts.

Adequate vascularization is an essential requirement for bone development, fracture healing and bone tissue engineering. We have previously described the coculture of primary human osteoblasts (hOBs) and human endothelial cells (HUVECs), designed to investigate the interactions between these cells. In this system, we showed that cocultivation of these two cell types leads to a downregulation of platelet-derived growth factor receptor-α (PDGFR-α) in hOBs, which was a consequence of reduced mRNA stability. In the current study we investigated the possible involvement of microRNAs in this process. Firstly, we performed a microarray analysis of osteoblastic miRNAs following cocultivation with HUVECs, revealing an upregulation of miR-126. This result was confirmed by RT-qPCR, and we observed that the increase is dependent on direct cell-to-cell contacts. Gain-of-function and loss-of-function experiments showed that miR-126 is a negative regulator of PDGFR-α mRNA. Additionally, migration of hOBs was inhibited by miR-126 overexpression and stimulated by miR-126 inhibition. Addition of PDGFR-α blocking antibody to hOB culture also inhibited hOB migration. There was no effect of miR-126 modulation on osteoblast proliferation, apoptosis rate or differentiation. In conclusion, we report that the miR-126/PDGFR-α system regulates the migratory behavior of human osteoblasts, without exerting effects on cell survival and differentiation.

miR-126 modulates angiogenic growth parameters of peripheral blood endothelial progenitor cells.

Vascularization plays an important role in tissue engineering applications. It is known that implantation of differentiated endothelial cells or endothelial progenitor cells (EPCs) from cord blood (cbEPCs) gives rise to the formation of a complex functional neovasculature, whereas EPCs isolated from peripheral blood (pbEPCs) have a limited capability to form blood vessels upon implantation. MicroRNA-126 (miR-126) has been shown to have pro-angiogenic effects in vivo. In this study, we investigated whether modulation of miR-126 expression in pbEPCs may alter their angiogenic properties. Gain of function and loss of function experiments revealed that miR-126 has anti-angiogenic effects in pbEPCs. Overexpression of miR-126 resulted in decreased proliferation, migration, invasion and tube formation, while inhibition of miR-126 induced the opposite effects. However, modulation of miR-126 expression did not influence apoptotic susceptibility of pbEPCs. This study provides evidence that inhibition of miR-126 improves angiogenesis-related growth parameters in pbEPCs and may represent a therapeutic option to ameliorate the angiogenic and vasculogenic properties of pbEPCs.

Osteoblastic alkaline phosphatase mRNA is stabilized by binding to vimentin intermediary filaments.

Vascularization is essential in bone tissue engineering and recent research has focused on interactions between osteoblasts (hOBs) and endothelial cells (ECs). It was shown that cocultivation increases the stability of osteoblastic alkaline phosphatase (ALP) mRNA. We investigated the mechanisms behind this observation, focusing on mRNA binding proteins. Using a luciferase reporter assay, we found that the 3'-untranslated region (UTR) of ALP mRNA is necessary for human umbilical vein endothelial cells (HUVEC)-mediated stabilization of osteoblastic ALP mRNA. Using pulldown experiments and nanoflow-HPLC mass spectrometry, vimentin was identified to bind to the 3'-UTR of ALP mRNA. Validation was performed by Western blotting. Functional experiments inhibiting intermediate filaments with iminodipropionitrile and specific inhibition of vimentin by siRNA transfection showed reduced levels of ALP mRNA and protein. Therefore, ALP mRNA binds to and is stabilized by vimentin. This data add to the understanding of intracellular trafficking of ALP mRNA, its function, and have possible implications in tissue engineering applications.

Endothelial progenitor cells from peripheral blood support bone regeneration by provoking an angiogenic response.

Neovascularization is crucial for fracture healing and plays an important role in long-time graft survival in tissue engineering applications. Endothelial progenitor cells (EPCs) can be isolated from peripheral blood avoiding donor site morbidity, which makes them attractive for autologous cell-based engineering of neovessels. However, contradictory results are published concerning the vasculogenic potential of this cell type. We could previously show that implanted human endothelial vein cells (HUVECs) gave rise to the formation of a complex functional human neovasculature in a heterotopic (subcutaneous) as well as in an orthotopic (calvarial defect) model of severe combined immunodeficiency (SCID) mice, where vessel formation could even be increased by coimplanting mesenchymal stem cells (MSCs) functioning as perivascular cells. In this study, we investigated whether coimplantation of MSCs which have been predifferentiated in vitro into SMCs (SMC-MSCs) may enable pbEPCs to form blood vessels upon implantation and, if this would be the case, whether the resulting enhanced vascularization may support bone regeneration. For this purpose, pbEPCs and SMC-MSCs were mono- or cocultured in collagen matrices and seeded into scaffolds consisting of decalcified processed bovine cancellous bone (PBCB, Tutobone). Neovascularization and osteogenesis were evaluated using a calvarial bone defect-model in SCID mice. Our experiments could show that the missing vasculogenic potential of pbEPCs is not rescued by coimplantation of SMCs derived from MSCs predifferentiated along the vascular smooth muscle lineage. However, implantation of both cell types alone, or in combination induced an angiogenic response, which correlated in a positive manner with bone formation within the implants.

A conformational change of C-reactive protein in burn wounds unmasks its proinflammatory properties.

Tissue damage in burn injury leads to a rapid increase of leukocytes and acute phase reactants. Plasma levels of C-reactive protein (CRP) rise within hours after the insult. No deficiency of this protein has been reported in humans, suggesting it plays a pivotal role in innate immunity. CRP in circulation is composed of five identical subunits [pentameric CRP (pCRP)]. Recently, deposits of structurally modified CRP (mCRP) have been found in inflammatory diseases. Little is known about this structural change and how it affects CRP functions. We analyzed CRP deposits in burn wounds and serum by immunohistochemistry, western blot and dot blot analysis. CRP was deposited in necrotic and inflamed tissue, but not in adjacent healthy tissue. Tissue deposited CRP was detected by mCRP-specific antibodies and structurally different from serum pCRP. mCRP but not pCRP induced reactive oxygen species production by monocytes and facilitated uptake of necrotic Jurkat cells by macrophages. In addition, it accelerated migration of keratinocytes in a scratch wound assay. The structural changes that occur in pCRP upon localization to damaged and inflamed tissue in burn wounds result in a functionally altered protein with distinct functions. mCRP exhibits opsonic, proinflammatory and promigratory properties which modulate wound healing.

In vivo stimulation of early peripheral axon regeneration by N-propionylmannosamine in the presence of polysialyltransferase ST8SIA2.

The key enzyme of sialic acid (Sia) biosynthesis is the bifunctional UDP-N-acetylglucosamine 2-epimerase/ManNAc kinase (GNE/MNK). It metabolizes the physiological precursor ManNAc and N-acyl modified analogues such as N-propionylmannosamine (ManNProp) to the respective modified sialic acid. Polysialic acid (polySia) is a crucial compound for several functions in the nervous system and is synthesized by the polysialyltransferases ST8SIA2 and ST8SIA4. PolySia can be modified in vitro and in vivo by metabolic glycoengineering of the N-acyl side chain of Sia. In vitro studies show that the application of ManNProp increases neurite outgrowth and accelerates the re-establishment of functional synapses. In this study, we investigate in vivo how ManNProp application might benefit peripheral nerve regeneration. In mice expressing axonal fluorescent proteins (thy-1-YFP), we transected the sciatic nerve and then replaced part of it with a sciatic nerve graft from non-expressing mice (wild-type mice or St8sia2(-/-) mice). Analyses conducted 5 days after grafting showed that systemic application of ManNProp (200 mg/kg, twice a day, i.p.), but not of physiological ManNAc (1 g/kg, twice a day, i.p.), significantly increased the extent of axonal elongation, the number of arborizing axons and the number of branches per regenerating axon within the grafts from wild-type mice, but not in those from St8sia2(-/-) mice. The results demonstrate that the application of ManNProp has beneficial effects on early peripheral nerve regeneration and indicate that the stimulation of axon growth depends on ST8SIA2 activity in the nerve graft.

Is revisional surgery mandatory when an unexpected sarcoma diagnosis is made following primary surgery?

BACKGROUND: Soft tissue sarcomas (STS) are often diagnosed unexpectedly after surgery, and many excisions are incomplete. As histopathological assessments are challenging, patients later referred to comprehensive cancer centers (CCC) often come with an unclear status. This can make treatment planning problematic. We investigated the reliability of primary histopathological assessments, whether revisional surgery improved resection status, and the prognostic value of residual tumor at re-excision. METHODS: We analyzed the demographic and clinical characteristics of all patients referred to our CCC between 2003 and 2013. We compared patients treated exclusively at our CCC with those who had primary surgery elsewhere, and focused on resection margins, re-excision type, residual tumor, resection status after re-excision, and oncological outcome. RESULTS: Over half (n = 110) of all patients (n = 204) were referred from elsewhere. Seventy-one had undergone an excision without suspicion of malignancy. Resection status in referred patients was significantly inferior to the CCC group (p < 0.0001), although the latter had significantly more serious tumors and advanced disease stages (p < 0.05). The residual tumor rate was 53.13%, with a significantly higher probability in an upper extremity (p = 0.001). Initial histopathological classification was misleading in 46.9% of cases. Re-excision improved resection status in 69% of cases. Residual tumor presumably leads to higher rates of local recurrence (p = 0.057) and significantly shorter times to recurrence (p < 0.05). CONCLUSIONS: Re-excision should always follow unplanned STS excisions. Resection margins and histopathological assessments from referring institutions are often unreliable and unsuitable for treatment planning. Residual tumor is a risk factor for earlier and more likely local recurrence.

Classification of the Aging Lips: A Foundation for an Integrated Approach to Perioral Rejuvenation.

BACKGROUND: Although perioral aging is highly individual with several distinct processes taking part simultaneously, there is scarce systematic information which helps to indicate the right rejuvenation approach among the multitude of proposed procedures. Existing data about perioral aging has not yet been transformed into a consistent therapeutic concept. The intention of this study was to provide a simple, yet reproducible classification and to offer appropriate rejuvenation approaches. METHODS: To identify reliable and constant landmarks of the ongoing process of perioral aging, 462 perioral photo documentations were morphometrically analyzed. Based upon the identified landmarks a two-dimensional classification was developed. The classification was validated by three plastic surgeons. Inter- and intra-rater reliability was calculated using Cohen's kappa coefficient. RESULTS: Perioral aging can be broken down into changes of the lip shape and changes of the lip surface. Both processes can be classified into three stages each: Lip shape according to the shape in profile view, the lip length in relation to the frontal incisors, and the degree of vermilion inversion. Lip surface according to the presence and degree of radial wrinkles and the visibility of the structural elements Cupid's bow, philtrum, and white roll. Inter-observer reliability was rated very good (kappa values between 0.819 and 0.963) and perfect for intra-observer reliability (1.0). CONCLUSION: A better understanding of perioral aging leads to a simple classification for the aging lips. Using the classification helps to tailor an appropriate treatment to the individual patient and aids to achieve a natural rejuvenation result.

Aesthetic surgery performed by plastic surgery residents: an analysis of safety and patient satisfaction.

BACKGROUND: Aesthetic surgery is an integral component of plastic surgery. Despite its importance, adequate training in aesthetic surgery is met with challenges. Although the educational benefit of resident clinics has been demonstrated, such clinics are rarely found outside the United States. The objective of the present study was to assess safety and patient satisfaction associated with aesthetic surgery procedures performed by plastic surgery residents at a German academic medical center. METHODS: The study had 2 components, namely, a retrospective chart review and an administration of a patient satisfaction survey. Only patients who underwent a surgical intervention by a plastic surgery resident between 2003 and 2011 were included in the study. Parameters of interest included age, sex, procedure performed, number of procedures, revenue (in &OV0556;), length of follow-up, revision rate, and postoperative complication rate. Patient satisfaction was assessed by the client satisfaction questionnaire-8. RESULTS: A total of 273 aesthetic procedures were performed in 206 patients with an increase in recent years. The median follow-up period was 49.5 months. The most frequently performed procedures were liposuction (n = 59), breast augmentation (n = 53), and upper eyelid blepharoplasty (n = 31). One hundred ninety-two (90.3%) patients had an uneventful postoperative course. The client satisfaction questionnaire-8 questionnaire was completed by 110 patients (response rate, 50.2%). The median value of 28 indicates a high degree of patient satisfaction. An association between occurrence of major complications and patient satisfaction was seen. CONCLUSIONS: Aesthetic surgery performed by plastic surgery residents under supervision by attending physicians is safe and provides for high levels of patient satisfaction postoperatively. Offering these services may be able to bridge the gap between providing high-quality aesthetic surgery training while yet recruiting an increasing number of patients who may appreciate the lower fees associated with these services.

The quality of aesthetic surgery training in plastic surgery residency: a survey among residents in Germany.

BACKGROUND: The importance of providing high-quality exposure and training in aesthetic and reconstructive surgery during residency has come to the forefront of plastic surgery education. Adequate training in aesthetic surgery, however, has traditionally been challenging. The authors were interested in how these challenges were met abroad. METHODS: A 17-item online survey was developed to assess the quality of training in aesthetic surgery in Germany. The survey had 3 distinct sections: demographic information, current state of aesthetic surgery training, and residents' opinions about the perceived quality of aesthetic surgery training. Only responses of senior residents were included in the final analysis. RESULTS: A total of 112 residents responded (30% response rate), of which 88 were senior plastic surgery residents. Ninety percent (n = 79) reported that a resident aesthetic surgery clinic was not part of their training experience. Eighty-eight percent (n = 77) reported that they did not have a dedicated aesthetic surgery rotation during their residency training. According to 69.3% (n = 61), no didactic training in aesthetic surgery was provided. Fifty-six percent (n = 49) of senior plastic surgery residents had performed only a maximum of 10 aesthetic surgery procedures at the time of the survey. Although only 43.2% of senior residents claimed to be interested in a predominantly aesthetic surgery practice, 90.9% (n = 80) felt that they require further training in aesthetic surgery (ie, fellowship). CONCLUSIONS: Deficiencies exist with respect to aesthetic surgery training among senior plastic surgery residents in Germany. Structural improvements in residency training with formal exposure and teaching in aesthetic surgery are warranted. The German Society of Plastic, Reconstructive and Aesthetic Surgeons is actively addressing deficiencies identified with the goal of improving the quality of training.

Monitoring molecular changes induced by ischemia/reperfusion in human free muscle flap tissue samples.

BACKGROUND: Our current knowledge of the pathophysiological sequelae of ischemia or reperfusion (I/R) injury in free tissue transfer in reconstructive surgery is based on data obtained in animal experiments. In this study, we investigated the histologic and molecular changes after 11 free microsurgical muscle transfers in human muscle tissue. METHODS: Biopsies of free muscle flap tissue were taken immediately before clipping of the pedicle and 5 days after ischemia and successful microanastomosis and restoration of the blood flow. Samples were analyzed histologically for edema formation and by immunohistochemistry for infiltration of inflammatory cells and angiogenesis. Expression levels of the inflammatory marker proteins interleukin-1ß and tumor necrosis factor α and of complement component 3 as a major mediator of I/R injury were analyzed by real-time polymerase chain reaction. A TUNEL (terminal desoxynucleotidyl transferase-mediated-dUTP-nick-end-labeling) assay was used to assess apoptosis levels within the human muscle tissue. RESULTS: I/R injury leads to a significant up-regulation of inflammatory parameters, infiltration of inflammatory cells, and angiogenesis. Increased complement component 3 deposition and apoptosis of cells were accompanied by interstitial edema as indication for a pronounced postischemic inflammatory reaction within the muscle tissue after free tissue transfer. CONCLUSIONS: Our findings of molecular changes induced by I/R injury in human striated muscle tissue validate data obtained in animal models of I/R injury. The parameters and inflammatory patterns defined in this study will allow for the monitoring of the success of novel pharmaceutical strategies in the future and will help to transfer data obtained in animal work to the in vivo setting in human beings.

Spheroid-based engineering of a human vasculature in mice.

The complexity of the angiogenic cascade limits cellular approaches to studying angiogenic endothelial cells (ECs). In turn, in vivo assays do not allow the analysis of the distinct cellular behavior of ECs during angiogenesis. Here we show that ECs can be grafted as spheroids into a matrix to give rise to a complex three-dimensional network of human neovessels in mice. The grafted vasculature matures and is connected to the mouse circulation. The assay is highly versatile and facilitates numerous applications including studies of the effects of different cytokines on angiogenesis. Modifications make it possible to study human lymphangiogenic processes in vivo. EC spheroids can also be coimplanted with other cell types for tissue engineering purposes.

Free tissue transfer in reconstruction following soft tissue sarcoma resection.

BACKGROUND: Radical surgical resection remains the single-most important treatment in the curative multimodal therapy of soft tissue sarcomas. Refinements in surgical techniques have resulted in the development of function preserving approaches increasingly avoiding limb amputation. PATIENTS AND METHODS: The records of all patients (n = 34) who underwent microsurgical soft tissue coverage subsequent to primary resection of soft tissue sarcoma of the upper or lower limb from 1999 to 2009 are reviewed regarding postoperative complications, time until start of adjuvant radiation and functional outcome (Toronto Extremity Salvage Score, TESS). RESULTS: Thirty-four patients (range: 21-86 years) received a total of 35 free flaps. Complete tumor resection was obtained in 33 patients, one patient required re-excision ultimately resulting in tumor-free margin status (R0 resection). Major complications were encountered in four cases including one patient with complete flap loss requiring an additional free flap and three patients with partial flap loss requiring split-thickness skin graft procedures. Minor complications were observed in three patients (9%). Extremity salvage could be achieved in 33 patients with adequate postoperative ambulation (TESS 84 ± 18) and adequate use of the upper extremity (TESS 80 ± 22). One patient underwent amputation. Mean time until start of adjuvant radiotherapy was 37 days (range 24-56 days). CONCLUSION: A synergetic center-based interdisciplinary approach is crucial in therapeutical management of soft tissue sarcomas with the aim of R0 resection status and limb preservation. Plastic surgery contributes by offering microsurgical reconstruction using free tissue transfer, thus broadening surgical possibilities. This increases the chance of both adequate oncosurgical resection and limb preservation.