Integrating AI in Lipedema Management: Assessing the Efficacy of GPT-4 as a Consultation Assistant

The role of artificial intelligence (AI) in healthcare is evolving, offering promising avenues for enhancing clinical decision making and patient management. Limited knowledge about lipedema often leads to patients being frequently misdiagnosed with conditions like lymphedema or obesity rather than correctly identifying lipedema. Furthermore, patients with lipedema often present with intricate and extensive medical histories, resulting in significant time consumption during consultations. AI could, therefore, improve the management of these patients. This research investigates the utilization of OpenAI's Generative Pre-Trained Transformer 4 (GPT-4), a sophisticated large language model (LLM), as an assistant in consultations for lipedema patients. Six simulated scenarios were designed to mirror typical patient consultations commonly encountered in a lipedema clinic. GPT-4 was tasked with conducting patient interviews to gather medical histories, presenting its findings, making preliminary diagnoses, and recommending further diagnostic and therapeutic actions. Advanced prompt engineering techniques were employed to refine the efficacy, relevance, and accuracy of GPT-4's responses. A panel of experts in lipedema treatment, using a Likert Scale, evaluated GPT-4's responses across six key criteria. Scoring ranged from 1 (lowest) to 5 (highest), with GPT-4 achieving an average score of 4.24, indicating good reliability and applicability in a clinical setting. This study is one of the initial forays into applying large language models like GPT-4 in specific clinical scenarios, such as lipedema consultations. It demonstrates the potential of AI in supporting clinical practices and emphasizes the continuing importance of human expertise in the medical field, despite ongoing technological advancements.

HER3 (ERBB3) amplification in liposarcoma - a putative new therapeutic target?

BACKGROUND

Liposarcomas are among the most common mesenchymal malignancies. However, the therapeutic options are still very limited and so far, targeted therapies had not yet been established. Immunotherapy, which has been a breakthrough in other oncological entities, seems to have no efficacy in liposarcoma. Complicating matters further, classification remains difficult due to the diversity of morphologies and nonspecific or absent markers in immunohistochemistry, leaving molecular pathology using FISH or sequencing as best options. Many liposarcomas harbor MDM2 gene amplifications. In close relation to the gene locus of MDM2, HER3 (ERBB3) gene is present and co-amplification could occur. Since the group of HER/EGFR receptor tyrosine kinases and its inhibitors/antibodies play a role in a broad spectrum of oncological diseases and treatments, and some HER3 inhibitors/antibodies are already under clinical investigation, we hypothesized that in case of HER3 co-amplifications a tumor might bear a further potential therapeutic target.

METHODS

We performed FISH analysis (MDM2, DDIT3, HER3) in 56 archived cases and subsequently performed reclassification to confirm the diagnosis of liposarcoma.

RESULTS

Next to 16 out of 56 cases needed to be re-classified, in 20 out of 54 cases, a cluster-amplification of HER3 could be detected, significantly correlating with MDM2 amplification. Our study shows that the entity of liposarcomas show specific molecular characteristics leading to reclassify archived cases by modern, established methodologies. Additionally, in 57.1% of these cases, HER3 was cluster-amplified profusely, presenting a putative therapeutic target for targeted therapy.

CONCLUSION

Our study serves as the initial basis for further investigation of the HER3 gene as a putative therapeutic target in liposarcoma.

Antiseptic management of critical wounds: differential bacterial response upon exposure to antiseptics and first insights into antiseptic/phage interactions - experimental studies

BACKGROUND

With the antibiotic crisis, the topical antibacterial control including chronic wounds gains increasing importance. However, little is known regarding tolerance development when bacteria face repetitive exposure to the identical antiseptics as commonly found in clinical practice.

MATERIALS AND METHODS

We exposed clinical isolates foremost of chronic wounds in vitro to dilutions of two antisepctics used for wound therapy: polyhexanide or octenidine. Adaptive response was determined by growth/kill curves, minimal inhibitory concentration (MIC), and whole genome sequencing. Antiseptic/bacteriophage combinations were studied by liquid-infection assays and bacterial plating.

RESULTS

Polyhexanide acted stronger against Escherichia coli and Proteus mirabilis while octenidine was more potent against Staphylococcus aureus. Otherwise, the antiseptic efficacy varied across isolates of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Upon repetitive exposure with constant antiseptic concentrations P. aeruginosa and P. mirabilis adaptation was evident by a reduced lag-phase and a two-fold increased MIC. Under increasing octenidine concentrations, P. aeruginosa adapted to an eightfold higher dosage with mutations in smvA, opgH and kinB affecting an efflux pump, alginate and biofilm formation, respectively. S. aureus adapted to a fourfold increase of polyhexanide with a mutation in the multiple peptide resistance factor MprF, also conferring cross-resistance to daptomycin. Antiseptic/bacteriophage combinations enhanced bacterial inhibition and delayed adaptation.

CONCLUSION

Different bacterial species/strains respond unequally to low-level antiseptic concentrations. Bacterial adaptation potential at phenotypic and genotypic levels may indicate the necessity for a more nuanced selection of antiseptics. Bacteriophages represent a promising yet underexplored strategy for supporting antiseptic treatment which may be particularly beneficial for the management of critical wounds.

Association between Donor Age and Osteogenic Potential of Human Adipose Stem Cells in Bone Tissue Engineering

Adipose stem cells (ASCs) have multilineage differentiation capacity and hold great potential for regenerative medicine. Compared to bone marrow-derived mesenchymal stem cells (bmMSCs), ASCs are easier to isolate from abundant sources with significantly higher yields. It is generally accepted that bmMSCs show age-related changes in their proliferation and differentiation potentials, whereas this aspect is still controversial in the case of ASCs. In this review, we evaluated the existing data on the effect of donor age on the osteogenic potential of human ASCs. Overall, a poor agreement has been achieved because of inconsistent findings in the previous studies. Finally, we attempted to delineate the possible reasons behind the lack of agreements reported in the literature. ASCs represent a heterogeneous cell population, and the osteogenic potential of ASCs can be influenced by donor-related factors such as age, but also gender, lifestyle, and the underlying health and metabolic state of donors. Furthermore, future studies should consider experimental factors in in vitro conditions, including passaging, cryopreservation, culture conditions, variations in differentiation protocols, and readout methods.

[Nerve Transfers in Children with Non-traumatic Amyoplasia]

BACKGROUND

The treatment of obstetric brachial plexus palsy through primary reconstruction and nerve transfers has been established in the past decades. In the case of non-traumatic diseases that lead to flaccid paralysis and the inability to move the extremities, such as transverse myelitis (TM) or arthrogryposis multiplex congenita (AMC), which can have a wide variety of causes, the focus has been on rehabilitative therapy so far, while surgical interventions have been used to a lesser extent, e. g., in the form of osteotomies or muscle transfers. Our aim is to establish nerve transfers as a surgical option to improve mobility in non-traumatic amyoplasia.

PATIENTS

This work presents the needs-adapted treatment of a total of 23 patients (aged 4 months to 64 months, 18 with AMC and 5 with TM) using nerve transfers on the upper extremity.

RESULTS

We were able to show that early nerve transfers in the upper extremity enabled the reanimation of muscles in both AMC and TM.

CONCLUSION

This work shows that the treatment of non-traumatic amyoplasia in children with selective nerve grafts is a successful method. Nerve transfers allow patients to gain or regain important functions for managing independent everyday life. The surgical methods have been established in the treatment of traumatic nerve injuries. They are well-known and can be carried out safely. We believe that this is an important treatment option for paediatric patients with paralysis associated with TM or AMC, which should also be known to the treating physicians.

[Anatomical variants of the median and musculocutaneous nerve - a case report]

Traumatische Schädigungen des Plexus brachialis resultieren häufig in einer eingeschränkten oder aufgehobenen Flexionsbewegung des Ellenbogens. Die Wiederherstellung dieser Bewegung ist ein wichtiges Ziel der chirurgischen Therapie 1 2. Maßgeblich für die Flexionsbewegung und Innervation der Zielmuskeln ist der N. musculocutaneus (MSC). Dieser bildet einen der beiden Endäste des Fasciculus lateralis des Plexus brachialis (C5-C7). In den meisten Fällen verläuft er an der ventralen Oberarmseite, in der Flexorenloge, zwischen dem M. brachialis und M. biceps brachii nach distal und gibt Äste zur motorischen Innervation der beiden Muskeln ab. Er verläuft anschließend durch den Sulcus bicipitalis lateralis und durchbricht die Fascia brachii in der Ellenbeuge 3 um als Nervus cutaneus antebrachii lateralis, sensibel den Unterarm zu versorgen. Variable Verläufe des Plexus brachialis in Zusammenschau mit dem N. musculocutaneus sind beschrieben und können auf vielseitige Art und Weisen imponieren 4 5. So kann der N. musculocutaneus direkte Verbindungen zum N.medianus aufweisen, oder diesen als direkter dritter Zuschuss anteilweise bilden. Der N. medianus kann also sowohl Äste an den N. musculocutaneus abgeben als auch solche von diesem erhalten. Vorliegende Kadaverstudien zeigen in über 50+% der Fälle Verbindungen zwischen dem N. musculocutaneus und dem N. medianus, wobei ein Großteil solcher Verbindungen proximal des Eintrittes des N. musculocutaneus in den M. coracobrachialis liegt 6. Trotzdem sind diese Variationen im klinischen Alltag meist Zufallsbefunde bei chirurgischen Interventionen 7.

GPR55 inhibits the pro-adipogenic activity of anandamide in human adipose stromal cells

The endocannabinoid anandamide (AEA) stimulates adipogenesis via the cannabinoid receptor CB1 in adipose stromal cells (ASCs). However, AEA interacts also with nonclassical cannabinoid receptors, including transient receptor potential cation channel (TRPV)1 and G protein-coupled receptor (GPR)55. Their roles in AEA mediated adipogenesis of human ASCs have not been investigated. We examined the receptor-expressions by immunostaining on human ASCs and tested their functionality by measuring the expression of immediate early genes (IEGs) related to the transcription factor-complex AP-1 upon exposition to receptor agonists. Cells were stimulated with increasing concentrations of specific ligands to investigate the effects on ASC viability (proliferation and metabolic activity), secretory activity, and AEA mediated differentiation. ASCs expressed both receptors, and their activation suppressed IEG expression. TRPV1 did not affect viability or cytokine secretion. GPR55 decreased proliferation, and it inhibited the release of hepatocyte growth factor. Blocking GPR55 increased the pro-adipogenic activity of AEA. These data suggest that GPR55 functions as negative regulator of cannabinoid mediated pro-adipogenic capacity in ASCs.

[Contralateral C7 Nerve Transfer]

Complex brachial plexus injuries with multiple or complete root avulsions make intraplexic reconstruction impossible in some cases. Such cases necessitate the use of extraplexic nerve donors such as the spinal accessory nerve or intercostal nerves. The contralateral C7 root represents a donor with a high axon count and can be used as an axon source in such cases. We summarise current indications, surgical technique and functional results after a contralateral C7 transfer in cases of brachial plexus injury, describing some of our own cases and including a selective literature review.

ITIH5 inhibits proliferation, adipogenic differentiation, and secretion of inflammatory cytokines of human adipose stem cells-A new key in treating obesity?

Inter-α-trypsin inhibitor heavy chain 5 (ITIH5) is widely expressed in the human body, and it is detected to be particularly abundant in adipose tissue. ITIH5 expression is increased in people with obesity compared to lean persons and is decreased by diet-induced weight loss. This suggests that ITIH5 may be involved in the development of adiposity and clinical metabolic variables, although its exact function remains unknown. We measured the protein concentration of ITIH5 in adipose samples from patients undergoing abdominoplasty and tested for correlation with the subjects' BMI as well as inflammatory mediators. We stimulated human adipose stem cells (ASCs) with recombinant (r)ITIH5 protein and tested for an effect on proliferation, differentiation, and immunosuppressive properties when the cells were exposed to an artificial inflammatory environment. We found positive correlations between ITIH5 levels and the BMI (p < .001) as well as concentrations of inflammatory cytokines (TNF-α, IL-6, and MCP-1) in adipose tissue (p < .01). Application of the rITIH5 protein inhibited both proliferation (p < .001) and differentiation of ASCs. Especially, the development of mature adipocytes was reduced by over 50%. Moreover, rITIH5 decreased the release of IL-6 and MCP-1 when the cells were exposed to TNF-α and IL-1β (p < .001). Our data suggest that ITIH5 is an adipokine that is increasingly released during human adipose tissue development, acting as a regulator that inhibits proliferation and adipogenic differentiation of ASCs. ITIH5 thus presents itself as a positive regulator of adipose tissue homeostasis, possibly protecting against both hyperplasia and hypertrophy of adipose tissue and the associated chronic inflammation.

Effects of epinephrine, lidocaine, and prilocaine on viability and differentiation capacity of human adipose stem cells

INTRODUCTION

Local anesthetics (LAs) are routinely administered in plastic and reconstructive surgery, e.g., as tumescent anesthesia adjunct in liposuction. Historically, these substances were assumed to act cytotoxically. Thus, the application of LA was avoided when handling adipose stem cells (ASCs). We recently determined that most LAs are not cytotoxic when ASCs are exposed to concentrations used for tumescent liposuction. However, there is limited information when combining LA with epinephrine and about the effects of prilocaine on ASCs.

METHODS

We analyzed the effects of prilocaine or lidocaine in co-exposure with epinephrine on the viability of primary human ASCs, i.e., proliferation, metabolic activity, and cytotoxicity, using crystal violet-staining, PrestoBlue®-, and WST-1 assay. We quantified the impact of short-term incubation of lidocaine and epinephrine on the differentiation of ASCs into the adipogenic, chondrogenic, and osteogenic lineage.

RESULTS

After 2 h, prilocaine (10 mM) significantly reduced metabolic activity and cell numbers, whereas lidocaine only inhibited metabolic activity. After 6 h, prilocaine (10 mM) and lidocaine significantly decreased metabolic activity as well as cell numbers. The application of high concentrations of epinephrine did not affect cell numbers but diminished metabolic activity. Combining lidocaine with epinephrine had no additional cytotoxic effect. Differentiation into the chondrogenic lineage was significantly inhibited by epinephrine.

CONCLUSIONS

Deducing from our data, neither lidocaine combined with epinephrine nor prilocaine has a cytotoxic impact on ASCs in vitro at concentrations equivalent to those in tumescent anesthesia and has no long-lasting effect on the differentiation capacity of ASCs into the osteogenic and adipogenic lineage.

Hyperbaric oxygen treatment in carbon monoxide poisoning - Does it really matter?

Carbon monoxide (CO) is an odorless and colorless gas that can lead to fulminant and life-threatening intoxications. Besides an early diagnosis, an appropriate treatment of the intoxication is important. In this context the reduction of CO concentration in blood and tissues is crucial revealing hyperbaric oxygen treatment (HBO) as a highly promising tool. However, the benefit of HBO in CO intoxications is still considered controversial. In this review, we discuss the evidence of the role of HBO treatment in isolated CO intoxication.

Comprehensive Analysis of Local Anesthetics Affecting Adipose Stem Cells In Vitro

BACKGROUND

Adipose stem cells (ASCs) hold a great regenerative capacity because of their differentiation capability and their secretory activity. Thus, ASC survival is of great significance during perioperative harvesting. Various local anesthetics are commonly applied during fat grafting procedures. These substances are known to impair cellular viability, which would affect graft survival and final outcomes, but the exact extent of their impact on ASC biology is unknown.

METHODS

The authors analyzed the short- and long-term effects of lidocaine, mepivacaine, ropivacaine, and bupivacaine at increasing concentrations (0.1 to 10 mM) on primary human ASC proliferation and metabolic activity. Trilinear differentiation was assessed by oil red O stain (adipogenesis), safranin O (chondrogenesis), and cresolphthalein (osteogenesis) labeling. In supernatants, cytokine [interleukin (IL)-6/IL-8, vascular endothelial growth factor, hepatocyte growth factor] secretion was analyzed by enzyme-linked immunosorbent assay.

RESULTS

Bupivacaine at greater than 100 µM demonstrated the strongest anti proliferative effects, whereas lidocaine and ropivacaine did not affect cell numbers. Mepivacaine evoked reciprocal results regarding cell count at greater than 1 mM. Each compound impaired trilinear differentiation. Secretion of hepatocyte growth factor and IL-8 was reduced significantly by local anesthetic exposure; levels were restored after substances were washed out.

CONCLUSIONS

In vitro data show that lidocaine, mepivacaine, and ropivacaine could be applied at concentrations of 1 to 10 mM without affecting ASC survival. In contrast, bupivacaine at concentrations greater than 100 µM should be administered with great caution. The differentiation of ASCs and the ASC's secretome might already be decreased by each local anesthetic at 1 mM.

CLINICAL RELEVANCE STATEMENT

The authors' experimental data can be of great significance to the clinical practice, as local anesthetics are routinely administered during liposuction as a tumescent anesthesia adjunct.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Three-Dimensional Bioprinting in Soft Tissue Engineering for Plastic and Reconstructive Surgery

Skeletal muscle tissue engineering (TE) and adipose tissue engineering have undergone significant progress in recent years. This review focuses on the key findings in these areas, particularly highlighting the integration of 3D bioprinting techniques to overcome challenges and enhance tissue regeneration. In skeletal muscle TE, 3D bioprinting enables the precise replication of muscle architecture. This addresses the need for the parallel alignment of cells and proper innervation. Satellite cells (SCs) and mesenchymal stem cells (MSCs) have been utilized, along with co-cultivation strategies for vascularization and innervation. Therefore, various printing methods and materials, including decellularized extracellular matrix (dECM), have been explored. Similarly, in adipose tissue engineering, 3D bioprinting has been employed to overcome the challenge of vascularization; addressing this challenge is vital for graft survival. Decellularized adipose tissue and biomimetic scaffolds have been used as biological inks, along with adipose-derived stem cells (ADSCs), to enhance graft survival. The integration of dECM and alginate bioinks has demonstrated improved adipocyte maturation and differentiation. These findings highlight the potential of 3D bioprinting techniques in skeletal muscle and adipose tissue engineering. By integrating specific cell types, biomaterials, and printing methods, significant progress has been made in tissue regeneration. However, challenges such as fabricating larger constructs, translating findings to human models, and obtaining regulatory approvals for cellular therapies remain to be addressed. Nonetheless, these advancements underscore the transformative impact of 3D bioprinting in tissue engineering research and its potential for future clinical applications.

Prospective analysis of grip strength and load distribution after surgical treatment of common diseases of the hand with novel's manugraphy® system

BACKGROUND

Carpal tunnel syndrome, A1 annular pulley stenosis and Dupuytren's contracture are among the most common conditions of the hand. In this study, we investigated the impact of surgical procedure on hand grip strength and high-resolution spatial load distribution in individuals suffering from those diseases over a follow-up period of one year.

MATERIALS AND METHODS

In this prospective study, data of 9 patients with carpal tunnel syndrome, 12 patients with A1 annular pulley stenosis and 7 patients with Dupuytren's contracture were evaluated. Only patients with unilateral disease were included providing the contralateral hand as an intra-individual control. Grip strength was measured with cylindrical instruments in two different sizes with respect to the hand size of the patients. Maximum and average values of grip strength as well as spatial load distribution in each finger, thenar, hypothenar and palm were analyzed. Data of the affected patients were collected preoperatively and 6 weeks, 6 months and 1 year postoperatively. Grip strength and spatial load distribution were compared preoperatively to postoperatively. In addition, DASH score, Levine score, 2-point discrimination and degree of flexion contracture were assessed.

RESULTS

The patients with A1 annular pulley stenosis showed a significant increase in grip strength 6 months and one year postoperatively. Patients with carpal tunnel syndrome and Dupuytren's contracture showed no significant difference in grip strength over the course of time. An increase in the percentual grip strength of the thenar in patients with carpal tunnel disease and within the affected finger in A1 annular pulley stenosis was observed over the course of time. The DASH score was significantly lower in all patient cohorts one year postoperatively.

CONCLUSION

Surgical procedure in carpal tunnel syndrome, A1 annular ligament stenosis and Dupuytren's contracture improves the functionality of the hand in everyday life. Some areas of the hand seem to compensate other weaker areas in grip strength.

First Series of Free Flap Reconstruction Using a Dedicated Robotic System in a Multidisciplinary Microsurgical Center

Robotic microsurgery is a novel technology for microsurgical free flap transplantation in reconstructive surgery. Recently, the first free flap transplantation using a dedicated robotic system for microsurgery (Symani Surgical System; Medical Microinstruments) was published for a single reconstructive case. For broader future application, evaluating its potential benefits in different anatomical regions, anastomotic configurations, and clinical scenarios is necessary. In this world-wide first free flap series using this robotic system, we describe our experience with this new technology in a multidisciplinary microsurgical center. The robotic system was used for different free flaps in a range of reconstructive applications in plastic surgery, oral and maxillofacial surgery, and head and neck surgery. A total of 23 flaps were performed, with all 23 arterial and a selection of two venous anastomoses being performed with the robotic system. Time for anastomoses was significantly longer than commonly. Five of the arterial robotic anastomoses had to be redone. All but one flap survived. We could show that this new dedicated microsurgical robotic system is feasible for carrying out robot-assisted anastomoses in end-to-end, as well as end-to-side fashion under varying clinical conditions and in different microsurgical subspecialties. However, some drawbacks still need to be overcome, which are partly related to individual and institutional learning curves, to finally estimate the potential benefit for robotic free flap surgery. Multidisciplinary application of the robotic system may accelerate this process by putting together different microsurgical backgrounds, while economic burden of establishing this new technology is spread among several departments.

Nerve Transfers Using a Dedicated Microsurgical Robotic System

Microsurgical demands in peripheral nerve surgery are increasing. Because of the development of multiple simultaneous selective nerve transfers, the transposition of very small nerves and even single fascicles has evolved. Coaptation of these increasingly smaller structures require high skills in microsurgical techniques. In addition, the surgical situs often has very limited access and is difficult to reach with conventional microsurgical options. Robot technology, the Symani Surgical System (Medical Microinstruments, S.p.A, Calci, Pisa, Italy), was used for epineural coaptation of three donor nerves (intercostal nerves 4-6) to the long thoracic nerve and the thoracodorsal nerve as recipient nerves in a patient with brachial plexus palsy. The coaptations could be carried out successfully with the microsurgical robot technology. In combination with a high-magnification (up to 26×) 3D-exoscope, the epineural sutures could be placed very precisely and accurately. Using this new microsurgical robotic system, successful coaptation of very small nerve structures is possible. This opens possibilities for the microsurgeon to carry out even finer, more targeted and more complex nerve transfers, including procedures in anatomical regions that are difficult to reach.

Reconstructive and Aesthetic Surgeries on the Female Genitalia. Guideline of the DGGG, DGPRÄC, OEGGG and SGGG (S2k-Level, AWMF Registry No. 009/019, May 2022)

Aim This official guideline was coordinated and published by the German Society for Gynaecology and Obstetrics (DGGG), the German Society for Plastic, Reconstructive and Aesthetic Surgery (DGPRÄC), the Austrian Society for Gynaecology and Obstetrics (OEGGG), and the Swiss Society for Gynaecology and Obstetrics (SGGG). The guideline aims to provide a consensus-based overview of reconstructive and aesthetic surgeries on female genitalia based on an evaluation of the relevant literature. Methods This S2k-guideline was developed by representative members from different medical professions on behalf of the guidelines commission of the DGGG, DGPRÄC, OEGGG and SGGG using a structured consensus process. Recommendations Statements and recommendations on the epidemiology, aetiology, classification, symptoms, diagnosis, and treatment of acquired changes of the external genitalia are presented and special situations are discussed.

Myogenic differentiation of human myoblasts and Mesenchymal stromal cells under GDF11 on NPoly-ɛ-caprolactone-collagen I-Polyethylene-nanofibers

BACKGROUND

For the purpose of skeletal muscle engineering, primary myoblasts (Mb) and adipogenic mesenchymal stem cells (ADSC) can be co-cultured and myogenically differentiated. Electrospun composite nanofiber scaffolds represent suitable matrices for tissue engineering of skeletal muscle, combining both biocompatibility and stability Although growth differentiation factor 11 (GDF11) has been proposed as a rejuvenating circulating factor, restoring skeletal muscle function in aging mice, some studies have also described a harming effect of GDF11. Therefore, the aim of the study was to analyze the effect of GDF11 on co-cultures of Mb and ADSC on poly-ε-caprolactone (PCL)-collagen I-polyethylene oxide (PEO)-nanofibers.

RESULTS

Human Mb were co-cultured with ADSC two-dimensionally (2D) as monolayers or three-dimensionally (3D) on aligned PCL-collagen I-PEO-nanofibers. Differentiation media were either serum-free with or without GDF11, or serum containing as in a conventional differentiation medium. Cell viability was higher after conventional myogenic differentiation compared to serum-free and serum-free + GDF11 differentiation as was creatine kinase activity. Immunofluorescence staining showed myosine heavy chain expression in all groups after 28 days of differentiation without any clear evidence of more or less pronounced expression in either group. Gene expression of myosine heavy chain (MYH2) increased after serum-free + GDF11 stimulation compared to serum-free stimulation alone.

CONCLUSIONS

This is the first study analyzing the effect of GDF11 on myogenic differentiation of Mb and ADSC co-cultures under serum-free conditions. The results of this study show that PCL-collagen I-PEO-nanofibers represent a suitable matrix for 3D myogenic differentiation of Mb and ADSC. In this context, GDF11 seems to promote myogenic differentiation of Mb and ADSC co-cultures compared to serum-free differentiation without any evidence of a harming effect.

Time course of functional recovery after 1 cm sciatic nerve resection in rats with or without surgical intervention - measured by grip strength and locomotor activity

The rat sciatic nerve (SN) is the most frequently used model in experimental research on peripheral nerve injuries. Within the broad range of evaluation methods to determine the experimental outcome, recovery of behavior represents the major criterion to assess functional regeneration. The grasping test indicates when recovery begins and its improvement with time. However, lesions of the SN have yet remained unstudied with this method. Therefore, rats received a SN resection and were divided into experimental groups: 1) control with lesion only, 2) nerve bridge, and 3) autograft. During weekly sessions, the grasping test measured the grip strength, and the locomotor behavior was assessed in the open field. Finally, the nerves were prepared for electrophysiology and histomorphometry. Autograft recovered grasping after 7 weeks with the strongest improvement afterwards. Nerve tube allowed grasping by week 12. Control animals did not recover. In the open field, no differences were observed between the groups. Recordings were possible only in the autograft group, which could be explained by higher number of regenerated fibers. This study indicates that grasping data correspond with physiological and anatomical findings. We conclude that the grasping test is a valid method to evaluate functional recovery after SN resection in rats.

Adipose and lipoma stem cells: A donor-matched comparison

Lipomas are slow growing benign fat tumors that develop in soft tissues of the mesoderm. Thus, the specific (dys-)function of mesenchymal stem cells (MSCs) has been suggested in the development of lipomas, but details of the tumor pathogenesis remain unclear. Existing studies comparing stem cells from native adipose (adipose stem cells [ASCs]) and lipomatous tissues (LSCs) have reported contradicting findings. However, harvesting ASCs and LSCs from different individuals might have influenced proper comparison. Therefore, we aimed to characterize donor-matched ASCs and LSCs to investigate metabolic activity, proliferation, capability for tri-linear differentiation (chondrogenesis, adipogenesis, osteogenesis), and the secretome of mature adipocytes and lipomacytes. Both stem cell types did not differ in metabolic activity, but ASCs demonstrated stronger proliferation than LSCs. While there was no difference in proteoglycan accumulation during chondrogenic differentiation, adipogenesis was higher in ASCs, with more lipid vacuole formation. Conversely, LSCs showed increased osteogenesis by higher calcium deposition. Lipomacytes showed stronger secretory activity and released higher levels of certain adipokines. Our findings indicated that LSCs possessed important characteristics of MSCs, including ASCs. However, LSCs' low proliferation and adipogenic differentiation behavior did not appear to account for enhanced tissue proliferation, but the secretome of lipomacytes could contribute to lipomatous neoplasm.

[Registry Research Funding of the German Society of Plastic, Reconstructive and Aesthetic Surgery (DGPRÄC) and Research Funding Report 2021/2022]

BACKGROUND

Research is an integral part of academic medicine. In plastic surgery, it sets the course for innovations in the specialty. The purpose of this study is to present the research performance of plastic surgeons in Germany for the period 2021/2022 and to compare it with previous periods.

MATERIALS AND METHODS

The directors of plastic surgical academic institutions reported all requested/approved and rejected research applications to public, non-public and industrial funding organizations. Data was gathered within an established online database. In addition, the DFG´s public database GEPRIS was screened for plastic surgical research grants. Data was also collected regarding research infrastructure and organization at the participating centers.

RESULTS

105 applications were reported to 54 different funding agencies from 20 plastic surgery centers. 37 funding applications were submitted to the major public funding agencies DFG, BMBF, BMWi, BMG, BMVg, G-BA and EU. Of these, 59,5% (22/37) were DFG, 13,5% (5/37) each BMBF and EU, 5,4% (2/37) BMWi, and 2,7% (1/37) each BMG, BMVg, and G-BA applications. The average funding volume of these proposals was 401,515 euros. Approved DFG proposals were most frequently assigned to the review board 205-27 Orthopedics, Trauma Surgery, Reconstructive Surgery (n=10/16, 62,5%). Over time, the research registry shows an increase in the number of proposals in general and those granted. 70,0% (14/20) of participating sites had their own experimental research laboratory, while only 40,0% (8/20) had their own clinical trial center.

CONCLUSION

The 2021/2022 Research Funding Report once again highlights the impressive research accomplishments of the plastic surgery community.

[New Technologies in Microsurgery: Potential, Indications and Economical Aspects - Report of the Consensus Workshop of the German-Speaking Society for Microsurgery of Peripheral Nerves and Vessels (DAM)]

Recently, several new technologies to support microsurgeons have received European market approval. This article summarizes and discusses the impressions of an expert panel to classify the potential of new technologies in terms of benefits for the surgeon, specific indications and economic aspects during the 42nd Annual Meeting of the German-speaking Working Group for Microsurgery of Peripheral Nerves and Vessels (DAM) in Graz, Austria. In general, the expert panel addressed the principles and prerequisite for the successful establishment of new technologies and, in particular, novel optical and robotic systems. For this purpose, the current scientific literature was reviewed and initial clinical experience in the context of case series and retrospective studies was presented by the members of the expert panel. In the ensuing discussion, it was pointed out that it will first be necessary to identify patient subgroups in which the use of the new technologies is most likely to achieve a clinical benefit. Since clinical approval has already been granted for some systems, an approach can be developed for immediate clinical application from the simplest possible use to ever finer applications, i. e. from microsurgery to supermicrosurgery. Initially, funding for cost-intensive systems would presumably not be possible through revenue from standard care, but only through grants or subsidized clinical trials. In a final survey, the majority of meeting participants see the need for a price reduction of both visualization and surgical robotics technologies to enable widespread clinical establishment. Likewise, a majority of participants would prefer a combination of an exoscope or robotic microscope and a surgical robot for clinical use. The present consensus work addresses the development of a strategy for the effective establishment of new technologies, which should further increase the surgical quality of selected interventions.

Measures for Preventing Infection in Burn Surgery

The skin is the largest human organ and an important barrier to protect against the environment. Burns damage the skin and thus destroy this anatomical barrier. This makes initially sterile wounds susceptible to colonization by pathogenic germs. In severely burned patients, immune competence decreases as part of the burn disease. Sepsis and multiple organ failure as a result of infection are the main causes of death in this cohort. Therefore, prevention and recognition of infections as well as surgical treatment and targeted anti-infective therapy are of great importance. In this article, we present up-to-date solutions for the treatment of burn wounds by means of plastic and reconstructive surgery to minimize the risk of infection. We demonstrate the principles of infection defense by the skin barrier. We outline the principles of burns and how to perform an appropriate diagnosis and therapy, from outpatient therapy to intensive care therapy, depending on the severity. We address the typical bacteria responsible for wound infections in severely burned patients and how to prevent and treat them. We also describe the hygiene measures that must be used in a severe burn unit to reduce the risk of complications such as infection and improve patient survival.

[Does it Always have to be the Abdomen? Alternative Flaps in Autologous Breast Reconstruction]

[English] Deep inferior epigastric artery perforator (DIEP) or muscle-sparing transverse rectus abdominis muscle (ms-TRAM) flaps remain the gold standard for autologous reconstruction in post-mastectomy patients, although many women may not be candidates for abdominally based free tissue transfer. In this scenario, there are several other donor site options based from the thigh (transverse and diagonal upper gracilis flaps, profunda artery perforator flap, lateral thigh flap), trunk (lumbar artery perforator flap), and buttock (superior and inferior gluteal artery perforator flaps). This article will provide insight into the history, relevant anatomy, surgical technique and novel applications (neurotization) for alternative flaps in autologous breast reconstruction.

Improving the Safety of DIEP Flap Transplantation: Detailed Perforator Anatomy Study Using Preoperative CTA

Background: Deep inferior epigastric perforator and muscle sparing transverse rectus abdominis muscle flaps are commonly used flaps for autologous breast reconstruction. CT-angiography allows to analyse the perforator course preoperatively. Our aim was to compare the different aspects of perforator anatomy in the most detailed study. Methods: CT-angiographies of 300 female patients with autologous breast reconstruction of 10 years were analysed regarding the anatomy of the deep inferior epigastric artery and every perforator. Results: Overall, 2260 perforators were included. We identified correlations regarding the DIEA branching point and number of perforators and their intramuscular course. The largest perforator emerged more often from the medial branch of the DIEA than the smaller perforators (70% (416/595) vs. 54% (878/1634), p < 0.001) and more often had a direct connection to the SIEV (large 67% (401/595) vs. small 39% (634/1634), p < 0.01). Medial row perforators were larger than the laterals (lateral 1.44 mm ± 0.43 (n = 941) vs. medial 1.58 mm ± 0.52 (n = 1304) (p < 0.001)). The larger and more medial the perforator, the more likely it was connected to the SIEV: perforators with direct connection to the SIEV had a diameter of 1.65 mm ± 0.53 (n = 1050), perforators with indirect connection had a diameter of 1.43 ± 0.43 (n = 1028), perforators without connection had a diameter of 1.31 mm ± 0.37 (n = 169) (p < 0.001). Medial perforators were more often directly connected to the SIEV than lateral perforators (medial 56% (723/1302) vs. lateral 35% (327/941), p < 0.001). A lateral perforator more often had a short intramuscular course than medial perforators (69% (554/800) vs. 45% (474/1055), p < 0.001), which was also more often observed in the case of a small perforator and a caudal exit of the rectus sheath. Conclusion: The largest perforator emerges more often from the medial branch of the DIEA and frequently has a direct connection to the SIEV, making medial row perforators ideal for DIEP flap transplantation.

Microsurgical Transplantation of Pedicled Muscles in an Isolation Chamber—A Novel Approach to Engineering Muscle Constructs via Perfusion-Decellularization

Decellularized whole muscle constructs represent an ideal scaffold for muscle tissue engineering means as they retain the network and proteins of the extracellular matrix of skeletal muscle tissue. The presence of a vascular pedicle enables a more efficient perfusion-based decellularization protocol and allows for subsequent recellularization and transplantation of the muscle construct in vivo. The goal of this study was to create a baseline for transplantation of decellularized whole muscle constructs by establishing an animal model for investigating a complete native muscle isolated on its pedicle in terms of vascularization and functionality. The left medial gastrocnemius muscles of 5 male Lewis rats were prepared and raised from their beds for in situ muscle stimulation. The stimulation protocol included twitches, tetanic stimulation, fatigue testing, and stretching of the muscles. Peak force, maximum rate of contraction and relaxation, time to maximum contraction and relaxation, and maximum contraction and relaxation rate were determined. Afterwards, muscles were explanted and transplanted heterotopically in syngeneic rats in an isolation chamber by microvascular anastomosis. After 2 weeks, transplanted gastrocnemius muscles were exposed and stimulated again followed by intravascular perfusion with a contrast agent for µCT analysis. Muscle constructs were then paraffin embedded for immunohistological staining. Peak twitch and tetanic force values all decreased significantly after muscle transplantation while fatigue index and passive stretch properties did not differ between the two groups. Vascular analysis revealed retained perfused vessels most of which were in a smaller radius range of up to 20 µm and 45 µm. In this study, a novel rat model of heterotopic microvascular muscle transplantation in an isolation chamber was established. With the assessment of in situ muscle contraction properties as well as vessel distribution after 2 weeks of transplantation, this model serves as a base for future studies including the transplantation of perfusion-decellularized muscle constructs.

OUP accepted manuscript

Adipose-derived stem or stromal cells (ASCs) possess promising potential in the fields of tissue engineering and regenerative medicine due to their secretory activity, their multilineage differentiation potential, their easy harvest, and their rich yield compared to other stem cell sources. After the first identification of ASCs in humans in 2001, the knowledge of their cell biology and cell characteristics have advanced, and respective therapeutic options were determined. Nowadays, ASC-based therapies are on the verge of translation into clinical practice. However, conflicting evidence emerged in recent years about the safety profile of ASC applications as they may induce tumor progression and invasion. Numerous in-vitro and in-vivo studies demonstrate a potential pro-oncogenic effect of ASCs on various cancer entities. This raises questions about the safety profile of ASCs and their broad handling and administration. However, these findings spark controversy as in clinical studies ASC application did not elevate tumor incidence rates, and other experimental studies reported an inhibitory effect of ASCs on different cancer cell types. This comprehensive review aims at providing up-to-date information about ASCs and cancer cell interactions, and their potential carcinogenesis and tumor tropism. The extracellular signaling activity of ASCs, the interaction of ASCs with the tumor microenvironment, and 3 major organ systems (the breast, the skin, and genitourinary system) will be presented with regard to cancer formation and progression.

Genetic deletion of the cannabinoid receptors CB1 and CB2 enhances inflammation with diverging effects on skin wound healing in mice

AIMS

Inflammation during wound healing is both essential and critical for restoring tissue integrity. Participating cells secrete soluble factors to regulate the inflammatory phase and to induce the adjacent regenerative processes. If pro-inflammatory signals are overexpressed, the wound stagnates in the inflammatory phase, which decelerates regular wound healing. The endocannabinoid system is ascribed great significance in maintenance of tissue homeostasis. It mediates several effects through the cannabinoid receptors CB1 and CB2.

MAIN METHODS

In order to clarify the role of these receptors in wound healing, excisional wounds were created on wildtype and CB1 and CB2 knockout mice. The wound closure was analyzed over a period of 14 days, and cytokine concentrations of tissue homogenisates were measured by ELISA. MSCs were isolated from the animals' subcutaneous adipose tissue and analyzed for viability and differentiation capacity, in vitro.

KEY FINDINGS

Deletion of CB2 increased Interleukin (IL)-6 and tumor necrosis factor (TNF)-α but did not affect tissue regeneration. In CB1-deficient animals, wound closure was delayed during early phases of healing, which was accompanied by increased concentrations of monocyte chemoattractant protein (MCP)-1 and TNF-α. CB1 and CB2 knockout MSCs presented altered viability and differentiation capacity compared to wildtype MSCs. The CB1-deficient MSCs released high levels of MCP-1 upon stimulation with TNF-α and IL-1β.

SIGNIFICANCE

The data indicate that both cannabinoid receptors regulate inflammation, and this study emphasizes the important role of CB1 in wound repair. Furthermore, our findings suggest that the secretome of CB1-deficient MSCs may contribute to the wound healing delay, in vivo.

Personalized medicine for reconstruction of critical-size bone defects - a translational approach with customizable vascularized bone tissue

Tissue engineering principles allow the generation of functional tissues for biomedical applications. Reconstruction of large-scale bone defects with tissue-engineered bone has still not entered the clinical routine. In the present study, a bone substitute in combination with mesenchymal stem cells (MSC) and endothelial progenitor cells (EPC) with or without growth factors BMP-2 and VEGF-A was prevascularized by an arteriovenous (AV) loop and transplanted into a critical-size tibia defect in the sheep model. With 3D imaging and immunohistochemistry, we could show that this approach is a feasible and simple alternative to the current clinical therapeutic option. This study serves as proof of concept for using large-scale transplantable, vascularized, and customizable bone, generated in a living organism for the reconstruction of load-bearing bone defects, individually tailored to the patient's needs. With this approach in personalized medicine for the reconstruction of critical-size bone defects, regeneration of parts of the human body will become possible in the near future.

Operative Therapiemöglichkeiten in der Lymphologie

Das Lymphgefäßsystem ist essenziell für den Rücktransport interstitieller Flüssigkeit aus dem Gewebe zurück in den Blutkreislauf. Bei Störungen des komplexen Netzwerkes kommt es zur Ausbildung von Ödemen und der Ansammlung und Ablagerung von Proteinen und Lipiden in der betroffenen Region. Obwohl das Lymphsystem schon seit Jahrhunderten Gegenstand der Forschung ist, haben lymphologische Krankheitsbilder wie das Lymphödem als mögliche Folge onkologischer Therapien erst in den vergangenen Jahren an Aufmerksamkeit gewonnen. So liegt die Inzidenz des sekundären Lymphödems, das durch traumatische, infektiöse oder iatrogene Schädigung auftritt, zwischen 0,13 und 2 % und betrifft meist Frauen. Auch das davon abzugrenzende Lipödem ist in den letzten Jahren zunehmend in den Fokus der Öffentlichkeit gerückt. Beide Erkrankungen können mit einer schmerzhaften Umfangsvermehrung, einer beruflichen und alltäglichen Einschränkung und einer Reduktion der Lebensqualität einhergehen. Neben der klinischen Untersuchung und Anamnese gewinnen neue bildgebende Verfahren eine zunehmende Bedeutung zur Verbesserung der Diagnosestellung, Stadieneinteilung und Therapieplanung, wenngleich immer noch oftmals Monate bis Jahre bis zur korrekten Diagnosestellung vergehen. Während konservative Therapiemethoden wie die komplexe physikalische Entstauungstherapie weiterhin die Grundlage der Behandlung bilden, kommen zunehmend auch operative Verfahren bei der Therapie des Lymphödems zum Einsatz. Hierbei unterscheidet man die reduzierenden Verfahren, die hauptsächlich auf die Symptomreduktion abzielen, von den rekonstruktiven Verfahren zur Wiederherstellung des Lymphsystems mittels mikrochirurgischer Techniken. Nachfolgend werden verschiedene operative Therapiemöglichkeiten in der Lymphologie dargestellt.

Treatment of Peripheral Nerve Compression Syndromes of the Upper Extremities: a Systematic Review

BACKGROUND

Nerve compression syndromes are referred to as chronic irritation or pressure palsies of peripheral nerves in areas of preformed anatomical constriction. Carpal tunnel syndrome is the most common nerve compression syndrome, followed by cubital tunnel syndrome. In addition, less frequent nerve compression syndromes of the upper extremities that affect the median, ulnar or radial nerves have been described. This review provides an overview of current treatment options for nerve compression syndromes of the upper extremities.

STUDY DESIGN

Systematic overview.

METHODS

Based on established national (AWMF) and international guidelines as well as the Cochrane Library, we performed a systematic literature search on PubMed (NLM), focusing on randomised controlled trials.

RESULTS

Over the research period (2012 - 2020), there were 43 randomised trials that investigated surgical carpal tunnel release methods, 68 that compared different conservative therapies and 12 that compared surgical versus conservative treatments. Furthermore, eight studies analysed surgical techniques and four analysed conservative techniques for cubital tunnel syndrome. No randomised trials were conducted on the less common peripheral nerve compression syndromes, but case reports and observational studies were conducted.

CONCLUSION

For carpal and cubital tunnel syndromes, there are evidence-based diagnostic methods as well as therapeutic recommendations based on randomised and controlled trials. When diagnosis is made after clinical examination and supported by radiological and electrophysiological evaluation, surgical treatment is considered superior to conservative treatment. In particular, excellent long-term results can be achieved by surgery for carpal and cubital tunnel syndromes. More controlled studies are needed to establish evidence-based therapeutic recommendations for the less common nerve compression syndromes, which are somewhat controversially and inconsistently defined.

The Role of Adipose Stem Cells in Bone Regeneration and Bone Tissue Engineering

Bone regeneration is a complex process that is influenced by tissue interactions, inflammatory responses, and progenitor cells. Diseases, lifestyle, or multiple trauma can disturb fracture healing, which might result in prolonged healing duration or even failure. The current gold standard therapy in these cases are bone grafts. However, they are associated with several disadvantages, e.g., donor site morbidity and availability of appropriate material. Bone tissue engineering has been proposed as a promising alternative. The success of bone-tissue engineering depends on the administered cells, osteogenic differentiation, and secretome. Different stem cell types offer advantages and drawbacks in this field, while adipose-derived stem or stromal cells (ASCs) are in particular promising. They show high osteogenic potential, osteoinductive ability, and immunomodulation properties. Furthermore, they can be harvested through a noninvasive process in high numbers. ASCs can be induced into osteogenic lineage through bioactive molecules, i.e., growth factors and cytokines. Moreover, their secretome, in particular extracellular vesicles, has been linked to fracture healing. The aim of this review is a comprehensive overview of ASCs for bone regeneration and bone tissue engineering.

The History of Carbon Monoxide Intoxication

Intoxication with carbon monoxide in organisms needing oxygen has probably existed on Earth as long as fire and its smoke. What was observed in antiquity and the Middle Ages, and usually ended fatally, was first successfully treated in the last century. Since then, diagnostics and treatments have undergone exciting developments, in particular specific treatments such as hyperbaric oxygen therapy. In this review, different historic aspects of the etiology, diagnosis and treatment of carbon monoxide intoxication are described and discussed.

Endocannabinoids increase human adipose stem cell differentiation and growth factor secretion in vitro

Adipose stem cells (ASCs) possess the capacity to proliferate, to differentiate into various cells types, and they are able to secrete growth factors. These characteristics are supposed to contribute to their potential for regenerative medicine approaches. In order to advance the therapeutic effects of ASCs, different modulatory procedures have been examined. In this context, the endocannabinoid system (ECS) represents an interesting possibility, since the increased availability of cannabinoids and the underlying molecular pathways of the ECS are of relevance for the development of new regenerative strategies. The effects of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) were investigated on ASC metabolic activity, quantified by PrestoBlue conversion, and cell numbers, evaluated by crystal violet staining. enzyme-linked immunosorbent assay (ELISA) measures were performed to determine cytokine release, and differentiation was assessed by specific labeling techniques. AEA increased the metabolic activity, while 2-AG decreased it in a concentration dependent manner. AEA significantly enhanced OilRed O staining after adipogenic differentiation by over 100%, and both compounds significantly increased cresolphthalein staining after osteogenic differentiation. By contrast, they did not affect sphere diameter or safranin O staining after chondrogenic differentiation. Both substances significantly increased the release of insulin-like growth factor-1 and hepatocyte growth factor, while only AEA enhanced transforming growth factor-β secretion. The results demonstrated that stimulating the ECS exerted significant effects on the biology of ASCs. Exposure to endocannabinoids modulated viability, induced release of regenerative growth factors, and promoted adipogenic and osteogenic differentiation. Our findings could be of specific relevance in ASC based therapies for regenerative medicine.

[Registry Research Funding of the German Society of Plastic, Reconstructive and Aesthetic Surgeons (DGPRÄC) and Research Funding Report 2019/2020]

BACKGROUND

 Since 2015/16 the DGPRÄC collects, evaluates and publishes the research activities of academic sections, departments and clinics for plastic surgery at university hospitals in Germany, in order to raise the awareness of plastic surgical research performance.

MATERIALS AND METHODS

 The directors of plastic surgical academic institutions were contacted via the DGPRÄC and asked to report any requested/approved and rejected research applications to public, non-public and industrial funding organizations. Data was collected in our previously established online database: https://docs.google.com/forms/d/e/1FAIpQLSe6F5xmTyw-k7VKJx_2jkPA4LBXsA0sgBGMrC3rx_4bHj6uzQ/viewform?usp=sf_link. In addition, applications were identified via the DFG's public database GEPRIS.

RESULTS

 A total of 41 funding applications to the public funding institutes DFG, BMBF, BMWi, BMG and EU were identified. 75.6 % (31/41) of the applications had already been approved at the time of data collection, of which 77.4 % (24/31) were DFG, 9.7 % (3/31) were BMWi, 6.5 % (2/31) were EU and 3.2 % (1/31) were BMBF or BMG applications. The average funding amounted to 358 301 Euro. In 50.0 % (12/24) of the cases, the approved DFG proposals were assigned to the subject review board 205-27 Orthopedics, Trauma Surgery, Reconstructive Surgery.

CONCLUSION

 The continuous publication of plastic surgical research funding reports submitted by the convention of university plastic surgeons of the DGPRÄC portraits the excellent, collaborative research activity in the field of plastic surgery.

Tissue Engineering of Lymphatic Vasculature in the Arteriovenous Loop Model of the Rat

Various therapeutic approaches, for example, in case of trauma or cancer require the transplantation of autologous tissue. Depending on the size and the origin of the harvested tissue, these therapies can lead to iatrogenic complications and donor-site morbidities. In future, these side effects could be avoided by transplanting artificially generated tissue consisting of different cell types and matrix components derived from the host body. Tissue that is grown in the patient could be advantageous compared with the more simply structured in vitro-grown alternatives. To overcome the limitations of graft vascularization, the arteriovenous (AV) loop technique has been established for different tissues in the last years and was adapted for lymphatic tissue engineering in the present study. We utilized the AV loop technique to grow human lymphatic vasculature in vivo in the Rowett nude (RNU) rat. A combination of human lymphatic endothelial cells (LECs) and bone marrow-derived mesenchymal stem cells was implanted in a fibrin matrix surrounding the AV loop. After 2 or 4 weeks of implantation, the animals were perfused and the tissue was harvested. It could be demonstrated by immunohistochemistry for human LYVE1, human CD31, and murine podoplanin that the implanted cells formed human lymphatic vasculature in the AV loop chamber. Beside development of murine podoplanin-positive vasculature in the AV loop tissue, vasculature positive for human marker proteins developed in comparable numbers. This suggests that implanted LECs are able to improve the lymphatic vascularization of the newly engineered tissue. Thus, we were able to establish an in vivo tissue engineering method to generate lymphatic vascularized soft tissue. An axially vascularized transplantable lymphatic vessel network was engineered without requiring advanced cell culture equipment, rendering the lymphatic AV loop highly suitable for applied regenerative medicine. Impact statement Various surgical procedures require the transplantation of autologous harvested tissue, for example, the vascularized lymph node transfer for the treatment of lymphedema. Tissue-engineered transplants could be used instead of autologous transplants and thereby help to reduce the side effects of those therapies. However, in vitro tissue engineering of large constructs requires a lot of know-how as well as advanced cell culture equipment, which might not be accessible in every hospital. In vivo tissue engineering approaches like the presented technique for the generation of transplantable networks of lymphatic vasculature could serve as an alternative for in vitro tissue engineering approaches in clinical settings.

Warp-Knitted Spacer Fabrics: A Versatile Platform to Generate Fiber-Reinforced Hydrogels for 3D Tissue Engineering

Mesenchymal stem cells (MSCs) possess huge potential for regenerative medicine. For tissue engineering approaches, scaffolds and hydrogels are routinely used as extracellular matrix (ECM) carriers. The present study investigated the feasibility of using textile-reinforced hydrogels with adjustable porosity and elasticity as a versatile platform for soft tissue engineering. A warp-knitted poly (ethylene terephthalate) (PET) scaffold was developed and characterized with respect to morphology, porosity, and mechanics. The textile carrier was infiltrated with hydrogels and cells resulting in a fiber-reinforced matrix with adjustable biological as well as mechanical cues. Finally, the potential of this platform technology for regenerative medicine was tested on the example of fat tissue engineering. MSCs were seeded on the construct and exposed to adipogenic differentiation medium. Cell invasion was detected by two-photon microscopy, proliferation was measured by the PrestoBlue assay. Successful adipogenesis was demonstrated using Oil Red O staining as well as measurement of secreted adipokines. In conclusion, the given microenvironment featured optimal mechanical as well as biological properties for proliferation and differentiation of MSCs. Besides fat tissue, the textile-reinforced hydrogel system with adjustable mechanics could be a promising platform for future fabrication of versatile soft tissues, such as cartilage, tendon, or muscle.

Mesenchymal Stem Cells and the Generation of Neomuscle Tissue

Skeletal muscle represents the largest mass of tissue in the body and is essential for motion and posture. Traumatic injury, tumor ablation, prolonged denervation or genetic defects lead to skeletal myopathies. The loss of muscle function or its regenerative properties often results in pain, deformity, and joint malfunction. The regenerative capacity of skeletal muscles depends on adult muscle stem cells, the so-called satellite cells; however, the population of these myogenic precursors, and thus their potential to restore large muscle tissue defects, is strongly limited. On the other hand, surgical treatment of skeletal muscle loss is hampered by the scarcity of functional replacement tissue. Only a few options currently exist to provide functional and aesthetic restoration of lost muscle tissues, other than free muscle flap transfer. While this reconstructive technique is a common practice, it involves the risk of significant donor-site morbidity. Therefore, alternative cells with the potential to regenerate muscle tissue need to be examined. Recently, many surgeons have studied the potential clinical application of mesenchymal stem cells (MSCs), which are an adult stem cell population that can undergo differentiation along the mesodermal lineage and secrete growth factors that can enhance tissue regeneration processes by promoting neovascularization. The regenerative potential of MSCs has been widely studied in vitro and in vivo in animal models. MSCs from adipose tissue as well as bone marrow have been shown to bear myogenic potential, which makes them ideal candidate stem cells for skeletal muscle tissue engineering applications. When compared to reconstructive procedures using autograft tissues, MSC therapy offers the potential of reducing or even eliminating donor-site morbidity. This review gives a comprehensive overview of the use of MSCs in in vitro muscle generation and in vivo muscle regeneration.

Plastic Surgery Reconstruction of Chronic/Non-Healing Wounds

In western countries, approximately 1 % of individuals are affected by chronic wounds during their lifetime. Due to changing demographics, this incidence will likely increase in the future. Additionally, the high prevalence is accompanied by substantial treatment expenditures. Therefore, it is of global interest to find effective treatment algorithms. In this article, we present up-to-date solutions for treating chronic / difficult to heal and complex wounds by means of plastic and reconstructive surgery. We outline the principles of chronic wounds and how to perform an appropriate diagnosis. Close cooperation and interdisciplinary exchange are important for optimizing treatment. We report the principles of wound debridement and the role of negative pressure wound therapy. Moreover, we discuss the state of the art of defect reconstruction by means of skin grafting, with or without acellular dermal matrices, local tissue transfers and free tissue transfers. In very complex cases, the local macrovascular blood flow is greatly reduced and there are few, if any, recipient vessels for free flap reconstruction. We discuss the role of arteriovenous loops to overcome this problem.

The effect of the macrophage migration inhibitory factor (MIF) on excisional wound healing in vivo

Background: The macrophage migration inhibitory factor (MIF) has been determined as a cytokine exerting a multitude of effects in inflammation and angiogenesis. Earlier studies have indicated that MIF may also be involved in wound healing and flap surgery. Methods: We investigated the effect of MIF in an excisional wound model in wildtype, Mif^-/- and recombinant MIF treated mice. Wound closure rates as well as the macrophage marker Mac-3, the pro-inflammatory cytokine tumor necrosis factor α (TNFα) and the pro-angiogenic factor von Willebrand factor (vWF) were measured. Finally, we used a flap model in Mif^-/- and WT mice with an established perfusion gradient to identify MIF's contribution in flap perfusion. Results: In the excision wound model, we found reduced wound healing after MIF injection, whereas Mif deletion improved wound healing. Furthermore, a reduced expression of Mac-3, TNFα and vWF in Mif^-/- mice was seen when compared to WT mice. In the flap model, Mif^-/- knockout mice showed mitigated flap perfusion with lower hemoglobin content and oxygen saturation as measured by O₂C measurements when compared to WT mice. Conclusions: Our data suggest an inhibiting effect of MIF in wound healing with increased inflammation and perfusion. In flaps, by contrast, MIF may contribute to flap vascularization.

Interdisciplinary Treatment of Breast Cancer After Mastectomy With Autologous Breast Reconstruction Using Abdominal Free Flaps in a University Teaching Hospital-A Standardized and Safe Procedure

Background: Breast cancer is the most common malignancy in women. The interdisciplinary treatment is based on the histological tumor type, the TNM classification, and the patient's wishes. Following tumor resection and (neo-) adjuvant therapy strategies, breast reconstruction represents the final step in the individual interdisciplinary treatment plan. Although manifold flaps have been described, abdominal free flaps, such as the deep inferior epigastric artery perforator (DIEP) or the muscle-sparing transverse rectus abdominis myocutaneous (ms-TRAM) flap, are the current gold standard for autologous breast reconstruction. This retrospective study focuses on the safety of autologous breast reconstruction upon mastectomy using abdominal free flaps. Methods: From April 2012 until December 2018, 193 women received 217 abdominal free flaps for autologous breast reconstruction at the University Hospital of Erlangen. For perforator mapping, we performed computed tomography angiography (CTA). Venous anastomosis was standardized using a ring pin coupler system, and flap perfusion was assessed with fluorescence angiography. A retrospective analysis was performed based on medical records, the surgery report, and follow-up of outpatient course. Results: In most cases, autologous breast reconstruction was performed as a secondary reconstructive procedure after mastectomy and radiotherapy. In total, 132 ms1-TRAM, 23 ms2-TRAM, and 62 DIEP flaps were performed with 21 major complications (10%) during hospital stay including five free flap losses (2.3%). In all cases of free flap loss, we found an arterial thrombosis as the main cause. In 24 patients a bilateral breast reconstruction was performed without free flap loss. The majority of free flaps (96.7%) did not need additional supercharging or turbocharging to improve venous outflow. Median venous coupler size was 2.5 mm (range, 1.5-3.5 mm). Conclusion: Using CTA, intraoperative fluorescence angiography, titanized hernia meshes for rectus sheath reconstruction, and venous coupler systems, autologous breast reconstruction with DIEP or ms-TRAM free flaps is a safe and standardized procedure in high-volume microsurgery centers.

Human adipose-derived stem cells support lymphangiogenesis in vitro by secretion of lymphangiogenic factors

Lymphedema is a chronic progressive disease ultimately resulting in severe, disfiguring swelling and permanent changes of the affected tissues. Presently, there is no causal treatment approach of lymphedema. Therefore, most therapies are purely symptomatic. However, the recent use of stem cell-based therapies has offered new prospects for alternative treatment options. The present study was performed to investigate the effects of human adipose-derived stem cells (ADSCs) on human dermal lymphatic endothelial cells (HDLECs) in terms of basic in vitro lymphangiogenic assays (WST-8 assay, scratch assay, transmigration assay, sprouting assay, tube formation assay). The influence of ADSC-conditioned medium (ADSC-CM) on HDLECs was compared to recombinant VEGF-C, bFGF and HGF. Further ADSC-CM was characterized by protein microarray and enzyme-linked immunosorbent assay (ELISA). Although key-lymphangiogenic growth factors - like VEGF-C - could only be detected in low concentrations within the conditioned medium (CM), HDLECs were potently stimulated to proliferate, migrate and to form tube like structures by ADSC-CM. Despite concentrations more than hundredfold higher than those found in the conditioned medium, stimulation with recombinant VEGF-C, bFGF and HGF was still weaker compared to ADSC-CM. These results highlight the effectiveness of growth factors secreted by ADSC to stimulate HDLEC, potentially providing a promising new therapeutic approach for the treatment of lymphedema.

Patient's quality of life after surgery and radiotherapy for extremity soft tissue sarcoma - a retrospective single-center study over ten years

Background and objectives

The purpose of this study is to analyze major complication rates and different aspects of health-related quality of life (HRQoL) in extremity soft tissue sarcoma (STS) patients treated with or without radio (chemo) therapy and surgery.

Methods

We performed a retrospective analysis of all patients who underwent Extremity STS excision from 2004 to 2014 (182 patients included). Patients’ data were collected from patients’ records. HRQoL was assessed by using EORTC QLQ-C30.

Results

A total of 182 patients underwent sarcoma resection. After neoadjuvant radiochemotherapy (RCT), the major-complication rate amounted to 28% (vs. 7%, no radiotherapy, p <  0.001). Major-complication rates after adjuvant radiotherapy (RT) occurred in 8% (vs. 7%, no radiotherapy, p = 0.265). Comparison QoL scores between treating with neoadjuvant RCT or without RT revealed significant worse scores with neoadjuvant RCT. Further stratification of disease control of these patients showed significant reduced scores in the group of disease-free patients with neoadjuvant RCT compared to irradiated disease-free patients.

Discussion

To date, there have only been a few investigations of QoL in STS. Retrospective study on quality of life have limitations, like a lack of baseline evaluation of QoL. Patient candidated to radiation therapy could have had worse QoL baseline due to more advanced disease. Disease status of the patients who answered the questionnaires could have been an influence of QoL and we could show reduced scores in the group of disease-free patients with neoadjuvant RCT, but not for the patients with recurrence or metastasis, so it is very hard to discriminate whether radiation therapy could really have an impact or not.

Conclusion

This study might assist in further improving the understanding of QoL in STS patients and may animate for prospective studies examining the oncological therapies impact on HRQoL.

[The "safe" flap - Preoperative perforator-mapping and intraoperative perfusion assessment to reduce flap-associated morbidity - Consensus statement of the German Speaking Working Group for Microsurgery of the Peripheral Nerves and Vessels]

Reconstructive microsurgery using free and pedicled flaps has become a reliable method with a high success rate. Preoperative perforator mapping and intraoperative assessment of perfusion might further reduce flap-associated morbidity.There are various techniques for perforator mapping and perfusion measurement, but no guidelines regarding their use. Therefore, an expert panel at the 40th Annual Meeting of the German-Speaking Working Group for Microsurgery of the Peripheral Nerves and Vessels (DAM) discussed and critically reviewed the current literature. The consensus statement represents the expert opinion based on the available literature and provides recommendations regarding the use of preoperative perforator mapping and intraoperative perfusion measurement.

Autologous Breast Reconstruction with Transverse Rectus Abdominis Musculocutaneous (TRAM) or Deep Inferior Epigastric Perforator (DIEP) Flaps: An Analysis of the 100 Most Cited Articles

Post-mastectomy autologous reconstruction with abdominal tissue has evolved over the past 4 decades and is a common reconstructive modality today. To gain more insight into this evolution, we performed an analysis of the 100 most commonly cited articles focusing on autologous breast reconstruction with transverse rectus abdominis musculocutaneous (TRAM) or deep inferior epigastric perforator (DIEP) flaps.

A review of the ISI Web of Knowledge database was performed. Only peer-reviewed articles in English were included for analysis. Articles were ranked by their total citations as well as citation density (citations divided by years since publication). The 100 most cited articles were analyzed by their bibliographic parameters.

The 100 most cited articles were published in 12 journals. The highest ranked plastic surgery journal published almost 2/3 of the articles. All articles were published within 23 years and marked the “rising age” of autologous breast reconstruction with TRAM and DIEP flaps. The focus of clinical research changed over this time period and ranged from innovations in surgical technique to analysis of clinical outcomes, comparative analyses with other reconstructive modalities, timing of reconstruction, and preoperative diagnostic workup, as well as cost-effectiveness analyses.

This literature review illustrates the dramatic change that has occurred subsequent to introduction of abdominal flaps for breast reconstruction. While the use of abdominal flaps has become widely accepted for breast reconstruction, many questions remain unanswered, thus highlighting the need for ongoing clinical investigation.

[Registry Research Funding of the German Society of Plastic, Reconstructive and Aesthetic Surgeons (DGPRÄC) and Research Funding Report 2017/2018]

INTRODUCTION

This report serves to publicize the research of academic institutions for Plastic Surgery within our society DGPRÄC in 2017/2018 and sequels the funding report of 2015/2016. Applications to public, non-public, or industrial funding organizations were evaluated. At the same time, this paper analyses the number of approved DFG applications in Plastic, Thoracic and Vascular Surgery in the GEPRIS system. Contrary to these specialties, Plastic Surgery is not classified as an independent speciality in the subject structure of the DFG review board which results in a lack of transparency concerning Plastic Surgery research work.

MATERIALS AND METHODS

Our previously established online database (https://docs.google.com/forms/d/1OaSnHyKTysawiI1ie7kfUxDf7nJP_RiTUJTsnb7Mq_E/edit) for reporting requested/ approved and rejected research applications to public, non-public and industrial funding organizations was continued and evaluated together with applications found in the DFG's public database GEPRIS.

RESULTS

Compared to the previous year's report, the number of approved applications from public research organizations (DFG, BMBF, BMWi, EU) was increased from 23 to 27. We identified 19 approved DFG applications from Plastic Surgery, as compared to 9 and 8 applications by Thoracic and Vascular Surgery, respectively.

SUMMARY

Taken together, this data emphasizes that our research is at least equal to that of other newly established surgical specialties within the framework of the DFG. Accordingly, we hope to provide further arguments for an adaptation of the DFG review boards subject structure to include Plastic Surgery as an independent specialty as it is for Vascular Surgery and Thoracic Surgery.

Myogenic differentiation of primary myoblasts and mesenchymal stromal cells under serum-free conditions on PCL-collagen I-nanoscaffolds

Background

The creation of functional skeletal muscle via tissue engineering holds great promise without sacrificing healthy donor tissue. Different cell types have been investigated regarding their myogenic differentiation potential under the influence of various media supplemented with growth factors. Yet, most cell cultures include the use of animal sera, which raises safety concerns and might lead to variances in results. Electrospun nanoscaffolds represent suitable matrices for tissue engineering of skeletal muscle, combining both biocompatibility and stability.

We therefore aimed to develop a serum-free myogenic differentiation medium for the co-culture of primary myoblasts (Mb) and mesenchymal stromal cells derived from the bone marrow (BMSC) and adipose tissue (ADSC) on electrospun poly-ε-caprolacton (PCL)-collagen I-nanofibers.

Results

Rat Mb were co-cultured with rat BMSC (BMSC/Mb) or ADSC (ADSC/Mb) two-dimensionally (2D) as monolayers or three-dimensionally (3D) on aligned PCL-collagen I-nanofibers. Differentiation media contained either AIM V, AIM V and Ultroser® G, DMEM/Ham’s F12 and Ultroser® G, or donor horse serum (DHS) as a conventional differentiation medium. In 2D co-culture groups, highest upregulation of myogenic markers could be induced by serum-free medium containing DMEM/Ham’s F12 and Ultroser® G (group 3) after 7 days. Alpha actinin skeletal muscle 2 (ACTN2) was upregulated 3.3-fold for ADSC/Mb and 1.7-fold for BMSC/Mb after myogenic induction by group 3 serum-free medium when compared to stimulation with DHS. Myogenin (MYOG) was upregulated 5.2-fold in ADSC/Mb and 2.1-fold in BMSC/Mb. On PCL-collagen I-nanoscaffolds, ADSC showed a higher cell viability compared to BMSC in co-culture with Mb. Myosin heavy chain 2, ACTN2, and MYOG as late myogenic markers, showed higher gene expression after long term stimulation with DHS compared to serum-free stimulation, especially in BMSC/Mb co-cultures. Immunocytochemical staining with myosin heavy chain verified the presence of a contractile apparatus under both serum free and standard differentiation conditions.

Conclusions

In this study, we were able to myogenically differentiate mesenchymal stromal cells with myoblasts on PCL-collagen I-nanoscaffolds in a serum-free medium. Our results show that this setting can be used for skeletal muscle tissue engineering, applicable to future clinical applications since no xenogenous substances were used.

Reconstruction of composite defects of the scalp and neurocranium-a treatment algorithm from local flaps to combined AV loop free flap reconstruction

Background

Reconstruction of cranial composite defects, including all layers of the scalp and the neurocranium, poses an interdisciplinary challenge. Especially after multiple previous operations and/or radiation therapy, sufficient reconstruction is often only possible using microsurgical free flap transplantation. The aim of this study was to analyze the therapy of interdisciplinary cases with composite defects including the scalp and neurocranium.

Methods

From 2009 to 2017, 23 patients with 18 free flaps and 10 pedicled/local flaps were analyzed. First choices for free flaps were muscle flaps followed by fasciocutaneous flaps.

Results

Except for four patients, a stable coverage could be reached in the first operation. Three of these patients received a local scalp rotation flap in the first operation and needed an additional free flap because the local flap was no longer sufficient for coverage after wound healing deficiency or tumor relapse. The superficial temporal artery or external carotid artery served as recipient vessels. In special cases, venous grafts or an arteriovenous loop (AV loop) were used as extensions for the recipient vessels.

Conclusions

In summary, an interdisciplinary approach with radical debridement of infected or necrotic tissue and the reconstruction of the dura mater are essential to reach a stable, long-lasting reconstructive result. Based on our experience, free flaps seem to be the first choice for patients after multiple previous operations and/or radiation therapy.