Dynamic cultivation of human mesenchymal stem/stromal cells for the production of extracellular vesicles in a 3D bioreactor system.

PURPOSE: 3D cell culture and hypoxia have been demonstrated to increase the therapeutic effects of mesenchymal stem/stromal cells (MSCs)-derived extracellular vesicles (EVs). In this study, a process for the production of MSC-EVs in a novel 3D bioreactor system under normoxic and hypoxic conditions was established and the resulting EVs were characterized. METHODS: Human adipose-derived MSCs were seeded and cultured on a 3D membrane in the VITVO® bioreactor system for 7 days. Afterwards, MSC-EVs were isolated and characterized via fluorescence nanoparticle tracking analysis, flow cytometry with staining against annexin V (Anx5) as a marker for EVs exposing phosphatidylserine, as well as CD73 and CD90 as MSC surface markers. RESULTS: Cultivation of MSC in the VITVO® bioreactor system demonstrated a higher concentration of MSC-EVs from the 3D bioreactor (9.1 × 109 ± 1.5 × 109 and 9.7 × 109 ± 3.1 × 109 particles/mL) compared to static 2D culture (4.2 × 109 ± 7.5 × 108 and 3.9 × 109 ± 3.0 × 108 particles/mL) under normoxic and hypoxic conditions, respectively. Also, the particle-to-protein ratio as a measure for the purity of EVs increased from 3.3 × 107 ± 1.1 × 107 particles/µg protein in 2D to 1.6 × 108 ± 8.3 × 106 particles/µg protein in 3D. Total MSC-EVs as well as CD73-CD90+ MSC-EVs were elevated in 2D normoxic conditions. The EV concentration and size did not differ significantly between normoxic and hypoxic conditions. CONCLUSION: The production of MSC-EVs in a 3D bioreactor system under hypoxic conditions resulted in increased EV concentration and purity. This system could be especially useful in screening culture conditions for the production of 3D-derived MSC-EVs.

[Comparison of Two Umbilicoplasty Techniques in 72 Patients after Breast Reconstruction with a Free DIEP Flap] / Vergleich zweier Techniken der Umbilikoplastik bei 72 Patientinnen nach Brustrekonstruktion mit freier DIEP-Lappenplastik.

INTRODUCTION: The appearance of the umbilicus after DIEP flap surgery or abdominoplasty plays an important role in aesthetic perception (1). Although the umbilicus has no function, there is no doubt about the importance of its shape for the self-esteem of patients, especially after breast cancer (2). In the present study, we compared two of the preferred techniques described in the literature on 72 patients in terms of aesthetic outcome, complications and sensitivity: the caudal flap (domed shape) and the oval shape of the umbilicus. PATIENTS AND METHODS: Seventy-two patients who underwent a DIEP flap for breast reconstruction between January 2016 and July 2018 were retrospectively included in this study. Two techniques for umbilical reconstruction were compared: the transverse oval shape of the umbilicus and umbilicoplasty using a caudal flap, which results in a dome shape of the umbilicus. To compare the aesthetic results, an evaluation by the patients and an assessment by three independent plastic surgeons were carried out at least 6 months postoperatively. Patients and surgeons were asked to rate the general appearance of the umbilicus, including scarring and shape, on a scale from 1 to 6 (1=very good, 2=good, 3=fair, 4=sufficient, 5=poor, 6=insufficient). Furthermore, the occurrence of wound healing disorders was examined, and patients were asked about the sensitivity of the umbilicus. RESULTS: Both techniques showed similar degrees of aesthetic satisfaction (p=0,49) as part of the patients' self-assessment. The plastic surgeons gave the caudal flap technique a significantly better rating than the umbilicus with a transverse oval shape (p=0,042). More wound healing disorders occurred in the caudal lobule (11,1%) compared with the transverse oval umbilicus. However, this was not significant (p=0,16). A surgical revision was not necessary. The caudal flap umbilicus showed a tendency to improved sensitivity (60 vs. 45%), but this was not significant (p=0,19). CONCLUSION: Patient satisfaction showed similar results for the two methods of umbilicoplasty. On average, both techniques were given a good rating for their results. However, surgeons rated the caudal flap umbilicoplasty as more aesthetically pleasing.

Decreasing Time Intervals in Recurring Capsular Contracture? A Single Center Retrospective Study over 6 Years.

Although breast implants of the current generation can, in principle, remain in the body for life, follow-up operations of the augmented or reconstructed breasts are regularly necessary. Capsular contracture is the leading cause for revisional surgery. The aim of this study was to evaluate indications and changes in time intervals between consecutive implant replacements with a focus on capsular contracture. Methods: In the period from 2012 to 2017, all patients with breast implant replacements or removals at our institution were identified. From the medical file, the time of the first implantation and earlier replacements were analyzed for indication and timing of surgery. Results: A total of 498 operations for implant replacement or removal were analyzed in 323 patients. Including prior operations, 717 procedures could be evaluated. If capsular contracture was the indication, revision surgery was performed on average 14.3 years or 8.4 years in aesthetic or reconstructive cases, respectively. In patients with more than one implant removal or replacement, we saw a reduction in the time interval between the first, second, and third follow-up operation. Conclusions: The main indication to perform implant replacements or removals was capsular contracture recurring at increasingly shorter intervals. Patients must be informed about this possible progression when changing implants, but also before the first operation. If capsular contracture occurs after a rather short time period in reconstructive cases, the opportunity of an alternative approach (eg, autologous reconstruction) instead of a renewed implant change should be discussed with the patient.

Retroauricular lymph node flap: An anatomic and surgical feasibility study.

BACKGROUND: The study investigated the anatomy of the retroauricular lymph node (LN) flap and evaluate its surgical feasibility as a new donor site for a free LN flap in lymphedema surgery. METHODS: Twelve adult cadavers were examined. The course and perfusion of the anterior auricular artery (AAA) and the location and sizes of the retroauricular LNs were studied. RESULTS: The AAA was available in 87% and absent in 13% specimens. The AAA's origin had a mean vertical distance of 12.2 ± 6.9 mm and a mean horizontal distance of 19.1 ± 4.2 mm from the superior attachment of the ear. The mean diameter of the AAA was 0.8 ± 0.2 mm. The mean number of LN per region was 7.7 ± 2.3, with an average LN size of 4.1 ± 1.9 × 3.2 ± 1.7 mm. The LN were categorized into anterior (G1) and posterior (G2) groups, with a total of 59 and 10 LN, respectively. In a cluster analysis, three LN clusters could be detected across the anterior group (G1). CONCLUSIONS: The retroauricular LN flap is a delicate but feasible flap with reliable anatomy, containing a mean of 7.7 LNs.

Sichere Diagnostik der Implantatrotation im hochauflösenden Ultraschall in Abhängigkeit vom Implantathersteller.

Rotation of an anatomical breast implant may require revisional surgery. High-resolution ultrasound can help determine the exact implant alignment. However, the directional markings of anatomical implants are implemented very inconsistently by manufacturers. Therefore, a definite diagnosis is often not possible without precise knowledge of the expected imaging. The aim of this work is a differentiation of the imaging of common implant brands in high-resolution ultrasound. Methods To simulate an authentic imaging, anatomical implants were viewed through abdominal skin thinned to 1.5-2 cm, which was obtained during a classic abdominoplasty. Implants from the companies Allergan, Eurosilicone, Mentor, Motiva, Nagor, Polytech and Sebbin were compared. The marking positions and dimensions were documented by ultrasound. Results Based on placement and shape, a clear allocation between alignment and manufacturer is basically possible among the implants used. The base plate and caudal markers could be clearly visualised for all brands. In Polytech implants, however, the visible structural change is limited to a very small central area. The visualisation of directional marks, base plate and implant shell also allow conclusions to be drawn about the manufacturer. In high-resolution ultrasound, a fast and reliable diagnosis of implant alignment is possible for all implants examined. Also it was possible to make a clear allocation between implant and manufacturer in this context. Flip over of the implant can also be reliably depicted. The cataloguing of the markings summarised here can be used to determine the exact alignment of the implant and thus provide diagnostic certainty, especially if the brand is unknown.

Topische Applikation von Tranexamsäure im Rahmen der subkutanen Mastektomie bei Frau-zu-Mann Transidentität.

INTRODUCTION: Tranexamic acid (TXA) is an antifibrinolytic drug that can be used to treat and prevent bleeding. Its application in plastic and reconstructive surgery has been very limited to date. To our knowledge, there is a lack of published data on the topical application of TXA in transgender patients undergoing subcutaneous mastectomy. METHODS: We performed a retrospective data analysis of female-to-male transgender patients who underwent subcutaneous mastectomy. A total of 22 patients were treated with topical TXA, while 29 patients served as controls. The primary endpoint was the amount of wound secretion in the first 48 hours after surgery. Secondary endpoints were the duration of drainage and the occurrence of postoperative bleeding. RESULTS: Within the first 48 hours, the TXA group had an average drain volume of 97±50 ml compared with 180±111 ml in the control group (p<0.01). There was a significantly lower flow rate over the entire period in the group of TXA patients (113±86 ml vs. 265±197 ml). The time of drains in situ was 2.3±0.7 days in TXA patients, while the drains in the control group were in place for an average of 3.4±1.3 days (p<0.01). In the group of patients treated with TXA, there was a tendency towards a lower number of postoperative bleeding and haematoma (9vs. 17%). DISCUSSION: There was a significant reduction in the amount of drain fluid within the first 48 hours and over the entire period after topical application of TXA. Also there was a reduction in the length of time patients had a drain in place in the TXA-treated patients. This study demonstrated a significant advantage for the topical application of TXA in subcutaneous mastectomy in female-to-male transgender patients.

[Treatment of phyllodes tumours of the breast: evaluation of 66 cases and literature review]. / Zur Therapie von Phylloides-Tumoren der Brust ­ eine Aufarbeitung von 66†Fällen mit Literaturübersicht.

Phyllodes tumours (PTs) of the breast are classified as benign, borderline and malignant based on the constellation of defined histological parameters. Surgical excision is the primary therapy, but the need to maintain certain safety margins is still controversially discussed for all three categories.This paper aims to provide a critical opinion on the existing recommendation on safety margins for resection.In our breast centre, all patients with phyllodes tumours were identified retrospectively on the basis of the histopathological documentation from 1999 to 2018. The cases were evaluated, in particular, with a view to recurrences and the occurrence of multicentricity.A total of 66 patients were diagnosed with a PT. In 38 cases, the tumours were benign, in 15 borderline and in 13 malignant. Local recurrences were observed in one benign PT, 7 borderline and 5 malignant PTs. Two PTs that were initially classified as borderline tumours progressed to malignant PTs. Multicentricity occurred in about 20 % of borderline and malignant PTs but only in 5 % of benign PTs.The resection margins for phyllodes tumours should be chosen depending on dignity and recurrence. The key question to be challenged is whether or not there is a need to maintain a certain safety margin in benign PTs. In case of recurrence of borderline or malignant PTs, a mastectomy should be considered early.

[How well are patients informed on the websites of German university breast centres about the possibilities of breast reconstruction?] / Wie gut werden Patientinnen auf Internetseiten von deutschen universitären Brustzentren über die Möglichkeiten der Brustrekonstruktion informiert?

INTRODUCTION: In recent decades, the internet has become one of the most important sources of information for patients. How substantial are the possibilities to find out about breast reconstruction on the homepages of university hospitals in Germany? Is there information about plastic surgery with its spectrum of modern reconstructive possibilities? METHODS: A total of 35 homepages of university breast centres in Germany was analysed for the indication of cooperation with a plastic surgeon or a department for plastic surgery and their links, with information on reconstructive possibilities such as implant reconstruction, autologous soft tissue reconstruction with pedicled and free flaps as well as lipofilling. RESULTS: A plastic surgeon or a cooperating department is mentioned on 49 % of the homepages. Of those homepages, 20 % contain a direct link. 91 % of the homepages describe the possibility of breast reconstruction in general, 80 % of the websites the use of autologous tissue. In 51 % of the cases, a free tissue transfer is mentioned, whereas only 23 % describe the procedures like DIEP flap, TMG, or I-GAP in more detail. Only two centres use detailed illustrations. Six websites (17 %) describe reconstruction by pedicled TRAM flap only. Breast reconstruction with a silicone implant is mentioned on 71 % of the websites. The possibility of lipofilling is discussed in 31 %. DISCUSSION: About half of the websites of university breast centres do not show any cooperation with a plastic surgeon. There are significant gaps in the information on free tissue transfer for breast reconstruction.

Monitoring intra-abdominal pressure after liver transplantation in children.

IAH after LTX can impair perfusion and threaten graft viability. This study aimed to assess the feasibility of longitudinal IAP measurements as an IAH screening method in children after LTX. A cohort of 23 children with a mean age (range) 3.1 (3 months-14 years) who underwent LTX between May 2017 and February 2018 were evaluated retrospectively. Longitudinal IAP measurements were compared to bedside Doppler US monitoring data. In total, 425 IAP measurements and 257 US examinations were performed. The mean ± SD (range) time expenditure for IAP measurement was 1.9 ± 0.4 (0.5-3.2) minutes. The mean post-operative IAP was 7.9 ± 3.6 (1-25) mm Hg. IAH (IAP ≥ 10 mm Hg) was noted in 102 (24%) of 257 measurements. Agitation had a significant impact on IAP (estimate: 9.3 mm Hg, CI: 6.72-11.97, P < .01). In patients with TAC, IAP was increased (6.7 ± 2.1 vs 8.7 ± 3.1 mm Hg, P = .02) while peak portal venous velocities decreased (38 ± 27 vs 26 ± 22 cm/s, P = .03) after patch reduction. An abdominal compartment syndrome with severely impaired vascular flow was noted in one patient. Episodes of elevated IAP were noted in a large proportion of patients, underscoring the need for IAP monitoring in pediatric liver transplant recipients. The safety and low time expenditure associated with IAP measurement could be included easily into standard nursing procedures for these patients.

Engineering a Multilayered Skin Substitute with Keratinocytes, Fibroblasts, Adipose-Derived Stem Cells, and Adipocytes.

A variety of skin substitutes that restore epidermal and dermal structures are currently available on the market. While the main focus in research and clinical application lies in dermal and epidermal substitutes, the development of a subcutaneous replacement, the hypodermis, is often neglected. This chapter describes the use of fibrin sealant as a hydrogel scaffold to generate a three-dimensional skin substitute. For the hypodermal layer adipose-derived stem cells (ASCs) and mature adipocytes are seeded within a fibrin hydrogel. On top, another fibrin clot with incorporated fibroblasts is placed for the construction of the dermal layer. Keratinocytes are added on top of the two-layered construct to form the epidermal layer. The three-layered construct is cultivated for up to 3 weeks with keratinocytes being exposed to air according to the air-liquid interface cultivation model.

Arterial catheterisation in neonates can result in severe ischaemic complications but does not impair long-term extremity function.

AIM: We evaluated the incidence of arterial catheterisation and analysed the risk factors and the extent and outcome of ischaemic complications in neonates. METHODS: This was a retrospective cohort study of 1506 neonates admitted to two, ten-bed neonatal intensive care units (NICUs) at the Medical University of Vienna, Austria, between 1 January 2011 and 31 December 2014. Medical charts, daily reports and photo documentation were reviewed for arterial catheterisation and ischaemic complications. Patients with severe ischaemic complications were followed up to evaluate extremity function, scaring and cosmetic results. RESULTS: There were 542 arterial catheterisations in 485 patients, including 275 born below 28 weeks, which resulted in severe complications in 19 of 485 (4%) patients. Three died before follow-up. Patients with complications had a significantly lower birthweight, lower postmenstrual age and higher rates of intracranial haemorrhage, retinopathy of prematurity and necrotising enterocolitis. They had also undergone multiple arterial catheterisations more often, needed longer inotropic support and had longer NICU stays than patients without complications. Extremity function was unimpaired in ten of 16 patients with severe ischaemic complications. CONCLUSION: Severe ischaemic complications in neonates following arterial catheterisation were rare events, but could cause devastating damage. Most patients didn't show impaired extremity function at follow-up.

Botulinum Toxin A: Dose-dependent Effect on Reepithelialization and Angiogenesis.

BACKGROUND: Botulinum (neuro)toxin A (BoNT) is widely used in the field of plastic and reconstructive surgery. Among treatment of pain, hyperhidrosis, or aesthetic purposes, it is also used to enhance wound healing and prevent excessive scar formation. Some clinical data already exist, but only little is known on a cellular level. The aim of this study was to evaluate the effect of BoNT on cells essential for wound healing in vitro. Therefore, primary human keratinocytes and endothelial cells were treated with different concentrations of BoNT and tested on proliferation, migration, and angiogenic behavior. METHODS: BoNT was exposed to human keratinocytes and endothelial cells in a low (1 IU/mL), medium (10 IU/mL), and high (20 IU/mL) concentrations in cell culture. Proliferation and migration of the 2 cell types were observed and also the angiogenic potential of endothelial cells in vitro. RESULTS: BoNT 20 IU/mL negatively influenced proliferation and migration of keratinocytes but not those of endothelial cells. Angiogenesis in vitro was less effective with the highest BoNT concentrations tested. Low concentrations of BoNT supported sprouting of endothelial cells. CONCLUSIONS: High concentrations of botulinum toxin interfered with wound closure as keratinocytes' proliferation and migration were deteriorated. Furthermore, BoNT concentrations of 20 IU/mL constrain in vitro vessel formation but do not influence proliferation or migration of endothelial cells.

Wound Healing Effect of Conditioned Media Obtained From Adipose Tissue on Human Skin Cells: A Comparative in Vitro Study.

BACKGROUND: Split-thickness skin grafting is the gold standard to cover extensive acute and chronic wounds with a well-vascularized wound bed. Although some headway has been made in developing biological agents to speed up healing, there is still no treatment that sufficiently replaces skin grafts to date. The use of secretory factors of adipose tissue may be a feasible approach to developing topical wound applications for faster wound healing. METHODS: In this study, the effect of conditioned media (CMs) of human adipose-derived stem cells (ASCs), adipocytes, or adipose tissue on human skin cells was evaluated for viability, proliferation, and migration in vitro. Differentiation potential of stem cells treated with CM was monitored by AdipoRed staining and qualitative real-time polymerase chain reaction. Angiogenic potential of human endothelial cells treated with CM was tested via sprouting assay. RESULTS: The CM of adipose tissue significantly enhanced ASC proliferation (P < 0.01). Treatment with CM showed no inductive effect on ASC differentiation into adipocytes but, at the same time, significantly induced cell sprouting of endothelial cells (P < 0.001). We show for the first time that CM of adipose tissue is a potent inducer of proliferation of ASCs and angiogenesis, with comparable effects with those of stem cell-enriched CM. CONCLUSIONS: We suggest the use of the secretome of adipose tissue to produce CM for topical application on wounds, rather than working with adipose tissue or including the difficult process of enriching the patients' stem cells in vitro.

Plastic reconstructive surgery techniques using VRAM or gracilis flaps in order to successfully treat complex urogenital fistulas.

BACKGROUND: Urogenital fistulas are devastating complications occurring after tumors or trauma. Surgical treatment is challenging. Thus, further surgical repair options are needed for treatment of complex fistulas within the pelvic region. METHODS: Twelve patients with urogenital fistulas were surgically treated in our department from 2004 to 2012. These selected cases fulfilled eligibility criteria for continence-preserving surgery - a history of fistula recurrences with ongoing incontinence after receiving at least two surgical attempts. Five VRAM and eight gracilis flaps were used to cover up given tissue defects and to perform functional continence-preserving reconstruction with mean follow-up of 6.3 years. Data were retrospectively reviewed, and standardized survey was performed to evaluate quality of life of all living patients (n = 10). RESULTS: In all cases, final surgical treatment of the given fistulae by VRAM or gracilis flaps could be achieved, with mean operating time of 5:31 h (range: 4:50-6:48 h) for VRAM flap and 3:11 h (range: 2:04-4:42 h) for gracilis flap. Outcome measures were primarily to avoid fistula recurrence after plastic surgical treatment, and secondary quality of life and survival. All patients had their continence preserved, but two patients died during follow-up period. Postoperative assessment revealed the following: VRAM flap patients (n = 3) showed slight incontinence during the follow-up period, whereas continence was restored in all patients with gracilis flap reconstruction (n = 7). Quality-of-life assessment indicated restoration of quality of life in comparison to general population (women > men). Furthermore, key points of the two presented surgical techniques are demonstrated in detail. CONCLUSION: With preformed VRAM or gracilis flaps, complex urogenital fistulas can be successfully eradicated and continence is restored. The main focus should be the recovery of quality of life, which could be successfully regained. Nevertheless, the continence success rate has to be defined on an individual, case-by-case basis. LEVEL OF EVIDENCE: Original work, cohort study level III.

Osteopontin promotes aromatase expression and estradiol production in human adipocytes.

Breast and endometrial cancer are often estrogen dependent, and their incidence and mortality are increased by obesity in postmenopausal women. Osteopontin (OPN) is a cytokine strongly upregulated in adipose tissue (AT) in obesity. OPN function is potentiated by cleavage by matrix metalloproteinases (MMP). OPN and MMPs play a role in cancer development and are prognostic markers in breast cancer progression. While induction of the estrogen-synthesizing enzyme aromatase by TNFa and IL1 has been shown in preadipocytes, an impact of OPN on aromatase expression in AT has not been investigated yet. Gene expression was determined in AT samples of 21 morbidly obese and matched non-obese subjects. Primary human adipocytes were treated with full-length OPN or MMP-cleaved OPN (cOPN). Protein and mRNA expressions were analyzed from cell lysates, or cells were subsequently supplied with testosterone to determine estradiol production and for indirect co-culture with the estrogen-dependent MCF-7 cell line. Aromatase expression strongly correlated with gene expression of OPN and various MMPs in visceral and MMPs in subcutaneous AT, but not with TNFα expression in both tissues. In vitro, cOPN more effectively than full-length OPN upregulated aromatase mRNA in adipocytes and significantly increased aromatase protein level and estradiol production, leading to increased MCF-7 growth in indirect co-culture. OPN and MMPs are upregulated in AT in obesity, and MMP-cleaved OPN is particularly effective in inducing aromatase activity in human adipocytes. Thereby, obesity-induced OPN expression in AT may contribute to estradiol production and thus to the association of obesity with estrogen-dependent cancers.

Generation of a Fibrin Based Three-Layered Skin Substitute.

A variety of skin substitutes that restore epidermal and dermal structures are currently available on the market. However, the main focus in research and clinical application lies on dermal and epidermal substitutes whereas the development of a subcutaneous replacement (hypodermis) is often disregarded. In this study we used fibrin sealant as hydrogel scaffold to generate a three-layered skin substitute. For the hypodermal layer adipose-derived stem cells (ASCs) and mature adipocytes were embedded in the fibrin hydrogel and were combined with another fibrin clot with fibroblasts for the construction of the dermal layer. Keratinocytes were added on top of the two-layered construct to form the epidermal layer. The three-layered construct was cultivated for up to 3 weeks. Our results show that ASCs and fibroblasts were viable, proliferated normally, and showed physiological morphology in the skin substitute. ASCs were able to differentiate into mature adipocytes during the course of four weeks and showed morphological resemblance to native adipose tissue. On the surface keratinocytes formed an epithelial-like layer. For the first time we were able to generate a three-layered skin substitute based on a fibrin hydrogel not only serving as a dermal and epidermal substitute but also including the hypodermis.

Immunological blockade of adipocyte inflammation caused by increased matrix metalloproteinase-cleaved osteopontin in obesity.

OBJECTIVE: Osteopontin (OPN) is upregulated in adipose tissue (AT) in obesity and contributes to subclinical inflammation, adipocyte dysfunction, and insulin resistance. OPN effects can be increased by cleavage by matrix metalloproteinases (MMP). This study aimed at investigating the presence of OPN cleavage products in human AT in obesity and their impact on adipocyte function and immunological blockade of these effects. METHODS: AT of severely obese and control donors was investigated for OPN and MMP expression and the presence of OPN cleavage fragments. Primary adipocytes were isolated from human donors for in vitro investigation of cleaved OPN effects. RESULTS: OPN and MMP-9 expression was highly correlated in AT from obese donors, and increased levels of cleaved OPN were detected in AT from obese individuals. The in vitro effect of OPN on adipocyte inflammation and insulin resistance was enhanced by protease cleavage, which could finally be blocked with a monoclonal antibody directed against the MMP cleavage site of OPN. CONCLUSIONS: These findings show that MMP cleavage of OPN in AT occurs in obesity, thereby enhancing OPN's inflammatory and pro-diabetic activity on adipocytes. Specifically targeting MMP-cleaved OPN opens avenues for prevention and treatment of obesity-induced type 2 diabetes.

Adipose-derived stem cells cultivated on electrospun l-lactide/glycolide copolymer fleece and gelatin hydrogels under flow conditions - aiming physiological reality in hypodermis tissue engineering.

INTRODUCTION: Generation of adipose tissue for burn patients that suffer from an irreversible loss of the hypodermis is still one of the most complex challenges in tissue engineering. Electrospun materials with their micro- and nanostructures are already well established for their use as extracellular matrix substitutes. Gelatin is widely used in tissue engineering to gain thickness and volume. Under conventional static cultivation methods the supply of nutrients and transport of toxic metabolites is controlled by diffusion and therefore highly dependent on size and porosity of the biomaterial. A widely used method in order to overcome these limitations is the medium perfusion of 3D biomaterial-cell-constructs. In this study we combined perfusion bioreactor cultivation techniques with electrospun poly(l-lactide-co-glycolide) (P(LLG)) and gelatin hydrogels together with adipose-derived stem cells (ASCs) for a new approach in soft tissue engineering. METHODS: ASCs were seeded on P(LLG) scaffolds and in gelatin hydrogels and cultivated for 24 hours under static conditions. Thereafter, biomaterials were cultivated under static conditions or in a bioreactor system for three, nine or twelve days with a medium flow of 0.3ml/min. Viability, morphology and differentiation of cells was monitored. RESULTS: ASCs seeded on P(LLG) scaffolds had a physiological morphology and good viability and were able to migrate from one electrospun scaffold to another under flow conditions but not migrate through the mesh. Differentiated ASCs showed lipid droplet formations after 21 days. Cells in hydrogels were viable but showed rounded morphology. Under flow conditions, morphology of cells was more diffuse. DISCUSSION: ASCs could be cultivated on P(LLG) scaffolds and in gelatin hydrogels under flow conditions and showed good cell viability as well as the potential to differentiate. These results should be a next step to a physiological three-dimensional construct for soft tissue engineering and regeneration.

Non-occlusive mesenteric ischaemia: the prevalent cause of gastrointestinal infarction in patients with severe burn injuries.

BACKGROUND: Gastrointestinal complications occur frequently in intensive care patients with severe burns. Intestinal infarction and its deleterious consequences result in high mortality despite rapid surgical intervention. Our objective was to evaluate the aetiology of gastrointestinal infarction in intensive care patients with severe burns. STUDY DESIGN: We retrospectively evaluated all of the severe-burn victims at the burn unit of the Medical University of Vienna from 01/2002 to 06/2012 for whom a gastrointestinal infarction was diagnosed during their inpatient stay on computed-tomography, in the context of acute laparotomy, or upon autopsy by aetiology. RESULTS: After a severe thermal injury, 17 patients suffered a gastrointestinal infarction during their stay. In 82% of those patients, non-occlusive mesenteric ischaemia (NOMI) was identified as the cause of the gastrointestinal infarction. Patients with an embolic infarction tended to be older (78.0years embolism vs. 53.4 NOMI, mean, p<0.01), with a lower abbreviated burn severity index (8.7 embolism vs. 10.4 NOMI, mean, p<0.02) and a smaller total body surface area burned (20% embolism vs. 48% NOMI, mean, p<0.01) than those with a non-occlusive mesenterial ischaemia. No patients with an embolic infarction or any of the females in the entire gastrointestinal infarction group survived this event, resulting in a mortality rate of 100% for the embolic infarction group and female group. The decisive factor for surviving a NOMI was age (median age: male survivors 28years vs. nonsurvivors 66years (of this median, males=72years and females=60years), p<0.02). CONCLUSION: The results of our study clearly demonstrate that in severe-burn intensive care patients, non-occlusive mesenteric ischaemia is the most frequent cause of gastrointestinal infarction and that the decisive factor for survival is the patient's age.