In vitro construction of artificial blood vessels using spider silk as a supporting matrix.

Recent research has vigorously pursued the development of tissue-engineered vascular grafts (TEVs). One of the striking points of the early phase is the instability of the artificial blood vessels and lack of vascular resistance, which is supposed to be a consequence of unstable scaffolds. Therefore, alternative biological approaches are necessary to improve the physical properties of the artificial vessel walls. We developed blood vessel-like constructs based on native spider silk as a scaffold. C2C12 and ST1.6R cells were seeded on the surface of scaffolds and cultivated under pulsatile flow (max. ~135  mmHg and min. ~90  mmHg) in a bioreactor. Constructed grafts were compared to human blood vessels and cell seeded scaffolds cultured in the absence of bioreactor. Mechanical properties, morphological structures and expression of marker genes were assessed by strength and strain experiments, SEM, histological staining, immunohistology, Western blotting and quantitative real-time PCR. The results indicate that the constructed vessel resembles native blood vessels in morphological structure as well as in function and expression of biomarkers. Spider silk scaffolds seem to provide an optimal and stable basis for vessel constructs.

Patients' association programs for adolescents and young adults: The JAP study.

INTRODUCTION: A dozen innovative care clinics have recently opened in France to support the transition of adolescents with chronic conditions between pediatric and adult healthcare units through various interventions. Some patients' associations have set up specific programs for adolescents and young adults (AYAs) in order to facilitate the transition process, but they are not well-known among healthcare professionals. Our aim was to describe these programs and to evaluate the quality of their implementation and transferability into transition clinics. MATERIEL AND METHODS: We conducted semistructured interviews with representatives of associations that proposed interventions dedicated to AYAs with chronic conditions. We collected quantitative and qualitative data to describe these interventions. Descriptive statistics were run on quantitative data and a thematic analysis of the qualitative data was made. RESULTS: A questionnaire was sent to 55 associations, 19 (36%) of them had established programs and were contacted; interviews were conducted with 16 of them. Thirteen were national associations, 11 focused on a specific chronic disease, three supported multiple chronic conditions, and two were available to any AYA with chronic disease. Programs were mainly camps (n=5; from 2days to 3weeks) and workshops (n=5). Educational considerations and hobbies were more frequently discussed when peers were directly involved in the program. Stakeholders were mainly other patients and peers (9/16). Fourteen out of 16 were perceived as successful (perceived improvement in AYA quality of life and/or positive feedback). Twelve out of 16 associations thought that their program could be transferable to transition clinics and all were interested in collaboration. DISCUSSION: This work highlights five key points to be considered in the clinical care setting before building programs: unique tailoring and customization, complementarity with existing programs in patients' associations, viability based on peer involvement and evaluation, a common main goal, and using transition clinics' assets to direct AYAs towards the most suitable program.

A multimodal infection control concept in a burn intensive care unit - lessons learnt from a meticillin-resistant Staphylococcus aureus outbreak.

BACKGROUND: Meticillin-resistant Staphylococcus aureus (MRSA) is a frequently encountered pathogen in burn units. Burn patients are especially susceptible to MRSA acquisition and MRSA spread may cause outbreaks in burn units. AIM: To report the characteristics and successful control of an MRSA outbreak and to demonstrate a multimodal infection control concept. METHODS: In addition to a pre-existing infection control concept, several control measures were implemented including weekly prevalence screenings for MRSA, reinforcement of disinfection, restriction of admissions, and short-term unit closure. Epidemiologic investigation and environmental examinations were performed. The outbreak isolates were analysed by pulsed-field gel electrophoresis and spa-typing. A PubMed search was conducted, focusing on MRSA outbreaks in burn units. FINDINGS: This outbreak of hospital-acquired MRSA affected eight patients during a seven-month period, yielding an attack rate of 8%. Epidemiologic and environmental examinations suggested patient-to-patient transmission, which was confirmed by molecular analysis of bacterial isolates revealing a monoclonal pattern. In accordance with findings from other outbreaks in burn units, the implemented measures including patient screening and temporary unit closure resulted in successful control of the outbreak. CONCLUSION: A comprehensive concept is required to control the spread of all multidrug-resistant micro-organisms including MRSA on a burn unit. Where patients colonized or infected with MRSA appear to be the main reservoir, transfer of these patients to other units, or temporary closure of the unit, accompanied by intensive cleaning are very effective measures to stop transmission events.

[Analysis of Critically Perfused Tissues by Laser Speckle Contrast Analysis (LASCA) Perfusion Imaging]. / Quantitative Perfusionsanalyse durch Laser Speckle Contrast Analysis (LASCA) Perfusions-Imaging von kritisch perfundierten Geweben Quantitative Perfusion.

Background: The success of tissue transplantation and long-term tissue stability after wound healing depends on sufficient tissue perfusion. Laser Doppler-supported procedures allow for an objective measurement of relative tissue perfusion. The development of Speckle-based Laser Doppler imaging now enables a real-time representation of tissue perfusion. The perfusion of tissues relevant in plastic surgery such as scars, phalangeal replantations and burn wounds were systematically analysed by Laser Speckle Contrast Analysis (LASCA) imaging. Method: Perfusion of skin, scars, replanted fingers and different burn wound degrees (IIa, IIb and III) were systematically examined by LASCA imaging. Baseline perfusion of control tissue and perfusion values of compromised tissues were quantified and compared. Results: LASCA imaging shows significant differences in baseline perfusion of skin compared to atrophic scars, hypertrophic scars and keloids. Finger replantations with subsequent replantation failure show a characteristic and significant hypoperfusion in line with the expected clinical feature. A significant difference in tissue perfusion is seen in superficial (IIa) and superficial deep (IIb) burns, which are hard to distinguish on clinical examination. Deep burns (III) are characterised by hypoperfusion, which differs significantly from grade IIa and IIb burn wound perfusion, but not from baseline skin perfusion. Furthermore, the characteristic perfusion values of different burn degrees correspond to the varying treatment strategies. Conclusion: LASCA imaging is a robust method of perfusion imaging, which combines high resolution and speed. Hypoperfusion of tissues relevant to plastic surgery such as scars, phalangeal replantations and the different burn degrees (IIa, IIb and III) can be detected by LASCA imaging with high precision. Ease of use and immediate real-time imaging make LASCA imaging a reliable tool for the evaluation of tissue perfusion after plastic surgery procedures, which may influence further treatment decisions.

Assessing burn depth in tattooed burn lesions with LASCA Imaging.

Tattoos are on the rise, and so are patients with tattooed burn lesions. A proper assessment with regard to burn depth is often impeded by the tattoo dye. Laser speckle contrast analysis (LASCA) is a technique that evaluates burn lesions via relative perfusion analysis. We assessed the effect of tattoo skin pigmentation on LASCA perfusion imaging in a multicolour tattooed patient. Depth of burn lesions in multi-coloured tattooed and untattooed skin was assessed using LASCA. Relative perfusion was measured in perfusion units (PU) and compared to various pigment colours, then correlated with the clinical evaluation of the lesion. Superficial partial thickness burn (SPTB) lesions showed significantly elevated perfusion units (PU) compared to normal skin; deep partial thickness burns showed decreased PU levels. PU of various tattoo pigments to normal skin showed either significantly lower values (blue, red, pink) or significantly increased values (black) whereas orange and yellow pigment showed values comparable to normal skin. In SPTB, black and blue pigment showed reduced perfusion; yellow pigment was similar to normal SPTB burn. Deep partial thickness burn (DPTB) lesions in tattoos did not show significant differences to normal DPTB lesions for black, green and red. Tattoo pigments alter the results of perfusion patterns assessed with LASCA both in normal and burned skin. Yellow pigments do not seem to interfere with LASCA assessment. However proper determination of burn depth both in SPTB and DPTB by LASCA is limited by the heterogenic alterations of the various pigment colours.

Les tatouages sont de plus en plus fréquents, et donc l'incidence des brûlures sur peau tatouée augmente. L'évaluation clinique correcte de la profondeur de la brûlure se heurte à la pigmentation du tatouage. Nous avons utilisé dans ce but l'imagerie laser, chez un patient porteur d'un tatouage multicolore, dans des zones le portant et ne le portant pas. La perfusion relative était mesurée en Unités de Perfusion (UP), comparée à des pigments colorés connus, et à l'aspect clinique. Les brûlures superficielles étaient plus perfusées que la peau normale, quand les brûlures profondes l'étaient moins. Les pigments bleus, rouges et rose entraînent une diminution des UP de la peau saine, les noirs une augmentation, l'effet artéfactuel des oranges et des jaunes étant non significatif. En cas de brûlure superficielle, les zones bleues et noires ont une perfusion diminuée, alors que le jaune ne change pas le résultat comparativement à une telle brûlure en zone non tatouée. L'aspect laser des brûlures profondes sur des tatouages noirs, rouges ou verts est semblable à celui observé avec les mêmes brûlures sur peau non tatouée. Les tatouages changent les résultats de l'évaluation laser de la perfusion cutanée, que la peau soit normale ou brûlée, sauf avec les pigments jaunes. En cas de tatouage multicolore, l'évaluation de la profondeur d'une brûlure par laser est prise en défaut.

Extrinsic Notch ligand Delta-like 1 regulates tip cell selection and vascular branching morphogenesis.

RATIONALE: In developing blood vessels, single endothelial cells (ECs) specialize into tip cells that sense vascular endothelial growth factor (VEGF) and contribute to vessel sprouting and branch formation. Tip cell differentiation is inhibited through lateral Notch signaling between ECs, which is controlled by Notch ligands expressed in vessel sprouts. The contribution of the Notch ligand Delta-like (Dll) 1 herein is unknown. OBJECTIVE: To investigate the role of Dll1 in vascular morphogenesis and tip cell formation in the mouse retina. METHODS AND RESULTS: Mice with heterozygous deletion of Dll1 had fewer tip cells during angiogenic sprouting of the superficial vascular plexus but also showed impaired vessel branching into deeper retinal layers and impaired deep plexus angiogenesis. Interestingly, the formation of vertical branches was also guided by filopodia-extending ECs located at the tip of branches, consistent with tip cells, which emerged from established vessels to form a secondary plexus within the deeper neuronal cell layers. During both phases of vascular patterning, Dll1 was not expressed in ECs but in the superficial neuronal layer in close contact with expanding vessels, where Dll1 expression coincided with tip cell formation in a spatiotemporal manner. In vitro, culture of ECs on DLL1 induced essential tip cell genes, including Dll4, VEGF receptor 3, and ephrin-B2, and stimulated VEGF responsiveness and vascular network formation. CONCLUSIONS: Dll1 acts as an extrinsic cue involved in tip cell selection, which directs vessel sprouting and branch formation.