Perfusion-decellularization of human ear grafts enables ECM-based scaffolds for auricular vascularized composite tissue engineering

Introduction: Human ear reconstruction is recognized as the emblematic enterprise in tissue engineering. Up to now, it has failed to reach human applications requiring appropriate tissue complexity along with an accessible vascular tree. We hereby propose a new method to process human auricles in order to provide a poorly immunogenic, complex and vascularized ear graft scaffold. Methods: 12 human ears with their vascular pedicles were procured. Perfusion-decellularization was applied using a SDS/polar solvent protocol. Cell and antigen removal was examined by histology and DNA was quantified. Preservation of the extracellular matrix (ECM) was assessed by conventional and 3D-histology, proteins and cytokines quantifications. Biocompatibility was assessed by implantation in rats for up to 60 days. Adipose-derived stem cells seeding was conducted on scaffold samples and with human aortic endothelial cells whole graft seeding in a perfusion-bioreactor. Results: Histology confirmed cell and antigen clearance. DNA reduction was 97.3%. ECM structure and composition were preserved. Implanted scaffolds were tolerated in vivo, with acceptable inflammation, remodeling, and anti-donor antibody formation. Seeding experiments demonstrated cell engraftment and viability. Conclusions: Vascularized and complex auricular scaffolds can be obtained from human source to provide a platform for further functional auricular tissue engineered constructs, hence providing an ideal road to the vascularized composite tissue engineering approach

Tissue Engineering in Oral and Maxillofacial Surgery : From Lab to Clinics

Regenerative medicine aims at the functional restoration of tissue malfunction, damage or loss, and can be divided into three main approaches. Firstly, the cell-based therapies, where cells are administered to re-establish a tissue either directly or through paracrine functions. Secondly, the often referred to as classical tissue engineering, consisting of the combined use of cells and a bio-degradable scaffold to form tissue. Thirdly, there are material-based approaches, which have made significant advances which rely on biodegradable materials, often functionalized with cellular functions (De Jong et al. 2014). In 1993, Langer and Vacanti, determined tissue engineering as an “interdisciplinary field that applies the principles of engineering and the life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function”. They published this definition in Science in 1993. Tissue engineering has been classically thought to consist of three elements: supporting scaffold, cells and regulating factors such as growth factors (Fig. 1). Depending on the tissue to be regenerated, all three vary. Currently, it is known, that many other factors may have an effect on the outcome of the regenerate. These include factors enabling angiogenesis, physical stimulation, culture media, gene delivery and methods to deliver patient specific implants (PSI) (Fig. 2). During the past two decades, major obstacles have been tackled and tissue engineering is currently being used clinically in some applications while in others it is just taking its first baby steps.Peer reviewe

ASTEMA: Design and preliminary performance assessment of a novel tele-microsurgery system

International audienceTo overcome the challenges of reconstructive microsurgery, a teleoperated robot called ASTEMA was built to help surgeons performing microanastomoses. The surgeons’ needs are first analyzed then the design steps are summarized. This robot is composed of three orthogonal linear actuators and a spherical wrist with its remote center of motion at the instrument tip. Geometric model of the spherical wrist was calibrated through mathematical optimization in order to compensate for imperfections of machining and assembling. Two preliminary experiments were carried out to assess the ASTEMA performance. The first was performed with a simple circular position trajectory. The second was a complex angular trajectory. Results show a significant improvement of gesture precision with respect to manual trajectory execution. They also show that subjects instinctively compensate the errors from the non-ideal wrist, thanks to visual feedback from microscope

Reduction of morbidity of the revascularization surgery in the management of mandibular osteoradionecrosis by basilar edge preservation.

The chronic complications of bone free-flap revascularization surgery are mainly characterized by skin fistulization of the osteosynthesis material, which sometimes leads to reactivation of the osteoradionecrotic phenomenon. The objective of the study is to evaluate the benefit of mandibular basilar edge preservation in bone reconstructive surgery in irradiated areas performed for the treatment of advanced mandibular osteoradionecrosis. A retrospective monocentric study conducted between 2003 and 2018 including all patients undergoing revascularization surgery for the treatment of advanced osteoradionecrotic lesion with respect to the basilar margin was conducted. Eight patients (7 males and 1 female, aged 50 to 63 years) who had a marginal mandibulectomy with reconstruction by bone free flap or composite free flap were included. The stability of the reconstruction (junction native mandible/bone free flap) was achieved on average by using 1.75 [range 0-4] mini plates (Medartis® Modus 2.0, Medartis AG, Basel, Switzerland). During the follow-up (30±13 months) no chronic complication related to a dissociation of the osteosynthesis material or a reactivation of the osteoradionecrotic phenomenon were identified. Despite the limited number of patients, it seems that the increase in the friction surface between the free flap and the native mandibular bone, linked to the preservation of the basilar edge, improves the primary stability of the reconstruction. This reduction in mechanical stress on osteosynthesis materials limits its use and reduces the rate of chronic complications of bone flap revascularization surgery in irradiated areas

Mechanical strength improvement of a soda-lime-silica glass by thermal treatment under flowing gas

International audienceThe incidence of thermal treatments in air, N-2 or NH3, on the mechanical properties of a soda-lime silica glass is presented. The effects of the treatment time and temperature were studied. Ammonia treatments lead to the most important compositional changes near the surface: SIMS and XPS techniques revealed a significant depletion in alkali and alkaline earth cations and a limited incorporation of nitrogen. IR-reflexion spectroscopy provided evidence for compositional changes near the surface, from a typical soda-lime glass towards a silica glass composition. The affected surface layer is typically about 1 mum deep and leads to significant changes of the local mechanical properties. Nanoindentation measurements showed that hardness increases whereas Young's modulus decreases both by similar to10% in a 300 nm thick surface layer. A significant increase of the indentation fracture toughness (K-c) from 0.72 to 0.89 MPa.m(1/2) was also noticed. The different processes leading to the cationic migration and to the changes of the glass surface properties were discussed. (C) 2003 Elsevier Ltd. All rights reserved

Use of a skin perforator flap pedicled by the intercostal muscle for reconstruction of a posterior cervical defect

International audienceA posterior cervical defect featuring exposed spinal and occipital bone can be covered in various ways. The “ideal” flap should be a low-morbidity, pedicled locoregional flap that can reach the occiput. Cervical adjuvant radiation therapy may limit the coverage options, because many pedicles are located in areas that are often irradiated. Here, we describe a new surgical technique; we used a skin perforator flap pedicled by the intercostal muscle to cover a posterior cervical defect in a patient with metastatic squamous cell lung carcinoma. This technique is a valuable option; the flap originated from outside the irradiated area and reached the occiput. It adds to the options for cervical coverage in patients who require head-and-neck reconstruction.Evidence-Based MedicineLevel V: opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.Les pertes de substances cervicales postérieures avec exposition osseuse peuvent être couvertes par plusieurs techniques. Le lambeau idéal doit avoir une faible morbidité, réalisable facilement, être un lambeau pédiculé locorégional et pouvoir atteindre l’occiput. En cas de radiothérapie cervicale, certains lambeaux classiques permettant de couvrir ce type de perte de substance peuvent avoir leur pédicule endommagé. Dans cet article, nous rapportons l’utilisation d’un lambeau perforant thoracique latéral pédiculé par les muscles intercostaux pour couvrir un defect cervical postérieur dans les suites d’une ostéosynthèse d’une métastase d’un carcinome pulmonaire. Ce lambeau est une alternative aux lambeaux traditionnels dont le pédicule est en dehors du champ d’irradiation. Il offre une option supplémentaire pour traiter ces defects

Detection of invasive plants using remote sensing: a case study of ragweed in the Rhone-Alps region, France

International audienceRagweed, Ambrosia artemisiifolia, is an annual plant, the pollen of which is responsible for respiratory allergies. In 2005, these allergies affected up to 20% of the population in parts of the department of Rhne. This is a major health problem for six of the eight departments of the Rhne-Alpes region (Ain, Ardche, Drme, Isre, Loire and Rhne). Our objective was to validate a method to map ragweed infestation in a village and then to extend this experiment to a department. Using methods developed by Auda et al. (2002a), we undertook a survey of ragweed infestation at the end of July 2005 in the village of Estrablin (Isre). Plots of land were registered in a Geographical Information System, with indications of crop type and ragweed infestation included in each plot. The sample area covered 3650km2 and constituted 30% of the total area of the village. The data were used to validate a SPOT 5 multispectral satellite image captured on 16 August 2005. Analysis of the ground data confirmed the extent of the ragweed infestation. More than 90% of the sample area was found to be infested. The image processing was based on crossing the crop type with the degree of infestation, using maximum likelihood classification. The accuracy of the method of detection used was demonstrated by the percentage of correctly classified pixels (45%), the reasons for confusion and the clarity of the visual representations. The success of our approach is highly influenced by the availability of high-quality images. Its feasibility, which is linked therefore to technical constraints, is examined in relation to space agency programmes

Role of flow magnetic resonance imaging in the monitoring of facial allotransplantations: preliminary results on graft vasculopathy.

Chronic vascular rejection characterized by the myointimal proliferation of smooth muscle cells that progressively obstruct the arterial graft lumen may become the main cause of long-term graft loss in vascularized composite allotransplantation (VCA), as observed in solid organ transplantation. As such, new diagnostic tools are required. The objective of this study was to evaluate the usefulness of flow magnetic resonance imaging (MRI) in the qualitative and quantitative monitoring of VCA in three patients transplanted between 2005 and 2012. Seven flow MRI acquisitions were performed concurrently with standardized clinical and histological monitoring between 2015 and 2017. A progressive reduction in the average flow rate and intraluminal diameter of the arterial pedicle of the grafts was demonstrated. During follow-up, two patients developed chronic vascular rejection requiring partial resection of the graft. For these patients, flow MRI acquisitions were characterized by a significant reduction in vascular signal, with a reduction in intravascular flow prior to anatomical injury. The results of this study confirm the feasibility of reproducible, non-invasive, and non-operator-dependent morphometric and haemodynamic radiological analysis, providing clinicians with new information on the vascular status of VCA over time and offering the prospect of an imaging technique specific to vascular outflow