Cell-assembled extracellular matrix (CAM): a human biopaper for the biofabrication of pre-vascularized tissues able to connect to the host circulationin vivo.

When considering regenerative approaches, the efficient creation of a functional vasculature, that can support the metabolic needs of bioengineered tissues, is essential for their survival after implantation. However, it is widely recognized that the post-implantation microenvironment of the engineered tissues is often hypoxic due to insufficient vascularization, resulting in ischemia injury and necrosis. This is one of the main limitations of current tissue engineering applications aiming at replacing significant tissue volumes. Here, we have explored the use of a new biomaterial, the cell-assembled extracellular matrix (CAM), as a biopaper to biofabricate a vascular system. CAM sheets are a unique, fully biological and fully human material that has already shown stable long-term implantation in humans. We demonstrated, for the first time, the use of this unprocessed human ECM as a microperforated biopaper. Using microvalve dispensing bioprinting, concentrated human endothelial cells (30 millions ml-1) were deposited in a controlled geometry in CAM sheets and cocultured with HSFs. Following multilayer assembly, thick ECM-based constructs fused and supported the survival and maturation of capillary-like structures for up to 26 d of culture. Following 3 weeks of subcutaneous implantation in a mice model, constructs showed limited degradative response and the pre-formed vasculature successfully connected with the host circulatory system to establish active perfusion.This mechanically resilient tissue equivalent has great potential for the creation of more complex implantable tissues, where rapid anastomosis is sine qua non for cell survival and efficient tissue integration.

French Otorhinolaryngology Society (SFORL) good practice guidelines for dental implant surgery close to the maxillary sinus.

OBJECTIVES: To draw up guidelines for ENT management associated with dental implant surgery with or without sinus lift. MATERIALS AND METHODS: The methodology followed the rules of laid down by the French Health Authority (HAS): "Methodological bases for drawing up professional recommendations by formalized consensus". The chosen method was the RAND/UCLA "RAND appropriateness method" (short version). RESULTS: In the pre-implantation check-up, it is recommended to systematically screen for sinonasal pathology on medical interview and to favor 3D CT or cone-beam imaging. It is recommended that imaging include the entire maxillary sinus when the patient does not have sinonasal history or functional signs on interview. Otherwise, examination of all sinonasal cavities is recommended. This attitude enables simultaneous analysis of maxillary infrastructure for pre-implantation work-up and assessment of sinonasal cavity status. Sinus mucosal incidentalomas are very common in the healthy population and must be assessed with reference to the clinical, endoscopic and radiological context. CONCLUSION: This formalized expert consensus establishes a common base of knowledge, to clarify the issues and clinical situations and to standardize practices.

What is the benefit of using amniotic membrane in oral surgery? A comprehensive review of clinical studies.

OBJECTIVES: Since its first use for the reconstruction of tissue defects in the oral cavity in 1985, human amniotic membrane (hAM) has been widely studied in the field of oral surgery. Despite the growing number of publications in this field, there is no systematic review or meta-analysis concerning its clinical applications, outcome assessments, and relevance in oral surgery. The aim of this review is to provide a thorough understanding of the potential use of hAM for soft and hard tissue reconstruction in the oral cavity. MATERIALS AND METHODS: A systematic electronic and a manual literature search of the MEDLINE-PubMed database and Scopus database was completed. Patient, Intervention, Comparison and Outcomes (PICO) technique was used to select the relevant articles to meet the objective. Studies using hAM for oral reconstruction, and conducted on human subjects, were included in this survey. RESULTS: A total of 17 articles were analyzed. Five areas of interest were identified as potential clinical application: periodontal surgery, cleft palate and tumor reconstruction, prosthodontics and peri-implant surgery. Overall, periodontal surgery was the only discipline to assess the efficacy of hAM with randomized clinical trials. The wide variability of preservation methods of hAM and the lack of objective measurements were observed in this study. CONCLUSION: hAM is already used in the field of oral surgery. Despite this, there is weak clinical evidence demonstrating convincingly the benefit of hAM in this area compared to standard surgery. CLINICAL RELEVANCE: Several studies now suggest the interest of hAM for periodontal tissue repair. Due to its biological and mechanical properties, hAM seems to be a promising treatment for wound healing in various areas of oral reconstruction. However, further randomized clinical trials are needed to confirm these preliminary results.

In-vitro and in-vivo design and validation of an injectable polysaccharide-hydroxyapatite composite material for sinus floor augmentation.

OBJECTIVE: Polysaccharide-based composite matrices consisting of natural polysaccharides, pullulan and dextran supplemented with hydroxyapatite (Matrix-HA) have recently been developed. The principal objective of this study was to evaluate the capacities of this composite material to promote new bone formation in a sinus lift model in the sheep. Secondary objectives were to evaluate in vitro properties of the material regarding cell adhesion and proliferation. METHODS: In this report, once such composite matrix was prepared as injectable beads after dispersion in a physiological buffer, and evaluated using a large animal model (sheep) for a sinus lift procedure. RESULTS: In vitro studies revealed that these microbeads (250-550µm in diameter) allow vascular cell adhesion and proliferation of Endothelial Cells (EC) after 1 and 7 days of culture. In vivo studies were performed in 12 adult sheep, and newly formed tissue was analyzed by Cone Beam Computed Tomography (CBCT scanning electron microscopy (SEM) and by histology 3 and 6 months post-implantation. CBCT analyses at the implantation time revealed the radiolucent properties of these matrices. Quantitative analysis showed an increase of a dense mineralized tissue in the Matrix-HA group up to 3 months of implantation. The mineralized volume over total volume after 6 months reached comparable values to those obtained for Bio-Oss® used as positive control. Histological examination confirmed that the Matrix-HA did not induce any long term inflammatory events, and promoted direct contact between the osteoid tissue and lamellar bone structures and beads. After 6 months, we observed a dense network of osteocytes surrounding both biomaterials as well as a newly vascularized formed tissue in close contact to the biomaterials. SIGNIFICANCE: In conclusion, the absence of animal components in Matrix-HA, the osteoconductive property of Matrix-HA in sheep, resulting in a dense bone and vascularized tissue, and the initial radiolucent property to follow graft integration offer great promises of this composite material for clinical use.

Pain-relieving effects of clonazepam and amitriptyline in burning mouth syndrome: a retrospective study.

This retrospective study aimed to evaluate the efficacy of clonazepam and amitriptyline in the treatment of burning mouth syndrome (BMS). A single-centre retrospective cohort study was performed among patients diagnosed with BMS. Either clonazepam or amitriptyline was administered. Patients were asked to evaluate their pain using a 10-point verbal numerical scale (VNS) at baseline, and at 6 weeks and 3 months of treatment. Mean pain-relief values were assessed according to the treatment received using the Kruskal-Wallis test. Thirty-nine patients (85% female) were included. The mean age was 65±10.5years. The mean VNS score at baseline was 7.1±2.0 in patients treated with clonazepam and 7.5±1.1 in those treated with amitriptyline. The mean VNS scores in the clonazepam and amitriptyline groups were 4.9±2.4 and 6.1±2.6, respectively, after 6 weeks of treatment (P=0.498) and 4.4±2.0 and 4.1±2.7, respectively, after 3 months (P=0.509). There was no difference between the two treatments in terms of pain reduction. Clonazepam as well as amitriptyline may be an effective treatment for BMS.

Effective parameters for film-free femtosecond laser assisted bioprinting.

Optimal conditions for femtosecond laser bioprinting setup are reported on in terms of numerical aperture and accuracy of focal spot location for different bioinks to deposit without using a metallic absorbing layer.

Cell interactions between human progenitor-derived endothelial cells and human mesenchymal stem cells in a three-dimensional macroporous polysaccharide-based scaffold promote osteogenesis.

Several studies have reported the benefits of mesenchymal stem cells (MSCs) for bone tissue engineering. However, vascularization remains one of the main obstacles that must be overcome to reconstruct large bone defects. In vitro prevascularization of the three-dimensional (3-D) constructs using co-cultures of human progenitor-derived endothelial cells (PDECs) with human bone marrow mesenchymal stem cells (HBMSCs) appeared as a potential strategy. However, the crosstalk between the two lineages has been studied in two-dimensional (2-D), but remains unknown in 3-D. The aim of this study is to investigate the cell interactions between PDECs and HBMSCs in a porous matrix composed of polysaccharides. This biodegradable scaffold promotes cell interactions by inducing multicellular aggregates composed of HBMSCs surrounded by PDECs. Cell aggregation contributes to the formation of junctional proteins composed of Connexin43 (Cx43) and VE-cadherin, and an activation of osteoblastic differentiation of HBMSCs stimulated by the presence of PDECs. Inhibition of Cx43 by mimetic peptide 43GAP27 induced a decrease in mRNA levels of Cx43 and all the bone-specific markers. Finally, subcutaneous implantations for 3 and 8 weeks in NOG mice revealed an increase in osteoid formation with the tissue-engineered constructs seeded with HBMSCs/PDECs compared with those loaded with HBMSCs alone. Taking together, these results demonstrate that this 3-D microenvironment favored cell communication, osteogenesis and bone formation.

High-throughput laser printing of cells and biomaterials for tissue engineering.

In parallel with ink-jet printing and bioplotting, biological laser printing (BioLP) using laser-induced forward transfer has emerged as an alternative method in the assembly and micropatterning of biomaterials and cells. This paper presents results of high-throughput laser printing of a biopolymer (sodium alginate), biomaterials (nano-sized hydroxyapatite (HA) synthesized by wet precipitation) and human endothelial cells (EA.hy926), thus demonstrating the interest in this technique for three-dimensional tissue construction. A rapid prototyping workstation equipped with an IR pulsed laser (tau=30 ns, lambda=1064 nm, f=1-100 kHz), galvanometric mirrors (scanning speed up to 2000 mm s(-1)) and micrometric translation stages (x, y, z) was set up. The droplet generation process was controlled by monitoring laser fluence, focalization conditions and writing speed, to take into account its mechanism, which is driven mainly by bubble dynamics. Droplets 70 microm in diameter and containing around five to seven living cells per droplet were obtained, thereby minimizing the dead volume of the hydrogel that surrounds the cells. In addition to cell transfer, the potential of using high-throughput BioLP for creating well-defined nano-sized HA patterns is demonstrated. Finally, bioprinting efficiency criteria (speed, volume, resolution, integrability) for the purpose of tissue engineering are discussed.

Mandibular reconstruction using induced membranes with autologous cancellous bone graft and HA-betaTCP: animal model study and preliminary results in patients.

Providing an acceptable quality of life for patients after reconstruction of mandibular segmental defects is challenging because the surgical techniques available have limitations. The authors evaluated two-stage mandibular reconstruction in rabbits and provide preliminary results in humans. 21 rabbits underwent bilateral segmental mandibulectomy and the defect was filled with methylmethacrylate. The methylmethacrylate was removed after 4 weeks and an iliac autograft performed on the right-hand side and an autogenous graft with hydroxyapatite and triphasic calcium phosphate (HA-betaTCP) on the left-hand side. Four patients with severe mandibular osteoradionecrosis underwent a two-stage reconstruction. No clinical or paraclinical complications were noted. Hematoxylin-eosin-saffron staining revealed an induced membrane lining the cavity of all samples with dense vascularity. Decalcified, undecalcified and histomorphometric analysis showed new bone formation in the biomaterial and the autograft. Calcium uptake was higher inside the new cortical bone, notably at sites with HA-betaTCP. CT scans at 6 months showed that two patients had a favorable outcome with cortico-cancellous bone. Microscopic and immunochemical analysis confirmed the experimental data. This study demonstrates the feasibility of mandibular reconstruction using the induced membranes technique. This technique is efficient, and the results would be better in non-irradiated patients with good general health.

[Oral ulcers in kidney allograft recipients treated with sirolimus]. / Ulcérations buccales chez les patients transplantés rénaux traités par sirolimus.

INTRODUCTION: Mouth ulcers are a major complication associated with sirolimus and occasionally result in discontinuation of treatment. However, they continue to be poorly understood and the data in the literature is frequently contradictory. The aim of this retrospective study is to help improve knowledge about such ulcers and about associated risk factors. PATIENTS AND METHODS: The dossiers of 37 renal transplant patients treated with sirolimus between June 2002 and February 2006 were analysed. The data collected consisted of patient age, gender, reason for transplantation, mean dose of sirolimus given and serum concentrations of the drug, ongoing treatments, presence of viral infection, blood picture and serum concentrations of folate, ferritin, iron and vitamin B12, coexistence of chronic inflammatory intestinal disease and local trauma, and presence or absence of mouth ulcers. Clinical investigation of the ulcers was based on notes and photographs taken during visits for oral mucosal disease. Patients presenting ulcers were treated with clobetasol cream and therapeutic efficacy was assessed in terms of progression of pain and speed of healing. RESULTS: Mouth ulcers were seen in eight of the 37 patients whose dossiers were examined. The sex ratio (M/F) was 1/1 in patients with ulcers and 3/1 in the 29 other patients. In patients presenting ulceration, the doses of sirolimus administered and serum sirolimus concentrations were respectively 3.2+/-1.05mg and 9.5+/-3.6ng/l versus 3.2+/-1.7mg and 9.8+/-4.1ng/l in patients without ulcers. The diseases responsible for renal failure were comparable in the two groups. 62% of patients with mouth ulcers discontinued sirolimus versus 65% of those without mouth ulcers. Only one patient stopped taking sirolimus partly on account of mouth ulcers. Mycophenolate mofetil was combined with sirolimus in 62.5% of patients with ulceration and in 62% of patients with no ulceration. The forms of ulceration varied, with a fibrinoid base. The edges were not excessively raised and no peripheral erythematous border was observed. Size ranged from 1 to 15mm, with between two and five ulcers being seen. The covering mucosa was involved in all cases, with sparing of the masticatory and specialised mucosa. Histological examination revealed non-specific ulceration associated with a polymorphous inflammatory infiltrate. Treatment with clobetasol reduced pain and shortened healing times between two- and three-fold. DISCUSSION: This study confirmed the incidence of mouth ulcers in renal transplant patients treated with sirolimus. The ulcers did not appear to be attributable to a dose-dependent mechanism, thus corroborating the results reported in the literature. However, a contributory role of transition from tacrolimus to sirolimus in their appearance was not seen in this study. Combination of sirolimus with mycophenolate mofetil appeared to have no bearing on the incidence of mouth ulcers. Clobetasol cream, whether or not given together with an anaesthetic solution, appears to reduce pain and shorten healing times, and could thus avoid discontinuation of treatment on account of mouth ulcers.

Use of gutta percha cores in CT scan imaging for patent nasopalatine duct.

Gutta percha cores were inserted in nasopalatine ducts to improve their visualization on CT scans. This simple method enhances the diagnostic quality of these images so that surgery can be performed more precisely.