Robust neurite extension following exogenous electrical stimulation within single walled carbon nanotube-composite hydrogels.

UNLABELLED: The use of exogenous electrical stimulation to promote nerve regeneration has achieved only limited success. Conditions impeding optimized outgrowth may arise from inadequate stimulus presentation due to differences in injury geometry or signal attenuation. Implantation of an electrically-conductive biomaterial may mitigate this attenuation and provide a more reproducible signal. In this study, a conductive nanofiller (single-walled carbon nanotubes [SWCNT]) was selected as one possible material to manipulate the bulk electrical properties of a collagen type I-10% Matrigel™ composite hydrogel. Neurite outgrowth within hydrogels (SWCNT or nanofiller-free controls) was characterized to determine if: (1) nanofillers influence neurite extension and (2) electrical stimulation of the nanofiller composite hydrogel enhances neurite outgrowth. Increased SWCNT loading (10-100-µg/mL) resulted in greater bulk conductivity (up to 1.7-fold) with no significant changes to elastic modulus. Neurite outgrowth increased 3.3-fold in 20-µg/mL SWCNT loaded biomaterials relative to the nanofiller-free control. Electrical stimulation promoted greater outgrowth (2.9-fold) within SWCNT-free control. The concurrent presentation of electrical stimulation and SWCNT-loaded biomaterials resulted in a 7.0-fold increase in outgrowth relative to the unstimulated, nanofiller-free controls. Local glia residing within the DRG likely contribute, in part, to the observed increases in outgrowth; but it is unknown which specific nanofiller properties influence neurite extension. Characterization of neuronal behavior in model systems, such as those described here, will aid the rational development of biomaterials as well as the appropriate delivery of electrical stimuli to support nerve repair. STATEMENT OF SIGNIFICANCE: Novel biomedical devices delivering electrical stimulation are being developed to mitigate symptoms of Parkinson's, treat drug-resistant depression, control movement or enhance verve regeneration. Carbon nanotubes and other novel materials are being explored for novel nano-neuro devices based on their unique properties. Neuronal growth on carbon nanotubes has been studied in 2D since the early 2000s demonstrating increased outgrowth, synapse formation and network activity. In this work, single-walled carbon nanotubes were selected as one possible electrically-conductive material, dispersed within a 3D hydrogel containing primary neurons; extending previous 2D work to 3D to evaluate outgrowth within nanomaterial composites with electrical stimulation. This is the first study to our knowledge that stimulates neurons in 3D composite nanomaterial-laden hydrogels. Examination of electrically conductive biomaterials may serve to promote regrowth following injury or in long term stimulation.

Paediatric liver transplanted patients and prevalence of hepatitis E virus.

BACKGROUND: Hepatitis E is an emerging disease in developed countries and is usually asymptomatic, particularly in children. Chronic infection is possible in immunocompromised individuals. In the context of a liver transplant, it can simulate a rejection. In this case, antiviral therapy may be considered, thus highlighting the need to diagnose hepatitis E virus (HEV) infection in this population. OBJECTIVES: Given the lack of data in France, we have studied the the prevalence of antibodies to HEV in the paediatric liver transplant population. STUDY DESIGN: This was a retrospective study, carried out in Lyon between 1st January 2010 and 31 May 2013. HEV serology (anti-HEV IgM &IgG) and HEV PCR were studied in 96 children who had undergone liver transplants (84 isolated liver and 12 combined liver and kidney transplants). RESULTS: Eight patients (8.3%; 62.5% girls; mean age:12.3 years) were HEV seropositive. The mean period since their transplantation was 10 years (range:2-21.8 years). Biliary atresia was the principal indication for transplantation. Seven of these eight children had received liver transplants. There were no differences between the epidemiological and clinical data concerning these patients and the remainder of the study population, particularly with respect to immunosuppression(7/8 tacrolimus; 50% dual immunosuppression). No cases of chronic hepatitis E were found, but 1/8 had chronic cytolysis(EBV&adenovirus infection). In all the patients tested(4/8), seroconversion had occurred after the transplant. There was no significant differences between the age groups in this study. CONCLUSIONS: This study showed that in France, the prevalence of antibodies to HEV in paediatric liver and combined liver and kidney transplant patients is 8.3%, as has been found by other European authors.

Neurite outgrowth on electrospun PLLA fibers is enhanced by exogenous electrical stimulation.

OBJECTIVE: Both electrical stimuli (endogenous and exogenous) and topographical cues are instructive to axonal extension. This report, for the first time, investigated the relative dominance of directional topographical guidance cues and directional electrical cues to enhance and/or direct primary neurite extension. We hypothesized the combination of electrical stimulation with electrospun fiber topography would induce longer neurite extension from dorsal root ganglia neurons than the presence of electrical stimulation or aligned topography alone. APPROACH: To test the hypothesis, neurite outgrowth was examined on laminin-coated poly-L-lactide films or electrospun fibers (2 µm in diameter) in the presence or absence of electrical stimulation. Immunostained neurons were semi-automatically traced using Neurolucida software and morphology was evaluated. MAIN RESULTS: Neurite extension increased 74% on the aligned fibers compared to film controls. Stimulation alone increased outgrowth by 32% on films or fibers relative to unstimulated film controls. The co-presentation of topographical (fibers) with biophysical (electrical stimulation) cues resulted in a synergistic 126% increase in outgrowth relative to unstimulated film controls. Field polarity had no influence on the directionality of neurites, indicating topographical cues are responsible for guiding neurite extension. SIGNIFICANCE: Both cues (electrical stimulation and fiber geometry) are modular in nature and can be synergistically applied in conjunction with other common methods in regenerative medicine such as controlled release of growth factors to further influence axonal growth in vivo. The combined application of electrical and aligned fiber topographical guidance cues described herein, if translated in vivo, could provide a more supportive environment for directed and robust axonal regeneration following peripheral nerve injury.

Epstein-Barr virus-associated smooth muscle tumors in a composite tissue allograft and a pediatric liver transplant recipient.

Epstein-Barr virus (EBV) is known to establish latent infections in B-lymphocytes that can cause lymphoproliferative disorders particularly in immunocompromised patients. More recently, the development of rare EBV-associated smooth muscle tumors has been reported in transplant recipients. We herein describe 2 new cases of EBV-associated post-transplant smooth muscle tumors (EBV-PTSMT), including the first in a facial composite tissue graft recipient. Among the striking features shared by these 2 patients were their young ages, the fact that they were naïve for EBV before the transplantation, that they developed a post-transplant lymphoproliferative disorder before the diagnosis of EBV-PTSMT, and that they responded favorably to reduction of immunosuppression. Radiological and histologic features of EBV-PTSMT are shown. Finally, pathophysiology and therapeutic management of EBV-PTSMT are discussed based on a comprehensive review of the literature.

[Long-term quality of life after pediatric liver transplantation]. / Qualité de vie à long terme après transplantation hépatique chez l'enfant.

We assessed quality of life in children after liver transplantation (LT) for at least 5years and in their parents, taking into account the physical, psychological, and social components, then compared the results of the patients with those of the general population and investigated the association between quality of life and somatic and psychosocial factors. Thirty-three patients, aged 8 to 18years and with a mean follow-up of 11.4years were included. Quality of life was assessed using generic self-administered questionnaires in 3 versions depending on age (pre-teens, teens, parents): the AUQUEI, OK Ado, and SQLP, respectively. Patient quality of life improved with age for all components and adolescent patients could exceed that of the general population. There was a negative impact of LT on parental quality of life, but family cohesion was strengthened. The parameters associated with patient quality of life were primarily psychosocial parameters, with special consideration for siblings and school. The somatic parameters related to LT had little impact on the quality of life of the patients but were strongly correlated with parental scores, especially when there were complications related to LT or immunosuppression. Quality-of-life assessment is complementary to clinical and laboratory data and is essential to optimize patient monitoring. Parental assessment is essential because of the long-term impact of LT on these families. A regular assessment of the quality of life of young liver transplant recipients is necessary to determine whether the encouraging results are confirmed on a larger cohort.

De novo malignancy after solid organ transplantation in children.

The aim of this study was to assess the prevalence of de novo malignancy after solid organ transplantation in childhood. A retrospective questionnaire-based survey was sent to 9 referral centers for pediatric organ transplantation in France. Among 1326 children who underwent solid organ transplantation since 1996, 80 (6%) presented with de novo malignancy posttransplantation during childhood: posttransplant lymphoproliferative disease was the most common (5% of pediatric recipients) comprising 80% of all tumors, with a disproportionately high prevalence among combined liver and small bowel recipients (18%). Various solid tumors were observed mainly among kidney recipients. No skin cancer was reported.

High throughput production, screening and analysis of adeno-associated viral vectors.

Recombinant adeno-associated viruses (rAAV) are promising candidates as gene vectors, as they transduce non-dividing cells and permit lasting transgene expression in a wide spectrum of tissues. In this paper, we describe a robust procedure for the high throughput production, screening and characterization of rAAV vectors. The technology includes the production of rAAV from rapid small scale plasmid preparations and the analysis of virus productivity (physical and infectious particles) and activity (transgene expression, replication). rAAV are produced by triple transfection (rAAV plasmid and AAV- and adenovirus (Ad)-helper plasmids) on 293 human embryo kidney (HEK) cells. The titers of physical and infectious particles are obtained by dot blot hybridization and by a serial dilution assay, followed by either dot blot hybridization or real-time PCR, respectively. rAAV can be produced and characterized from plasmid mixtures containing as little as 1/100 productive molecules. Experiments on rAAV replication kinetics and Ad helper functions are discussed. All steps are performed in 96-well microtiter plates. The process is reproducible, high throughput, linear and ready for automation.

The introduction of high-purity products in Canada.

In October 1993, the Canadian Blood Agency, the agent for the provinces/territories in Canada, agreed to the introduction of high-purity coagulation products, either recombinant or highly purified factor concentrates, for the management of coagulation deficiencies. This represented a cost increase of approximately $30 million (40%) for the national coagulation product inventory. Representatives of the relevant recipients of the products, some of the treaters, the distributor and the funders met on a regular basis in order to monitor the impact of these new products. The Association of Hemophilia Clinic Directors of Canada also agreed to include some specific outcome studies over a longer period of time to include evaluation of inhibitor formation, prophylaxis regimens, immune status and the incidence of thrombosis. The 'Hemophilia and Von Willebrand's Disease' clinical practice guidelines were also developed under their auspices. A usage monitoring system has been implemented and has been continuously managed by the Canadian Blood Agency. This resulted in trends of practice and rationales for unexpected use being identified early for planning and funding purposes. The Working Group set up under the auspices of the Canadian Blood Agency was an effective vehicle to evaluate the conversion and the impact of these new products in the country and can serve as a model for future endeavours.