Evaluation of the early changes occurring in the draining lymph node upon subcutaneous stimulation

Adjuvants have been shown since many years to have an important role in enhancing the immune responses against the co-administered antigens used as vaccines. The continuous study of the mechanism of action of adjuvants is necessary to develop further safe and efficacious vaccines. Complete Freund's adjuvant (CFA) is currently in use as adjuvant to induce some autoimmune diseases in murine models, therefore the study of the mechanisms involved in the generation of the related immune responses could be instrumental for the understanding of the induction of inflammatory Thl7 responses. In the present work, we showed in C57B1/6 mice that CFA peripheral administration induces very early, at 6 h, a potent influx of CDllb+ cells, mainly neutrophils (CD11b+Ly6GhighLy6Cint) and monocytes (CD11b+Ly6GlowLy6Chigh), in the draining lymph node. By investigating the route by which neutrophils reach the lymph node we observed that, around 20% of them arrive from the afferent lymph and the majority stains positive for Mycobacterium tuberculosis. We also observed a correlation between the influx of neutrophils and an increase in IL-23 and IL-Ιβ, together with several inflammatory chemokines, in the draining lymph node. Concomitantly, we detected the expression of the IL-23 receptor on CDllc+ DCs. Moreover, we confirmed the ability of murine neutrophils to express IL-23 both, in vitro by stimulating bone-marrow extracted PMNs with Mycobacterium tuberculosis, and on total cells from draining lymph node by immunohistochemistry. We also observed by in vivo priming a reduction in the percentage of IFN-γ and CXCR3 expressing Τ cells upon depletion of neutrophils. Altogether, we show that upon stimulation from the periphery, the draining lymph node undergo changes in cytokine/chemokine production leading to the recruitment of different leukocytes subpopulations. Here we show that CFA induces a rapid influx of neutrophils which are responsible for the production of IL-23 that in turn influences the generation of Τ helper cells.

cAMP prevents the glucose-mediated stimulation of GLUT2 gene transcription in hepatocytes.

Glucose homoeostasis necessitates the presence in the liver of the high Km glucose transporter GLUT2. In hepatocytes, we and others have demonstrated that glucose stimulates GLUT2 gene expression in vivo and in vitro. This effect is transcriptionally regulated and requires glucose metabolism within the hepatocytes. In this report, we further characterized the cis-elements of the murine GLUT2 promoter, which confers glucose responsiveness on a reporter gene coding the chloramphenicol acetyl transferase (CAT) gene. 5'-Deletions of the murine GLUT2 promoter linked to the CAT reporter gene were transfected into a GLUT2 expressing hepatoma cell line (mhAT3F) and into primary cultured rat hepatocytes, and subsequently incubated at low and high glucose concentrations. Glucose stimulates gene transcription in a manner similar to that observed for the endogenous GLUT2 mRNA in both cell types; the -1308 to -212 bp region of the promoter contains the glucose-responsive elements. Furthermore, the -1308 to -338 bp region of the promoter contains repressor elements when tested in an heterologous thymidine kinase promoter. The glucose-induced GLUT2 mRNA accumulation was decreased by dibutyryl-cAMP both in mhAT3F cells and in primary hepatocytes. A putative cAMP-responsive element (CRE) is localized at the -1074/-1068 bp region of the promoter. The inhibitory effect of cAMP on GLUT2 gene expression was observed in hepatocytes transfected with constructs containing this CRE (-1308/+49 bp fragment), as well as with constructs not containing the consensus CRE (-312/+49 bp fragment). This suggests that the inhibitory effect of cAMP is not mediated by the putative binding site located in the repressor fragment of the GLUT2 promoter. Taken together, these data demonstrate that the elements conferring glucose and cAMP responsiveness on the GLUT2 gene are located within the -312/+49 region of the promoter.

Ultrasound-guided suprascapular nerve block, description of a novel supraclavicular approach.

BACKGROUND AND OBJECTIVES: The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative. METHODS: In the first step, 60 volunteers were scanned with US, both in the supraclavicular and the classic target area. The visibility of the SSN in both regions was compared. In the second step, 20 needles were placed into or immediately next to the SSN in the supraclavicular region of 10 cadavers. The accuracy of needle placement was determined by injection of dye and following dissection. RESULTS: In the supraclavicular region of volunteers, the nerve was identified in 81% of examinations (95% confidence interval [CI], 74%-88%) and located at a median depth of 8 mm (interquartile range, 6-9 mm). Near the suprascapular notch (supraspinous fossa), the nerve was unambiguously identified in 36% of examinations (95% CI, 28%-44%) (P < 0.001) and located at a median depth of 35 mm (interquartile range, 31-38 mm; P < 0.001). In the cadaver investigation, the rate of correct needle placement of the supraclavicular approach was 95% (95% CI, 86%-100%). CONCLUSIONS: Visualization of the SSN with US is better in the supraclavicular region as compared with the supraspinous fossa. The anatomic dissections confirmed that our novel supraclavicular SSN block technique is accurate.

Reverse transcription quantitative real-time polymerase chain reaction reference genes in the spared nerve injury model of neuropathic pain : validation and literature search

La douleur neuropathique est définie comme une douleur causée par une lésion du système nerveux somato-sensoriel. Elle se caractérise par des douleurs exagérées, spontanées, ou déclenchées par des stimuli normalement non douloureux (allodynie) ou douloureux (hyperalgésie). Bien qu'elle concerne 7% de la population, ses mécanismes biologiques ne sont pas encore élucidés. L'étude des variations d'expressions géniques dans les tissus-clés des voies sensorielles (notamment le ganglion spinal et la corne dorsale de la moelle épinière) à différents moments après une lésion nerveuse périphérique permettrait de mettre en évidence de nouvelles cibles thérapeutiques. Elles se détectent de manière sensible par reverse transcription quantitative real-time polymerase chain reaction (RT- qPCR). Pour garantir des résultats fiables, des guidelines ont récemment recommandé la validation des gènes de référence utilisés pour la normalisation des données ("Minimum information for publication of quantitative real-time PCR experiments", Bustin et al 2009). Après recherche dans la littérature des gènes de référence fréquemment utilisés dans notre modèle de douleur neuropathique périphérique SNI (spared nerve injury) et dans le tissu nerveux en général, nous avons établi une liste de potentiels bons candidats: Actin beta (Actb), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ribosomal proteins 18S (18S), L13a (RPL13a) et L29 (RPL29), hypoxanthine phosphoribosyltransferase 1 (HPRT1) et hydroxymethyl-bilane synthase (HMBS). Nous avons évalué la stabilité d'expression de ces gènes dans le ganglion spinal et dans la corne dorsale à différents moments après la lésion nerveuse (SNI) en calculant des coefficients de variation et utilisant l'algorithme geNorm qui compare les niveaux d'expression entre les différents candidats et détermine la paire de gènes restante la plus stable. Il a aussi été possible de classer les gènes selon leur stabilité et d'identifier le nombre de gènes nécessaires pour une normalisation la plus précise. Les gènes les plus cités comme référence dans le modèle SNI ont été GAPDH, HMBS, Actb, HPRT1 et 18S. Seuls HPRT1 and 18S ont été précédemment validés dans des arrays de RT-qPCR. Dans notre étude, tous les gènes testés dans le ganglion spinal et dans la corne dorsale satisfont au critère de stabilité exprimé par une M-value inférieure à 1. Par contre avec un coefficient de variation (CV) supérieur à 50% dans le ganglion spinal, 18S ne peut être retenu. La paire de gènes la plus stable dans le ganglion spinal est HPRT1 et Actb et dans la corne dorsale il s'agit de RPL29 et RPL13a. L'utilisation de 2 gènes de référence stables suffit pour une normalisation fiable. Nous avons donc classé et validé Actb, RPL29, RPL13a, HMBS, GAPDH, HPRT1 et 18S comme gènes de référence utilisables dans la corne dorsale pour le modèle SNI chez le rat. Dans le ganglion spinal 18S n'a pas rempli nos critères. Nous avons aussi déterminé que la combinaison de deux gènes de référence stables suffit pour une normalisation précise. Les variations d'expression génique de potentiels gènes d'intérêts dans des conditions expérimentales identiques (SNI, tissu et timepoints post SNI) vont pouvoir se mesurer sur la base d'une normalisation fiable. Non seulement il sera possible d'identifier des régulations potentiellement importantes dans la genèse de la douleur neuropathique mais aussi d'observer les différents phénotypes évoluant au cours du temps après lésion nerveuse.

Distinct ASIC currents are expressed in rat putative nociceptors and are modulated by nerve injury.

The H(+)-gated acid-sensing ion channels (ASICs) are expressed in dorsal root ganglion (DRG) neurones. Studies with ASIC knockout mice indicated either a pro-nociceptive or a modulatory role of ASICs in pain sensation. We have investigated in freshly isolated rat DRG neurones whether neurones with different ASIC current properties exist, which may explain distinct cellular roles, and we have investigated ASIC regulation in an experimental model of neuropathic pain. Small-diameter DRG neurones expressed three different ASIC current types which were all preferentially expressed in putative nociceptors. Type 1 currents were mediated by ASIC1a homomultimers and characterized by steep pH dependence of current activation in the pH range 6.8-6.0. Type 3 currents were activated in a similar pH range as type 1, while type 2 currents were activated at pH < 6. When activated by acidification to pH 6.8 or 6.5, the probability of inducing action potentials correlated with the ASIC current density. Nerve injury induced differential regulation of ASIC subunit expression and selective changes in ASIC function in DRG neurones, suggesting a complex reorganization of ASICs during the development of neuropathic pain. In summary, we describe a basis for distinct cellular functions of different ASIC types in small-diameter DRG neurones.

Autophagy promotes survival of retinal ganglion cells after optic nerve axotomy in mice.

Autophagy is an essential recycling pathway implicated in neurodegeneration either as a pro-survival or a pro-death mechanism. Its role after axonal injury is still uncertain. Axotomy of the optic nerve is a classical model of neurodegeneration. It induces retinal ganglion cell death, a process also occurring in glaucoma and other optic neuropathies. We analyzed autophagy induction and cell survival following optic nerve transection (ONT) in mice. Our results demonstrate activation of autophagy shortly after axotomy with autophagosome formation, upregulation of the autophagy regulator Atg5 and apoptotic death of 50% of the retinal ganglion cells (RGCs) after 5 days. Genetic downregulation of autophagy using knockout mice for Atg4B (another regulator of autophagy) or with specific deletion of Atg5 in retinal ganglion cells, using the Atg5(flox/flox) mice reduces cell survival after ONT, whereas pharmacological induction of autophagy in vivo increases the number of surviving cells. In conclusion, our data support that autophagy has a cytoprotective role in RGCs after traumatic injury and may provide a new therapeutic strategy to ameliorate retinal diseases.

Effets de la stimulation sousthalamique bilatérale sur la voix et la parole de patients parkinsoniens

La maladie de Parkinson (MP) est une maladie neurodégénérative atteignant 1-2% des¦personnes de plus de 60 ans (1). Ses signes cliniques ont été décrits par James Parkinson¦en 1817 dans : « An essay on the Shaking palsy» (2). Les signes cardinaux sont le¦tremblement de repos, la rigidité et la bradykinésie. Certaines définitions y ajoutent l'instabilité¦posturale. D'autres manifestations, non motrices, telles qu'une dysfonction autonome et¦sensitive, des troubles de l'humeur, des troubles du sommeil et des démences peuvent¦apparaître en cours d'évolution. Le traitement actuel de la MP est principalement¦pharmacologique. Il consiste en l'administration du précurseur de la dopamine, la levodopa¦(L-dopa). Pourtant, l'utilisation à long terme de la L-dopa induit des fluctuations motrices telles¦que dyskinésies et dystonies. Au cours du siècle dernier, de nombreux traitements¦chirurgicaux ont été tentés, en particulier des procédures ablatives (thalamotomie,¦pallidotomie, subthalamotomie). Elles ont le désavantage d'induire des séquelles non¦négligeables telles que des parésies et des troubles neurocognitifs. La chirurgie ablative a¦été abandonnée avec l'arrivée de la L-dopa dans les années 1960. Les limitations de la¦thérapie par la L-dopa associées aux améliorations de la neuro-imagerie, de la sécurité des¦procédures neurochirurgicales ainsi que des techniques d'implantation ont permis le¦développement de procédures stimulatrices dans les années 1990. La stimulation cérébrale¦profonde des noyaux sous-thalamiques est devenue une stratégie thérapeutique bien établie¦chez les patients atteints d'une MP avancée. Malgré une excellente réponse motrice des¦membres, l'impact de la stimulation cérébrale profonde sur la parole est controversé (2).¦Le but de cette étude est de déterminer l'influence aigüe des stimulateurs sous-thalamiques¦sur des paramètres objectifs et quantitatifs, ainsi que sur un paramètre subjectif de la¦dysarthrie parkinsonienne. Nous allons comparer dans notre groupe de patients deux¦conditions successives: patient avec stimulateurs éteints et sans médication (OFF/nm)¦versus avec stimulateurs allumés et sans médication (ON/nm). Nous allons ensuite effectuer¦des analyses statistiques afin de déterminer si les stimulateurs sous-thalamiques ont un effet¦aigu bénéfique ou non sur certains paramètres vocaux, puis sur l'intelligibilité globale de la¦parole. En effet, l'intelligibilité nous informe sur la capacité de communication du patient avec¦son entourage.

MOLECULAR REORGANIZATION FOLLOWING SENSORY STIMULATION IN THE ADULT MOUSE BARREL CORTEX

Sensory information is an important factor in shaping neuronal circuits during development and adulthood. In the barrel cortex of adult rodents, cells from layer IV are able to adapt their functional state to an increased flow of sensory information from the mystacial whisker follicles. Previous studies in our group have shown that whisker stimulation induces the formation of inhibitory synapses in the corresponding barrel (Knott et al., 2002) and decreases neuronal responses toward the deflection of the stimulated whisker (Quairiaux et al., 2007). Together these observations have turned the barrel cortex into a model to study homeostatic plasticity. At the cellular level, neuronal activity triggers intracellular signaling cascades leading to a transcriptional response. To further characterize the molecular pathways involved in the synaptic changes after whisker stimulation in the adult mouse, a previous doctoral student in our group performed a microarray analysis on laser-dissected barrels in sections through layer IV. This study identified the regulation (up and down) of a series of genes in the stimulated barrels (thesis of Johnston-Wenger, 2010). We here focused on ten genes that presented the highest fold change according to the microarray analysis. Out of these genes, 7 are known as neuronal activity-dependent genes (Tnncl, Nptx2, Sorcs3, Ptgs2, Nr4a2, Npas4 and Adcyapl) whereas three have so far not been related to neuronal plasticity (Scn7a, Pcdhl5 and Cede3). The study aimed at confirming the results of the microarray analysis and localizing molecular modifications in the stimulated barrel column at the cellular level. In situ hybridization for Pcdhl5 after different periods of whisker stimulation (3, 6, 9, 15, 24 hrs) allowed us to confirm that the 1.25 fold change used for the microarray analysis is an appropriate threshold for considering a regulation significant after sensory-stimulation. Moreover, we confirmed with in situ hybridization a significant upregulation of the genes of interest in the stimulated barrels. In situ hybridization and immunohistochemistry allowed us to observe the distribution of the genes of interest and the corresponding protein products at the cellular level. Three observations were made: 1) alterations of the expression was restricted to the stimulated barrels for all genes tested; 2) within a barrel column not all cells responded to whisker stimulation with an altered gene expression; 3) in the stimulated barrels, two different patterns of mRNA and protein expression can be distinguished. We hypothesize that this segregation of the activity-induced gene expression reflects the segregation of the two principal thalamocortical pathways conveying the sensory information to the barrel cortex. Moreover, only neurons reaching the critical threshold will modify their gene expression program resulting in structural as well as physiological modifications that prevent the subsequent propagation of the excess of excitation to the postsynaptic targets. The activity-induced gene expression is therefore adapted in a cell-type-specific manner to induce a homeostatic response to the entire neuronal network involved in the integration of the sensory information. This to our knowledge the first study showing the distinct, but complementary contribution of the two thalamocortical pathways in experience-dependent plasticity in the adult mouse barrel cortex. -- L'information sensorielle nous permet de continuellement façonner nos circuits neuronaux autant durant le développement qu'à l'âge adulte. Chez le rongeur l'information sensorielle perçue par les vibrisses est intégrée au niveau du cortex somatosensoriel primaire (appelé en anglais « barrel cortex ») dont les cellules de la couche IV sont capables d'adapter leur état fonctionnel en réponse à une augmentation d'activité neuronale. Ce modèle expérimental a permis à notre groupe de recherche d'observer des changements rapides du circuit neuronal en fonction de l'activité sensorielle. En effet, la stimulation continue d'une vibrisse d'une souris adulte pendant 24 heures induit non seulement un remaniement synaptique (Knott et al., 2002), mais également des changements physiologiques au niveau des neurones du tonneau correspondant (Quairiaux et al., 2007). Ces observations nous permettent d'affirmer que le « barrel cortex » est un modèle approprié pour y étudier la plasticité synaptique. Au niveau cellulaire, l'activité neuronale déclenche des cascades de signalisation intracellulaire résultant en une réponse transcriptionnelle. Afin de caractériser les voies moléculaires impliquées dans la plasticité synaptique, une puce à ARN nous a permis de comparer l'expression de gènes entre un tonneau correspondant à une vibrisse stimulée et un tonneau d'une vibrisse non-stimulée (Nathalie). Cette analyse a révélé un certain nombre de gènes régulés de manière positive ou négative par l'augmentation de l'activité neuronale. Nous nous sommes concentrés sur 10 gènes dont l'expression est fortement régulée. L'expression de sept d'entre eux a déjà été démontrée comme dépendante de l'activité neuronale (Tnncl, Nptx2, Sorcs3, Ptgs2, Nr4a2, Npas4 otAdcyapl) alors que l'expression des trois autres (Scn7a, Pcdhl5 et Cedei) n'a pour le moment pas encore été liée à la plasticité neuronale. Le but de cette thèse est de confirmer les résultats de la puce à ARN et de déterminer dans quel type cellulaire ces gènes sont exprimés. L'hybridation in situ pour le gène Pcdhl5, après différentes périodes de stimulation des vibrisses (3, 6, 9, 15 et 24 heures), nous a permis de confirmer que le seuil de 1.25x utilisé dans l'analyse de la puce à ARN est approprié pour considérer qu'un gène est régulé de manière significative par la stimulation sensorielle. Nous avons également pu confirmer à l'aide de cette technique que la stimulation sensorielle augmente significativement l'expression de ces dix gènes. L'expression de ces gènes au niveau cellulaire a été observée à l'aide des techniques d'hybridation in situ et d'immunohistochimie. Trois observations ont été faites : 1) la régulation de ces gènes est restreinte aux tonneaux correspondants aux vibrisses stimulées ; 2) au niveau d'une colonne corticale correspondant aux vibrisses stimulées, seules certaines cellules présentent une altération de leur expression génique ; 3) au niveau des tonneaux stimulés, deux profils d'expression d'ARNm et de protéines sont observés. Notre hypothèse est que cette distribution pourrait correspondre à la terminaison ségrégée des deux voies thalamocortical qui amènent l'information sensorielle dans le cortex cérébral. De plus, seul les neurones atteignant le seuil critique d'activation modifient leur expression génique en réponse à la stimulation sensorielle. Ces changements d'expression géniques vont permettre à la cellule de modifier ses propriétés structurales et physiologiques de manière a prevenir la propagation d'un excès d'activité neuronale au niveau de ses cibles postsynaptics. L'activité neuronale agit donc spécifiquement sur certains types cellulaires de maniere a induire une réponse homéostatique au niveau du réseau neuronal impliqué dans l'integration de l'information sensorielle. Nos travaux démontrent pour une première fois que les deux voies sensorielles contribuent d'une manière distincte et complémentaire à la plasticité corticale induite par un changement de l'activité sensorielle chez la souris adulte.

An analysis of the components of pain, function, and health-related quality of life in patients with failed back surgery syndrome treated with spinal cord stimulation or conventional medical management

Objectives: Failed back surgery syndrome (FBSS) patients experience pain, functional disability, and reduced health-related quality of life (HRQoL) despite anatomically successful surgery. Examining sub-dimensions of health outcomes measures provides insight into patient well-being. Materials and Methods: The international multicenter PROCESS trial collected detailed HRQoL (EuroQol-5D; Short-Form 36) and function (Oswestry Disability Index) information on 100 FBSS patients. Results: At baseline, patients reported moderate-to-severe leg and back pain adversely affecting all dimensions of function and HRQoL. Compared with conventional medical management alone, patients also receiving spinal cord stimulation (SCS) reported superior pain relief, function, and HRQoL at six months on overall and most sub-component scores. The majority of these improvements with SCS were sustained at 24 months. Nonetheless, 36-40% of patients experienced ongoing marked disability (standing, lifting) and HRQoL problems (pain/discomfort). Conclusions: Longer-term patient management and research must focus on these refractory FBSS patients with persisting poor function and HRQoL outcomes.

Changes induced in Biomphalaria glabrata (Say, 1818) following trials for artificial stimulation of its internal defense system

Biomphalaria glabrata can react through different pathways to Schistosoma mansoni miracidium penetration, according to the degree of resistance/susceptibility presented by different snail strains, which is a genetically determined character, resistance being the dominant feature. However, it has been observed that previous susceptible snail strain may change its reactive behavior along the course of infection, exhibiting later a pattern of cercarial shedding and histopatopathological picture compatible with high resistance. Such observation suggests the possibility of B. glabrata to develop a sort of adaptative immunity face a schistosome infection. To explore on this aspect, the present investigation looked for the behavior of S. mansoni infection in B. glabrata previously subjected to different means of artificial stimulation of its internal defense system. Snails previously inoculated with irradiated miracídia (Group I); treated with S. mansoni antigens (Group II) or with a non-related parasite antigen (Group III) were challenged with 20 viable S. mansoni miracidia, and later looked for cercarial shedding and histopathologic changes at different times from exposition. Nodules of hemocyte accumulations were found at the site of antigen injection. These nodules resembled solid granulomas, and were larger and more frequent in snails injected with S. mansoni products as compared to those injected with Capillaria hepatica. However, the presence of such granulomas did not avoid the S. mansoni challenge infection from developing in a similar way as that seen in controls. The data are indicative that hemocytes are able to proliferate locally when stimulated, such capacity also remaining localized, not being shared by the population of hemocytes located elsewhere within the snail body.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS).

A group of European experts was commissioned to establish guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS) from evidence published up until March 2014, regarding pain, movement disorders, stroke, amyotrophic lateral sclerosis, multiple sclerosis, epilepsy, consciousness disorders, tinnitus, depression, anxiety disorders, obsessive-compulsive disorder, schizophrenia, craving/addiction, and conversion. Despite unavoidable inhomogeneities, there is a sufficient body of evidence to accept with level A (definite efficacy) the analgesic effect of high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the pain and the antidepressant effect of HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC). A Level B recommendation (probable efficacy) is proposed for the antidepressant effect of low-frequency (LF) rTMS of the right DLPFC, HF-rTMS of the left DLPFC for the negative symptoms of schizophrenia, and LF-rTMS of contralesional M1 in chronic motor stroke. The effects of rTMS in a number of indications reach level C (possible efficacy), including LF-rTMS of the left temporoparietal cortex in tinnitus and auditory hallucinations. It remains to determine how to optimize rTMS protocols and techniques to give them relevance in routine clinical practice. In addition, professionals carrying out rTMS protocols should undergo rigorous training to ensure the quality of the technical realization, guarantee the proper care of patients, and maximize the chances of success. Under these conditions, the therapeutic use of rTMS should be able to develop in the coming years.

Collagen (NeuraGen®) nerve conduits and stem cells for peripheral nerve gap repair.

Collagen nerve guides are used clinically for peripheral nerve defects, but their use is generally limited to lesions up to 3 cm. In this study we combined collagen conduits with cells as an alternative strategy to support nerve regeneration over longer gaps. In vitro cell adherence to collagen conduits (NeuraGen(®) nerve guides) was assessed by scanning electron microscopy. For in vivo experiments, conduits were seeded with either Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC) or left empty (control group), conduits were used to bridge a 1cm gap in the rat sciatic nerve and after 2-weeks immunohistochemical analysis was performed to assess axonal regeneration and SC infiltration. The regenerative cells showed good adherence to the collagen walls. Primary SC showed significant improvement in distal stump sprouting. No significant differences in proximal regeneration distances were noticed among experimental groups. dMSC and dASC-loaded conduits showed a diffuse sprouting pattern, while SC-loaded showed an enhanced cone pattern and a typical sprouting along the conduits walls, suggesting an increased affinity for the collagen type I fibrillar structure. NeuraGen(®) guides showed high affinity of regenerative cells and could be used as efficient vehicle for cell delivery. However, surface modifications (e.g. with extracellular matrix molecule peptides) of NeuraGen(®) guides could be used in future tissue-engineering applications to better exploit the cell potential.