After big loos of substances of peripheral nerves, in order to connect proximal with distal stump, it is possible to use, in alternative to autologous grafting, different kind of conduits. The chitosan conduit and the muscle in vein technique showed very good results in pre clinical and clinical settings. We compared in this study the efficacy of empty chitosan conduit versus chitosan conduit enriched with fresh muscle fibbers (MIT) to improve peripheral nerve regeneration.

The median nerve of rat was repaired by means of empty chitosan conduit or MIT (nerve gam 6mm, conduit length 10 mm). As control group we used auto grafting technique. We performed analysis at short term (7,14,28 days) and at long term (12 weeks) in order to register bimolecular modification (quantitative real time PCRand western blot), morphological modification (optic and electronic microscope) and functional changing (grasping test).

Bimolecular analysis showed that muscle fibbers produced and released Neuregulin1, needed for regeneration and activity of Schwann cells. Otherwise also the autograft product Neuregulin1, instead no production was observed in empty conduit. So muscle fibbers compensate this fact. Morphological analysis showed that the first myelinc fibbers appear in MIT after 14 days, but not in empty tube.

The results of our work are very interesting because can merge the easiness of the implantation of chitosan tube and the efficacy of fresh muscle fibbers, as previously demonstrated by muscle in vein technique.

From a clinical point of view this procedure could be an alternative to auto grafting that is nowadays the gold standard for nerve repair, but present soma disadvantages.

Scar tissue formation between nerve and surrounding muscle is one of the most undesired occurrence in nerve surgery In order to prevent scar tissue apposition after surgery, a lot of biocompatible products have been developed and tested first of all on animal models and then in surgical practice. we tested the efficacy of a CMC-PEO gel in reduction of perineural scar tissue formation in a mice model and in a small group of patients

We performed surgical procedures on 26 male mices The animals were randomized into three groups. In each group the muscular bed of sciatic nerve was burned with diathermocoagulator. In treated group we applied the tested gel in order to reduce the post surgical scar. After 3 weeks the strenght of the scar was studied using a specific tool. Also histologic analysis was performed. We also reported the results of CMC-PEO gel on 8 patients who underwent surgical decompression of peripheral nerves affected by recurrent compressive syndrome

The biomechanical analysis showed that gel application strongly reduces scar tissue. The difference between not treated and treated group was statistically significative. The histological analysis confirmed this data showing a cleavage plan between scar tissue and sciatic nerve. In patients we monitored VAS pre and post operative and we described reduction from 8 to 1 in 6 patients and from 6 to 1 in two patients.

In conclusion, our study proves the efficacy in animal models of Dynavisc in scar tissue formation prevention and discloses the absolute security and biocompatibility of this products. Moreover also the small sample of patients showed the safety of this product on human, and proved its efficacy on recurrent nerve compression syndrome associated with neurolysis.

Aims: Multiple nerve repair by means of a Y-shaped nerve guide represents a good model for studying the specificity of peripheral nerve fiber regeneration. Here we have employed this model for investigating the specificity of axonal regeneration in mixed nerves of the rat forelimb model. Specificity of nerve regeneration can be defined as the ability of the nerve fibers of a peripheral nerve, after a lesion. Tree types of specificity on nerve regeneration has been postulated: “tissue specificity” (the preferential reinnervation of distal nerve tissue versus other types of tissue), topographic specificity (regenerating nerve fibers are preferentially attracted by analogous distal pathways (e.g. preferential regeneration along tibial nerve pathways by tibial nerve fibers), and end-organ specificity, which is the hypothesis that distal end-organs (muscle vs. sensory targets) specifically attracts the respective (motor vs. sensory) regenerating nerve fibers. Exists no agreement regarding the presence and features of the two last type of specificity.

Methods: The left median and ulnar nerves, in adult female rats, were transected and repaired with a 14-mm Y-shaped conduit. The proximal end of the Y-shaped conduit was sutured to the proximal stump of either the median nerve or the ulnar nerve. Ten months after surgery, rats were tested for functional recovery of each median and ulnar nerve. Quantitative morphology of regenerated myelinated nerve fibers was then carried out by the two-dimensional disector technique.

Results: Results showed that partial recovery of both median and ulnar nerve motor function was regained in all experimental groups. Performance in the grasping test was significantly lower when the ulnar nerve was used as the proximal stump. Ulnar test assessment showed no significant difference between the two Y-shaped repair groups. The number of regenerated nerve fibers was significantly higher in the median nerve irrespectively of the donor nerve, maintaining the same proportion of myelinated fibers between the two nerves (about 60% median and 40% ulnar). On the other hand, nerve fiber size and myelin thickness were significantly larger in both distal nerves when the median nerve was used as the proximal donor nerve stump. G-ratio and myelin thickness/ axon diameter ratio returned to normal values in all experimental groups.

Conlusions: These results demonstrate that combined Y-shaped-tubulization repair of median and ulnar nerves permits the functional recovery of both nerves, independently from the proximal donor nerve employed, and that tissue, and not topographic, specificity guides nerve fiber regeneration in major forelimb mixed nerves of rats.

Aims: The combination of microsurgical techniques with engineering of pseudo-nerves has recently seen an increased employment for the repair of peripheral nerve defects. Over the last ten years, we have investigated a particular type of bio-engineered nerve guide, the muscle-vein-combined tube, which is made by filling a vein with skeletal muscle. However, the basic mechanism underlying the effectiveness of this surgical technique are still unclear and yet an experimental study on its efficacy on functional recovery compared to traditional nerve autografts is still lacking in the literature. The aim of the present study was thus to fill this gap.

Methods: In rats, 10-mm-long median nerve defects were repaired using either traditional autografts or fresh muscle-vein-combined bioengineered scaffolds. Posttraumatic nerve recovery was assessed by grasping test. The samples were collected at different times after surgery: 5, 15, 30 days and 6 months. Analysis was carried out by light and electron microscopy. In addition, reverse transcription polymerase chain reaction (RT-PCR) was used to investigate the expression of mRNAs coding for glial markers as well as glial growth factor (NRG1) and its receptors (erbB2 and erbB3).

Results: Results showed that both types of nerve repair techniques led to successful axonal regeneration along the severed nerve trunk as well as to a partial recovery of the lost function as assessed by grasping test. Rats operated on by traditional nerve autografts performed better in the grasping test. Biomolecular analysis by RT-PCR demonstrated early overexpression during nerve regeneration of the gliotrophic factor NRG1 and two of its receptors: erbB2 and erbB3.

Conclusions: Our results confirmed that use of muscle-vein-combined tissue-engineered conduits is a good approach for bridging peripheral nerve defects in selected cases when traditional autografts are not employable and disclosed one of the basic biological mechanism that support the effectiveness of this surgical technique. Our experience also suggested that the rat forelimb experimental model is particularly appropriate for the study of microsurgical reconstruction of major mixed nerve trunks. Furthermore, since the forelimb model is less compromising for the animal, it should be preferred to the hindlimb model for many research purposes.

Aims: Biosynthetic scaffolds made of degradable bio-materials enriched with cultured cells holds promise for peripheral nerve repair after complex traumatic injuries. In the perspective of future transplantation applications, the aim of this study was to investigate how cultures of olfactory ensheathing cells (OECs), in particular neonatal olfactory ensheathing cells (NOBECs), grow up in vitro on degradable polymeric films made with polycap-rolactone matrices and multi-block polyesterurethane respectively. In addition, since several transplantation studies use green fluorescent protein (GFP) positive cells so that they can be easily located in the receiving tissues, the cDNA encoding for GFP was cloned in expression vector and transfected in NOBECs.

Methods: To characterize NOBECs we employed electron microscopy, immunohistochemistry, RT-PCR and western blotting analyses. Moreover the proliferative ratio of NOBECs and the ability of the cells to migrate in a three dimensional environment were evaluated under basal and experimental culture conditions. Finally, the GFP-positive NOBEC were seeded on two types of synthetic films and their behaviour was analyzed to determine cell adhesion, survival and proliferation.

Results: We examined the expression of glial markers and NRG1/ErbB system in the NOBEC cell line at RNA and protein level. Results showed that NOBECs express both glial markers (GFAP and S-100), ErbB receptors (ErbB1, ErbB2 and ErB3) and different isoforms of NRG1. NOBECs exhibited a remarkable proliferation activity and a high basal migration activity. GFP positive NOBECs showed no significant difference in their behaviour as compared to untransfected parental cells. Finally, both normal and GFP-NOBECs showed good cell adhesion, survival and proliferation properties when seeded on both films employed in this study.

Conclusion: Taken together, results of our study showed that the glial cell line has similar biochemical properties as primary cultures of OECs. Moreover, we showed that NOBECs survive, proliferate and migrate on two different types of synthetic films that were prepared in the perspective of build up nerve scaffolds. Therefore, our results indicated that the NOBECs produce growth-promoting proteins and possess regeneration-promoting capabilities that make them a potentially good transplant material to enhance axonal regeneration inside synthetic tubes used to bridge nerve lesion with substance loss.

Aims: Muscle fat degeneration and fibrosis following long time denervation is today the main cause of poor functional recovery after peripheral nerve surgery especially for reconstruction of proximally located lesions of median and ulnar nerves such as those at brachial plexus level. External electro-stimulation is actually one possible way to avoid muscular atrophy and degeneration and is frequently used in the post-operative of patients with neurological palsy. A new approach that has been proposed to prevent denervation-related muscle atrophy is sensory protection performed by direct neurotization of a denervated muscle with a branch of a sensitive nerve passing nearby. The aim of this study was to study the effectiveness of sensory protection on denervated muscles as a technique to avoid their atrophic process.

Methods: In four groups of rats (A,B,C and D), the median nerves were transected at right and left forearm. In group A,B and C, denervated muscles were “reinnervated” with a sensory nerve (sensory protection). Animals of group A was sacrificed after six months for a morphologic study of muscles. Animals of groups B and C were reinnervated after six months either keeping sensory protection (group B) or removing it (group C) and sacrificed after one year. Group D (without sensory protection) was reinnervated after six months and sacrificed after one year (control group). Muscle histology was performed on all samples. Functional comparison of different group was perfor-mend by means of the grasping test.

Results: Histological analysis showed that sensory protection led to a better muscular trophism in all experimental groups. Also the functional testing showed better performances in sensory protected animals and especially in group C (de-protected before re-innervation) compared with group B (not de-protected before re-innervation) and D (control).

Conclusions: Initial data analisys obtained in this study showed that sensory protection is effective in reducing denervation-related muscle atrophy. De-protection of the muscle before its reinnervation is also important to ameliorate post-surgical functional recovery. A new trial will be carried out with a larger number of cases in order to confirm these results which could have important applications in the clinical perspective.