Mesenchymal bone marrow stem cells within polyglycolic acid tube observed in vivo after six weeks enhance facial nerve regeneration.

Autografting is the gold-standard method for facial nerve repair with tissue loss. Its association with high-quality scaffolds and cell implants has disclosed distinct experimental outcomes. The aim of this study was to evaluate the functional and histological effects of bone marrow stem cells (BMSC) combined with polyglycolic acid tube (PGAt) in autografted rat facial nerves. After neurotmesis of the mandibular branch of the rat facial nerve, surgical repair consisted of nerve autografting (groups A-E) contained in pGAT (groups B-E), filled with basement membrane matrix (groups C-E) with undifferentiated BMSC (group D) or Schwann-like cells that had differentiated from BMSC (group E). Axon morphometrics and an objective compound muscle action potentials (CMAP) analysis were conducted. Immunofluorescence assays were carried out with Schwann cell marker S100 and anti-ß-galactosidase to label exogenous cells. Six weeks after surgery, animals from either cell-containing group had mean CMAP amplitudes significantly higher than control groups. Differently from other groups, facial nerves with Schwann-like cell implants had mean axonal densities within reference values. This same group had the highest mean axonal diameter in distal segments. We observed expression of the reporter gene lacZ in nerve cells in the graft and distally from it in groups D and E. Group-E cells had lacZ coexpressed with S100. In conclusion, regeneration of the facial nerve was improved by BMSC within PGAt in rats, yet Schwann-like cells were associated with superior effects. Accordingly, groups D and E had BMSC integrated in neural tissue with maintenance of former cell phenotype for six weeks.

Peroneal nerve reconstruction by using glycerol-preserved veins: histological and functional assessment in rats

PURPOSE: To compare the degree of neural regeneration in rats upon interposition of autologous nerve graft, autogenous vein, glycerol-preserved autogenous vein, and glycerol-preserved allogeneic vein using qualitative and quantitative histological analyses as well as functional assessments. METHODS: Peroneal nerves were reconstructed differently in four groups of animals. Functional assessments were performed pre- and postoperatively for a period of six weeks. After six weeks, the animals were sacrificed and histological evaluations were performed. RESULTS: Histological patterns of autogenous veins without preservation showed pronounced neoangiogenesis and extensive axonal rarefaction, as confirmed by axonal counting and functional assessments. Glycerol-preserved veins had results similar to the control. CONCLUSIONS: Glycerol-preserved autogenous or allogeneic veins showed similar results to autograft results. The autogenous vein (without preservation in glycerol) presented histological and functional outcomes statistically lower than other groups.

Effects of hyperbaric oxygen therapy on facial nerve regeneration.

CONCLUSION: Hyperbaric oxygen treatment (HBOT) promoted an increase of the mean axonal diameter in the group evaluated 2 weeks after lesion induction, which suggests a more advanced regeneration process. However, the number of myelin nerve fibers of the facial nerve of the rabbits was similar when compared to the control and treatment groups, in both evaluation periods. OBJECTIVE: To evaluate the effect of HBOT on the histological pattern of the facial nerve in rabbits exposed to a nerve crush injury. MATERIALS AND METHODS: Twenty rabbits were exposed to facial nerve crush injury. Ten rabbits received HBOT, 10 rabbits comprised the control group. The rabbits were sacrificed 2 and 4 weeks after the trauma. Qualitative morphological analysis, measurement of the external axonal diameters and myelin fiber count were carried out in an area of 185 000 microm2. RESULTS: There was an increase in the area of the axons and thicker myelin in the 2 weeks treatment group in comparison with the control group. The mean diameter of the axons was of 2.34 microm in the control group and of 2.81 microm in the HBOT group, with statistically significant differences. The 2 week control group had a mean number of myelin fibers of 1865.2 +/- 664, and the HBOT group had a mean number of 2026.3 +/- 302; this was not statistically significant. The 4 week control group presented a mean of 2495.1 +/- 479 fibers and the HBOT group presented a mean of 2359.9 +/- 473; this was not statistically significant.

Evaluation of the systemic use of riluzole in post-traumatic facial nerve regeneration: experimental study in rabbits.

CONCLUSIONS: Riluzole promoted increase and/or preservation of axon density in the animals treated with this drug as compared to the control group; it did not increase the mean diameter of facial nerve fibres as compared to the non-treated group; and it did not provide a better functional motor recovery than in the control group. OBJECTIVE: Traumatic peripheral facial paralysis is a frequent affection. In incomplete nerve injuries, systemic drugs acting on regeneration may decrease the patient's period of morbidity. This study aimed to determine the effect of the drug riluzole on regeneration of the facial nerve of rabbits submitted to post-traumatic facial paralysis. MATERIALS AND METHODS: Eighteen rabbits were submitted to compression of the facial nerve and divided into control (A) and treated (B) groups. The animals were sacrificed 4 weeks after the injury and their nerves were studied regarding density of myelinated axons and measure of external axon diameters. RESULTS: Partial functional recovery was observed within 2 weeks and complete recovery 5 weeks after injury. Mean neural density was 12,679.7 axons/mm2 (SD+/-237.5) in group A, and 19,073.8 axons/mm2 (SD+/-3549.9) in group B. Group A presented less than two-thirds the density of group B. There was no statistical difference in axon diameters between the studied groups.

Pharmacological immunomodulation enhances peripheral nerve regeneration

To assess the effect of N-Acetylmuramyl-L-Alanyl-D-Isoglutamine MDP topically administrated on the regenerating peripheral neurons, twelve male C57BL/6J adult mice were equally distributed into three groups. Four mice underwent unilateral sciatic nerve transection and polyethylene tubulization, with a 4mm gap between the proximal and distal nerve stumps and were implanted with collagen + PBS (COL). Other four animals underwent the same surgical procedure but received collagen + MDP (COL/MDP) inside the prosthesis. Four animals were not operated and served as control group (NOR). After 4 weeks, the regenerated nerve cables were processed for total myelinated axon counting and myelinated fiber diameter measurement. The L5 dorsal root ganglion (DRG) was also removed and sectioned for sensory neurons counting and measurement. The results revealed significant difference (p<0.05) in axonal counting among the groups NOR (4,355±32), COL (1,869±289) and COL/MDP (2,430±223). There was a significant reduction in the axonal diameter in the operated groups (COL=3.38µm±1.16 and COL/MDP=3.54µm±1.16) compared to NOR (6.19µm±2.45). No difference was found in the number of DRG neurons between the experimental groups (COL=564±51; COL/MDP=514±56), which presented fewer sensory neurons compared to NOR (1,097±142). Data obtained indicate that locally applied MDP stimulates peripheral nerve regeneration in mice.

Para avaliar o efeito do NAcetilmuramil- L-Alanil-D-Isoglutamina administrado topicamente em neurônios periféricos em regeneração, doze camundongos C57BL/6J machos adultos foram igualmente separados em três grupos. Quatro animais sofreram transecção unilateral do nervo ciático que foi ancorado no interior de um tubo de polietileno, mantendo-se 4 mm de distância entre as extremidades dos nervos e receberam colágeno + PBS (COL) dentro do tubo. Outros quatro animais sofreram o mesmo procedimento cirúrgico, porém receberam colágeno + MDP (COL/MDP) no interior da prótese. Quatro animais não foram operados e serviram como controle de normalidade (NOR). Após quatro semanas, os cabos de regeneração foram coletados para determinação do número de axônios mielínicos e da mêdia do diâmetro das fibras mielínicas regeneradas. O gânglio da raiz dorsal L5 também foi coletado para contagem e mensuração dos neurônios sensitivos. Os resultados revelaram diferença significativa no número de axônios entre os grupos NOR (4355±32), COL (1869±289) e COL/MDP (2430±223). Houve redução significativa no diâmetro das fibras mielínicas nos grupos que receberam as próteses tubulares (COL=3,38µm±1,16 e COL/ MDP=3,54µm±1,16) quando comparados ao grupo NOR (6,19µm±2,45). O número de neurônios não diferiu entre os grupos experimentais (COL=564±51 e COL/MDP=514±56), os quais apresentaram menor número de neurônios sensitivos em relação ao grupo não operado (NOR=1097±142). Os dados obtidos indicam que a aplicação local do MDP estimula a regeneração de nervos em camundongos.

Correlation between parameters of electrophysiological, histomorphometric and sciatic functional index evaluations after rat sciatic nerve repair.

The rat sciatic nerve is a well-established model for the study of recovery from peripheral nerve injuries. Traditional methods of assessing nerve regeneration after nerve injury and repair, such as electrophysiology and histomorphometry, despite widely used in neural regeneration experiments, do not necessarily correlate with return of motor and sensory functions. The aim of this experimental study is to investigate the possible correlation between several parameters of peripheral nerve regeneration after repair of sectioned sciatic nerve in Wistar rat. A two-stage approach was used to obtain 17 parameters after electrophysiological, morphometric and sciatic functional index evaluations. Pearson's correlation analysis was performed between these results. Only two positives correlations between different classes of peripheral nerve assessments were noted, between sciatic functional index and proximal nerve fiber diameter (r=0.56, p<0.01) and between sciatic functional index and distal fiber diameter (r=0.50, p<0.01). The data presented in our study demonstrates that there is a poor correlation between the sciatic functional index and outcome measures of electrophysiological and morphometric evaluations.

Intervençöes farmacológicas no trauma raquimedular: uma nova visäo terapêutica / Pharmacological interventions in spinal cord trauma: a therapeutic approach

O imenso déficit neurológico decorrente da lesao da medula espinhal advém do somatório de dois eventos distintos: a lesao mecânica inicial e a lesao endógena secundária conseqüente à primeira. A lesao secundária da medula espinhal envolve complexas mudanças bioquímicas, que podem ser minimizadas pela introduçao de agentes farmacológicos recentes. Para limitar o dano tecidual e promover o reparo funcional, essas alteraçoes teciduais patológicas devem ser interrompidas. Avanços clínicos e científicos indicam que as lesoes agudas na medula espinhal podem ser manipuladas por terapêuticas farmacológicas utilizadas em curto espaço de tempo. A metilprednisolona administrada dentro das primeiras oito horas pós-trauma é o primeiro agente farmacológico a demonstrar melhora significativa na recuperaçao do trauma raquimedular em seres humanos. Outras drogas, como tilirazade e o GM-1, ainda sob investigaçao clínica, apresentam excelentes resultados preliminares. Esses avanços podem representar grande melhora na qualidade de vida de pacientes com lesao da medula espinhal, desde que sejam adotados pela prática clínica.

An ultrastructural study of the temporal progress of neuromuscular junction regeneration after sciatic nerve transection and tubulization repair

The aim of this investigation was to study the timecourse of motor endplates in the extensor digitorum logus (EDL) muscle after peripheral nerve transection and tubulization repair. Adult male C57BL/6J mice received sciatic nerve transection at midhigh level and both proximal and distal nerve stumps were stured into a 5-mm long polyethylene tube to bridge a final nerve gap distance of 3mm. At 2 to 40 weeks postoperatively the EDL muscle on the operated side was fixed in situ and processed histochemically for visualization of cholinesterase-rich sites. Groups of muscle fibers containing motor endplates were then processed for electron microscopy (EM). Two weeks after tubulization the EDL muscle was entirely denervated: Schwann cells came into contact with the post-synaptic folds of the muscle fibers; there was an increase in concentration of collagen and fibroblasts at the synaptic sites. Reinnervation began 4 weeks after tube implantation, when the first axon terminals established contact with a small portion of the specialized subneural region, many synaptic folds were still covered by collagen fibers and, in some cases, Schwann cells remained interposed between the folds and the synaptic terminals. Twelve weeks after surgery all the neuromuscular junctions examined were reinnervated and looked normal; motor terminals were alawys located at the primary synaptic clefts, although rarely some subneural folds lacking nerve terminals were seen. At 12 to 40 weeks all motor endplates appeared normally innervated by EM criteria.