RESUMEN

The preconditioning hypoxia for stem cells is a strategy to achieve effective conditions for cell therapy, indicate increased expression of regenerative genes in stem cell therapy, and enhance the secretion of bioactive factors and therapeutic potential of their cultured secretome. Objectives: This study aims to explore the response of Schwann-like cells derived from adipose-derived mesenchymal stem cells (SLCs) and Schwann cells rat sciatic nerve-derived stem cells (SCs) with their secretomes under normoxic and hypoxic conditions in vitro. Material and methods: SLCs and SCs were isolated from the adipose tissue and the sciatic nerve of the adult white male rat strain Wistar. Cells were incubated in 21% O2 (normoxic group) and 1%, 3%, and 5% O2 (hypoxic group) conditions. Concentration values of transforming growth factor-ß (TGF-ß), basic Fibroblast Growth factor (bFGF), brain-derived neurotrophic factor, glial-derived neurotrophic factor, vascular endothelial growth factor, and nerve growth factor were detected and calculated utilizing an enzyme-linked immunosorbent assay, and the growth curve was described. Results: SLCs and SCs indicated positive expression for mesenchymal markers and negative expression for hematopoietic markers. Normoxic conditions SLCs and SCs showed elongated and flattened morphology. Under hypoxic conditions, SLCs and SCs showed a classic fibroblast-like morphology. Hypoxia 1% gave the highest concentration in TGF-ß and bFGF from the SLCs group and TGF-ß, bFGF, brain-derived neurotrophic factor, and vascular endothelial growth factor from the SCs group. No significant differences in concentration of growth factors between the SLCs group compared to SCs group in all oxygen groups. Conclusions: Preconditioning hypoxia has an effect on the composing of SLCs, SCs, and their secretomes in vitro; no significant differences in concentration of growth factors between the SLCs group compared with the SCs group in all oxygen groups.

RESUMEN

Objective.The objective of this study was to investigate the effects of micromagnetic stimuli strength and frequency from theMagneticPen(MagPen) on the rat right sciatic nerve. The nerve's response was measured by recording muscle activity and movement of the right hind limb.Approach.The MagPen was custom-built to be stably held over the sciatic nerve. Rat leg muscle twitches were captured on video, and movements were extracted using image processing algorithms. EMG recordings were also used to measure muscle activity.Main results.The MagPen prototype, when driven by an alternating current, generates a time-varying magnetic field, which, according to Faraday's law of electromagnetic induction, induces an electric field for neuromodulation. The orientation-dependent spatial contour maps of the induced electric field from the MagPen prototype have been numerically simulated. Furthermore, in thisin vivowork onµMS, a dose-response relationship has been reported by experimentally studying how varying the amplitude (Range: 25 mVp-pthrough 6Vp-p) and frequency (range: 100 Hz through 5 kHz) of the MagPen stimuli alters hind limb movement. The primary highlight of this dose-response relationship (repeated overnrats, wheren= 7) is that for aµMS stimuli of higher frequency, significantly smaller amplitudes can trigger hind limb muscle twitch. This frequency-dependent activation can be justified by Faraday's Law, which states that the magnitude of the induced electric field is directly proportional to the frequency.Significance.This work reports thatµMS can successfully activate the sciatic nerve in a dose-dependent manner. The impact of this dose-response curve addresses the controversy in this research community about whether the stimulation from theseµcoils arise from a thermal effect or micromagnetic stimulation. MagPen probes do not have a direct electrochemical interface with tissue and therefore do not experience electrode degradation, biofouling, and irreversible redox reactions like traditional direct contact electrodes. Magnetic fields from theµcoils create more precise activation than electrodes because they apply more focused and localized stimulation. Finally, unique features ofµMS, such as the orientation dependence, directionality, and spatial specificity, have been discussed.

Asunto(s)

RESUMEN

Matrix metalloproteinases (MMPs) are important contributing factors of tissue remodeling and wound healing. MMP9, a predominant soluble MMP, has been discovered as one of the most up-regulated genes in peripheral nerves after nerve injury, implying the potential regulatory roles of MMP9 during peripheral nerve regeneration. Considering that Schwann cell is a main cell population in peripheral nerves and MMP9 is secreted by Schwann cells, here, we investigated the biological functions of MMP9 on Schwann cell phenotype modulation. MMP9 gene knockdown or MMP9 recombinant protein exposure significantly hinders or elevates the migration ability of cultured Schwann cells, respectively. Direct application of MMP9 recombinant protein to sciatic nerve injured rats promotes Schwann cell migration, blood vessel formation, axon elongation, and myelin wrapping. Genetic exploration of MMP9-induced changes indicates that MMP9 regulates the extracellular region as well as the intracellular metabolism of Schwann cells. Our present study illuminates the importance of elevated MMP9 after nerve injury from the functional aspect and enhances our comprehension of the mechanisms underlying peripheral nerve regeneration.

Asunto(s)

RESUMEN

Schwann cells provide essential physical and chemical support for neurons and play critical roles in the peripheral nervous system. To acquire an enhanced understanding of the genetic characteristics of Schwann cells, we analyzed single-cell transcriptional profiling of Schwann cells in neonatal rat sciatic nerves, ordered the pseudotemporal states of Schwann cells, and determined the magnitude of RNA velocity vectors as well as cell cycle stages of Schwann cell subtypes. We discovered the cellular heterogeneity of Schwann cells in neonatal rat sciatic nerves, revealed the dynamic changes of Schwann cell subtypes, and pointed out the differentiation trajectory from Timp3- and Col5a3-expressing Schwann cell subtype 3 to other Schwann cell subtypes. The functional interpretation further indicated that subtype 3 Schwann cells display genetic signatures of DNA replication and the acquisition of mesenchymal traits. Our study presents a transcriptional summarization of the differentiation states of Schwann cell subtypes in neonatal rat sciatic nerves at single-cell resolution and may serve as a foundation for a deeper comprehension of the involvement of Schwann cells in the development and regeneration of peripheral nerves.

Asunto(s)

RESUMEN

Nerve guides are medical devices designed to guide proximal and distal ends of injured peripheral nerves in order to assist regeneration of the damaged nerves. A 3D-printed polycaprolactone (PCL) nerve guide using an aligned gelatin-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) electrospun mat, seeded with PC12 and Schwann cells (SCs) is produced. During characterization with microCT and SEM porosity (55%), pore sizes (675 ± 40 µm), and fiber diameters (382 ± 25 µm) are determined. Electrospun fibers have degree of alignment of 7°, indicating high potential for guidance. On Day 14, PC12 cells migrated from proximal to distal end of nerve guide when SCs are seeded on the guide. After 28 days, over 95% of PC12 are alive and aligned. PC12 cells express early differentiation marker beta-tubulin 10 times more than late marker NeuN. In a 10 mm rat sciatic nerve injury, functional recovery evaluated by using static sciatic index (SSI) is observed in mat-free guides and guides containing mat and SCs. Nerve conduction velocities are also improved in these groups. Histological stainings showed tissue growth around nerve guides with highest new tissue organization being observed with mat and cell-free guides. These suggest 3D-printed PCL nerve guides have significant potential for treatment of peripheral nerve injuries.

Asunto(s)

RESUMEN

Objective. Maximizing the stability of implanted neural interfaces will be critical to developing effective treatments for neurological and neuromuscular disorders. Our research aims to develop a stable neural interface using wireless communication and intrafascicular microelectrodes to provide highly selective stimulation of neural tissue.Approach. We implanted a wireless floating microelectrode array into the left sciatic nerve of six rats. Over a 38 week implantation period, we recorded stimulation thresholds and movements evoked at each implanted electrode. We also tracked each animal's response to sensory stimuli and performance on two different walking tasks.Main results. Presence of the microelectrode array inside the sciatic nerve did not cause any obvious motor or sensory deficits in the hindlimb. Visible movement in the hindlimb was evoked by stimulating the sciatic nerve with currents as low as 4.1µA. Thresholds for most of the 96 electrodes we implanted were below 20µA, and predictable recruitment of plantar flexion and dorsiflexion was achieved by stimulating rat sciatic nerve with the intrafascicular microelectrode array. Further, motor recruitment patterns for each electrode did not change significantly throughout the study.Significance. Incorporating wireless communication and a low-profile neural interface facilitated highly stable motor recruitment thresholds and fine motor control in the hindlimb throughout an extensive 9.5 month assessment in rodent peripheral nerve. Results of this study indicate that use of the wireless device tested here could be extended to other applications requiring selective neural stimulation and chronic implantation.

Asunto(s)

RESUMEN

BACKGROUND: Histomorphometry quantitatively evaluates nerve regeneration. Total myelinated fiber count (TMFC) is most accurately obtained manually across full nerve cross-sections, but most researchers opt for automated, sampled analysis. Few of the numerous techniques available have been validated. The goal of this study was to compare common histomorphometric methods (full manual [FM], sampled manual [SM], and sampled automatic [SA]) to determine their reliability and consistency. MATERIAL AND METHODS: Twenty-four rats underwent sciatic nerve (SN) repair with 20mm isografts; SNs distal to the graft were analyzed. TMFC was manually determined in each full cross-section. Counts were also extrapolated from sampled fields, both manually and automatically with ImageJ software. Myelinated fiber diameter, axon diameter, and myelin sheath thickness were measured manually in full and sampled fields; G-ratio was calculated. Repeated-measures MANOVA, Spearman correlation, and Wilcoxon signed-rank tests were performed. A systematic review of histomorphometry in rat SN repair was performed to analyze the variability of techniques in the literature. RESULTS: FM TMFC was 13,506 ± 4,217. Both sampled methods yielded significantly different TMFCs (SM:14.4 ± 13.4%, P< 0.001; SA:21.8 ± 44.7%, P = 0.037). All three methods strongly correlated with each other, especially FM and SM (rs = 0.912, P< 0.001). FM fiber diameter, axon diameter, and myelin sheath thickness did not differ from SM (P = 0.493, 0.209, and 0.331, respectively). 65% of papers used sampling; 78% utilized automated or semi-automated analysis. Software, sampling, and histomorphometric parameters varied widely. CONCLUSION: SM and SA analysis are reliable with standardized, systematic sampling. Transparency is essential to allow comparison of data; meanwhile, researchers must be cognizant of the wide variety of methodologies in the literature.

Asunto(s)

RESUMEN

Peripheral compressive neuropathy causes significant neuropathic pain, muscle weakness and prolong neuroinflammation. Surgical decompression remains the gold standard of treatment but the outcome is suboptimal with a high recurrence rate. From mechanical compression to chemical propagation of the local inflammatory signals, little is known about the distinct neuropathologic patterns and the genetic signatures after nerve decompression. In this study, controllable mechanical constriction forces over rat sciatic nerve induces irreversible sensorimotor dysfunction with sustained local neuroinflammation, even 4 weeks after nerve release. Significant gene upregulations are found in the dorsal root ganglia, regarding inflammatory, proapoptotic and neuropathic pain signals. Genetic profiling of neuroinflammation at the local injured nerve reveals persistent upregulation of multiple genes involving oxysterol metabolism, neuronal apoptosis, and proliferation after nerve release. Further validation of the independent roles of each signal pathway will contribute to molecular therapies for compressive neuropathy in the future.

Asunto(s)

RESUMEN

Some experimental research indicates that low-frequency pulsed electromagnetic field (PEMF) stimulation may accelerate regeneration in sciatic nerve injury. However, little research has examined the electrophysiological and functional properties of regenerating peripheral nerves under PEMF. The main aim of the present study is to investigate the effects of PEMF on sciatic nerve regeneration in short- and long-term processes with electrophysiologically and functionally after crushing damage. Crush lesions were performed using jewelery forceps for 30 s. After crush injury of the sciatic nerves, 24 female Wistar-Albino rats were divided into 3 groups with 8 rats in each group: SH(Sham), SNI (Sciatic Nerve Injury), SNI+PEMF(Sciatic Nerve Injury+Pulsed Electromagnetic Field). SNI+PEMF group was exposed to PEMF (4 h/day, intensity; 0.3mT, low-frequency; 2 Hz) for 40-days. Electrophysiological records (at the beginning and 1st, 2nd, 4th and 6th weeks post-crush) and functional footprints (at 1st, 2nd, 3rd, 4th, 5th and 6th weeks post crush) were measured from all groups during the experiment. The results were compared to SNI and SNI+PEMF groups, it was found that amplitude and area parameters in the first-week were significantly higher and latency was lower in the SNI+PEMF group than in the SNI group (p < 0,05). However, the effect of PEMF was not significant in the 2nd, 4th, 6th weeks. In addition, in the 1st and 2nd weeks, the SSI parameters were significantly higher in SNI+PMF group than SNI group (p < .05). These results indicate that low-frequency PEMF is not effective for long-periods of application time while PEMF may be useful during the short-term recovery period.

Asunto(s)

RESUMEN

BACKGROUND: Cytokines are essential cellular modulators of various physiological and pathological activities, including peripheral nerve repair and regeneration. However, the molecular changes of these cellular mediators after peripheral nerve injury are still unclear. This study aimed to identify cytokines critical for the regenerative process of injured peripheral nerves. METHODS: The sequencing data of the injured nerve stumps and the dorsal root ganglia (DRGs) of Sprague-Dawley (SD) rats subjected to sciatic nerve (SN) crush injury were analyzed to determine the expression patterns of genes coding for cytokines. PCR was used to validate the accuracy of the sequencing data. RESULTS: A total of 46, 52, and 54 upstream cytokines were differentially expressed in the SNs at 1 day, 4 days, and 7 days after nerve injury. A total of 25, 28, and 34 upstream cytokines were differentially expressed in the DRGs at these time points. The expression patterns of some essential upstream cytokines are displayed in a heatmap and were validated by PCR. Bioinformatic analysis of these differentially expressed upstream cytokines after nerve injury demonstrated that inflammatory and immune responses were significantly involved. CONCLUSIONS: In summary, these findings provide an overview of the dynamic changes in cytokines in the SNs and DRGs at different time points after nerve crush injury in rats, elucidate the biological processes of differentially expressed cytokines, especially the important roles in inflammatory and immune responses after peripheral nerve injury, and thus might contribute to the identification of potential treatments for peripheral nerve repair and regeneration.

Asunto(s)

RESUMEN

The regenerative capacity of peripheral nerves is limited after nerve injury. A number of growth factors modulate many cellular behaviors, such as proliferation and migration, and may contribute to nerve repair and regeneration. Our previous study observed the dynamic changes of genes in L4-6 dorsal root ganglion after rat sciatic nerve crush using transcriptome sequencing. Our current study focused on upstream growth factors and found that a total of 19 upstream growth factors were dysregulated in dorsal root ganglions at 3, 9 hours, 1, 4, or 7 days after nerve crush, compared with the 0 hour control. Thirty-six rat models of sciatic nerve crush injury were prepared as described previously. Then, they were divided into six groups to measure the expression changes of representative genes at 0, 3, 9 hours, 1, 4 or 7 days post crush. Our current study measured the expression levels of representative upstream growth factors, including nerve growth factor, brain-derived neurotrophic factor, fibroblast growth factor 2 and amphiregulin genes, and explored critical signaling pathways and biological process through bioinformatic analysis. Our data revealed that many of these dysregulated upstream growth factors, including nerve growth factor, brain-derived neurotrophic factor, fibroblast growth factor 2 and amphiregulin, participated in tissue remodeling and axon growth-related biological processes Therefore, the experiment described the expression pattern of upstream growth factors in the dorsal root ganglia after peripheral nerve injury. Bioinformatic analysis revealed growth factors that may promote repair and regeneration of damaged peripheral nerves. All animal surgery procedures were performed in accordance with Institutional Animal Care Guidelines of Nantong University and ethically approved by the Administration Committee of Experimental Animals, China (approval No. 20170302-017) on March 2, 2017.

RESUMEN

This work proposes and computationally investigate the use of magnetic neural stimulation as an alternative to electrical stimulation to achieve selective activation of rat sciatic nerve. In particular, they assess the effectiveness of an array of small coils to obtain selective neural stimulation, as compared to a single coil. Specifically, an array of four mm-sized coils is used to stimulate rat sciatic nerve, targeting the regions of fascicles that are associated with different muscles of the leg. To evaluate the selectivity of activation, a three-dimensional heterogeneous multi-resolution nerve model is implemented using the impedance method for the computation of the magnetic and electric fields in the nerve. The performance metric 'selectivity index' is defined that measures the recruitment of the targeted region compared to other non-targeted regions of the nerve. The selectivity index takes values between -1 (least selective) and 1 (most selective). For each targeted region, a selectivity index of 0.75 or better is predicted for the proposed array configuration. The results suggest that an array of coils can provide superior spatial control of the electric field induced in the neural tissue compared to traditional extraneural electrode arrays, thus opening the possibility to applications where selective neurostimulation is of interest.

RESUMEN

BACKGROUND: Peripheral nerves can self-regenerate after traumatic injury, although their self-regeneration ability is limited after severe nerve injury. After peripheral nerve injury, the distal nerve stumps undergo Wallerian degeneration while the proximal nerve stumps undergo a regeneration process. METHODS: Here, to decipher genetic changes and involved biological processes in the proximal nerve stumps after peripheral nerve injury, microarray data (GSE30165) were analyzed. Differentially expressed genes in the proximal nerve stumps at 0.5 h, 1 h, 3 h, 6 h, 9 h, 1 d, 4 d, 7 d, and 14 d after rat sciatic nerve transection were subjected to Ingenuity pathway analysis (IPA) bioinformatic analysis. RESULTS: Cytokine signaling, cellular immune response, nuclear receptor signaling, disease-specific pathways, and organismal growth and development were significantly activated in the proximal nerve stumps after nerve transection. Organ development, inflammation and immune response, diseases and organ abnormalities, and cellular behavior-related biological functions were highly involved. CONCLUSIONS: The expression levels of differentially expressed genes in biological function "Organismal Injury and Abnormalities" were displayed and validated. Our current study helps to obtain a better understanding of the biological processes of peripheral nerve regeneration, especially the regeneration process in the proximal nerve stumps, and thus may help to discover new therapeutic methods that can promote nerve regeneration.

RESUMEN

BACKGROUND: Nervous system injuries in mammals often involve transection or segmental loss of peripheral nerves. Such injuries result in functional (behavioral) deficits poorly restored by naturally occurring 1-2 mm/d axonal outgrowths aided by primary repair or reconstruction. "Neurorrhaphy" or nerve repair joins severed connective tissues, but not severed cytoplasmic/plasmalemmal extensions (axons) within the tissue. NEW METHOD: PEG-fusion consists of neurorrhaphy combined with a well-defined sequence of four pharmaceutical agents in solution, one containing polyethylene glycol (PEG), applied directly to closely apposed viable ends of severed axons. RESULTS: PEG-fusion of rat sciatic nerves: (1) restores axonal continuity across coaptation site(s) within minutes, (2) prevents Wallerian degeneration of many distal severed axons, (3) preserves neuromuscular junctions, (4) prevents target muscle atrophy, (5) produces rapid and improved recovery of voluntary behaviors compared with neurorrhaphy alone, and (6) PEG-fused allografts are not rejected, despite no tissue-matching nor immunosuppression. COMPARISON WITH EXISTING METHODS: If PEG-fusion protocols are not correctly executed, the results are similar to that of neurorrhaphy alone: (1) axonal continuity across coaptation site(s) is not re-established, (2) Wallerian degeneration of all distal severed axons rapidly occurs, (3) neuromuscular junctions are non-functional, (4) target muscle atrophy begins within weeks, (5) recovery of voluntary behavior occurs, if ever, after months to levels well-below that observed in unoperated animals, and (6) allografts are either rejected or not well-accepted. CONCLUSION: PEG-fusion produces rapid and dramatic recovery of function following rat peripheral nerve injuries.

Asunto(s)

RESUMEN

Reconstruction of joint-crossing digital nerves requires the application of nerve guides with a much higher flexibility than used for peripheral nerve repair along larger bones. Nevertheless, collapse-resistance should be preserved to avoid secondary damage to the regrowing nerve tissue. In recent years, we presented chitosan nerve guides (CNGs) to be highly supportive for the regeneration of critical gap length peripheral nerve defects in the rat. Now, we evidently increased the bendability of regular CNGs (regCNGs) by developing a wavy wall structure, that is, corrugated CNGs (corrCNGs). In a comprehensive in vivo study, we compared both types of CNGs with clinical gold standard autologous nerve grafts (ANGs) and muscle-in-vein grafts (MVGs) that have recently been highlighted in the literature as a suitable alternative to ANGs. We reconstructed rat sciatic nerves over a critical gap length of 15 mm either immediately upon transection or after a delay period of 45 days. Electrodiagnostic measurements were applied to monitor functional motor recovery at 60, 90, 120, and 150 (only delayed repair) days postreconstruction. Upon explanation, tube properties were analyzed. Furthermore, distal nerve ends were evaluated using histomorphometry, while connective tissue specimens were subjected to immunohistological stainings. After 120 days (acute repair) or 150 days (delayed repair), respectively, compression-stability of regCNGs was slightly increased while it remained stable in corrCNGs. In both substudies, regCNGs and corrCNGs supported functional recovery of distal plantar muscles in a similar way and to a greater extent when compared with MVGs, while ANGs demonstrated the best support of regeneration. Anat Rec, 301:1697-1713, 2018. © 2018 Wiley Periodicals, Inc.

Asunto(s)

RESUMEN

BACKGROUND: The aim of this study was to assess the effect of seeding the distal nerve suture with nerve fragments in rats. METHODS: On 20 rats, a 15 mm sciatic nerve defect was reconstructed with a nerve autograft. In the Study Group (10 rats), a minced 1 mm nerve segment was seeded around the nerve suture. In the Control Group (10 rats), a nerve graft alone was used. At 4 and 12 weeks, a walking track analysis with open field test (WTA), hystomorphometry (number of myelinated fibers (n), fiber density (FD) and fiber area (FA) and soleus and gastrocnemius muscle weight ratios (MWR) were evaluated. The Student t-test was used for statistical analysis. RESULTS: At 4 and 12 weeks the Study Group had a significantly higher n and FD (p = .043 and .033). The SMWR was significantly higher in the Study Group at 12 weeks (p = .0207). CONCLUSIONS: Seeding the distal nerve suture with nerve fragments increases the number of myelinated fibers, the FD and the SMWR. The technique seems promising and deserves further investigation to clarify the mechanisms involved and its functional effects.

Asunto(s)

RESUMEN

The rat sciatic nerve has attracted widespread attention as an excellent model system for studying autophagy alterations in peripheral neuropathies. In our laboratory, we have developed an original rat model, which we used currently in routine novel drug screening and to evaluate treatment strategies for chronic inflammatory demyelinating polyneuropathy (CIDP) and other closely related diseases. Lewis rats injected with the S-palmitoylated P0(180-199) peptide develop a chronic, sometimes relapsing-remitting type of disease. Our model fulfills electrophysiological criteria of demyelination with axonal degeneration, confirmed by immunohistopathology and several typical features of CIDP. We have set up a series of techniques that led us to examine the failures of autophagy pathways in the sciatic nerve of these model rats and to follow the possible improvement of these defects after treatment. Based on these newly introduced methods, a novel area of investigation is now open and will allow us to more thoroughly examine important features of certain autophagy pathways occurring in sciatic nerves.

RESUMEN

Investigating the effect of four types of artificial nerve graft (ANG) structures on rat sciatic nerve defect repair will aid future ANG designs. In this study, fibroin fibers and polylactic acid were used to prepare four ANGs with differing structures: nerve conduit with micron-sized pores (Conduit with pore group), nerve conduit without micron-sized pores (Conduit group), nerve scaffold comprising Conduit with pore group material plus silk fibers (Scaffold with pore group), and nerve scaffold comprising Conduit group material plus silk fibers (Scaffold group). ANGs or autologous nerves (Autologous group) were implanted into 10 mm rat sciatic nerve defects (n = 50 per group). Twenty weeks after nerve grafting, the time required to retract the surgical limb from the hot water was ranked as follows: Conduit with pore group > Scaffold with pore group > Conduit group > Scaffold group > Autologous group. The static sciatic index was ranked in descending order: Autologous group > Scaffold group > Conduit group > Scaffold with pore group > Conduit with pore group. Immunofluorescence staining identified significant differences in the distribution and number of axons, Schwann cells, and fibroblasts. These findings indicate that ANGs with micron-sized pores had a negative impact on the repair of peripheral nerve defects, while internal microchannels were beneficial. © 2017 The Authors. Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3077-3085, 2017.

Asunto(s)

RESUMEN

The present study seeks to systematize morphological and morphometrical parameters and brings new data on the main branch of the lumbosacral plexus ­ i.e., sciatic nerve ­ in Wistar rats aged four and seven weeks. Sixteen female were divided into two groups, namely animals aged four weeks, and animals aged seven weeks. The specimens were studied at proximal and distal segments of the right hind limb sciatic nerves. Semi-thin transverse sections (0.25 µm thickness) were stained with 1 % toluidine blue, and the morphometric analysis was processed through the KS 400 software. Except for the number of fascicles and fascicular diameter, no differences were found between the proximal and distal segments. We observed differences when morphometric values were compared between 4- and 7- week old animals, with some exceptions (number of fascicles and myelinated fibers, and capillary area and number). The macroscopic data disagree with a previous description of the sciatic nerve being composed by two fascicles. Instead, sciatic nerve's only fascicle trifurcates or quadrifurcates at the distal third of the thigh. The total capillary area and density were calculated, and these are the first referential data for the sciatic nerve. Histograms of myelinated fiber and axons considering the animal ages were built. The results presented here are important because experimental studies, mainly studies on nerve regenerations require comparison with normal reliable data.

El objetivo fue sistematizar los parámetros morfológicos y morfométricos y traer nuevos datos sobre el ramo principal del plexo lumbosacro - es decir nervio ciático - en ratas Wistar de 4 a 7 semanas. Dieciséis ratas fueron divididas en dos grupos, con 4 y 7 semanas de edad. Las muestras estudiadas fueron los segmentos proximal y distal del nervio ciático derecho. Secciones delgadas (espesor 0,25 mm) fueron teñidas con azul de toluidina al 1 % y el análisis morfométrico se llevó a cabo utilizando el programa KS 400. Excepto para el número de fascículos y diámetro fascicular, no se encontraron diferencias entre los segmentos proximal y distal. Fueron observadas diferencias cuando se compararon los valores morfométricos entre animales de 4 y 7 semanas, con algunas excepciones (número de fascículos y fibras mielinizadas, área y número de capilares). Los datos macroscópicos no están de acuerdo con la descripción anterior del nervio ciático siendo compuesto por dos fascículos. En cambio, sólo trifurcación o cuadrifurcación fueron encontrados en el tercio distal del muslo. El área total capilar y la densidad fueron calculadas y estos constituyen los primeros datos de referencia para el nervio ciático. Se construyeron histogramas de fibras mielínicas y axones, teniendo en cuenta las edades de los animales. Los resultados presentados aquí son importantes porque los estudios experimentales, en especial aquellos sobre la regeneración nerviosa, requieren comparación con datos confiables normales.

Asunto(s)

RESUMEN

This study proposes the use of a porous polyethylene (PPE) tube as the conductive element in the regeneration in the sciatic nerve sectioning and evaluates the use of fill with autologous fat. The subject was divided randomly into five groups, 3 control and 2 experimental (PPE tube graft with/ without autologous fat). Each group was selected for functional, histological and morphometric evaluation of the sciatic nerve. Functional analysis of the sciatic nerve occurred through the "footprint" values near -100 refer sectioned sciatic nerve, near 0 (zero) refer to control group. On histological analysis of the experimental groups lots of dense connective tissue replacing nerve tissue was observed. In morphometric analysis the group EGPGf got higher performance in all of variables. The use of PPE has shown promise in nerve regeneration with favorable results when associate with fat as a trophic factor in the regeneration.

Este estudio propone el uso de un tubo de polietileno poroso (PPE) como elemento conductor en la regeneración del nervio ciático seccionado y evaluar el uso de relleno con grasa autóloga. Al azar se formaron cinco grupos, 3 y 2 de control experimental (PPE prótesis tubular con / sin grasa autóloga). Cada grupo fue seleccionado para estudiar la forma funcional, histológica y evaluación morfométrica del nervio ciático. Un análisis funcional del nervio ciático se produjo a través de los valores de "huella", cerca de -100 se refiere al nervio ciático seccionado; cerca de 0 (cero) se refiere al grupo control. En el análisis histológico de los grupos experimentales se observó una gran cantidad de tejido conjuntivo denso que sustituye el tejido nervioso. En el análisis morfométrico, el grupo experimental de injerto de polietileno lleno de grasa (EGPGf) obtuvo un mayor rendimiento en todas las variables. El uso de PPE ha mostrado ser prometedor en la regeneración del nervio, con resultados favorables cuando se asocia con la grasa como un factor trófico en la regeneración.

Asunto(s)