Intraneural IFG-1 in Cryopreserved Nerve Isografts Increase Neural Regeneration and Functional Recovery in the Rat Sciatic Nerve.

BACKGROUND: Insulin-like growth factor 1 (IGF-1) was found to stimulate Schwann cell mitosis. Exogenous IGF-1 may improve nerve regeneration after cryopreservation. OBJECTIVE: To evaulate the effect of intraneural administration of IGF-1 in cryopreserved nerve isografts. METHODS: Eighteen millimeter grafts were used for bridging an 18-mm defect in the rat sciatic nerve. A total of 57 rats were randomly divided into three groups: (1) autograft (Group 1); (2) cryopreserved isograft (Group 2); (3) cryopreserved isograft with intraneural IGF-1 administration (Group 3). 12 weeks after surgery, functional recovery (Sciatic functional index [SFI], Swing speed [SS], nerve conduction velocity [NCV], amplitude of compound motor action potentials [CMAP], and gastrocnemius muscle index [GMI]) and nerve regeneration (myelin sheath area, total fiber counts, fiber density, and fiber width) were all evaluated. RESULTS: The intraneural injection of IGF-1 significantly improved SFI and SS at weeks 10 and 12. There were no statistical differences between Groups 1 and 3 in any of the SFI or SS evaluations. CMAP and NCV in Group 1 were significantly higher than in Groups 2 and 3, and Group 3 had significantly higher CMAP and NCV compared to Group 2. No significant differences were found in fiber width. The number of nerve fibers, percentage of myelinated fibers, fiber density, and GMI was significantly higher in Group 1 compared to Group 2, but no significant differences were found between Groups 1 and 3. CONCLUSION: The results show that intraneural injection of IGF-1 in an 18 mm cryopreserved isograft improve axonal regeneration and functional recovery.

Revisión de casos de schwannoma en la Unidad de Miembro Superior del Servicio de Cirugía Plástica de La Coruña, España / Case review of schwannoma at the Superior Member Unit, La Coruña Plastic Surgery Service, Spain

Introducción y Objetivo: Los tumores derivados de las células de Schwann (schwannomas, neurinomas o neurilemomas) son los más frecuentes de los dependientes de tejido nervioso en el miembro superior. Frecuentemente se confunden con tumores de otra índole, principalmente con los derivados de tejido adiposo o lipomas. Aunque pueden compartir algunas características clínicas, existen ciertos síntomas específicos de los schwannomas que sugieren su diagnóstico y permiten realizar el tratamiento adecuado. En algunos casos, son necesarias técnicas microquirúrgicas para su extirpación y posterior reparación del nervio afectado. El presente trabajo pretende realizar una evaluación epidemiológica en nuestro medio, mediante revisión retrospectiva de casos, teniendo en cuenta la presentación clínica, el diagnóstico, el tratamiento y la evolución presentada tras el tratamiento mediante la existencia o no de secuelas. Material y Método: Revisamos retrospectivamente 10 casos de schwannoma en miembro superior recogidos en el Servicio de Cirugía Plástica de La Coruña (España) a lo largo de 4 años. Evaluamos la edad, género, localización, signos clínicos, estudios electrofisiológicos, imágenes, tratamiento, seguimiento y secuelas. Realizamos el análisis mediante tablas comparativo-descriptivas. Resultados: El 60% de la muestra fueron varones, con edad media de 47.5 años. El nervio mediano fue el más frecuentemente afectado. El dolor local y las parestesias los síntomas más frecuentes, con Tinel positivo en el 90% de los casos. El 30% de los pacientes presentó bloqueo nervioso (motor/sensitivo) en la electrofisiología y 2 casos discontinuidad del nervio. La escisión microquirúrgica bajo magnificación óptica fue el tratamiento de elección en el 80% de los casos; 20% necesitaron injerto de nervio sural para la reparación del nervio afectado. Con un seguimiento medio de 12 meses, el 80% de los casos no presentó secuelas tras el tratamiento. Conclusiones: Los schwannomas suelen producir poca sintomatología y cuando lo hacen, la clínica suele ser local. Su origen más frecuente en nuestra serie fue el nervio mediano. El diagnóstico adecuado exige sospecha clínica y confirmación mediante resonancia magnética. Los tumores mal delimitados pueden incluir pequeños fascículos nerviosos que, a pesar de la magnificación óptica, resulta imposible identificar y conservar. En la medida de lo técnicamente posible se deben respetar los fascículos sanos, o en su defecto, reconstruir el fascículo nervioso para restablecer su continuidad

Background and Objective: Tumors derived from Schwann cells (schwannomas, neurinomas or neurilemomas) are the most frequently nervous tissue tumors of the upper limb. They usually get confused with other kind of tumors, mainly those derived from adipose tissue also call lipomas. Although they may share some clinical characteristics, there are certainly some specific symptoms in schwannomas that allow making a correct differential diagnosis. In some cases, microsurgical techniques are necessary for its removal and subsequent reconstruction of the affected nerve. The present study carries out a retrospective epidemiological review of a series of cases in our center, considering the clinical presentation, diagnosis, treatment and the outcomes in terms of the presence or absence of sequelae. Methods: We retrospectively reviewed 10 cases of schwannoma in the upper member collected in the Plastic Surgery Service of La Coruña (Spain) over the last 4 years. We describe age, gender, location, clinical signs, electrophysiological studies, images, treatment, follow-up and sequelae. We perform the analysis using comparative-descriptive tables. Results: Sixty percent of the sample were men, the median age was 47.5 years, and the median nerve was the most frequently affected. Local pain and paresthesias were the most frequent symptoms, with Tinel sign in 90% of the cases. Thirty percent of patients had nerve block (motor / sensitive) in electrophysiology study. Two cases presented discontinuity of the nerve. The microsurgical excision under optical magnification was the choice for treatment in 80% of the cases and 20% needed a sural nerve graft for repairing the affected nerve. With a mean follow-up of 12 months, 80% of the cases did not present sequelae after treatment. Conclusions: Schwannomas usually produce limited symptomatology and when they do, are oftenly local symptoms. The most frequent origin was the median nerve. The adequate diagnosis requires clinical suspicion and confirmation by magnetic resonance. Those ill-defined tumors may include small nerve fascicles that, despite of optical magnification, are impossible to identify and preserve. As far as it is technically possible, healthy fascicles should be respected or if not, reconstructed to restore its continuity

The addition of albumin improves Schwann cells viability in nerve cryopreservation.

The purpose of the current study was to establish a valid protocol for nerve cryopreservation, and to evaluate if the addition of albumin supposed any advantage in the procedure. We compared a traditional cryopreservation method that uses dimethyl sulfoxide (DMSO) as cryoprotectant, to an alternative method that uses DMSO and albumin. Six Wistar Lewis rats were used to obtain twelve 20 mm fragments of sciatic nerve. In the first group, six fragments were cryopreserved in 199 media with 10% DMSO, with a temperature decreasing rate of 1 °C per minute. In the second group, six fragments were cryopreserved adding 4% human albumin. The unfreezing process consisted of sequential washings with saline in the first group, and saline and 20% albumin in the second group at 37 °C until the crioprotectant was removed. Structural evaluation was performed through histological analysis and electronic microscopy. The viability was assessed with the calcein-AM (CAM) and 4',6-diamino-2-fenilindol (DAPI) staining. Histological results showed a correct preservation of peripheral nerve architecture and no significant differences were found between the two groups. However, Schwann cells viability showed in the CAM-DAPI staining was significantly superior in the albumin group. The viability of Schwann cells was significantly increased when albumin was added to the nerve cryopreservation protocol. However, no significant structural differences were found between groups. Further studies need to be performed to assess the cryopreserved nerve functionality using this new method.