RESUMEN
When not enough conventional autologous nerve grafts are available, alternatives are needed to bridge nerve defects. Our aim was to study regeneration of nerves in chemically-extracted acellular nerve grafts from frogs, mice, humans (fresh and stored sural nerve), pigs and rats when defects in rat sciatic nerves were bridged. Secondly, we compared two different extraction procedures (techniques described by Sondell et al. and Hudson et al.) with respect to how efficiently they supported axonal outgrowth, and remaining laminin and myelin basic protein (MBP), after extraction. Isografts (rat) and xenografts (mouse) were transplanted into defects in rat sciatic nerves. Acellular nerve allografts from rats, extracted by the Sondell et al's technique, had an appreciably longer axonal outgrowth based on immunohistochemical staining of neurofilaments, than acellular nerve xenografts except those from the pig. Among acellular xenografts there was considerably longer axonal outgrowth in the grafts from pigs compared with those from humans (fresh), but there were no other differences among the xenografts with respect to axonal outgrowth. Axonal outgrowth in acellular nerve xenografts from mice, extracted by the method described by Sondell et al. was longer than in those extracted by Hudson et al's method, while there was no difference in outgrowth between extracted nerve isografts from rats. Electrophoretic analysis of extracted acellular nerve grafts showed remaining laminin, but not MBP, after both extraction procedures. These preserved laminin and removed MBP in acellular nerve grafts. Such grafts can be used to reconstruct short defects in nerves irrespective of their origin. However, selecting and matching a suitable combination of graft and host species may improve axonal outgrowth.
Asunto(s)
Regeneración Nerviosa/fisiología , Nervios Periféricos/fisiología , Nervios Periféricos/trasplante , Animales , Anuros , Axones/trasplante , Western Blotting , Electroforesis , Femenino , Rechazo de Injerto , Supervivencia de Injerto , Humanos , Ratones , Ratones Endogámicos , Modelos Animales , Distribución Aleatoria , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Especificidad de la Especie , Estadísticas no Paramétricas , Recolección de Tejidos y Órganos/métodos , Trasplante Heterólogo/métodos , Trasplante Homólogo/métodos , Trasplante Isogénico/métodosRESUMEN
Costimulation blockade can prevent rejection of nerve allografts in short-term studies. We tested if costimulation blockade also prevented rejection of nerve allografts in long-term experiments, thereby improving functional recovery. A 7-mm sciatic nerve defect in C57/BL6 mice was bridged either by nerve allografts from Balb/C mice or by isogenic nerve grafts (isografts) from C57/BL6 mice. Costimulation blockade in the form of a triple treatment with anti-LFA-1, anti-CD40L, and CTLA4Ig was given at post-operative days 0, 2, 4, and 6 (intraperitoneal). Control mice (placebo; allografts) with nerve grafts were treated with isotype antibodies during the same time period. After 49 days, tetanic muscle force, wet weight of gastrocnemius muscle, histology, and morphometry in the tibial nerve were evaluated. Costimulation blockade diminished rejection of the nerve allografts. Axons bridged the graft. Treatment increased wet weight of the gastrocnemius muscle and resulted in a higher mean myelin area/nerve fiber in the tibial nerve distal to the nerve grafts. Tetanic muscle force and number of axons in tibial nerve showed no differences between groups. We conclude that rejection is suppressed by costimulation blockade. Treatment improves recovery of target muscle and myelination after nerve allografting.
Asunto(s)
Rechazo de Injerto/prevención & control , Inmunosupresores/uso terapéutico , Regeneración Nerviosa/efectos de los fármacos , Nervio Ciático/trasplante , Linfocitos T/efectos de los fármacos , Abatacept , Animales , Anticuerpos/uso terapéutico , Ligando de CD40/antagonistas & inhibidores , Femenino , Inmunoconjugados/uso terapéutico , Antígeno-1 Asociado a Función de Linfocito/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Músculo Esquelético/inervación , Recuperación de la Función/efectos de los fármacos , Nervio Ciático/efectos de los fármacos , Trasplante Homólogo , Trasplante IsogénicoRESUMEN
The aim of this study was to investigate if costimulation blockade could be used to modulate the immune response, to prevent rejection, and to stimulate regeneration into nerve allografts. Nerve allografts from Balb/C mice, and isogenic nerve grafts (isografts) from C57/BL6 mice, were used to bridge a 7-mm gap of the sciatic nerve in C57/BL6 mice. Allograft recipients were treated with either a triple treatment with anti-lymphocyte function antigen-1 (anti-LFA), anti-CD40 ligand (anti-CD40L), and cytotoxic T-lymphocyte antigen 4 immunoglobulin (anti-CTLA4Ig) or isotype antibodies (placebo) at postoperative days 0, 2, 4, and 6 (intraperitoneal). After 5 or 9 days, the nerve grafts, together with the proximal and the distal nerve segments, were evaluated by histology and immunocytochemistry for inflammatory cells [CD4-positive (CD4+) and CD8-positive (CD8+) staining cells] and axonal outgrowth (neurofilaments). The immune response was inhibited by costimulation blockade with less extensive inflammation and a lower number of CD4+ staining cells in triple-treated allografts at 9 days. The regeneration rate was significantly faster in isografts (0.75 mm/day) compared with allografts with placebo treatment (0.39 mm/day), but not when compared with triple-treated allografts (0.49 mm/day). At 9 days, the axons were significantly longer in nerve isografts than in nerve allografts, irrespective of treatment. Hence, costimulation blockade neither increased the regeneration rate nor the outgrowth length in triple-treated allografts. We conclude that costimulation blockade inhibits the immune response in nerve allografts without deterring early axonal outgrowth.
Asunto(s)
Anticuerpos/uso terapéutico , Rechazo de Injerto/prevención & control , Regeneración Nerviosa/efectos de los fármacos , Nervio Ciático/trasplante , Tolerancia al Trasplante/efectos de los fármacos , Abatacept , Animales , Linfocitos T CD4-Positivos/inmunología , Ligando de CD40/antagonistas & inhibidores , Ligando de CD40/inmunología , Linfocitos T CD8-positivos/inmunología , Femenino , Inmunoconjugados/inmunología , Inmunoconjugados/metabolismo , Inmunohistoquímica , Antígeno-1 Asociado a Función de Linfocito/inmunología , Antígeno-1 Asociado a Función de Linfocito/metabolismo , Ratones , Regeneración Nerviosa/inmunología , Nervio Ciático/efectos de los fármacos , Nervio Ciático/lesiones , Trasplante HomólogoRESUMEN
Effects of FK506 [5.0 mg/kg body weight (BW), subcutaneous, daily] on nerve regeneration and presence of macrophages in lesioned rat sciatic nerves were studied. Models of autologous nerve graft or a nerve crush lesion were used and regeneration was evaluated by immunocytochemistry (also used to detect ED1/ED2 macrophages) and sensory pinch reflex test, respectively. Treatment with FK506 did not increase regeneration distance or regeneration rate in the autologous nerve grafts. However, regeneration distances after nerve crush were significantly longer following treatment with FK506. The number of macrophages (ED1/ED2) in nerve grafts increased over time, but treatment with FK506 had limited effects only in the presence of ED2 macrophages. Present and previously published studies may imply that there is a time-related and type-of-injury-related profile of FK506's pro-regenerative effect.