循环牵张应力对组织工程化周围神经功能恢复的影响

The effects of cyclic tensile strain on functional recovery of tissue-engineered nerve grafts

目的 通过应用组织工程化周围神经修复兔坐骨神经缺损,研究循环牵张应力对组织工程化周围神经功能恢复的影响.方法 采用低渗联合冻干改良化学萃取法制备同种异体脱细胞神经支架并与雪旺细胞复合,分别施加0％、5％、10％及15％形变量、频率0.25 Hz的周期性循环牵张微应变刺激3h.将其植入周围神经缺损动物模型体内,修复神经缺损.于术后4、8周超声观察支架在体内缝合口的生长情况.8周时行神经电生理检查,计算神经传导速度,并计算腓肠肌湿重比.结果 四种形变量刺激的支架超声长轴图像可见缝合口处神经外膜平滑延续,无离断;短轴图像显示神经纤维束结构清晰完整.神经电生理检查结果显示10％形变量神经传导速度明显高于其余三种形变量组,且0％、5％、15％组可见低电压、多相电位的新生电位,10％组可见短时程、高波幅的再生电位.10％组双侧腓肠肌湿重比明显高于其余三种形变量组.结论 适当形变量的循环牵张应力可明显促进组织工程化周围神经的功能恢复.

Objective To investigate the effects of cyclic tensile strain on functional recovery of tissueengineered nerve gratis in rabbits.Methods The traditional chemically decellularized nerve scaffolds were improved by the technique of hypotonic buffer combined with freeze-drying.Then Schwann cells （SCs） were seeded into the scaffolds and cultured for a week.The scaffolds were stimulated continuously for 3 hours by cyclic tensile strain at a frequency of 0.25Hz and gradient of deformations of 0%,5%,10% and 15%.After cychc tensile strain stimulation the 1cm long SCs-scaffold composites were used to repair sciatic nerve defects in rabbits.The growth of SCs-scaffold composites was observed with ultrasound at 4 and 8 weeks postoperatively.Neurophysiological examination was carried out at 8 weeks to calculate nerve conduction velocity （NCV）.Muscle wet weight recovery of the gastrocnemius was also calculated to assess functional recovery.Results Ultrasound images of the long axis of the grafted nerve scaffolds revealed smooth and continuous epinettrium at the coaptation sites in all four deformation groups.Short axis image showed clear and complete structures of nerve fascicles.NCV of the 10% deformation group was significantly higher than that of the other three deformation groups.Low amphtude and multiphasic nascent potentials were seen in 0 %,5 % and 15 % deformation groups.Regeneration potentials of short duration and high amplitude were recorded in the 10% deformation group.The wet muscle weight recovery rate of the gastrocnemius in the 10% deformation group was significantly higher than that in the other three deformation groups.Conclusion Applying cyclic tensile strain with appropriate deformation to tissue-engineered nerve scaffold can significantly promote the functional recovery of the nerve repaired by the scaffold.