The Estblishment Of Two New Technology Of Promoting Nerve Regeneration And The Research Of Related Mechanism

Peripheral nervous system (PNS) connects thecentralnervous system(CNS) and thetarget organ,makes the body be dominated accurately by the brain and spinal cord. Thetreatment of PNS injury, especially lengthy peripheral nerve defects is still a greatchallenge in the field of regenerative medicine. Although autologous nerve graft is still thegolden standard of to bridge the nerve gap. However, autograft transplantation is limitedby donor nerve availability and postoperative complications of donor sites. As the rapidlydevelopment of the tissue engineering, many artificial nerve scaffolds have beendeveloped to bridge lengthy nerve defect, and has been shown to partially restore nerveregeneration by providing guiding cues for regenerating axons. Because of the differencesbetween the artificial grafts and normal nerve and the lack of stimulating factors, it alwayslimits nerve regeneration and functional recovery after nerve injury. Therefore, it’s crucialto establish and regulate the suitable microenvironment. To further promote axonal regeneration, many supportive cells have been introduced to nerve scaffolds to establish abeneficial local micro-environment for regenerating axons at the site of nerve defect,which holds great potential to replace nerve autograft in repairing nerve defect. However,there is no strategy which is capable of overcoming the hypoxic status within cell-basednerve scaffolds. In addition, it’s reported that pulsed electromagnetic fields can enhancenerve regenertion after the PNS injury. But there is no study of using chronotherapy tomake the PEMFs promoting the nerve regeneration more effective. establishing themicroenvironment. The purpose of this study is to investigate the effects of establishingthe microenvironment after nerve regeneration.The whole studies were divided into twoparts:Part IA synthetic oxygen carrier-olfactory ensheathing cell compositionsystem for the promotion of sciatic nerve regenerationBackgrounds：As the key factors of promoting the nerve regeneration, functional seed cells andgrowth factors support the nutrient for the regenerated nerve. However, low oxygensupply was found within nerve scaffolds after their implantation in vivo, which has beenshown to result in death or loss of function of supportive cells, and significantly limitsnerve regeneration and functional recovery after nerve injury repair. Therefore, thestrategy which is capable of overcoming the hypoxic status within nerve scaffolds holdsgreat potential to improve the efficacy of cell-based nerve scaffolds in promoting nerveregeneration and functional recovery.Objectives:Investigate the effect of the synthetic oxygen carrier-olfactory ensheathing cellcomposition system promoting the sciatic nerve regeneration.Methods: Preparing a―PFTBA-OECs‖enriched fibrin hydrogel, which was injected into acollagen-chitosan nerve scaffold uniformly. Then the nerve conduits were used to bridge a 15-mm-long sciatic nerve defect in rats. The viability and distribution of OECs withinscaffolds after surgery were examined by GFP labeling. The effect of―PFTBA-OECs‖conduits on axonal regeneration and functional recovery was evaluated by bothmorphological analysis and functional assessments.Result:These findings indicate that both PFTBA and OECs could independently promoteaxonal regeneration and motor functional recovery of sciatic nerve after injury. In addition,our study also showed that the PFTBA significantly increased the number ofGFP-expressing OECs in the experiment group, which showed comparable axonalregeneration and functional recovery to that in the autograft group.Conclusion: The PFTBA within OECs/fibrin matrix is capable of improving the survivalof OECs under the hypoxic environment in the early stage of implantation, which mightcontribute, at least in part, to the beneficial effect of―PFTBA-OECs‖combination onnerve regeneration.Part II The chronotheraputic of promoting peripheral nerveregeneration by pulsed electromagnetic fieldsBackgrounds：Electromagnetic environment plays an important role in peripheral nerve regeneration.A suitable microenvironment can not only accelerate the nerve regeneration, but enhancethe quality of it. Chronotheraputic, as a newly-developing concept, is widely used inmedical treatment. But there is still no related research about the chronotheraputic ofbridging the nerve gap by pulsed electromagnetic fields.Objectives:Investigate the effect of chronotheraputic of enhance the nerve regeneration by PEMFsafter peripheral nerve injury. Methods: Preparing the collagen-chitosan nerve conduits, use it to bridge a10-mm-longsciatic nerve defect in rats. Then the rats of experiment group are exposured to PEMFs ofcertain parameters at9:00AM-11:00AMand9:00PM-11:00PM, respectively. The effect ofaxonal regeneration and functional recovery was evaluated by both morphological analysisand functional assessments.Result:The effect of the groups which are exposured to PEMFs is better than the controlgroup which not exposured to PEMFs. In addition, the group of day-time exposure showsbetter stimulus effcacycompared with the group of night-time exposure.Conclusion:These findings indicate that PEMFs could promote axonal regeneration and motorfunctional recovery of sciatic nerve after injury. The effect of chronotheraputic raises theeffcacy of the treament.Some scientists reported rats and human show diametricallyopposite sleep-wake cycles and rhythm patterns of the inner physiological activities.Therefore, a better preventive effect in human might be achieved during the nighttimewhen the bone turnover is remarkably higher.