Study On Drug Delivery System Of Nerve Repair With Electrical Stimulation And Angiogenesis

To date,peripheral nerve injury（PNI）is still a serious problem in the international neuromedicine community.In view of the traditional clinical neurosurgical treatment methods such as autologous nerve catheter transplantation,there are often surgical problems such as difficulty in donor source,scar hyperplasia in the vascular area,nerve tumor formation,motor functional dysfunction,etc.And nerve catheter is favored by the majority of nerve repair researchers because of its combination of biology,medicine,materials science and other disciplines and it can effectively protect nerve defects and effectively release drug factors.The ideal nerve catheter should have the characteristics of being able to load drug factors,have excellent drug-loading and releasing performance,have a suitable space structure,sufficient mechanical properties and good biocompatibility.At present,there is no recognized nerve catheter that can completely to meet the needs.For this problem,the subject intends to construct a double-layer stent nerve catheter to meet the needs of nerve repairing.The inner stent is loaded with drug factors,and the outer stent is loaded with conductive substances to cooperate with bioelectrical stimulation to repair nerve damage.Preparing of gelatin（GLT）-chitosan（CS）drug-loaded by vacuum freeze-drying technology and load release of vascular endothelial growth factor（VEGF）to obtain different volume ratios of GLT/CS/VEGF;Screen out the most suitable ratio of GLT/CS/VEGF through various characterizations;the nanofibers use GLT/CS/VEGF as the receiver to spin the Poly-DL-lactide（PDLLA）/graphene oxide（GO）on the outer surface by electrostatic spinning technology to obtain the nerve repair drug loading system GLT/CS/PDLLA/GO/VEGF（hereinafter abbreviated as GCP/GO/VEGF）with electrical stimulation and angiogenesis GO/VEGF,the most suitable GCP/GO/VEGF conditions were screened through various characterizations,and the drug loading system was investigated through cell and animal experiments,with a view to synergistic treatment of peripheral nerves in many ways damage.This includes:First,the preparation of GLT/CS/VEGF was completed by vacuum freeze-drying technology.GLT/CS/VEGF was characterized and analyzed in terms of mechanical properties,porosity,microstructure,drug loading rate,etc.,and GLT/CS was selected.The optimal condition of/VEGF is that the mass ratio of GLT to CS is 1:1,and then the lyophilized GLT/CS/VEGF inner tube is used as the outer layer of the receiver for PDLLA/GO electrospinning to obtain the drug loading system GCP/GO/VEGF,comprehensive micro-morphology,mechanical properties,electrical conductivity and water contact angle and other indicators have determined that the best conditions for GCP/GO/VEGF are that the mass fraction of GO is 5%and the concentration of PDLLA is 10%.At this time,GCP/GO/VEGF has a tensile strength of4.33±0.26MPa,a conductivity of 0.78±0.08×10^-3 s/cm,and a water contact angle of71.5±0.23°,which meets the needs of the experiment.Secondly,the degradation performance and drug-loading performance of the nerve repair drug-loading system after molding were investigated.Through the measurement of changes in the amount of drug release from the degradation solution of the neural catheter stent at various time points during drug degradation,the changes in p H,quality,morphology and structure were investigated.The results showed that GCP/GO/VEGF had GLT/CS/VEGF’s drug loading characteristics,the drug loading rate reaches 69.3±3.1%,and the effective sustained release rate can reach 70.56±2.56%within 24 hours.It also has the advantage of PDLLA/GO and can maintain the weightlessness rate at 27.55±2.4 within 12 weeks The p H value of the sustained-release solution is maintained at 7.19±0.025 to be neutral,and the basic structure can be maintained after 12 weeks of degradation to meet the needs of fully stable drug loading and controllable easy degradation in the experimental design.Then,select Schwann cells（RSC96）and adrenal pheochromocytoma cells（PC12cells）to carry out cell experiments with different experimental group drug-loading systems,and examine the cytotoxicity and cell proliferation of each experimental group by CCK-8 detection of cell OD value Rate to evaluate the effect of each experimental group on the growth rate of various cells.Compare the effects of different neural catheter stents on cell growth under external electrical stimulation.The results show that the nerve catheter does not show cytotoxicity under electrical stimulation,and can effectively promote the growth of nerve cells under the synergistic effect of appropriate electrical stimulation.Finally,the SD rat sciatic nerve defect repair test was selected.Corresponding to the experimental requirements,the corresponding rat sciatic nerve injury model was established,and various criteria of the sciatic nerve of SD rats implanted with nerve catheters 1 and 3 months after the operation were investigated,and the repair effects of different nerve catheters on rat sciatic nerve injury were evaluated.Gait analysis and muscle nerve index results show that the GCP/GO/VEGF drug-loading system can effectively promote the repair of peripheral nerve injury.The above shows that the drug-loading system GCP/GO/VEGF has good VEGF release performance,can provide sufficient protection and support for nerves,and at the same time,synergistic electrical stimulation can effectively promote peripheral nerve regeneration,repair peripheral nerve damage and VEGF in nerve conduits The application field has good development potential and application prospects.