Construction Of Polycaprolactone/Chitosan Nerve Guidance Conduits With Multiple Channels And Repair Of Sciatic Nerve Injury In Rats

Peripheral nerve injuries(PNI)can be easily caused by traffic accidents,trauma,tumor resection and other traumatic diseases.When the distance of peripheral nerve injury is short(< 5 mm),the body can self-repair,but when the distance is long,human intervention is needed,if it cannot be repaired in time and effectively,it would lead to sensory dysfunction,dyskinesia and even affect the normal life of the patient.With the deepening of research,the material of biodegradable artificial nerve guidance conduits(NGCs)has become a research hotspot in the field of peripheral nerve injury repair.However,most of the NGCs currently studied are single-channel structures(hollow conduits),which are prone to collapse in actual application due to the lack of internal support.At present,although some scholars have studied multi-channel NGCs,limited by the small diameter(?3 mm)of the conduits,multichannel neural catheters have few channels(?6)and no bionic structure.In addition,the microporous structure of NGCs has a great influence on the effect of nerve repair,but there are few relevant studies.Based on this,this research used polycaprolactone(PCL)and chitosan(CS)as raw material,through independent design of multi-channel mold,with the mold-freeze drying preparation to create a new type of PCL/CS multi-channel NGC,combined with the properties characterization in vivo and vitro,and evaluated the effect of the catheter on the regeneration and repair of rat sciatic nerve defects.In this paper,the PCL/CS blend material was prepared and its microstructure was regulated.The optimal microporous structure for cell growth was determined by optimizing the blending process parameters.Then,PCL/CS multi-channel NGC,PCL/CS multi-channel and PCL/CS hollow NGC(control study)were prepared by independently designed molds,and necessary physicochemical and biological properties were characterized.Finally,to evaluate the potential of NGC in peripheral nerve injury,we implanted them into rats for sciatic nerve regeneration.Through the above studies,the following conclusions are obtained:(1)Acetic acid solution was used as co-solvent to blend PCL and CS,and the freeze-drying PCL/CS materials have adjustable microporous structure by changing the blending conditions.When 18% PCL and CS(blending ratio = 9/1)were in 90% acetic acid aqueous solution,the pore size and structure of the PCL/CS NGC was most uniform: the internal structure of the material is regular and the micropores are connected with each other.The porous structure can improve the specific surface area of the material,provide more growth sites for cell adhesion,and facilitate nerve regeneration.(2)PCL/CS multi-channel NGC with 16 micro-channels and bionic structure can be prepared by independently designed mold(polyvinyl alcohol yarn was used as channel sacrificial template).The results of mechanical,hydrophilic,swelling,specific surface area and in vitro biocompatibility test showed that this conduit has excellent comprehensive performance and is suitable for peripheral nerve injury repair.(3)An animal model of sciatic nerve injury was established to evaluate the nerve repair effect of PCL/CS multi-channel NGC.The results showed that the PCL/CS multichannel NGC could promote sciatic nerve regeneration in rats after 12 weeks.