Study On Electrospun Polypyrrole/Polylactide Compositefilms For Nerve Tissue Engineering

Nerve injury repair has always been a medical challenge.Eventhough drug therapy and autograft transplantation have shown great effect on nerve injury repair,many drawbacks and limitationsexisted.Tissue engineering scaffoldis anew method with great potential for nerve regeneration by providing a helpful environment.As nerve is conductive and aligned arranged,aligned conductive fibrous films were fabricated in this work primarily mimicking theenvironment of nerve tissue.Schwann cells were used to evaluate the cytocompatibility of the films.Combined with electrical stimulation,human umbilical cord mesenchymal stem cells differentiated into nerve cells on the aligned conductive fibrous films,exhibiting a possibility for the construction of nerve tissue engineering scaffold.In this work,polypyrrole nanoparticles were prepared by soft templates firstly.Uniform sizes and gooddispersion of polypyrrole nanoparticles were visualized by SEM and TEM.Conductive composite films with random or aligned fibers were fabricated via electrospinning by embedding polypyrrole in polylactide.The morphology of fibers and the distribution of polypyrrole in fibers were also viewed by SEM and TEM.The mechanical characterization demonstrated that the incorporation of polypyrrole increased the young's modulus of the film.The anisotropic characters of aligned films exhibited significantly in their mechanical properties.Schwann cells play an important role in nerve repair.Observed by laser confocal fluoresce microscope,isolated Schwann cells demonstrated nice bioactivity on electrospun composite films and elongated along the fibers.Human umbilical cord mesenchymal stem cells cultured on electrospun conductive nanofibrous films,also demonstrated good cytocompatibility.Direct current was introduced to investigate the interaction between human umbilical cord mesenchymal stem cells and the conductive films.It can be seen that cells strongly interacted with fibers and grew along fibers no matter the films were random or aligned.However,no guidance effect of electrical stimulation was observed on the cells on films.Without inductive medium,nanofibrous structure films suppressed m RNA expression of osteogenic,adipogenic,myogenic and chondrogenic markers,while m RNA expressions of neurogenic markers,neurofilament-lowest and nestin,were significantly enhanced under the coeffect of alignment and electrical stimulation.In conclusion,aligned andconductive electrospun nanofibrous films were fabricated and proven to becytocompatible.Nerve tissue engineering scaffold may be constructed combined with stem cells and electrical stimulation,which provides a new chance for nerve repair.