Fundamental Research On Preparation And Performance Of Multi-channel Artificial Nerve Conduit

Peripheral nerve injury is a relatively common traumatic sequelae whose incidence is estimated to be 13 to 23 per 100 people.When the nerve is transected,the best method is to perform end-to-end tension-free suturing,but it is only applicable to the shortsegment repair of nerve defects within a few millimeters.For long-segment injuries,the current best treatment is autologous sensory nerve transplantation.The problem of immune rejection can be avoided.However,there are problems with the supply of autologous nerve grafts,and clinically there are usually problems such as secondary surgery and matching with the damaged site.For these reasons,clinicians and scientists have developed artificial nerve conduitss including biomaterials and artificial materials as axon guide channels.The purpose of these tubular structures is to bridge the gaps of the transverse nerves,to enable the regenerative nerve fibers to grow in a directional manner along the conduits,to promote the reconnection of neurons,and to restore neurological function.In this paper,based on the analysis of natural nerve structure,a new type of multi-channel composite structure nerve conduit is proposed.Its material(polycaprolactone PCL)and its preparation process are studied exploratoryally and in vitro.The main content includes the following aspects.Biomimetic design of the conduits structure.Peripheral nerves are heterogeneous composite structures composed of bundled axons.Four layers of connective tissue sheaths constitute nerves.From the outside to the inside,it consists of the mesenterium,the epineurium,the perineurium,and the endoneurium.Therefore,we combine natural neural structures to simulate axonal growth and guidance characteristics and propose a "invisible scaffold" in structural design.From the cellular and molecular level,the fiberguided and tissue-inducible function of the scaffold,the relationship between the structure and the growth of the nerve fiber,and the mechanism of each other's response were explored.Conduits preparation process.In this paper,we developed a nerve conduit with a multi-channel composite structure that contains an inner microporous stent and an outer semipermeable membrane that wraps the stent.Its processing method uses a continuous manufacturing process,including photolithography,ultra-thin grinding wheel cutting to make molds for repeated preparation of PCL film.The composite structure nerve conduit manufacturing process includes micro-slot film and planar film preparation,micro-slot film crimping,planar film stretching and laser drilling,conduits assembly,and finally thermoplastic type.Finally,a comparative study of process parameters was conducted to analyze the internal relationship between the parameters.Conduits in vitro performance test.The ideal nerve conduit should have excellent mechanical and biological properties under the premise of reasonable structure.It plays a role of stent after being implanted in the body and guides the growth of nerve cells.It should also have periodic gradual degradation until it is repaired.After complete degradation,absorbed by the tissue,and the product does not cause foreign body reaction characteristics.For this purpose,in vitro experiments were conducted on new composite nerve conduits,including conduits degradation tests,conduits axial stretching and radial compression tests,and in vitro cell fusion experiments.The aim is to further understand the in-vitro performance of the conduits under theoretical parameter design,provide feedback for more reasonable conduits design and provide data reference for the next in vivo experiment.