Preparation And Properties Of The Nerve Regeneration Conduit With A Tube In Tube Braided Structure

In recent years, the majority of the scholars at home and abroad paid more and more attention on the research of the nerve repairing. Autologous nerve graft or other neurological substitute applications can solve the problem of nerve defects, nerve autograft brought problems to the impaired area available for transplant, and nerve sources were limited. Today, by using of the basic principles and methods of tissue engineering, nerve regeneration conduit, as a carrier material with good biocompatibility according to the biological characteristics of nerve regeneration,repair peripheral nerve injury. Scholars did many studies on single or double layer braided nerve regeneration conduits, but little literatures were focused on the conduit construction about different repairing speed of the various parts in the process of nerve regeneration, thus affected the speed, quality and distance of nerve regeneration.In order to solve problems above, this paper designed a braided renewable nerve conduit with tube in tube structure, also degradation gradient. The following were the design concept:by changing inner tube and outer tube materials of the tube in tube structure renewable nerve conduit, the braiding parameters, the number of the inner tubes, we can get different degradation time between outer tube and inner tube, form degradation gradient; when the inner tube degraded firstly, it didn’t inhibit nerve growth, the outer tube degraded lately, protected the nerve regeneration process without fibrous tissue invasion, and avoided the formation of neuroma.Firstly, this paper discussed degradation performance in vitro of the three biodegradable materials: polyethylene cross-ester (PGA), glycolide and lactide copolymer (PGLA), dioxanone (PDO), by the testing of mass loss rate and strength loss rate, we found:the degradation rate of PDO was slower than PGLA’s, the degradation rate of PGLA was slower than PGA’s, PGA can be degraded completely by4～5weeks generally.7～8weeks for PGLA,PDO was more difficult foe biodegradable degradation. The paper introduced the design concept, braiding and shaping process of renewable nerve conduit with the tube in tube braided structure. The paper elaborated the effects of chitosan coating on the PGA renewable nerve conduit in vitro degradation, firstly, explored the impact of the coating on the pH value of conduit in vitro degradation, and found that the environment were suitable for cell growth when the coating layer was one; Secondly, through the measurement of strength loss and mass loss of conduits in vitro degradation, we found that strength loss and mass loss of PGA renewable nerve catheter were relatively slow with the increasing of the number of the coating, since coated chitosan played a role of a protective layer. At last, the paper described structural parameters, apparent properties,mechanical properties, and the impact of the coating on the mechanical properties among the various catheters, we found:resistance to compression capacity of conduits with PDO outer tube was much higher than the conduits with PGLA outer tube; so did the axial tensile properties; after coating, the axial breaking strength, axial elongation at break and radial load force were enhanced, but radial elastic recovery rate was decreased, so the resistance to deformation was enhanced. The paper studied the changes of performance in vitro degradation of various renewable nerve conduits, the study found that axial strength and compressive strength of conduits with PDO outer tube were much higher than the conduits with PGLA outer tube in the entire process of degradation;so did the axial tensile strength loss rate and radial compressive strength loss rate; For the same materials of outer tube, the impact of materials of inner tube on axial strength and compressive strength of the catheters in the degradation process was not great..