The Experimental Study Of Amniotic Soft Tissue Filling Material In Prevention Of Peripheral Nerve Adhesion

Abstract: To explore the effectiveness and mechanics of humnanacellular amniotic membrane for preventing postoperative adhesion ofperipheral nerve injury repair, hoping providing a new method and materialwhich could prevent postoperative adhesion of peripheral nerve injury repair.In the past, sodium hyaluronate and prednisolone acetate, chitosan and othermedicines are often used in locally injecting for preventing postoperativeadhesion of peripheral nerve injury, expectantly solving the problem ofperipheral nerve injury postoperative neural adhesion. However, their barrierfunction cannot meet our expect for the process of degradation and absorptionin the body is fast because of their unique chemical qualities. And also thesesubstances don’t have the specialty of promoting the growth of epithelial cellsand inhibiting the growth of fibroblast. All these lead to disappointing resultsin the experiment and clinics. A ideal material is in need. In clinicalexperiments we found that humnan acellular amniotic membrane has thecharacter of both permeability and barrier, which could prevent formation ofadhesion between nerves and the surrounding tissue. Because of its goodcompatibility, the regenerative chamber could promote the process of neverhealing. In this experiment, we hope to provide theoretical basis for theclinical application of amniotic membrane material of soft tissue and a newmaterial of preventing postoperative adhesion after nerve injury.Method:48clean grade SD rats, male or female, provided by the animalexperimental center of Hebei Medical University.1operation method: Experimental group: Fix24rats after anesthesiawhich were selected randomly on the operating table and operate on one lowerlimb which was also selected randomly after preoperative preparation. Take amiddle longitudinal cut on the femoral back, separate subcutaneous tissue and expose the sciatic nerve. Cut the sciatic nerve at2.0cm from the exit of thesciatic nerve, making a model of nerve injury. Suture the cut with9-0noninvasive microscopy sutures under operating microscope by6pin on theouter membrane of the nerve. Cover the sutured cut with amniotic soft tissuefilling material. All these procedures were completed by one man, ensuringthe consistence of operation. Finish the operation by suturing the cut of theskin with4-0silk suture and apply amikacin lotion on sutured cut. Continue tofeed the rats in the breeding cages. Control group: generally follow theprocedures in experimental group but without covering the cut with thematerial.2test method: Observe the nerve generally in20,30and40days after theexposure by successful anesthesia. Classify and evaluate the sciatic nervebased on the degree of the adhesion between the nerve and surrounding tissues.Macroscopic observation and light and electrophysiological examinationshould be performed.Electron microscope, light microscope,electrophysiological examination should be performed in40days after theoperation.Results: the wounds were healing in6days after the operation. Thelimbs operated in the experiment totally cannot make a active back flexion inthe two groups. All rats swelled in the limbs operated in the experiment,partof in which occur the falling of toes or skin ulcer around one week. The skinulcer healed difficultly. There is no significant difference between the twogroups in this situation. In control group, we found that adhesion between thenerver and the surrounding tissues made the nerve barely move and it wasdifficult to separate the nerve from the surrounding muscles, while inexperimental group, the nerve departed from the surrounding tissues clearlyand there are a few filaments adhesion which was easily separated.Theamniotic soft tissue filling material covered on the nerve was found safe andsound,without significant degradation. The amplitude restoration rate ofevoked potentials of the sciatic nerve in experimental group is higher than thatin control group.And the difference is significant.And the delay rate of the incubation period is lower than that in control group with significantdifference.The material covered on the nerve was clearly seen in thehistological observation, with clear boundaries with both the nerve and thesurrounding tissues. Renewable fiber arrangement was neat and there was noobvious connective tissue hyperplasia occurred in the nerve. The outermembrane of the nerve is thicker in control group, with fibroblasts and a largeamount of fibrous tissues formation, connective tissue hyperplasia occurredaround the sutures. The amount of the myelin in nerve cells did not differsignificantly between the two groups under the electron microscopeobservation. In control group, fusion and swelling were seen in the myelin.Fusion and disappearance happened in mitochondria of the axon. Inexperimental group, separation, fusion and hyperplasiawere seen in themyelin. Fusion happened in mitochondria of the axon and the spine ofmitochondria disappeared.Conclusion:1The application of amniotic membrane soft tissue filling material forrepairing the injured nerve can prevent the adhesion of nerve and thesurrounding tissue from scar hyperplasia effectively.2The characteristic of permeability and barrier of amniotic membrane softtissue filling material doesn’t affect the transmission of the nerve nutritionneeded for healing.3Because of its good compatibility, the regenerative chamber couldpromote the process of never healing, without remaining permanentforeign body.