| Chronic nerve compression(CNC)is a common form of peripheral nerve injury,which often leads to pain,numbness,muscle atrophy and motor dysfunction in the innervation area.90% of the clinically diagnosed CNC patients are carpal tunnel syndrome,which affects 4.9% to 7.1% of the population in the world every year.CTS affects middle-aged active workers,which is related to a large number of health care costs and economic burden.In the United States,for example,the total cost of CTS related years exceeds$2 billion.The operation can accurately relieve the pressure,relieve symptoms and restore functions.But bleeding,nerve and surrounding tissue injury will inevitably lead to nerve adhesion and scar formation,and serious causes recurrence.After nerve compression,how to protect the nerve,minimize the secondary damage and restore its conduction function as soon as possible is still a problem that has not been solved.Through the deep research on the nerve structure,recovery mechanism and adhesion reasons,many methods and materials to prevent nerve adhesion and promote nerve recovery were explored.Amniotic membrane is a layer of membrane on the surface of amniotic membrane cavity,which is abundant in source,without the membrane structure of blood vessels,lymph and nerves,low immunogenicity,rich in collagen,elastin and many growth factors,which can inhibit inflammatory response,reduce scar formation,improve microenvironment and promote the repair of Shenjing.Its unique structure and properties make it an ideal biomaterial.In clinical application,the research group found that the amniotic membrane degradation is fast,the mechanical strength is low,the anti extrusion ability is poor,easy to tear,and it can not support enough space for nerve repair.In order to overcome the limitation of the above mentioned amniotic membrane materials,other materials are needed to play a great potential of amniotic membrane materials.In this paper,the biological amniotic membrane was prepared by electrospinning on two surface of amniotic membrane,and the PCL nanofiber was prepared.The membrane strength was larger,the time of storage in vivo was prolonged,and the regeneration room of nerve recovery was supported,which provided a strong guarantee for the nerve recovery after loosening.The purpose of this study was to follow up to verify the effectiveness of chronic nerve compression release in preventing neuroadhesion,and to establish a chronic compression model of sciatic nerve in rats to evaluate the effect of PCL amniotic membrane on the prevention and treatment of neuroadhesion and the promotion of repair.The results showed that: 1.after the open and loose operation of carpal tunnel syndrome,the grip strength and kneading force of motor function were increased obviously after the treatment of prevention of central nerve adhesion with chitosan.The sensory function was also recovered obviously.Bctq and dash scale scores were improved obviously,and the recovery time was obviously shortened,and the satisfactory effect was achieved.2.PCL amniotic membrane can effectively prevent the invasion of macrophages,reduce inflammatory response,inhibit the synthesis of Co L-I and col-iii,reduce the deposition of fibrin,protect the nerve from scar tissue invasion and prevent nerve adhesion to surrounding tissues.3.PCL amniotic membrane can support the sciatic nerve after chronic compression release to support a relatively stable microenvironment.By releasing bioactive substances such as NGF,BDNF,NT-3,GDNF,CNTF,and then spreading to the compression site through the pores of nanofiber membrane,NGF and GAP-43 expression can be improved,and the nerve repair and regeneration can be promoted,and good therapeutic effect can be obtained.PCL nanofiber membrane as inner layer maintains the sliding of nerve and tendon through its moderate hydrophilic and smooth properties.In this paper,PCL amniotic membrane nanofiber membrane was constructed by electrospinning technology,which increased the mechanical strength of amniotic membrane,prolonged the time of amniotic membrane in vivo,reduced inflammatory reaction,inhibited the synthesis of Co L-I and col-III,reduced the deposition of fibrin and prevented nerve adhesion.It can support the microenvironment after release,release a variety of growth factors to promote the recovery of nerve,and provide a new treatment strategy for solving the clinical problems of neuroadhesion and recovery after release,and has a broad application prospect.Part One Clinical study on prevention of median nerve adhesion after carpal tunnel syndrome operationObjective: peripheral nerve compression(CNC),such as carpal tunnel syndrome,is a common and frequently occurring disease in hand surgery.Postoperative nerve adhesion and scar formation are common causes of recurrence,so far there is no effective solution.This study was to explore whether chitosan combined with OCTR is more effective than OCTR alone in improving the clinical symptoms of patients with median nerve adhesion.Methods: a total of 61 patients with carpal tunnel syndrome were collected from the Third Hospital of Hebei Medical University and Cangzhou Hospital of integrated traditional Chinese and Western medicine in Hebei Province.They were divided into control group and experimental group according to whether chitosan was used during operation.The patients were evaluated before operation and 1,3,6 months after operation.The incidence of postoperative columnar pain and the time of postoperative recovery were recorded.The grip strength,pinch strength and two-point discrimination of distal phalanx of index finger were measured.Bctq and dash scales were filled in to evaluate the clinical effect of chitosan combined with OCTR in preventing median nerve adhesion.Results: the recovery time of the experimental group was shorter than that of the control group,the grip strength and pinch strength values at each time point were greater than those of the control group,the two-point discrimination was less than that of the control group,the bctq score was lower than that of the control group,the difference was statistically significant;the incidence of postoperative columnar pain and DASH score at the first month after operation of the experimental group were not statistically significant compared with those of the control group,and the DASH score at other time points was lower than that of the control group The difference was statistically significant.Conclusion: in OCTR combined with chitosan to prevent median nerve adhesion,the follow-up confirmed that the motor function,grip strength and pinch strength of the patients were significantly increased,the two-point discrimination of sensory function was also significantly restored,the bctq and DASH scores were significantly improved,the recovery time was significantly shortened,and the satisfactory effect was achieved.Part Two Experimental study of electrospun polycaprolactone(PCL)-amniotic nanofiber membrane on inhibition of Co L-I,IIIsynthesis and prevention of adhesion after neurolysisObjective: adhesion and scar formation after neurolysis are common causes of recurrence.The purpose of this chapter is to apply electrospun polycaprolactone(PCL)-amniotic membrane nanofiber membrane to chronic compression model of sciatic nerve in rats,and to determine its effect on preventing adhesion.Methods: the sciatic nerve entrapment model was established by Mac Kinnon method.Four weeks later,the sciatic nerve was released and randomly divided into control group,chitosan group and PCL amniotic membrane group.Gross observation and histological observation were performed at 2,4,8 and 12 weeks after operation.The content of type I and type III collagen was determined by Western blot.Results: after the sciatic nerve was released,the adhesion of the sciatic nerve became more and more serious with the extension of time.At 12 weeks,the electrospun amniotic membrane in PCL amniotic membrane group was partially absorbed,and the adhesion between the nerve and the surrounding tissue was loose and easy to be separated.In the chitosan group,the chitosan was absorbed completely,the nerve adhered to the surrounding tissue extensively,and it was not easy to separate passively.The adhesion between the control group and the surrounding tissue was extensive and dense,and blunt separation was difficult.Histological observation showed that the total number of CD68 positive activated macrophages and CCR7 positive pro-inflammatory M1 macrophages in PCL amniotic membrane group at each time point were less than those in chitosan group and control group.The relative content of type I and III collagen in PCL amniotic membrane group was lower than that in chitosan group,and that in chitosan group was lower than that in control group at each time point after operation.There was significant difference among the three groups(P < 0.05).Conclusion: PCL amniotic membrane can effectively prevent the invasion of macrophages,reduce the inflammatory reaction,inhibit the synthesis of Co L-I and col-III,reduce the deposition of fibrin,protect the nerve from the invasion of scar tissue,and prevent the nerve adhesion to the surrounding tissue.It provides theoretical basis and animal experimental basis for solving the clinical problem of adhesion after neurolysis.Part Three Electrospun polycaprolactone(PCL)-amniotic membrane nanofiber membrane promotes the expression of NGF and GAP-43 and accelerates the repair of neurolysisObjective: after neurolysis,how to protect the released nerve and recover its conduction function as soon as possible is still an unsolved problem.The purpose of this chapter is to apply electrospun poly(caprolactone)(PCL)-amniotic membrane nanofiber membrane to chronic compression model of sciatic nerve in rats,and to clarify its effect on promoting nerve recovery.Methods: Ninety-six adult male SD rats(provided by Experimental Animal Center of Hebei Medical University)were selected and randomly divided into PCL-amniotic membrane group,chitosan group,and control group,with 32 rats in each group.A rat model of chronic compression of the sciatic nerve was prepared according to the Mackinnon method.After 4 weeks,it was verified that the model was successfully lysis of the sciatic nerve.The nerve compression of the PCL-amniotic membrane group was wrapped with PCL-amniotic membrane and the chitosan group was treated with medical chitosan gel Wrap,the control group did not do any treatment,postoperative gross and histological observation,gastrocnemius wet weight ratio and muscle bundle area ratio,hot plate test,sciatic nerve function index and RT-PCR to detect the expression of NGF and GAP-43 m RNA.Results: compared with the control group,PCL amniotic membrane group had less postoperative hyperemia and edema,loose adhesion with surrounding tissues,less inflammatory reaction,thicker myelin sheath and larger axon diameter;compared with chitosan group,PCL amniotic membrane group had less postoperative hyperemia and edema,thicker myelin sheath and better nerve recovery at 8 and 12 weeks;neuroelectrophysiology was better Results: compared with the control group,the PCL amniotic membrane group had higher amplitude and faster conduction velocity,There was no significant difference between PCL amniotic membrane group and chitosan group at 2and 4 weeks after operation,but PCL amniotic membrane group had higher amplitude and faster conduction velocity than chitosan group at 8 and 12 weeks after operation(P < 0.05);immunohistochemical results showed that the expression of S-100 protein in nerve was significantly higher in PCL amniotic membrane group than in chitosan group and control group;the wet weight ratio and muscle bundle area of gastrocnemius were significantly higher in PCL amniotic membrane group than in chitosan group The results of hot plate test showed that the latent period of heat stimulation gradually shortened with time,the latent period of PCL amniotic membrane group was significantly shorter than that of control group at each time point,and the latent period of PCL amniotic membrane group was shorter than that of chitosan group after 4 weeks(P < 0.05);the results of RT-PCR showed that NGF and GAP-43 in sciatic nerve were significantly higher than that of control group The relative content of m RNA expression in amniotic membrane group was higher than that in chitosan group and control group(P< 0.05).Conclusion: PCL amniotic membrane can support a relatively stable microenvironment for the sciatic nerve after chronic compression release in rat model of chronic compression.By releasing NGF,BDNF,NT-3,GDNF,CNTF and other bioactive substances,PCL amniotic membrane can diffuse to the compression site through the pores of nanofiber membrane,increase the expression of NGF and GAP-43,promote nerve repair and regeneration,and obtain good therapeutic effect.It provides a new treatment strategy to solve the clinical problem of adhesion after neurolysis,and has a broad application prospect. |
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