Study On The Prevention Of Postoperative Adhesion With PEG/PLGA Electro-spun Absorbable Polymeric Membrane

Objective: In recent years,anti-adhesion membrane has been utilized more and more widely in surgeries,since it can effectively prevent tissue adhesion after operation.The nano-fibers prepared by electro-spinning technology have attracted much attention in biomedical fields because of their excellent properties,such as large surface area,high porosity,fine fiber size and good mechanical strength,and have been applied in the field of wound repair,tissue engineering and absorbable anti-adhesion membranes.Poly-L-lactic/glycolic acid(PLGA)and polyethylene glycol(PEG)was used to prepare PEG/PLGA absorbable electro-spun polymer film by electrostatic spinning technology.The effects of PEG/PLGA electro-spun absorbable polymeric membrane on the prevention of postoperative abdominal adhesion in rats were observed by establishing an animal model of caecum adhesion.To provide the theoretical basis and technical method for the clinical prevention and treatment with PEG/PLGA electro-spun polymeric membrane in the surgical abdominal cavity.At the same time,the animal model of tendon adhesion in rats is established to observe the effect of PEG/PLGA electro-spun absorbable polymeric membrane on preventing tendon adhesion after tendon rupture in rats,which helps to provide experimental basis for the prevention and treatment of tendon adhesion after tendon rupture by PEG/PLGA electro-spun absorbable polymeric membrane.Methods:1.PEG and PLGA were accurately weighed,and solvent was added.After completely dissolved at 60 ?,the films were prepared by casting film forming method and electrostatic spinning method,respectively,and were used in animal studies in vivo.Aiming to explore the preventive and therapeutic effects of PEG/PLGA membrane prepared by different methods and to select a better method to prepare anti-adhesion membrane,which will provide an effective treatment method for clinical prevention of postoperative adhesion.2.The pure PLGA and PEG-PLGA with the ratio of 5 / 95,25 / 75 were dissolved in organic solvents,and then stirred and dissolved into a stable and transparent solution under a constant temperature water bath.The membrane was prepared by mixing electrostatic spinning at room temperature after cooling.Scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and differential scanning calorimetry(DSC)were used to determine the surface morphology and physicochemical properties of each membrane.Appropriate performance fibrous membranes were selected to implant into the abdominal cavity of rats to observe the adhesion and the degradation of the fibrous membrane.And then the optimal ratio of PEG/PLGA was selected for the comprehensive and systematic study,in order to be used as the material for preventing and treating postoperative adhesion of abdominal cavity.3.(1)Under a sterile environment,the membrane was implanted into the back of the New Zealand rabbit,with 4 implantation sites on each side,and then closed with a suture line.Reopen the operative site to observe the change of tissue structure and the degradation of the implanted material at 1,2,6 and 9 weeks after operation,respectively.To evaluate the safety of the implanted membrane.What's more,the histo-compatibility of the PEG/PLGA absorbable electro-spun polymer film was preliminarily evaluated.(2)PLGA and PEG are mixed with the ratio of 19:1,then dissolved in organic solvent.Utilizing the mixed contents to prepare PLGA/PEG absorbable electrospun polymer membrane by electro-spinning,and then run the gross observation and scanning electron microscope observation.And the experimental study was carried out with the absorbable electro-spun polymeric film that owning uniform morphology and appropriate properties.Sprague-Dawley rats were randomly divided into normal control group,PEG / PLGA membrane group and positive membrane group.Abdominal adhesion model was established by mechanical injury of cecum serosa.PEG/PLGA membrane was locally covered in cecum wound in PEG/PLGA membrane group during operation.The positive membrane group was covered with Dikang absorbable medical membrane,and the model group without any treatment.The abdominal adhesion was observed 3 days and 1,2,8 weeks after operation according to the self-determined standard,the degradation of membranes were observed and histological observation was made at each time point.(3)SD rats were divided into blank group,model group,PEG / PLGA membrane group and positive membrane group to study the preventive effect of PEG/PLGA membrane on tendon adhesion after operation.The third flexor digitorum profundus tendon was operated by lateral incision and transected 50%.Sutured the broken tendon with suture in figure-eight.And then the model of tendon adhesion was made.The model group did not do any treatment,the tested membrane group and the positive membrane group wrapped the corresponding membrane at the broken tendon,and then the skin was sutured.After the experiment,the experimental animals were put back into the cage and raised in a single cage.At the end of experimental period,the animals were dissected and observed in general and histology.Results: 1.Compared with the traditional casting method,the PEG/PLGA film prepared by electro-spinning technology has good adhesion property.It is not easy to fall off during the experimental process,and has good toughness and good biodegradability in animals.Therefore,utilizing electro-spinning technology to prepare anti adhesion is more advantageous.2.The surface of 5% PEG/PLGA electro-spun film is smoother and more uniform when compared that with pure PLGA film.Compared with 25% PEG/PLGA membrane,5% PEG/PLGA membrane has better physical and chemical properties.The experimental results in vivo also showed that 5% PEG/PLGA membrane could effectively prevent postoperative adhesion and had better biodegradability.Therefore,it is more suitable to be used as the experimental material for the prevention of postoperative adhesion.Consequently,the PEG/PLGA absorbable electro-spun polymeric membrane at the ratio 5% is mainly used as the research material in this study.3.(1)On the subcutaneous implantation experiment in New Zealand rabbit,animals survived until the end of the experiment,there was no acute inflammatory reaction in the animals that 5% PEG/PLGA absorbable electro-spun polymeric membrane implanted,and no abscess was found in the implanted site.There was no significant difference with normal tissue.At the first week of implantation,the 5% PEG/PLGA membrane was folded into half and was white.At the same time,the positive membrane was also folded.For 2 weeks,the 5% membrane was white and folded into stripe shape,which could be easily stripped,while the Hongjian membrane became white with the phenomenon of extension,and easily fractured.In the PEG / PLGA film group,fragmentation was observed at 6 weeks,partial film degradation was completed,while the positive film was lacerated flat,and the film was partially degraded.The anatomical results showed that the film was partially degraded after 9 weeks of implantation,the 5% PEG/PLGA membrane was completely degraded,while the membrane in the positive membrane was still chapped or granular,and the membrane was not completely degraded.(2)Using the electro-spinning technique,PLGA/PEG film was prepared successfully,which appeared white and opaque,with soft texture.Scanning electron microscopy observation showed PLGA/PEG membrane is mainly composed of disorderly staggered nano-fibers,with micro-porous structure.All rats survived to the end of the experiment.Gross observation showed PLGA/PEG membrane was gradually degraded after implantation in vivo,and the degree of adhesion in the PLGA/PEG group was significantly lower than that in the model group,the adhesion grading comparison differences at each time point were statistically significant(p<0.05),but it had not yet reached the level of the control group(p<0.05).The histological observation showed,the proliferation of cecal fibrous connective tissue slow down significantly at each time point PLGA/PEG group compared with the model group,and adhesion severity decreased significantly,only with a small amount of inflammatory cell infiltration.Nevertheless,it was not up to the level of the control group.(3)In the experiment of preventing adhesion after tendon operation,during the experimental period,the healing of the animal was good.When the tendon was exposed again,the adhesion between the model group and the surrounding tissue was relatively close,and the tendon was expanded at the transverse section,and it was difficult to separate.In the positive membrane group and the tested membrane group,the membrane was visible and still wrapped in the tendon,some of which had been degraded,and the tendon healed better.Conclusion: 5% PEG/PLGA absorbable electro-spun polymer membrane has good histo-compatibility,and 5% PEG/PLGA absorbable electro-spun polymer film can effectively prevent postoperative abdominal adhesion.Moreover,5% PEG/PLGA absorbable electro-spun polymer film with good biodegradability.It can significantly reduce the incidence of high grade adhesion after tendon rupture.