A Feasibility And Efficacy Study Of Guide Tissue Regeneration Collagen For Repairing Rat Stomach Defects

Background and aimsIn recent years,rapid development of endoscopy has brought great benefits to the detection and minimally invasive treatment of gastrointestinal tumors.Endoscopic mucosal resection?EMR?and endoscopic submucosal dissection?ESD?have been recommended as the first-line treatment of early gastrointestinal tumors.Endoscopic techniques like submucosal tunneling endoscopic resection?STER?,peroral endoscopic myotomy?POEM?and natural orifice transluminal endoscopic surgery?NOTES?derived from ESD,expand the endoscopic indications.Although these methods are minimally invasive,the number of iatrogenic perforations resulting from endoscopic procedure is increasing.Once perforation happens,the digestive juice will leak out and result in systemic inflammatory response syndrome?SIRS?.Clinicians should identify the location of the perforation as soon as possible and close the perforation immediately to prevent severe infections.For a long time,surgical repair,an invasive intervention,was the standard treatment for acute gastrointestinal perforation.Complications like postoperative anastomotic stenosis,anastomotic leakage or fistula might occur,which could severely influence patients'quality of life.Early detection of perforation,rapid repairment,and rapid healing are important to patients'prognosis.Currently,endoscopic sutures like endoscopic metal clips,purse-string sutures and over-the-scope clips?OTSC?,or stent placement are commonly used.Small perforation can be detected and repaired by endoscopy immediately,while laparoscopic or open surgery is still needed for larger perforations.The rapid close of perforation and the reconstruction of the complete digestive tract are key problems for perforation repairment.At present,three common repairing methods are used surgically,including autologous tissue transplantation,allogeneic tissue transplantation and artificial tissue replacement.Artificial synthetic materials are most studied due to the severe limitation of autologous tissue and allogeneic tissue.Patches of different materials for repairing gastrointestinal perforation achieved excellent results in some experiments and studies.Most perforations were eventually closed owe to scar tissue hyperplasia and tissue heterogeneity.Restoration of organizational structure and functions cannot be achieved.Besides,there are few materials to achieve satisfactory results of endoscopic or laparoscopic perforation repairment.As an important component of the extracellular matrix?ECM?,collagen was demonstrated to be able to promote cell proliferation and growth.Therefore,a sparse-complex double-layered artificial collagen was used to repair the full-thickness stomach defects of rats,and its efficacy and feasibility were explored in this study.MethodsPart I:A total of 16 SD rats were randomly divided into 2 groups and were used to established stomach defect models.The perforations were then repaired by guide tissue regeneration?GTR?collagen patches and polylactic acid?PLA?patches respectively.The abnormal temperature,abdominal distension,diarrhea and peritonitis were recorded.Six weeks after the operation,the survival rates,body weight changes,wound healing,abdominal adhesion of the rats were compared.Histopathological analysis was also performed to investigate the feasibility and efficacy of the two materials for repairing perforations.Part II:32 rats were used to establish the stomach defect models by the same method and repaired with GTR collagen patches.The rats were sacrificed after anesthesia on the 3^rd day,1^st week,2^nd week,4^th week after surgery?8 rats at each time?to observe the condition of postoperative abdominal adhesion,defect healing,and tissue regeneration.Histopathological analysis was also taken to evaluate the tissue regeneration procedure guided by GTR collagen patches.And its histocompatibility with normal tissue was also observed.ResultsPart I:The full-thickness stomach defect models were established and repaired by GTR collagen patches?n=8?or PLA patches?n=8?successfully.During the day of surgery and the first day after surgery,all rats survived well.But 4 rats repaired by PLA patches died in the following several days?perforations happened again at the repaired sites?.Another rat developed diarrhea but recovered spontaneously within one week.No abnormalities were observed in the remaining rats.A total of 4 rats survived to the6^th week after surgery in PLA group,and the survival rate was 50%?4/8?.The rats repaired by GTR collagen patches survived well without bloating,diarrhea and peritonitis.The body weight increased steadily after surgery.All rats survived to 6weeks after operation,and the survival rate was 100%?8/8?.The body weight of rats in GTR group was higher than that of PLA group?P<0.05?.Both groups showed slightly adhesions,but there was no significant difference in adhesion score between the two groups?P>0.05?.The area of mucosal defect in the PLA group was about?1.39±0.20?mm2and was much larger than that in the GTR group?P<0.05?.Pathological analysis showed that the rats in the GTR group had lower levels of inflammatory cells infiltration,better collagen fibers organization,more neovascularization at the 6^th week postoperative.And tissue structure of regeneration sites tended to be normal.Part II:32 SD rats with stomach full-thickness defects were successfully repaired by GTR collagen patches.The postoperative conditions of the rats were well,and the survival rate was 100%?32/32?.Three days after operation,the GTR collagen patches adhered to the surrounding normal tissue well,without any sign of peritoneal effusion and leakage.Pathological analysis showed a large number of cells crawling on the surface of the collagen membrane.The perforations closed within 1 week and the perforation sites adhered to the abdominal cavity slightly.The area of mucosa defect at the 1^st,2^nd,and 4^th week after surgery was?39.79±0.55?mm²,?7.40±0.43?mm²,?0.91±0.08?mm²,and the area of mucosa defect at the 4^th week was smaller than that of PLA group at the 6^th week,suggesting that GTR collagen can repair the perforation and promote tissue regeneration sooner after the surgery.During repairing procedure,the level of inflammatory cells decreased gradually.There was no excessive inflammatory reaction and no excessive deposition of collagen.The score of collagen organization and vascularization gradually increased.ConclusionsRat perforation models were reliable in this study.The efficacy of GTR collagen repairing was much better than PLA.GTR collagen was an ideal material for tissue regeneration,with the advantage of good histocompatibility,controllable degradation time,and rapid tissue regeneration.The GTR collagen could also promote the recovery of tissue structure.The development of this material might bring hope for the treatment of gastrointestinal perforation and refractory fistula.