| Background:Endoscopic submucosal dissection(ESD)is a minimally invasive method for the treatment of gastrointestinal tumors that has also become the treatment of gastrointestinal tumors and precancerous lesions of early treatment of choice.ESD surgery complications is high-with the development of its technology and related equipment,indications are broadening to some extent,which makes the shortcomings have been magnified.Therefore,one of the key factors of complications has become an obstacle to the extensive ESD.ESD technical characteristics that reach at least the gastric submucosal resection inevitably artificial construct of this layer deep ulcers-it is easy to cause ESD postoperative wound bleeding,perforation and other complications.So choosing the right way to protect and promote postoperative wound healing of ulcers is an important factor in improving the technology.Although ESD surgery will use a variety of methods to deal with wounds,but these methods are not only complex operation and require skilled operator operates,but the effect is limited.With the rapid development of biomedicine,which is incorporated into the ESD postoperative wound healing research-gives ESD prevention of postoperative complications with a new opportunity.Biodegradable materials in recent years become a hot research ESD wound repair,there are a lot of studies show that it can effectively protect the postoperative wound,promote ulcer healing.Injectable chitosan/glycerophosphate temperature-sensitive hydrogel is widespread concern temperature-sensitive biological materials.It is liquid at room temperature,by endoscopic injection pipe to the site of the defect,its adhesion to the surface,and changes in the physiological body temperature of a solid gel,sealing and repair the defect.However,the traditional chitosan/glycerophosphate gel glue contributed slow,poor wound healing ability and degradation rate-those drawbacks is difficult to meet ESD's needs.Type ?collagen is a widely applied in wound repair biodegradable materials.It is a natural extracellular matrix,in addition to a good repair and degradation of good,but also significantly reduce the chitosan/glycerophosphate gel gel time.Therefore,this issue will introduce a type ? collagen to chitosan/glycerophosphate gel system,proposed by the preparation of chitosan,collagen,glycerol phosphate combination of new gel system.Let it be an alternative ESD surgery,can effectively protect and repair the ulcer new biomaterials.Objective:To prepare different formulations of injectable chitosan/collagen/glycerol phosphate thermo-sensitive hydrogel.And in accordance with the requirements of ESD surgery,screening and optimization of physical and chemical properties of the formulation,and strive to find the best solution.Then test the gel on human gastric toxicity and epithelial cell barrier protection(GES-1)to provide basic data for further feasibility animal and clinical trials.Method:by a certain ratio to prepare different temperature-sensitive gel system and its physical and chemical properties were measured,including:1,observe the liquid flow through the tube upside down;2.heated to 37 ? desired gel time;3.using the PH Miriam were tested before and after the PH value into glue;4.the use of isolated pig stomach wounds after ESD simulation performed adhesion testing;5.at 37 ?,the gel has been formed to detect the acidic environment in different PH values The degradation rate.6.optimized by orthogonal experiment,select the best formula.7.Then CCK-8 method to test this temperature-sensitive gel on human gastric epithelial cells(GES-1)in the relative growth rate,to assess their cytotoxicity.8.The GES-1 were seeded in the upper chamber transwell dish,until the fusion temperature-sensitive gel will be placed on the cell layer grow together.On the adjustment room PH value change,and then test the PH change transwell lower chamber,while the use of CCK-8 method to test the proliferation rate of GES-1.Results:1.prepared chitosan/collagen/glycerophosphate hydrogels at low temperature(0-4 ?)under flow at room temperature can be injected.After the temperature was raised to 37 ? may situ gelling about 6min,colloidal soft,moist,and has a certain flexibility pressure resistance,and can be firmly adhered to the body tissue from.2.both before and after the gel has a physiological PH,about 6.5-7.0.3 in simulated physiological environment PH ?2,6,7 acidic medium(HCL + pepsin),and this has a degradation gradient gel,and 7 days on average degradation rate can reach 40%.4.optimized formulation by orthogonal experiment,the best ratio of preferred programs are as follows:chitosan/collagen/glycerol phosphate hydrogel volume ratio of 8:1:1,chitosan(97%degree of deacetylation concentration of 2%,the concentration of acetic acid to dissolve chitosan 0.25mol/L);collagen concentration of 10mg/ml;?-glycerophosphate concentration of 0.8mg/ml for the best.5,normal gastric epithelial cells(GES-1)can grow well in the temperature-sensitive gel scaffold,low cytotoxicity.6,by co-culture chamber,temperature-sensitive gel showed good acid resistance and barrier protection.Conclusion:temperature-sensitive gel may be prepared to meet the ESD repair surgery demand includes injectable at room temperature,the low temperature flow ability,37? rapidly formed in situ possess the natural physiological PH value of the gel.Colloidal soft,moist and strong adhesion,flexibility and having a certain pressure resistance,and can be in different PH acidic environment degradation and exhibit degradation gradient.The temperature-sensitive gel for normal gastric epithelial cell GES-1cells showed no toxicity,but also to promote their health,but also has acid resistance and barrier protection.Therefore chitosan/collagen/glycerol phosphate temperature-sensitive gel is expected to be used in wound repair surgery ESD materials. |
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