| Objective:Endoscopic submucosal dissection (ESD) was developed to provide minimally invasive treatment for early gastrointestinal tumors. A considerable proportion of complications such as perforation, hemorrhage occurred during operation. It is the most effective and simple way of preventing the complications to maintain an enough thick cushion in submucosal layer by injecting fluid into the submucosal under endoscopy. In this study, we used a biological gel substance--elastin-like polypeptide (ELP) as a new submucosal injection to explore the effectiveness and possibility for ESD by comparing with the traditional submucosal agents with the purpose of provding the basis for further clinical application.Materials and Methods:1Preliminary animal experiment:54healthy male SD rats were randomly allocated into there parts (n=18) by submucosal injection of different agents. Each part were randomly divide into three groups (n=6). Respectively, the increase of mucosal thickness was observed and record; the amount of bleeding from the lesion and histological appearance of submucosal elevation of each submucosal injection agents were measured. It was preliminary evolution of the role of ELP in the mucosal dissection.2ESD simulation experiments:6miniature pigs were randomly allocated into two groups by injecting different submucosal agents for stomach ESD.ELP (I) group (1000uM、500uM、250uM) and Glycerol as control group. ELP groups with different concentrations were used by1-1,1-2,1-3.All groups agents were injected with the four locations of fundic, gastric antrum, gastric angle for ESD.Results:1Preliminary animal experiment1.1The change of submucosal elevationComparison of submucosal elevation after injection within60minutes:The initial submucosal elevations after injection was4.14±0.37mm,3.77±0.43mm,3.43±0.67mm with ELP, SH and NS group respectively.The submucosal elevation height using ELP injection was significantly thicker than either SH or NS (P<0.05), whereas SH was thicker than NS (P<0.05). The elevation retention was80%,62%and20%at60min.The ELP-induced elevation lasted longer than either SH or NS.1.2The amount of bleeding from the stomachThe amount of bleeding was854.±98.9mg,726.3±104.8mg and1144.0±112.4mg for ELP、SH and NS during20min. The group with administration of ELP and SH showed significantly lower values compared with NS (P<0.05).1.3Histological analysisHistological appearances of tissue in administration sites of ELP after injection was showed that the gastric submucosa was significantly thicker than that of the other groups.It did not find significant inflammation and damage necrosis of the tissue from the ELP submucosal injection compared with SH and NS.2. ESD simulation experiments2.1The procedure time of ESDThe procedure time of ESD was55.23±2.43min,38.88±2.55min,57.48±3.21min,58.79±2.52min with1-1,1-2,1-3and control group,respectively.The group of with administration of1-2was significantly shorten time compared with control group (P<0.05). The group of1-2was significantly shorten time compared with1-1and1-3group. There were no significant differences of the procedure time between the other groups(P>0.05).2.2Submucosal injection doseThe initial injection dose of1-1,1-2,1-3and control groups were10.00±1.45ml,10.16±1.25ml,4.42±2.06ml and15.00±2.14ml, respectively, with significant differences between groups(P<0.05).The total dose was10.00±1.45ml,10.16±1.25ml,24.92±4.01ml and27.58±3.93ml with significant differences(P<0.05).There were significant differe nces between1-1,1-2group and control group (P<0.05).1-1and1-2groups were significant differences with1-3group (P<0.05).2.3The injection pressureThe injection pressure between groups was264.33±4.76kpa,247.50±4.18kpa,246.30±4.08kpa and230.66±3.55kpa,respectively (P<0.05).There was no differences between 1-2group and control group (P>0.05).I-2group compared with1-1and1-3groups of injection pressure, there was some statistically significant difference (P<0.05).2.4The complication of ESDThere were no perforations under endoscopic observation with all the ESD procedure. It was not shown hemorrhage in the1-1group and1-2group, whereas1-3group and control group had different degrees of bleeding with4and6cases respectively with the success of APC electrocoagulation.2.5The observation of woundThe release specimens were containing visible surgical marker region and no residual mark area under endoscopic observation with intact mucosa. The wound region was gradually reduced artificial ulcers and healing after1,2and4weeks by endoscopy, and each group no significant difference. There was no significant difference between each other.Conclutions:1. It was showed that submucosal elevation produced by ELP as a solution of submucosal injection appeared higher and longer time compared with traditional agents.besides, it had no tissue damage.2.500μM ELP, which had the advantage of injection easier, submucosal dissection easier, and no interfered postoperative wound healing,could improve the effectiveness of ESD as an suitable concentration of submucosal injection.3. The thermally sensitive ELP could prevent perforations and reduce vessel damage and amount of bleeding to enhance the safety of ESD. It may be a promising and novel submucosal injection agent for ESD in future. |
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