Experimental fortification of intestinal anastomoses with nanofibrous materials in a large animal model

Abstract

Anastomotic leakage is a severe complication in gastrointestinal surgery. It is often a reason for reoperation together with intestinal passage blockage due to formation of peritoneal adhesions. Different materials as local prevention of these complications have been studied, none of which are nowadays routinely used in clinical practice. Nanofabrics created proved to promote healing with their structure similar to extracellular matrix. We decided to study their impact on anastomotic healing and formation of peritoneal adhesions. We performed an experiment on 24 piglets. We constructed 3 hand sutured end-to-end anastomoses on the small intestine of each pig. We covered the anastomoses with a sheet of polycaprolactone nanomaterial in the first experimental group, with a sheet of copolymer of polylactic acid with polycaprolactone in the second one and no fortifying material was used in the Control group. The animals were sacrificed after 3 weeks of observation. Clinical, biochemical and macroscopic signs of anastomotic leakage or intestinal obstruction were monitored, the quality of the scar tissue was assessed histologically, and a newly developed scoring system was employed to evaluate the presence of adhesions. The material is easy to manipulate with. There was no mortality or major morbidity in our groups. No statistical difference was found inbetween the groups in the matter of level of peritoneal adhesions or the quality of the anastomoses. We created a new adhesion scoring system. The material appears to be safe however needs to be studied further to prove itsʹ positive effects.

Reinforcement of Colonic Anastomosis with Improved Ultrafine Nanofibrous Patch: Experiment on Pig

“…We successfully created a model of anastomosis with a defect on the large intestine of a pig. We used the Testini's [16] modified model from previous experiments [26] in order to move the anastomosis to a location with bacterial contamination and higher risk of healing complications. The defect was chosen to be small enough to simulate a technical fault (which is also one of the contributing factors of AL [34]) and large enough to induce imperfect healing.…”

“…The abdominal cavity was inspected and checked for signs of AL (visible free intestinal contents or purulent secretion, macroscopic changes of peritoneal surfaces), visible defects in the site of anastomosis, changes in the intestinal diameter (stenosis of the anastomosis, dilation of oral segments of the intestine) or any other visible postoperative changes. At same time, the extent and location of PAs (according to qualitative Zühlke's grading and quantitative Peritoneal Adhesions Amount Score (PAAS) (Supplementary Figure S2) [26]), amount and macroscopic quality of peritoneal fluid and the position and appearance of the nanofibrous material (if present) were recorded.…”

“…The evaluation area for samples with a defect of the muscular layer or pseudodiverticulum was defined as 2 mm orally and aborally from the defect margins. The volume of endothelial cells, volume of MAC387 positive cells and volume of collagen was assessed using stereological methods in a similar way as in a previous study [26].…”

“…Our team developed and tested several versions of these materials [26,27]. A complex histological, clinical and macroscopic evaluation system has been perfected in recent works [26].…”

“…Based on the results of our previous experiments and on the presumption that a certain level of metabolic exchange between the sutured intestine and the surrounding peritoneal surfaces is needed to maintain the healing process rather than creating a sealed barrier, we decided to create a very fine porous nanofibrous patch. Such a patch should allow this metabolic exchange while maintaining the pro-healing properties of a nanofibrous mesh we proposed in the previous studies [26,27]. The process conditions for fabricating a material with a low surface density were optimized via needleless electrospinning.…”