Anastomotic sealing by extracellular matrices (ECM) improves healing of colonic anastomoses in the critical early phase

Clinical results after external reinforcement of colorectal anastomosis: a systematic review

OBJECTIVE

The aim of this review is to describe and assess the existing methods to cover colorectal anastomoses with biomaterials and their clinical impact in reducing anastomotic leakage (AL).

SUMMARY BACKGROUND DATA

The most serious complication in colorectal surgery is AL. Despite improvements in its diagnosis and management, AL remains an unresolved issue. To prevent its appearance and clinical consequences, different external reinforcement techniques with synthetic or biomaterials have been described.

METHODS

A systematic review search of the available literature until June 2022 was performed, looking for all literature regarding external reinforcement of colonic or colorectal anastomoses. After the review process, a classification of materials was proposed into solid and liquid materials, and an assessment of their clinical impact was performed. The study protocol has been registered at PROSPERO and has been reported in the line with PRISMA and AMSTAR Guidelines 11,12 .

RESULTS

Ninety-seven articles that fulfilled inclusion criteria, were identified and revised. Overall, 18 of the selected articles focused on human clinical trials and 79 on animal models. Only fibrin sealants, collagen patches, and omentoplasty have shown positive results in humans.

CONCLUSIONS

Fibrin sealants, collagen patches, and omentoplasty are, so far, the most studied biomaterials. However, further studies are required to confirm these findings before definite recommendations can be made.

Western Diet-induced Transcriptional Changes in Anastomotic Tissue Is Associated With Early Local Recurrence in a Mouse Model of Colorectal Surgery

OBJECTIVE

To determine the timeframe and associated changes in the microenvironment that promote the development of a diet-induced local-regional recurrence in a mouse model of colorectal surgery.

BACKGROUND

Postoperative recurrence and metastasis occur in up to 30% of patients undergoing attempted resection for colorectal cancer (CRC). The underlying mechanisms that drive the development of postoperative recurrences are poorly understood. Preclinical studies have demonstrated a diet and microbial-driven pathogenesis of local-regional recurrence, yet the precise mechanisms remain undefined.

METHODS

BALB/C mice were fed a western diet (WD) or standard diet (SD), underwent a colon resection and anastomosis, given an Enterococcus faecalis enema on postoperative day (POD) 1, and subjected to a CT26 cancer cell enema (mimicking shed cancer cells) on POD2. Mice were sacrificed between POD3 and POD7 and cancer cell migration was tracked. Dynamic changes in gene expression of anastomotic tissue that were associated with cancer cell migration was assessed.

RESULTS

Tumor cells were identified in mice fed either a SD or WD in both anastomotic and lymphatic tissue as early as on POD3. Histology demonstrated that these tumor cells were viable and replicating. In WD-fed mice, the number of tumor cells increased over the early perioperative period and was significantly higher than in mice fed a SD. Microarray analysis of anastomotic tissue found that WD-fed mice had 11 dysregulated genes associated with tumorigenesis.

CONCLUSIONS

A WD promotes cancer cells to permeate a healing anastomosis and migrate into anastomotic and lymphatic tissue forming viable tumor nodules. These data offer a novel recurrence pathogenesis by which the intestinal microenvironment promotes a CRC local-regional recurrence.

New Technologies to Prevent Anastomotic Leak

Leaks from anastomoses can be a serious complication of any gastrointestinal resection. Leaks lead to increased morbidity, delayed postoperative recovery, and potential delays in adjuvant treatment in cancer cases. Prevention of anastomotic leak has been an area of ongoing research for decades. Methods of assessing bowel perfusion have been developed that may provide forewarning of anastomotic compromise. Physical reinforcement of the anastomosis with buttressing material is an available method employed with the goal of preventing leaks. Liquid-based sealants have also been explored. Lastly, interactions between the gut microbiome and anastomotic healing have been investigated as a mean of manipulating the microenvironment to reduce leak rates. Though no single technology has been successful in eliminating leaks, an understanding of these developing fields will be important for all surgeons who operate on the gastrointestinal tract.

Comparison of the efficacy of growth factor collagen and antibiotic collagen on colon anastomosis in experimental animals with peritonitis

INTRODUCTION

In spite of advances in surgical techniques, the significance of anastomosis leak continues in colorectal surgery. There is no ideal method in spite of all studies and technical advances in this field. Our aim of this study was to use fibroblast growth factor collagen (FGF-C) and antibiotic collagen (AB-C) to increase the rate of anastomosis healing in experimental animals with peritonitis.

METHODS

This animal experimental study received ethics committee approval. The animals were divided into three groups of seven animals each; the first group was control, the second group was the fibroblast growth factor collagen group, and the third group was the antibiotic collagen group. Under anesthesia, more than 50% of the colonic lumen was opened 4-5 cm distal to the ileocecal junction to create a defect. Twenty-four hours later, primary anastomosis was performed. The second group had the anastomosis line covered with a cover containing FGF-C. The third group had the anastomosis line covered by material containing AB-C. The experiment was concluded on the postoperative 7th day, and the anastomosis burst pressure, tissue hydroxyproline level, and histopathological assessment were performed.

RESULTS

Though the burst pressure was higher in the experimental groups, it was not statistically significant. In the second and third groups, vascular proliferation and fibroblastic activity appeared to be better than in the control group. Hydroxyproline values were statistically significant in the experimental groups compared to the control group.

CONCLUSION

FGF-C and AB-C may have potential utility in anastomosis healing, especially in those susceptible to infection due to anastomosis leak.

In vivo performance of a bilayer wrap to prevent abdominal adhesions

There is a high prevalence of intra-abdominal adhesions following bowel resection, which can result in chronic pain, bowel obstruction, and morbidity. Although commercial adhesion barriers have been widely utilized for colonic resections, these barriers do not prevent anastomotic leakage resulting from reduced healing of the anastomosis, which can result in long-term health problems. To address this limitation, we have developed an adhesive bilayer wrap with selective bioactivity to simultaneously prevent intra-abdominal adhesion formation and promote anastomotic healing. Reactive electrospinning was used to generate a crosslinked gelatin mesh to serve as a cell-instructive substrate to improve anastomotic healing. A coating of poly(ethylene glycol) (PEG) foam was applied to the bioactive mesh to generate an antifouling layer and prevent intra-abdominal adhesions. After in vitro confirmation of selective bioactivity, the composite wrap was compared after 2 weeks to a commercial product (Interceed^Ⓡ) in an in vivo rat colonic abrasion model for prevention of intra-abdominal adhesions. The composite bilayer wrap was able to prevent intra-abdominal adhesions when clinical placement was maintained. The composite bilayer wrap was further modified to include tissue adhesive properties for improved efficacy. Preliminary studies indicated that the adhesive composite bilayer wrap maintained a maximum shear strength comparable to Interceed^Ⓡ and greater than fibrin glue. Overall, this work resulted in an initial proof-of-concept device that was shown to effectively prevent intra-abdominal adhesion formation in vivo. The composite bilayer wrap studied here could lead to an improved technology for improved healing of intestinal anastomoses.

Bio-inspired swellable hydrogel-forming double-layered adhesive microneedle protein patch for regenerative internal/external surgical closure

Significant tissue damage, scarring, and an intense inflammatory response remain the greatest concerns for conventional wound closure options, including sutures and staples. In particular, wound closure in internal organs poses major clinical challenges due to air/fluid leakage, local ischemia, and subsequent impairment of healing. Herein, to overcome these limitations, inspired by endoparasites that swell their proboscis to anchor to host's intestines, we developed a hydrogel-forming double-layered adhesive microneedle (MN) patch consisting of a swellable mussel adhesive protein (MAP)-based shell and a non-swellable silk fibroin (SF)-based core. By possessing tissue insertion capability (7-times greater than the force for porcine skin penetration), MAP-derived surface adhesion, and selective swelling-mediated physical entanglement, our hydrogel-forming adhesive MN patch achieved ex vivo superior wound sealing capacity against luminal leaks (139.7 ± 14.1 mmHg), which was comparable to suture (151.0 ± 23.3 mmHg), as well as in vivo excellent performance for wet and/or dynamic external and internal tissues. Collectively, our bioinspired adhesive MN patch can be successfully used in diverse practical applications ranging from vascular and gastrointestinal wound healing to transdermal delivery for pro-regenerative or anti-inflammatory agents to target tissues.

Is Circular Fibrin Sealing of Low Rectal Anastomosis Able to Prevent Leakage in 21-Day Follow-up? Randomized Experimental Trial in Pigs

Purpose. Clinically apparent anastomotic leakage (AL) after low anterior rectal resection (LAR; <7 cm from anal verge) using circular double-stapled anastomosis without defunctioning stoma is up to 37.5%. However, it is unclear whether there is reduction of LAR after 21 postoperative days without defunctioning stoma but with extraluminal anastomotic application of fibrin sealant. Methods. Forty-eight-week-old pigs underwent LAR and circular double-stapled anastomosis in end-to-end technique (descendo-rectostomy). Animals were randomized into therapy and control group (cg). Therapy group (n = 20) received additional extraluminal circular anastomotic application of fibrin sealant. Objective was to assess incidence of clinically apparent and nonclinically apparent leakage through the 21st postoperative day. Remaining animals were sacrificed on the 21st day, and anastomotic region was analyzed. In case of earlier diagnosed AL, animals were sacrificed. Results. In cg, we observed clinically and nonclinically AL in 20% (n = 4). No animal was identified with a nonclinical-apparent leakage in this group, and all 4 animals with leakages presented clinical signs. In the therapy group, no animal (0/20) developed clinically apparent leakage signs. There were no leakages in this group, but 3 animals had ulcerative lesions without leak and without clinical signs. These lesions were observed intraluminally at crossing of staple lines after 21 days. In one of these animals, incomplete leakage was observed, blocked by fibrin sealant. Conclusion. In circular stapled colorectal anastomosis, circular fibrin glue sealant successfully protected anastomotic intraluminal wall defects at crossing of staple lines, reducing leakage rate from 20% to 0% (cg vs therapy group) after 21 postoperative days.

Pluronic F127 blended polycaprolactone scaffolds via e-jetting for esophageal tissue engineering

Several attempts have been made to fabricate esophageal tissue engineering scaffolds. However, most of these scaffolds possess randomly oriented fibres and uncontrollable pore sizes. In order to mimic the native esophageal tissue structure, electro-hydrodynamic jetting (e-jetting) was used in this study to fabricate scaffolds with aligned fibres and controlled pore size. A hydrophilic additive, Pluronic F127 (F127), was blended with polycaprolactone (PCL) to improve the wettability of the scaffolds and hence the cell adhesion. PCL/F127 composite scaffolds with different weight ratios (0-12%) were fabricated. The wettability, phase composition, and the mechanical properties of the fabricated scaffolds were investigated. The results show that the e-jetted scaffolds have controllable fibres orientated in two perpendicular directions, which are similar to the human esophagus structure and suitable pore size for cell infiltration. In addition, the scaffolds with 8% F127 exhibited better wettability (contact angle of 14°) and an ultimate tensile strength (1.2 MPa) that mimics the native esophageal tissue. Furthermore, primary human esophageal fibroblasts were seeded on the e-jetted scaffolds. PCL/F127 scaffolds showed enhanced cell proliferation and expression of the vascular endothelial growth factor (VEGF) compared to pristine PCL scaffolds (1.5- and 25.8- fold increase, respectively; P < 0.001). An in vitro wound model made using the PCL/F127 scaffolds showed better cell migration than the PCL scaffolds. In summary, the PCL/F127 e-jetted scaffolds offer a promising strategy for the esophagus tissue repair.

2-Octylcyanoacrylate for the prevention of anastomotic leak

BACKGROUND

Anastomotic leak after colorectal surgery is a significant cause of morbidity and mortality. The aim of this study was to evaluate the impact of a reinforced colo-colonic anastomosis with tissue adhesive, 2-octylcyanoacrylate (2-OCA), on the integrity of anastomotic healing as measured by anastomotic bursting pressure.

METHODS

Sixty-eight female Sprague-Dawley rats underwent a rectosigmoid colon transection and a sutured end-to-end anastomosis followed by randomization to receive no further intervention or reinforcement with the tissue adhesive, 2-OCA. After seven postoperative days, a macroscopic assessment of the anastomosis, mechanical assessment to determine anastomotic bursting pressure, and a detailed semi-quantitative histopathologic healing assessment were performed.

RESULTS

Thirty-four animals were randomized to each group. Study characteristics did not differ between the groups. There was also no difference in the degree of adhesions present postoperatively. Although there was no difference between the net proximal and distal luminal areas in the two groups (0.37 cm²versus 0.55 cm², P = 0.26), the 2-OCA group exhibited evidence of stricture in 15% of anastomoses as compared with 3% in the suture-only group (P < 0.0001). Histologically, the presence of only fibroblasts density was statistically more evident in the 2-OCA group compared with the sutured-only anastomosis (P = 0.0183). There was not a significant increase in mechanical strength in the 2-OCA group (238.9 mm Hg) versus in the suture-only group (231.8 mm Hg). There was no difference in the rate of anastomotic leak in the 2-OCA as compared with the suture-only group (9.1 versus 8.8%).

CONCLUSIONS

Application of 2-OCA to reinforce a colo-colonic anastomosis clinically provides no benefit to its mechanical strength and detrimentally increases the rate of obstruction and/or stricture in this in vivo model.

Impact of tissue adhesives on the prevention of anastomotic leakage of colonic anastomoses: an in vivo study

BACKGROUND

Tissue adhesives (TA) may be useful to strengthen colorectal anastomoses, thereby preventing anastomotic leakage (AL). Previous studies have identified cyanoacrylate (CA) TAs as the most promising colonic anastomotic sealants. This study investigates the protective effects of sealing colonic anastomoses with various CAs.

MATERIALS AND METHODS

Fifty-five Wistar rats underwent laparotomy and transection of the proximal colon. An anastomosis was created with 4 interrupted sutures followed by either application of Histoacryl Flexible, Omnex, Glubran 2, or no TA seal. An additional control group was included with a 12-suture anastomosis and no TA seal. After 7 days, the rats were sacrificed and scored for the presence of AL as the main outcome. Secondary outcomes were the occurrence of bowel obstruction, adhesions, and anastomotic bursting pressure. Histological evaluation was performed.

RESULTS

The highest AL rate was found in the Glubran 2 group (7/11), followed by the 4-sutures group without TA (5/11), and the Omnex group (5/11). Histoacryl Flexible showed the lowest AL rate (2/11). In the control group, only one rat showed signs of AL. Histologically, the highest influx of inflammatory cells was found in the 4-suture group without TA and for Omnex and Glubran 2. Histoacryl Flexible caused more mature collagen deposition when compared to the other TA groups.

CONCLUSIONS

Histoacryl Flexible showed the lowest leakage rate compared to the other TA groups and to the 4-suture control group. Glubran 2 showed the highest AL rate and a high inflammatory response. Histoacryl Flexible was associated with the presence of more mature collagen and seems to promote anastomotic healing.

Tannin-based adhesive for protection of colonic anastomosis in the open abdomen

This study was aimed to evaluate the effect of tannin acid- polyethylene glycol (TP) adhesive on the wound healing process of primary colonic anastomosis in the open abdomen (OA). Adhesion strength test, degradation and hemostatic ability of TP were investigated. In a rat model, after standard colonic anastomoses, rats were divided into three groups: OA group; OA + FG (fibrin glue) group; OA + TP group. Five days after surgery, body weight, anastomotic bursting pressure (ABP), and histology of anastomotic tissue were evaluated. Performance of adhesion strength and hemostatic ability of TP was better than that of FG. The weight of TP decreased by over 50% after 11-day incubation. All rats survived well after surgery. Compared to OA group and OA + FG group, OA + TP group showed a significant improvement in body weight, ABP and healing state. Application of TP adhesive, used as an auxiliary treatment of colonic anastomosis operation, improved the wound strength and promoted the anastomotic healing after OA.

International consensus statement regarding the use of animal models for research on anastomoses in the lower gastrointestinal tract

PURPOSE

This project aimed to reach consensus on the most appropriate animal models and outcome measures in research on anastomoses in the lower gastrointestinal tract (GIT). The physiology of anastomotic healing remains an important research topic in gastrointestinal surgery. Recent results from experimental studies are limited with regard to comparability and clinical translation.

METHODS

PubMed and EMBASE were searched for experimental studies investigating anastomotic healing in the lower GIT published between January 1, 2000 and December 31, 2014 to assess currently used models. All corresponding authors were invited for a Delphi-based analysis that consisted of two online survey rounds followed by a final online recommendation survey to reach consensus on the discussed topics.

RESULTS

Two hundred seventy-seven original articles were retrieved and 167 articles were included in the systematic review. Mice, rats, rabbits, pigs, and dogs are currently being used as animal models, with a large variety in surgical techniques and outcome measures. Forty-four corresponding authors participated in the Delphi analysis. In the first two rounds, 39/44 and 35/39 participants completed the survey. In the final meeting, 35 experts reached consensus on 76/122 items in six categories. Mouse, rat, and pig are considered appropriate animal models; rabbit and dog should be abandoned in research regarding bowel anastomoses. ARRIVE guidelines should be followed more strictly.

CONCLUSIONS

Consensus was reached on several recommendations for the use of animal models and outcome measurements in research on anastomoses of the lower GIT. Future research should take these suggestions into account to facilitate comparison and clinical translation of results.

Colorectal anastomotic healing: why the biological processes that lead to anastomotic leakage should be revealed prior to conducting intervention studies

BACKGROUND

Anastomotic leakage (AL) remains the most dreaded complication after colorectal surgery and causes high morbidity and mortality. The pathophysiology of AL remains unclear, despite numerous studies that have been conducted on animals and humans, probably due to the undetermined healing process of colorectal anastomoses. Increasing basic knowledge on this healing process may shed more light on causal factors of AL, and additionally reduce the quantity and accelerate the quality of experimental studies. In this debate article, our aim was to provide different perspectives on what is known about the colorectal healing process in relation to wound healing and AL.

DISCUSSION

Since knowledge on anastomotic healing is lacking, it remains difficult to conclude which factors are essential in preventing AL. This is essential information in the framework of humane animal research, where the focus should lie on Replacement, Reduction and Refinement (3Rs). While many researchers compare anastomotic healing with wound healing in the skin, there are substantial recognized differences, e.g. other collagen subtypes and different components involved. Based on our findings in literature as well as discussions with experts, we advocate stop considering anastomotic healing in the gastrointestinal tract and cutaneous healing as a similar process. Furthermore, intervention studies should at least address the anastomotic healing process in terms of histology and certain surrogate markers. Finally, the anastomotic healing process ought to be further elucidated - with modern techniques to achieve 3Rs in animal research--to provide starting points for potential interventions that can prevent AL.

Staple line/anastomotic reinforcement and other adjuncts: do they make a difference?

Since the development of the stapled intestinal anastomosis, efforts have been aimed at reducing complications and standardizing methods. The main complications associated with stapled anastomoses include bleeding, device failure, and anastomotic failure (leaks and strictures). These complications are associated with increased cost of care, increase in cancer recurrence, decreased overall survival, poor quality of life, and in some cases the need for further procedures including a diverting ostomy. Reducing these complications therefore has important implications. To this end, techniques to reduce the incidence of anastomotic complications have been the focus of many investigators. In this review, we summarize the current staple line reinforcement technology as well as other adjunctive measures, and specifically discuss the role of biologic materials in this realm.

Protection of colonic anastomosis with platelet-rich plasma gel in the open abdomen

BACKGROUND

Although evidence for colonic anastomosis in the damage control abdomen continues to accumulate, anastomotic leak is common and associated with greater morbidity. The purposes of our study was to evaluate the effect of platelet-rich plasma (PRP) gel on the healing of colon anastomosis and anastomotic strength in the open abdomen.

METHODS

PRP was prepared by enriching whole blood platelet concentration from healthy rat. In the rodent model, standard colonic anastomoses followed by closure of abdomen (Control; n=10) and anastomoses followed by open abdomen (OA; n=10) were compared to PRP-sealed anastomoses in open abdomen (OA+PRP; n=10). One week after surgery, body weight, anastomotic bursting pressure, hydroxyproline concentration, and histology of anastomotic tissue were evaluated.

RESULTS

All rats survived surgery and had no signs of anastomotic leakage. Compared with the control and PRP group, OA group exhibited a significant decrease in body weight, anastomotic bursting pressure, hydroxyproline concentration, and collagen deposition. No significant difference was detected in these variables between the PRP group and the control group.

CONCLUSION

PRP gel application prevented delayed anastomotic wound healing after open abdomen, which suggested that anastomotic sealing with PRP gel might improve outcome of colonic injuries in the setting of open abdomen.

Bovine pericardium patch wrapping intestinal anastomosis improves healing process and prevents leakage in a pig model

Failure of intestinal anastomosis is a major complication following abdominal surgery. Biological materials have been introduced as reinforcement of abdominal wall hernia in contaminated setting. An innovative application of biological patch is its use as reinforcement of gastrointestinal anastomosis. The aim of study was to verify whether the bovine pericardium patch improves the healing of anastomosis, when in vivo wrapping the suture line of pig intestinal anastomosis, avoiding leakage in the event of deliberately incomplete suture. Forty-three pigs were randomly divided: Group 1 (control, n = 14): hand-sewn ileo-ileal and colo-colic anastomosis; Group 2 (n = 14): standard anastomosis wrapped by pericardium bovine patch; Group 3 (n = 1) and 4 (n = 14): one suture was deliberately incomplete and also wrapped by patch in the last one. Intraoperative evaluation, histological, biochemical, tensiometric and electrophysiological studies of intestinal specimens were performed at 48 h, 7 and 90 days after. In groups 2 and 4, no leak, stenosis, abscess, peritonitis, mesh displacement or shrinkage were found and adhesion rate decreased compared to control. Biochemical studies showed mitochondrial function improvement in colic wrapped anastomosis. Tensiometric evaluations suggested that the patch preserves the colic contractility similar to the controls. Electrophysiological results demonstrated that the patch also improves the mucosal function restoring almost normal transport properties. Use of pericardium bovine patch as reinforcement of intestinal anastomosis is safe and effective, significantly improving the healing process. Data of prevention of acute peritonitis and leakage in cases of iatrogenic perforation of anastomoses, covered with patch, is unpublished.

Growth factors and gastrointestinal anastomotic healing

BACKGROUND

Failure of anastomotic healing in the gastrointestinal tract is a major source of surgery-related morbidity, repeated surgical procedures, and impaired quality of life. Growth factors have been shown to be involved in healing processes in various tissues including the gastrointestinal tract. This opens the perspective to use growth factors therapeutically to support impaired anastomotic healing. The aim of the present study was to review the particular role of several growth factors in different phases of anastomotic healing, experimental approaches of growth factor application, and to discuss possibilities and limitations of growth factor-directed interventions in gastrointestinal surgery.

MATERIALS AND METHODS

A PubMed search was performed to examine the potential role of fibroblast growth factor, epidermal growth factor, heparin binding EGF-like growth factor, transforming growth factor β, insulin-like growth factor I, vascular endothelial growth factor, and platelet-derived growth factor during anastomotic healing.

RESULTS

Growth factors show beneficial effects on a broad range of cell types and regulate various processes during all phases of tissue healing. Despite extensive research in the field of growth factors, additional evidence is needed before translating into a clinical setting.

CONCLUSIONS

Future research should focus on adequate sustained but limited drug delivery. Undesired side effects, such as formation of strictures, development of peritoneal adhesions, and potential induction of malignancies, have to be reflected. Although growth factor application is currently far from clinical routine in gastrointestinal surgery, it might find application in selected patients at risk for impaired anastomotic healing, such as patients with long-time steroid therapy, immunosuppressives, inflammatory disorders, sepsis, hemodynamic shock, malnutrition, or neoadjuvant radiochemotherapy.

Effects of bromopride on the healing of left colonic anastomoses in rats with induced abdominal sepsis

PURPOSE

To evaluate the effects of bromopride on the healing of left colonic anastomoses in rats with induced abdominal sepsis.

METHODS

Forty rats were divided into two groups to receive either bromopride (experimental group- E) or saline (control group- C). Each group was divided into subgroups of ten animals each to be euthanized on third (E3 and C3) or seventh day (E7 and C7) after surgery. Sepsis was induced by cecal ligation and puncture. The rats underwent segmental left colon resection and end-to-end anastomosis. Adhesion formation, tensile strength and hydroxyproline concentration were assessed. Histomorphometry of collagen and histopathological analysis were also performed.

RESULTS

On postoperative third day, anastomoses in bromopride-treated animals showed lower tensile strength (p=0.02) and greater reduction in hydroxyproline concentration (p=0.04) than in control animals. There was no statistical difference in these parameters on seventh day, and the remaining parameters were similar across subgroups. Collagen content was also similar across subgroups.

CONCLUSION

In the presence of abdominal sepsis, the administration of bromopride was associated with decreased tensile strength and hydroxyproline concentration in left colonic anastomoses in rats three days after surgery.

Expression of metalloproteinases and interleukins on anastomoses in septic rats

BACKGROUND

Anastomotic dehiscence is the most severe complication of colorectal surgery and its incidence increases in the presence of infection. It has been reported that immune factors or the activity of matrix metalloproteinases (MMP) may mediate the loss of anastomotic strength in the first postoperative days. In this study, we investigated the effects of abdominal sepsis on the MMP and interleukin (IL) gene expression in left colonic anastomoses in rats.

MATERIALS AND METHODS

Forty rats were divided into two groups of 20 animals according to the presence (group S) or absence (group N) of sepsis induction by cecal ligation and perforation during left colonic anastomosis. Each group was divided into subgroups for euthanasia on the third (N3 and S3) or seventh (N7 and S7) postoperative day (POD). A colonic segment containing anastomosis was removed for analysis of the expression of MMP1a, MMP8, MMP13, IL1β, IL6, IL10, TNFα, and IFNγ genes.

RESULTS

The anastomoses with abdominal sepsis showed increased MMP1a gene expression and decreased MMP8 gene expression both on the third and seventh POD. There was no change in the expression of MMP13. There was an increase in the expression of IL10 only on the third POD and a negative modulation of IL1β, IFNγ, and IL6 genes on both periods. The TNFα gene expression was negatively modulated on the third POD and became not modulated on the seventh POD.

CONCLUSION

Abdominal sepsis induced a specific inflammatory pattern with increased MMP1a and IL10 gene expression and negative modulation of MMP8, IL1β, IFNγ, and TNFα gene expression in left colonic anastomoses in rats.

External coating of colonic anastomoses: a systematic review

PURPOSE

Colon anastomotic leakage remains both a frequent and serious complication in gastrointestinal surgery. External coating of colonic anastomoses has been proposed as a means to lower the rate of this complication. The aim of this review was to evaluate existing studies on external coating of colonic anastomoses.

METHODS

CINAHL, EMBASE, and PubMed were searched up to September 2011 to identify studies evaluating external coating of colonic anastomoses.

RESULTS

Forty studies have evaluated 20 different coating materials, of which only fibrin sealant, omental pedicle graft, and hyaluronic acid/carboxymethylcellulose have been used in humans. Fibrin sealant has shown positive, however not significant, results. Omental pedicle graft can be used safely, yet without beneficial effects, whereas hyaluronic acid/carboxymethylcellulose should be avoided due to increased complications. The remaining coating materials have solely been evaluated in experimental animals with many contradictory and few positive results.

CONCLUSIONS

External coating of colonic anastomoses has yet failed to show convincing results. Randomized clinical trials and high-quality experimental studies are warranted to determine the role of fibrin sealant, omental pedicle graft, and other coating materials for prevention of colon anastomotic leakage.

A highly elastic and adhesive gelatin tissue sealant for gastrointestinal surgery and colon anastomosis

BACKGROUND

We describe the development of a highly elastic and adhesive surgical tissue sealant, based on photochemically crosslinked gelatin, for sealing sutured incisions in the gastrointestinal (GI) tract in a rabbit surgical model and in a canine colon anastomosis study.

METHODS

The study included in vitro assessment of mechanical parameters of the tissue sealant and in vivo analysis of burst strength and histology at 24 h, 3 days and 7 days post surgery, in a rabbit model, to assess progress of wound healing at the suture sites. Utility of this sealant to repair and seal a lower colonic resection and anastomosis procedure in a canine model was also investigated.

RESULTS

We show that a photopolymerised gelatin tissue sealant provides effective sealing of GI incisions and facilitates wound healing with no evidence of inflammation up to 28 days post-surgery. Blending of derivatised gelatin with underivatised gelatin allowed tuning of elasticity and elastic modulus of the photopolymerised sealant to suit surgical applications. High tissue adhesive strength was maintained at all blend ratios and exceeded 100 kPa.

CONCLUSIONS

This highly elastic and adhesive photopolymerised gelatin tissue sealant offers a number of advantages over currently available sealants suitable for GI surgical procedures.

The effect of fibrin glue on the early healing phase of intestinal anastomoses in the rat

PURPOSE

Protecting the anastomotic integrity using suture or staple line reinforcement remains an important goal for ongoing research. The present comprehensive study aims to establish the effects of fibrin glue on the early phase of anastomotic healing in the rat intestine.

METHODS

One hundred and eight young adult male Wistar rats underwent resection and anastomosis of both the ileum and colon. In half, fibrin glue was applied around the anastomoses. Parameters for repair included wound strength, both bursting pressure and breaking strength at days 1, 3, and 5 after operation; hydroxyproline content; and histology, the latter also after 7 days.

RESULTS

A transient colonic ileus was observed in the experimental group. Anastomotic breaking strength was always similar in both the control and fibrin glue groups. Anastomotic bursting pressures remained low at days 1 and 3, without any differences between the groups. In both groups, the bursting pressure increased sharply (p < 0.001) between days 3 and 5. At day 5, the bursting pressure in the fibrin glue group remained below than that in the controls, although only significantly (p = 0.0138) so in the ileum. At day 5, but not at day 7, the wounds in the fibrin glue group contained less collagen. Other aspects of microscopic wound architecture appeared to be the same.

CONCLUSIONS

There is no justification for using fibrin glue on patent anastomoses constructed under low-risk conditions. Its potential benefit under conditions where chances for anastomotic leakage are enhanced needs further investigation.

Extracellular matrices for gastrointestinal surgery: Ex vivo testing and current applications

AIM: To assess the effects of bile and pancreatic juice on structural and mechanical resistance of extracellular matrices (ECMs) in vitro.

METHODS: Small-intestinal submucosa (SIS), porcine dermal matrix (PDM), porcine pericardial matrix (PPM) and bovine pericardial matrix (BPM) were incubated in human bile and pancreatic juice in vitro. ECMs were examined by macroscopic observation, scanning electron microscopy (SEM) and testing of mechanical resistance.

RESULTS: PDM dissolved within 4 d after exposure to bile or pancreatic juice. SIS, PPM and PDM retained their integrity for > 60 d when incubated in either digestive juice. The effect of bile was found to be far more detrimental to mechanical stability than pancreatic juice in all tested materials. In SIS, the loss of mechanical stability after incubation in either of the digestive secretions was less distinct than in PPM and BPM [mFmax 4.01/14.27 N (SIS) vs 2.08/5.23 N (PPM) vs 1.48/7.89 N (BPM)]. In SIS, the extent of structural damage revealed by SEM was more evident in bile than in pancreatic juice. In PPM and BPM, structural damage was comparable in both media.

CONCLUSION: PDM is less suitable for support of gastrointestinal healing. Besides SIS, PPM and BPM should also be evaluated experimentally for gastrointestinal indications.