Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Cross-linked electrospun cartilage acellular matrix/poly(caprolactone-co-lactide-co-glycolide) nanofiber as an antiadhesive barrier

In this work, we chose cartilage acellular matrix (CAM) as a promising antiadhesive material because CAM effectively inhibits the formation of blood vessels, and we used electrospinning to prepare antiadhesive barriers. Additionally, we synthesized N-hydroxysuccinimide (NHS)-poly(caprolactone-co-lactide-co-glycolide)-NHS (MP) copolymers (to tune degradation) as a cross-linking agent for CAM. This is the first report on the development of electrospun cross-linked (Cx) CAM/MP (CA/P) nanofiber (NF) (Cx-CA/P-NF) with a tunable degradation period as an antiadhesive barrier. Compared with the CA/P-NF before cross-linking, the electrospun Cx-CA/P-NF after cross-linking showed different biodegradation. Cx-CA/P-NF significantly inhibited the in vitro attachment and proliferation of human umbilical vein endothelial cells (HUVECs), as confirmed by an MTT assay and scanning electron microscopy images. Cx-CA/P-NFs implanted between a surgically damaged peritoneal wall and cecum gradually degraded in 7 days; this process was monitored by NIR imaging. The in vivo evaluation of the anti-tissue adhesive effect of Cx-CA/P-NFs revealed little adhesion, few blood vessels, and negligible inflammation at 7 days determined by hematoxylin and eosin staining. ED1 staining of Cx-CA/P-NFs showed infiltration of few macrophages because of the inflammatory response to the Cx-CA/P-NF as compared with an untreated injury model. Additionally, Cx-CA/P-NFs significantly suppressed the formation of blood vessels between the peritoneal wall and cecum, according to CD31 staining. Overall, Cx-CA/P-NFs yielded little adhesion, infiltration by macrophages, or formation of blood vessels in a postoperative antiadhesion assay. Thus, it is reasonable to conclude that the Cx-CA/P-NF designed herein successfully works as an antiadhesive barrier with a tunable degradation period.

STATEMENT OF SIGNIFICANCE

The cartilage acellular matrix (CAM) can inhibit the formation of fibrous tissue bridges and blood vessels between the tissue at an injured site and the surrounding healthy tissues. However, CAM has not been rigorously investigated as an antiadhesive barrier. In this manuscript, the cross-linked CAM nanofiber (Cx-CA/P-NF) designed herein successfully works as an antiadhesive barrier. Cx-CA/P-NFs yielded little adhesion, infiltration by macrophages, or formation of blood vessels in a postoperative antiadhesion assay. Moreover, we demonstrated the suitable properties of Cx-CA/P-NF such as easy cross-linking by maintaining the antiadhesive properties, controllable biodegradation, and in vivo antiadhesive effect of Cx-CA/P-NF.

Prevention of Intraabdominal Adhesions: An Experimental Study Using Mitomycin-C and 4% Icodextrin

Background:

Intraabdominal adhesions remain a significant cause of morbidity and mortality. Moreover, intraabdominal adhesions can develop in more than 50% of abdominal operations.

Aims:

We compared the anti-adhesive effects of two different agents on postoperative adhesion formation in a cecal abrasion model.

Study Design:

Experimental animal study.

Methods:

Forty Wistar albino type female rats were anesthetized and underwent laparotomy. Study groups comprised Sham, Control, Mitomycin-C, 4% Icodextrin, and Mitomycin-C +4% Icodextrin groups. Macroscopic and histopathological evaluations of adhesions were performed.

Results:

The frequencies of moderate and severe adhesions were significantly higher in the control group than the other groups. The mitomycin-C and Mitomycin-C +4% Icodextrin groups were associated with significantly lower adhesion scores compared to the control group and 4% Icodextrin group scores (p=0.002 and p=0.008, respectively). The adhesion scores of the Mitomycin-C group were also significantly lower than those of the 4% Icodextrin group (p=0.008).

Conclusion:

Despite its potential for bone marrow toxicity, Mitomycin-C seems to effectively prevent adhesions. Further studies that prove an acceptable safety profile relating to this promising anti-adhesive agent are required before moving into clinical trials.

Evaluation of 4DryField® PH as Adhesion Prevention Barrier Tested in an Optimized Adhesion Model in Rats

BACKGROUND

Adhesions due to pelvic/abdominal surgery are a common serious pathology possibly entailing severe complications. This study investigates the adhesion prevention capability of the novel starch-based agent 4DryField® PH, which together with saline solution forms a barrier gel. Herein, an optimized adhesion model (OPAM) inducing severe adhesions/agglutinations with high reproducibility was used.

METHODS

In 19 Lewis rats, a 1 × 2 cm abdominal wall defect was created, the peritoneum of the neighboring cecum was abraded, and both injured areas were approximated by suture. Rats were randomized to control (n = 10) or 4DryField PH treatment (n = 9) groups. Another 8 rats had sham surgery for safety assessment of 4DryField PH. At day 7, the quantity and quality of adhesions were assessed macro-/microscopically and evaluated statistically.

RESULTS

4DryField PH treatment significantly reduced the incidence and severity of adhesions as verified by significantly improved adhesion scorings (0.4 vs. 4.5; 1.1 vs. 9). Histology revealed reconstitution of the cecum and abdominal wall including regeneration of the visceral/parietal peritoneum. In sham-operated rats, 4DryField PH did not induce adhesion formation.

CONCLUSIONS

4DryField PH gel was highly effective in preventing adhesions. Histologically, the injured cecum and abdominal wall regenerated well in the presence of 4DryField PH. Considering the severity of OPAM trauma, the potential of 4DryField PH to prevent adhesions can be rated excellent.

Cell-based therapy for preventing postoperative adhesion and promoting regeneration after hepatectomy

Postoperative adhesion is a critical clinical issue after almost all abdominal or pelvic surgeries including liver surgery. Postoperative adhesion causes several complications, such as small bowel obstruction and chronic abdominal pain. Furthermore, it makes reoperation much more difficult, leading to increased mortality and morbidity rate. Postoperative adhesion is particularly problematic for repeated hepatectomy, since hepatic malignant neoplasm recurs frequently and repeated hepatectomy is widely used as one of the most curative treatments. Several treatments to reduce postoperative adhesion have been developed, which include laparoscopic surgery, administration of pharmacological agents and use of prophylactic barrier materials. However, none of them are optimal. We have proposed a novel treatment using a cell sheet of fetal liver mesothelial cells (FL-MCs) to prevent postoperative adhesion in a novel mouse model. Besides adhesion, repeated hepatectomy has another serious problem; although the liver has a remarkable ability to regenerate, the recovery of liver mass and function of the remnant liver after multiple repeated hepatectomy is limited. The FL-MC cell sheet enhances proliferation of hepatocytes after hepatectomy by providing growth factors for hepatocytes. Thus the FL-MC sheet could simultaneously solve the two problems associated with repeated hepatectomy.

Effect of Hypericum perforatum on intraperitoneal adhesion formation in rats

INTRODUCTION

The aim of this study was to evaluate the efficacy of Hypericum perforatum for prevention of adhesion formation in rats.

MATERIAL AND METHODS

Twenty-four female wistar rats underwent left uterine horn adhesion model. Rats were randomised into 4 groups. Group 1 (Control): Closure of abdominal incision without any agent administration. Group 2: Closure of incision after administration of intraperitoneal (i.p.) Ringer's lactate solution. Group 3: Closure of incision after administration of i.p. olive oil (diluent of H. perforatum). Group 4: Hypericum perforatum extract (Ecodab(®)) was administered i.p. before the closure of incision. Fourteen days later, relaparatomy was performed and surgical adhesion scores, inflammation and fibrosis scores were noted. Groups were compared according to these scores.

RESULTS

There was statistical significant difference between ringer's lactate group and olive oil group according to surgical adhesion score (p = 0.009). However, groups were not different according to inflammation and fibrosis scores (p > 0.05).

CONCLUSIONS

Despite antiinflammatory, antioxidants and antimicrobial properties of H. perforatum, our results revealed no positive effect of H. perforatum on the prevention of intraperitoneal adhesion formation.

Prevention of intraabdominal adhesions by local and systemic administration of immunosuppressive drugs

Background:

Intraperitoneal adhesion formation is a serious postsurgical issue. Adhesions develop after damage to the peritoneum by surgery, irradiation, infection or trauma.

Objectives:

Using a rat model, we compared the effectiveness of systemic and intraperitoneally administered common immunosuppressive drugs for prevention of postoperative intraperitoneal adhesions.

Materials and Methods:

Peritoneal adhesions were induced in 98 female Wistar-Albino rats by cecal abrasion and peritoneal excision. Rats were randomly separated into seven groups, each containing fourteen rats, and the standard experimental model was applied to all of rats. 14 days later, rats were euthanized, intraperitoneal adhesions were scored and tissues were examined histologically using hematoxylin/eosin and Masson’s trichrome staining.

Results:

Throughout the investigation, no animal died during or after surgery. In all of experimental groups, decrease in fibrosis was statistically significant. Decrease in fibrosis was most prominently in intraperitoneal tacrolimus group (P = 0.000), and decrease was least in intraperitoneal cyclosporine group (P = 0.022). Vascular proliferation was significantly decreased in all experimental groups (P < 0.05) except for systemic tacrolimus group (P = 0.139). Most prominent reduction in vascular proliferation was in intraperitoneal tacrolimus group (P = 0.000).

Conclusions:

Administration of immunosuppressive drugs is effective for prevention of intraperitoneal adhesions.

Is there a role for intraperitoneal administration of heparin in hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis of colorectal cancer origin? Current data and future orientations

In experimental studies, the intraperitoneal administration of heparin has been shown to attenuate cancer growth, reduce the formation of postoperative adhesions and possess immunomodulatory properties of oncological benefit for peritoneal carcinomatosis of colorectal cancer origin. Combined with data suggesting that the intraperitoneal administration of heparin can reduce the permeability and increase the ultrafiltration of the peritoneal membrane, we hypothesize that intraperitoneally administrated heparin could be a useful adjunction to the currently used hyperthermic intraperitoneal chemotherapy (HIPEC) regimens.

Adhesion prevention in an intraperitoneal wound model: performance of two resorbable hemostats in a controlled study in rabbits

Adhesions, particularly in the abdominal and pelvic cavities, represent a significant clinical problem. Among other complications, they are considered the most common cause of intestinal obstructions in the Western world. The purpose of this study was to evaluate two commercially available hemostats for their ability to prevent adhesion formation in an abdominal wound model. The hemostats, a microfibrillar collagen-based composite and microporous polysaccharide spheres were used in a rabbit abdominal model. In the model the cecum was abraded and a peritoneal defect was created on the abdominal sidewall. The test materials were applied over the defects. Clinical and histological results were compared with control (no application of any hemostat at the defect site) on postoperative day 14. The results showed a significant reduction in the incidence, extent and severity of adhesions for both surgical hemostat materials compared with control. The microfibrillar collagen-based composite showed a total absence of adhesions and a high level of reperitonealization. This preclinical study suggests that the use of surgical hemostats may help to reduce or eliminate adhesions and may promote reperitonealization.

Seprafilm® adhesion barrier: (1) a review of preclinical, animal, and human investigational studies

The aim of this study was to provide a single site resource for investigators, clinicians, and others seeking preclinical, animal, and human investigational studies concerning the postsurgical, anti-adhesion barrier Seprafilm™ (Genzyme Corporation, Cambridge, MA). All published preclinical, animal, human extra-abdominal research as of July 2011 have been summarized and included in this document. Searches of Medline and EMBASE Drugs and Pharmaceuticals databases were conducted for original preclinical, animal, and human extra-abdominal studies involving Seprafilm. Preclinical, animal, and extra-abdominal human investigational studies are the study selection for this manuscript. Intraabdominal use is discussed in the accompanying manuscript. Data extraction includes systematic manuscript review. Summary of preclinical, animal, and extra-abdominal human investigational use of Seprafilm by surgical discipline were gathered for data synthesis. The clinical use of Seprafilm, which was approved by the FDA for intra-abdominal procedures, is supported by preclinical and animal studies relating to general surgical and obstetrical/gynecological applications. Findings from preclinical, animal, and human investigational studies at other sites throughout the body raises the potential for additional human clinical trials to assess efficacy and safety following surgical procedures at non-abdominal locations.

A membrane slurry reduces postoperative adhesions in rat models of abdominal surgery

BACKGROUND

Sodium hyaluronate and carboxymethylcellulose (HA-CMC) membrane is an effective barrier material for limiting postoperative adhesions, but can be difficult to apply in certain situations due to its physical properties. We tested whether HA-CMC membrane hydrated in saline (slurry) is an effective alternative to HA-CMC membrane for preventing surgical adhesions in rat models of abdominal surgery.

MATERIALS AND METHODS

All studies were performed in rat cecal abrasion or sidewall defect models of adhesion formation. Adhesions were examined 7 d after surgery. In separate studies, the effects of variations in slurry composition, volume, and site of application on anti-adhesive properties were studied and compared with untreated controls. Finally, the effectiveness of HA-CMC membrane slurry for preventing adhesions was compared with that of conventional HA-CMC membrane.

RESULTS

Application of HA-CMC membrane slurry to traumatized tissue resulted in a significant reduction in the incidence of adhesions compared with untreated controls in both rat surgery models. Slurry was equally effective when applied in low and high film-to-volume formulations, but had minimal effect when applied in a small volume or at a location distal to the injury. Comparison of HA-CMC membrane slurry and conventional HA-CMC membrane indicated similar efficacy for reducing postoperative adhesions.

CONCLUSIONS

In rat models of abdominal surgery, HA-CMC membrane slurry reduced postoperative adhesion formation and may be an effective alternative for HA-CMC membrane in situations where its use is limited by its physical properties.

Reduction of postsurgical adhesions in a rat model: a comparative study

BACKGROUND

Adhesion formation after peritoneal surgery is a major cause of postoperative bowel obstruction, infertility, and chronic pelvic pain. In this study, we compared the possible individual effects of phosphatidylcholine (PC), Seprafilm II, and tissue plasminogen activator (t-PA) and the combined effects of phosphatidylcholine and t-PA on postoperative adhesion formation in a rat surgical model.

MATERIALS AND METHODS

A total of 50 Wistar male rats underwent median laparotomy and standardized abrasion of the visceral and parietal peritoneum. phosphatidylcholine, Seprafilm II, and t-PA alone and phosphatidylcholine and t-PA in combination were applied intraperitoneally at the end of the surgical procedure. Seven days after surgery, a relaparotomy was performed for adhesion grading and histopathological examination.

RESULTS

A comparison of adhesion stages demonstrated a significant difference between the control group and the study groups (p<0.001). The adhesion grade of the combined treatment group was statistically different from that of the other groups (p<0.05). In the t-PA group and the combined group, six and two rats, respectively, developed hematomas locally on the cecum.

CONCLUSIONS

PC, t-PA, and Seprafilm II used individually reduced the adhesion grade. The t-PA and phosphatidylcholine combination was most effective in reducing adhesion formation. On the other hand, usage of t-PA alone or in combination may increase risk of bleeding. More detailed studies are needed, and future studies on the efficacy of a material for decreasing adhesion formation should include a comparison of several control materials in the same model.