Evaluation of a Spray-type, Novel Dextrin Hydrogel Adhesion Barrier Under Laparoscopic Conditions in a Porcine Uterine Horn Adhesion Model

Update on antiadhesion barriers and therapeutics in gynecological surgery

PURPOSE OF REVIEW

Postoperative adhesions remain a clinical challenge to both patients and providers, as they are associated with significant complications and a high economic burden. This article provides a clinical review of currently available antiadhesive agents and promising new therapies that have advanced past animal studies.

RECENT FINDINGS

Several agents have been investigated on their ability to reduce adhesion formation; however, there is no widely acceptable option. The few available interventions are barrier agents and while low-quality evidence suggests that they may be more effective than no treatment, there is no general agreement on their overall efficacy. There is an abundance of research on new solutions; however, their clinical efficacy is yet to be determined.

SUMMARY

Although a wide range of therapeutics have been investigated, majority are halted in animal models with only a select few being studied in humans and ultimately available in the market. Many agents have shown effectiveness in reducing adhesion formation, however, that has not been translated to improvement in clinically relevant outcomes; hence the need for high-quality large randomized trials.

Prevention of postoperative adhesion with a colloidal gel based on decyl group-modified Alaska pollock gelatin microparticles

Postoperative adhesion, bonding of the abdominal wall to damaged organs, causes severe complications after abdominal surgery. Despite the availability of physical barriers (i.e., solutions, films, and hydrogels), adhesion prevention materials that are a single-substance system with stability in wet tissue and ease of use have not been reported. Here, we report a microparticle based, sprayable adhesion prevention material comprising decyl group modified Alaska pollock gelatin (C10-ApGltn). C10-ApGltn microparticles (C10-MPs) were prepared by a coacervation method, freeze drying, and thermal crosslinking. The C10-MPs adhered to and formed a colloidal gel layer on intestinal serosal tissue by hydration without any crosslinking agents. After hydration of the C10-MPs, the resulting colloidal gel layer did not adhere to other tissues. Additionally, the C10-MP colloidal gel layer formed on the stomach serosal tissue showed stability when submersed in saline for 2 days. The colloidal gel layer also showed tissue followability. An in vivo rat adhesion model revealed that C10-MP colloidal gel layer on the cecum and abdominal wall defects effectively reduced postoperative adhesion and induced tissue remodeling, including re-mesothelialization. Therefore, C10-MPs are a potential anti-adhesion material for preventing postoperative adhesion. STATEMENT OF SIGNIFICANCE: We evaluated the postoperative adhesion prevention ability of a colloidal gel based on decyl group modified Alaska pollock gelatin (ApGltn) microparticles (C10-MPs). These microparticles are sprayable and form a colloidal gel with only hydration on the gastrointestinal tissue. We revealed that the modification of the decyl group into ApGltn improved the stability of C10-MP colloidal gel on the tissue by hydrophobic interaction in the in-vitro experiments. The gel prevented postoperative adhesion by being a physical barrier in the in-vivo rat adhesion model.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Co-Culture of Bone Marrow Mesenchymal Stem Cells Regulates the Fibrotic Response of Endometrial Stromal Cells

This study explored the protective effects and mechanisms of bone marrow mesenchymal stem cells (BMSCs) on the fibrotic response of endometrial stromal cells. The endometrial cells were isolated from intrauterine adhesions (IUA) patients and assigned into control group, TGF-β1 group, BMSC group which was co-cultured with BMSCs in presence of TGF-β1; Exo group (treated with BMSCs-originated exosomes); Exo-inhibitor group (treated with exosome-specific inhibitors) followed by analysis of α-SMA and Vimentin level, cell viability and expression of TGFBR2, TGFβ-1, Fibronectin (FN), α-SMA, Collagen 1α1 (Col1a1), Smad2/3 and p-Smad2/3. After TGF-β1 treatment, cells exhibited higher expression of p-Smad2/3, TGFBR2, FN, TGF-SMA and COL1A1 along with reduced cell proliferation. However, BMSCs-originated exosomes or co-culture with BMSCs reversed these changes which could be inverted by exosome-specific inhibitors. In conclusion, BMSCs-originated exosomes and BMSCs exerted an anti-fibrosis effect, which was possibly through regulation of TGFβ1/Smad2/Smad3 signalling pathway in endometrial stromal cells.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

A new spray-type adhesion barrier (AdSpray) improves condition for surgical treatment in the reversal of Hartmann procedure: A case report

RATIONALE

Hartmann procedure (HP) often causes severe postoperative adhesions in the pelvic space; therefore, the reversal of Hartmann procedure (RHP) is a challenging surgery. A new spray-type antiadhesion agent, AdSpray, has been reported to be useful in three-dimensional fields such as the liver. However, there are no reports of its use in HP. We present a case of a male patient with rectal cancer who underwent laparoscopic HP with AdSpray to prevent postoperative adhesions.

PATIENT CONCERNS

A 52-year-old man presented with melena and constipation.

DIAGNOSIS

Colonoscopy revealed an almost obstructive type II tumor at the rectosigmoid colon, and histopathological examination revealed moderately differentiated adenocarcinoma. Enhanced abdominal computed tomography revealed slightly enlarged regional lymph nodes but no ascites around the tumor, and there was no metastasis to the liver or lungs. Therefore, we diagnosed clinical stage T4aN1bM0 rectosigmoid colon cancer. Intraoperatively, a metastatic tumor of the liver surface and a high degree of valve retention in the oral colon were identified.

INTERVENTIONS

After performing laparoscopic HP with AdSpray, we scheduled a laparoscopic RHP with staged hepatic surgery for synchronous liver metastasis from colorectal cancer 1 month later.

OUTCOMES

No postoperative inflammatory adhesions were observed in the pelvis or around the rectal stump, allowing us to perform RHP by a single-incision laparoscopic surgery from the stoma site without any problem. The operation time for RHP was 80 minutes; the patient was in good general condition after the operation, and he was discharged on postoperative day 7.

LESSONS

In laparoscopic HP, Adspray was easy to use for three-dimensional fields such as the pelvis and effectively prevented postoperative inflammatory adhesions. Thus, RHP may become less risky and be performed more as a minimally invasive surgery.

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.

Clinical use of indocyanine green during nerve-sparing surgery for deep endometriosis

OBJECTIVE

To describe the anatomic and technical highlights of a novel nerve-sparing surgery in deep endometriosis (DE) using near-infrared (NIR) fluorescence technology and indocyanine green (ICG).

DESIGN

Stepwise demonstration of this method with narrated video footage.

SETTING

An urban general hospital.

PATIENT(S)

A 48-year-old woman was referred for severe chronic pelvic pain, dysmenorrhea, and pain on defecation, all of which were resistant to medication therapy. Magnetic resonance imaging revealed uterine adenomyosis and left ovarian endometrioma with DE involving the uterosacral ligament, posterior cervix, and surface of the rectum, with complete cul-de-sac obliteration.

INTERVENTION(S)

An intravenous injection of 0.25 mg/kg body weight of ICG for intraoperative NIR fluorescence imaging. Ethics approval was obtained from the institutional review board at our hospital (IRB No.: 985).

MAIN OUTCOME MEASURE(S)

Evaluation of blood perfusion of DE nodule and achieving better visualization of anatomic relationship to the pelvic autonomic nerves.

RESULT(S)

The procedure was performed using the following eight steps with the da Vinci Xi surgical platform: Step 0, observing peritoneal endometriotic lesions; Step 1, adhesiolysis and adnexal surgery; Step 2, separation of the nerve plane; Step 3, dissection of the ureter; Step 4, reopening of the pouch of Douglas; Step 5, complete removal of DE lesions while avoiding injury to the nerve plane; Step 6, hysterectomy (if the patient desires nonfertility-sparing surgery); Step 7, checking for rectal injury using air leakage test and tissue perfusion; and Step 8, barrier agents for adhesion prevention. During surgery, we could easily identify ischemic nodules, which included DE and fibrosis under NIR fluorescence imaging, beyond the limits of macroscopic disease. Endometriosis or fibrosis was confirmed pathologically from all resected tissues, and resection margins of these tissues were negative for the disease. These results suggest that this technique might be feasible for objectively identifying the border between DE lesions and healthy tissue. Furthermore, the hypogastric nerve and inferior hypogastric plexus were strongly highlighted by ICG and objectively preserved with the assessment of perfusion. The patient developed no perioperative complications, including postoperative bladder or rectal dysfunction after surgery.

CONCLUSION(S)

To our knowledge, this is the first reported use of ICG during nerve-sparing surgery for gynecologic disease. Application of ICG with NIR fluorescence appears potentially useful, not only to remove DE, but also to improve nerve-sparing.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Prevention of postoperative intrapericardial adhesion by dextrin hydrogel

OBJECTIVE

Postoperative intrapericardial adhesion increases the risk of complications in patients undergoing reoperation. We investigated the effect of a bioabsorbable dextrin hydrogel (DHG) on the formation of intrapericardial adhesions.

METHODS

Intrapericardial adhesion was surgically induced in Japanese white rabbits with DHG treatment (Adh + DHG) or without DHG treatment (Adh). The sham group was not treated with DHG and intrapericardial adhesion was not induced. The extent of intrapericardial adhesion was assessed by adhesion scoring and crystal violet staining of the pericardial cavity. Bromodeoxyuridine (BrdU) uptake assay was performed to assess the proliferative response to the injury in the tissue beneath the intrapericardial adhesion.

RESULTS

The Adh + DHG group showed looser intrapericardial adhesions compared to the Adh group. The adhesion area of the Adh + DHG group was 4.6 ± 2.2%, whereas that of the Adh group was 32.6 ± 6.4% at the end of the 28-day observation period (p < 0.01). The induction of intrapericardial adhesion resulted in a proliferative response mainly in the cardiac tissue just beneath the adhesion. There were 48.6 ± 10.7 cells/0.1 mm² BrdU-positive cells in the Adh + DHG group and 135.7 ± 23.8 cells/0.1 mm² BrdU-positive cells in the Adh group on day 28 (p < 0.05).

CONCLUSION

These findings indicate that DHG effectively prevented intrapericardial adhesion in this model.

Evaluation of adhesion barrier types in a rat hepatectomy-induced adhesion model

Background

Adhesion formation after hepatectomy creates problems for repeat hepatectomy. This study aimed to compare the effectiveness of a spray (AdSpray) and sheet adhesion barrier (Seprafilm) in a rat hepatectomy-induced adhesion model.

Methods

Thirty male Sprague-Dawley rats underwent partial resection of the left lateral liver lobe. They were randomly assigned to control (n = 10), AdSpray (n = 10), and Seprafilm groups. Seven days after surgery, the animals were sacrificed, and adhesions at the hepatic resection surface were blindly evaluated.

Results

In the control group, adhesions were formed in all 10 animals (100%), with a 69% adhesion extent (mean). In the AdSpray group, the incidence of adhesions (40%) and the adhesion extent (mean, 10%) were significantly lower than in the control group (incidence; p = 0.0147, adhesion extent; p = 0.0007). In the Seprafilm group, the incidence of adhesions was 70%. The adhesion extent of Seprafilm (mean, 30%) was significantly lower than in the control group (p = 0.0492). No significant differences were observed between the AdSpray and Seprafilm groups. As for histopathological examination, animals in the AdSpray group showed a similar healing profile to that of the control group without delayed healing and regeneration of mesothelial cells. In contrast, the Seprafilm group showed ongoing foreign body reaction to Seprafilm, and regeneration of mesothelial cells was immature at 7 days.

Conclusions

Both the spray-type gel and sheet adhesion barriers significantly reduced adhesion formation after hepatectomy. The spray-type adhesion barrier caused no adverse events and induced favorable healing. These adhesion barriers may be effective in hepatectomy. Further animal studies and clinical trials are required to determine their benefits in clinical use.

Practical considerations in the use of a porcine model (Sus scrofa domesticus) to assess prevention of postoperative peritubal adhesions

Infertility has been a common postoperative problem caused by peritoneal adhesions. Since several prophylactic agents have recently shown promising preliminary results, more complete studies comparing their real efficacy and safety are needed urgently. The aim of this study was to investigate and describe practical considerations of a porcine model that can be used to assess such prophylactic agents. First, 10 healthy 5½ months old female pigs (24.3-31.3 Kg) underwent a standardized laparoscopy to provoke peritubal adhesion formation without prophylactic agents. After 30 days, a second-look laparoscopy was performed to evaluate adhesions and perform adnexectomy for histopathological evaluation. Adhesions at different sites were classified by grade, for which the scores range from 0 (no adhesion) to 3 (very strong vascularized adhesions), and also by area, with scores ranging from 0 (no adhesion) to 4 (>75% of the injured area). The histopathological evaluation of the distal uterine horns, oviducts and ovaries were compared withthose from a control group of six healthy pigs with no previous surgery. Biological samples were collected to assess vitality, inflammation and renal, hepatic and hematopoietic systems. There were small (but significant) changes in serum albumin (P = 0.07), globulin (P = 0.07), C-reactive protein (P = 0.011), fibrinogen (P = 0.023) and bilirubin (P<0.01) after 30 days, but all values were within the normal range. No inflammation or abscess formation was observed, but different degrees of adhesion were identified. The estimated occurrence of adhesion (scores >0) and of strong / very strong adhesion (scores >1) was 75% (95% CI: 55-94.9) and 65% (95% CI: 45-85), respectively. The porcine model represents a useful animal platform that can be used to test the efficacy and safety of candidate prophylactic agents intended to prevent postoperative peritubal adhesions formation. We present several practical considerations and measures that can help to minimize animal suffering and avoid problems during such experiments.

Adhesive small bowel obstruction - an update

Small bowel obstruction (SBO) accounts for 12-16% of emergency surgical admissions and 20% of emergency surgical procedures. Even with the advent of laparoscopic surgery, intra-abdominal adhesions remain a significant cause of SBO, accounting for 65% of cases. History and physical examination are essential to identify signs of bowel ischemia as this indicates a need for urgent surgical exploration. Another critical aspect of evaluation includes establishing the underlying cause for obstruction and distinguishing between adhesive and non-adhesive etiologies as adhesive SBO (ASBO) can be managed non-operatively in 70-90% of patients. A patient with a history of abdominopelvic surgery along with one or more cardinal features of obstruction should be suspected to have ASBO until proven otherwise. Triad of severe pain, pain out of proportion to the clinical findings, and presence of an abdominal scar suggest possible closed-loop obstruction. Computed tomography has higher sensitivity and specificity compared to plain films and is recommended by the Bologna guidelines. Correcting fluid and electrolyte imbalance is an initial crucial step to mitigate severe hypovolemia. Patients should proceed with surgery if symptoms of bowel compromise are present, or if symptoms do not resolve or have worsened. Surgery is indicated in patients with ischemia, strangulation, perforation, peritonitis, or failure of non-operative treatment. With advances in minimal access technology and increasing experience, laparoscopic adhesiolysis is recommended. Mechanical adhesion barriers are an effective measure to prevent adhesion formation.