The effect of mitomycin-C in reducing pericardial adhesion after cardiac surgery in rabbits

A review of animal models for post-operative pericardial adhesions

Post-operative pericardial adhesions remain a serious complication after cardiac surgery that can lead to increased morbidity and mortality. Fibrous adhesions can destroy tissue planes leading to injury of surrounding vasculature, lengthening of operation time, and increased healthcare costs. While animal models are necessary for studying the formation and prevention of post-operative pericardial adhesions, a standardized animal model for inducing post-operative pericardial adhesions has not yet been established. In order to address this barrier to progress, an analysis of the literature on animal models for post-operative pericardial adhesions was performed. The animal model, method used to induce adhesions, and the time to allow development of adhesions were analyzed. Our analysis found that introduction of autologous blood into the pericardial cavity in addition to physical abrasion of the epicardium caused more severe adhesion formation in comparison to abrasion alone or abrasion with desiccation (vs. abrasion alone p = 0.0002; vs. abrasion and desiccation p = 0.0184). The most common time frame allowed for adhesion formation was 2 weeks, with the shortest time being 10 days and the longest being 12 months. Finally, we found that the difference in adhesion severity in all animal species was similar, suggesting the major determinants for the choice of model are animal size, animal cost, and the availability of research tools in the particular model. This survey of the literature provides a rational guide for researchers to select the appropriate adhesion induction modality, animal model, and time allowed for the development of adhesions.

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.

The Effect of Mitomycin C on Reducing Endometrial Fibrosis for Intrauterine Adhesion

<strong>BACKGROUND</strong> Intrauterine adhesion (IUA) is a common reproductive system disease in women, characterized by endometrial stromal cell proliferation, increasing fibroblasts and increasing extracellular matrix secretion. The purpose of this study was to investigate the effect of mitomycin C on reducing endometrial fibrosis for IUA. <strong>MATERIAL AND METHODS</strong> Firstly, a rat IUA model was constructed by intrauterine mechanical injury. The endometrial stromal cells and fibroblasts were isolated and treated with mitomycin C. After that, Cell Counting Kit-8 (CCK-8) assay was used to investigate the endometrial stromal cell viability. Furthermore, cell cycle and apoptosis assays of endometrial stromal cells and fibroblasts were performed, respectively. Finally, the cell viability of human endometrial cells or human uterus adhesion fibroblasts treated with mitomycin C was determined using CCK-8 assay with or without estradiol. <strong>RESULTS</strong> Endometrial stromal cells were isolated from a rat IUA model. Cell cycle assay results showed that mitomycin C inhibited cell viability and promoted G1 cell cycle arrest and apoptosis in rat IUA endometrial stromal cells. Fibroblasts were also isolated from the rat IUA model. We found that mitomycin C inhibited the synthesis and secretion of collagen type I by western blotting analysis. Furthermore, mitomycin C promoted G1 cell cycle arrest and apoptosis in IUA rat uterine fibroblasts. We found that estradiol decreased the inhibitory effects of cell viability of human endometrial cells and human uterus adhesion fibroblasts by mitomycin C. <strong>CONCLUSIONS</strong> Our findings revealed that mitomycin C could reduce endometrial fibrosis for intrauterine adhesion.

Controlled release of Mitomycin C from modified cellulose based thermo-gel prevents post-operative de novo peritoneal adhesion

The complications from surgery associated peritoneal adhesion can be alleviated by combination of physical isolation and pharmaceutical treatment. This work aims to develop thermo-sensitive hydrogel barrier by combining mitomycin C (MMC) with modified tempo oxidized nanocellulose (cTOCN) through EDC/NHS-chemical conjugation followed by integration with methyl cellulose (MC). The MMC was successfully combined with cTOCN and ensured controlled release of MMC from hydrogel throughout 14 days. Amount of MC (1.5, 2.5, 3.5% w/v) was proportional to gelation time and inversely proportional to degradation of hydrogel. The optimized hydrogel (C2.5T1M0.2) needed only 30 s for thermoreversible sol-gel (4℃-37℃) phenomenon and did not show in vitro fibroblast cells toxicity as well as ensured complete adhesion prevention efficacy, reperitonealization in rat side wall-cecal abrasion model. Overall, the developed C2.5T1M0.2 thermo-gel advances state-of-the-art in view of cytocompatibility, mechanical stability, optimum degradation, good injectability, sustain drug release from surgical sites, and satisfactory de novo anti-adhesion capacity.

Battling adhesions: from understanding to prevention

Adhesions represent a major burden in clinical practice, particularly following abdominal, intrauterine, pericardial and tendon surgical procedures. Adhesions are initiated by a disruption in the epithelial or mesothelial layer of tissue, which leads to fibrin adhesion sites due to the downregulation of fibrinolytic activity and an increase in fibrin deposition. Hence, the metabolic events involved in tissue healing, coagulation, inflammation, fibrinolysis and angiogenesis play a pivotal role in adhesion formation. Understanding these events, their interactions and their influence on the development of post-surgical adhesion is crucial for the development of effective therapies to prevent them. Mechanical barriers, antiadhesive agents and combination thereof are customarily used in the battle against adhesions. Although these systems seem to be effective at reducing adhesions in clinical procedures, their prevention remains still elusive, imposing the need for new antiadhesive strategies.

Antifibrotic effect of mitomycin-C on human vocal cord fibroblasts

OBJECTIVE

Acquired laryngotracheal stenosis is a potentially life-threatening situation and a very difficult and challenging problem in laryngology. Therefore, new trends and innovative approaches based on antifibrotic drugs and minimally invasive regimens are being developed to attenuate laryngotracheal fibrosis and scarring. The purpose of this study was to examine the efficacy of mitomycin-C (MMC) to reverse the transforming growth factor (TGF)-β-induced differentiation of MRC-5 fibroblast and human primary vocal cord fibroblasts to reveal the possible applicability of MMC to laryngotracheal fibrotic conditions.

METHODS

Human primary fibroblast cells were isolated from vocal cord specimens of patients undergoing total laryngectomy. The established primary vocal cord fibroblast cell cultures as well as the MRC-5 human fibroblast cells were treated with 5 ng/mL TGF-β alone and then with 0.5 µg/mL MMC for 24 hours. Differentiation of fibroblasts was characterized by α-smooth muscle actin (α-SMA) immunhistochemistry, Western blot analysis, and real-time polymerase chain reaction. Cell motility was assessed by wound-healing assay.

RESULTS

Elevated α-SMA mRNA and protein expression as well as increased cell motility were observed upon TGF-β exposures. However, after MMC treatments the TGF-β-induced fibroblasts exhibited a significant decrease in α-SMA expression and wound-healing activity. Therefore, TGF-β-stimulated fibroblast-myofibroblast transformation was reversed at least in part by MMC treatment. Histopathological examinations of tissue specimens of a laryngotracheal stenosis patient supported these findings.

CONCLUSION

Antifibrotic effects of MMC were demonstrated on the human MRC-5 cell line and on primary vocal cord fibroblast cultures. These results verify that MMC can be used with success to reverse upper airway stenosis by reverting the myofibroblast phenotype.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E255-E262, 2019.

Effect of Temperature-Sensitive Poloxamer Solution/Gel Material on Pericardial Adhesion Prevention: Supine Rabbit Model Study Mimicking Cardiac Surgery

Objective

We investigated the mobility of a temperature-sensitive poloxamer/Alginate/CaCl₂ mixture (PACM) in relation to gravity and cardiac motion and the efficacy of PACM on the prevention of pericardial adhesion in a supine rabbit model.

Methods

A total of 50 rabbits were randomly divided into two groups according to materials applied after epicardial abrasion: PACM and dye mixture (group PD; n = 25) and saline as the control group (group CO; n = 25). In group PD, rabbits were maintained in a supine position with appropriate sedation, and location of mixture of PACM and dye was assessed by CT scan at the immediate postoperative period and 12 hours after surgery. The grade of adhesions was evaluated macroscopically and microscopically two weeks after surgery.

Results

In group PD, enhancement was localized in the anterior pericardial space, where PACM and dye mixture was applied, on immediate post-surgical CT scans. However, the volume of the enhancement was significantly decreased at the anterior pericardial space 12 hours later (P < .001). Two weeks after surgery, group PD had significantly lower macroscopic adhesion score (P = .002) and fibrosis score (P = .018) than did group CO. Inflammation score and expression of anti-macrophage antibody in group PD were lower than those in group CO, although the differences were not significant.

Conclusions

In a supine rabbit model study, the anti-adhesion effect was maintained at the area of PACM application, although PACM shifted with gravity and heart motion. For more potent pericardial adhesion prevention, further research and development on the maintenance of anti-adhesion material position are required.

Assessment of the efficacy of Ankaferd blood stopper on the prevention of postoperative pericardial adhesions

Objectives

Ankaferd has been used as a blood-stopping agent and it may also have an anti-inflammatory effect. We investigated the efficacy of Ankaferd in preventing postoperative pericardial adhesions in an experimental rabbit model.

Methods

Sixteen New Zealand white rabbits were used and categorised into two groups: an Ankaferd and a control group. The Ankaferd group of rabbits was treated with a sponge impregnated with Ankaferd solution, which was applied over the abraded epicardium. A sponge impregnated with 0.9% isotonic NaCl solution was applied to the control group using the same protocol. Scores for adhesion and visibility of coronary vessels were graded by macroscopic examination, and pericardial tissues were analysed microscopically in terms of inflammation and fibrosis.

Results

In the Ankaferd group, the adhesion scores were significantly higher than in the control group (p = 0.007). When the groups were compared according to the prevalence of fibrosis and degree of inflammation, the Ankaferd group was found to be statistically significantly different from the control group in terms of prevalence of fibrosis (p = 0.028).

Conclusion

Topical application of Ankaferd to prevent postoperative pericardial adhesions increased adhesion and fibrosis scores.