Baseline performance of the ischaemic button model for induction of adhesions in laboratory rats

Establishment and evaluation of a stable and reliable rat model of peritoneal adhesions

BACKGROUND

In this study, we aimed to establish a stable and standardized animal model of peritoneal adhesions.

METHODS

Forty-eight male Sprague-Dawley rats were randomly divided (n = 12 each) into blank control, classic cecum sidewall, ischemic button, and cecum-sidewall suture groups. The modified American Fertility Society adhesion score was used on postoperative day 7 to evaluate adhesions. Sixty male Sprague-Dawley rats were used to dynamically observe the adhesion characteristics of cecum-sidewall ischemic injury suture model at different time points (n = 60, randomly divided into groups a-e with 12 rats each). The modified American Fertility Society and Zühlke histologic scoring systems, hematoxylin-eosin staining, Masson staining, and computed tomography of the abdomen were used to evaluate adhesions on postoperative days 1, 3, 5, 7, and 14.

RESULTS

No peritoneal adhesions were observed in the blank control group on postoperative day 7. In the classic cecum sidewall group, 8 rats had inconsistent adhesions, which had a modified American Fertility Society adhesion score of 2.25 ± 1.96. All rats in the ischemic button and cecum-sidewall suture groups developed significant adhesions with modified American Fertility Society scores of 3.08 ± 1.31 and 4.67 ± 0.78, respectively. When the modified American Fertility Society score was used, statistically significant differences were observed between the classic cecum sidewall groups and cecum-sidewall suture groups and between the ischemic button groups and cecum-sidewall suture groups. All animals in groups a-e developed adhesions; adhesion scores increased gradually with time.

CONCLUSIONS

The cecum-sidewall ischemic injury suture model is a stable and standardized animal model of peritoneal adhesions.

Peritoneal adhesions: Occurrence, prevention and experimental models

Peritoneal adhesions (PA) are a postoperative syndrome with high incidence rate, which can cause chronic abdominal pain, intestinal obstruction, and female infertility. Previous studies have identified that PA are caused by a disordered feedback of blood coagulation, inflammation, and fibrinolysis. Monocytes, macrophages, fibroblasts, and mesothelial cells are involved in this process, and secreted signaling molecules, such as tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), tissue plasminogen activator (tPA), and type 1 plasminogen activator inhibitor (PAI-1), play a key role in PA development. There have been many attempts to prevent PA formation by anti-PA drugs, barriers, and other therapeutic methods, but their effectiveness has not been widely accepted. Treatment by biomaterial-based barriers is believed to be the most promising method to prevent PA formation in recent years. In this review, the pathogenesis, treatment approaches, and animal models of PA are summarized and discussed to understand the challenges faced in the biomaterial-based anti-PA treatments.

Prevention of incisional hernia using different suture materials for closing the abdominal wall: a comparison of PDS, Vicryl and Prolene in a rat model

Purpose

An incisional hernia occurs frequently after a midline incision with an incidence of 12.8%. The choice in suture material used for abdominal wall closure is not straightforward and the conflicting literature focuses on clinical outcomes. This study compares a non-absorbable, slow-absorbable and fast-absorbable suture in a rat model, focusing on histological outcomes predicting better fascia healing.

Methods

33 male Wistar rats, divided over three groups, each received two separate 1 cm incisions closed with either Prolene 4/0, PDS 4/0 or Vicryl 4/0. At 7 days and 21 days, one of the incisions was explanted. Tissue was semi-quantitatively scored regarding inflammatory cells and collagen fibres present. Using qPCR macrophage polarisation, fibroblast activity and vascularisation were evaluated. Data were analysed by Kruskal–Wallis test with Mann–Whitney U post hoc test. A p value of 0.017 was considered significant after Bonferroni correction.

Results

All animals recovered without complications and completed the 21 days of follow-up. The Vicryl group showed a higher presence of macrophages after 21 days in comparison with Prolene (p = 0.003) and PDS (p = 0.006) and more foreign body giant cells compared to Prolene at 7 days (p = 0.010) and PDS at 21 days (p < 0.001). qPCR showed 2.5-fold higher expression of clec10A in PDS compared to Prolene after 7 days (p = 0.007).

Conclusions

The results of this study carefully support the use of PDS suture, compared to Prolene and Vicryl, in abdominal wall closure based on a favourable macrophage response. The heterogeneity and variability in the data might be explained by the spectrum of the macrophage subtype paradigm.

Electronic supplementary material

The online version of this article (10.1007/s10029-019-01941-9) contains supplementary material, which is available to authorized users.