Combined intraoperative administration of a histone deacetylase inhibitor and a neurokinin-1 receptor antagonist synergistically reduces intra-abdominal adhesion formation in a rat model

Efficacy of gelatin sponge in the prevention of post-surgical intra-abdominal adhesion in a rat model

Although different products have been developed to prevent post-surgical adhesion, their efficacy remains unsatisfactory. This study aimed to evaluate the efficacy of the gelatin sponge in the prevention of post-surgical intra-abdominal adhesions in a rat model. Rats were randomly divided into sham, adhesion, and gelatin groups. All rats, except the sham group, underwent cecal abrasion to establish an adhesion model. After celiotomy, a sterile gelatin sponge was applied intra-abdominal on the abraded cecum in the gelatin group. Rats were sacrificed on day 14 post-surgery and intra-abdominal adhesions were evaluated and scored. Adhesion tissues were evaluated by histological, histochemical, and immunohistochemical analysis. Intra-abdominal adhesions were recorded in all rats of the adhesion group. Intra-abdominal application of gelatin sponge significantly (P < 0.001) reduced intra-abdominal adhesions by 91% in the gelatin group relative to the adhesion group. The histological analysis revealed a marked decrease (P < 0.001) in the inflammatory score and neovascularization in the gelatin group. The histochemical analysis found that gelatin sponge administration reduced adhesion formation and thickness of adhesion tissue. Moreover, gelatin sponge significantly (P < 0.0001) increased MMP-9 expression and decreased macrophage marker expression in adhesive tissue. This study revealed that the application of gelatin sponge markedly reduced the post-surgical intra-abdominal adhesions and suggests new guidance for using gelatin sponge as an anti-adhesive substance in clinical practice.

Valproic acid and bladder healing: an experimental study in rats

PURPOSE

to recognize the effects of valproic acid (VPA), an epigenetic drug, on the bladder healing process, in rats.

METHOD

twenty male Wistar rats were divided in two groups: experimental (A), treated with VPA (150mg/Kg/day), and control (B) with 0.9% sodium chloridrate. Healing was analyzed on the third and seventh days, evaluating the inflammatory reaction, collagen synthesis and angiogenesis.

RESULTS

inflammatory reaction on the third day was minimal and acute in both groups. On the seventh day, it was subacute in both groups, moderate intensity in group A and minimal in group B (p=0.0476). Collagen III intensity, marked by immunohistochemistry, was similar in both groups. Collagen I intensity on the third day was similar in both groups, but on the seventh day it was higher in experimental than control (p=0.0476). Collagen evaluation by picrosiriusred allowed to verify that the presence of collagen III was similar in both groups (p=0.3312) on the third day, and it was higher in control on the seventh day (p=0.0015). Collagen I showed similarity on the third day (p=0.3100), and it was higher in control on the seventh day (p=0.0015). Vessel marked with anti-SMA counting showed fewer vessels on the third (p=0.0034) and seventh day (p=0.0087) in experimental group. The lower intensity of angiogenesis was confirmed with anti-CD34, on the third day (p=0,0006) and on the seventh day (p=0,0072).

CONCLUSION

VPA determined alterations in the bladder healing process, in rats, with lower collagen density and less angiogenic activity, but without compromising the integrity of the organ.

The effects of valproic acid on skin healing: experimental study in rats

Purpose:

To recognize the effects of valproic acid (VPA), an epigenetic drug, on the skin healing process.

Methods:

Sixty male Wistar rats were divided into two groups: the experiment treated with VPA (100 mg/kg/day); and the control, with 0.9% sodium chloride by gavage. Skin healing was studied in three moments (the third, the seventh, and the 14th day), evaluating the parameters: inflammatory reaction and its intensity (anti-LCA), angiogenesis (anti-CD34), collagen I and III (anti-collagen I, anti-collagen III and Picrosirius-red F3BA) and myofibroblasts (anti-alpha-AMS).

Results:

The inflammatory reaction was acute or sub-acute in both groups on the third day. On the seventh and the 14th day, chronic predominated in the control (p=0.006), and sub-acute in the experiment (p=0.020). There was a greater number of leukocytes in the group treated only on the third day (p=0.036). The number of vessels was lower in the treated group at the three times (p3=0.002, p7<0.001, and p14=0.027). Myofibroblasts were rare in the third day and moderate quantity in the remaining periods. Collagen I density was higher in the control at the three times (p<0.001) and collagen III in the treated group (p<0.001).

Conclusions:

VPA led to a more intense inflammatory reaction, decreased angiogenesis and collagen deposition, especially type I collagen.

Ácido valpróico e cicatrização em bexiga: estudo experimental em ratos

RESUMO Objetivo: reconhecer os efeitos do ácido valpróico (VPA), uma droga epigenética, no processo de cicatrização da bexiga, em ratos. Método: vinte ratos Wistar machos foram divididos em dois grupos: experimental (A), utilizando VPA (150mg/Kg/dia), e controle (B), tratados com cloreto de sódio 0,9% por gavagem. A cicatrização da bexiga foi analisada no terceiro e sétimo dia, estudando-se a reação inflamatória, síntese de colágeno, reepitelização e angiogênese. Resultados: a reação inflamatória no terceiro dia foi mínima e aguda em ambos os grupos. No sétimo dia, foi subaguda em ambos os grupos com intensidade moderada no grupo A e mínima no grupo B (p=0,0476). A intensidade do colágeno III, marcada pela imuno-histoquímica, foi semelhante nos dois grupos, nos dois tempos estudados. A intensidade de colágeno I no terceiro dia foi semelhante nos dois grupos, e maior no sétimo dia no grupo experimental (p=0,0476). A avaliação do colágeno pelo picrosiriusred mostrou que a presença de colágeno III foi semelhante em ambos os grupos (p=0,3312) no terceiro dia, e maior no controle no sétimo dia (p=0,0015). O colágeno I foi semelhante no terceiro dia (p=0,3100), e maior no controle no sétimo dia (p=0,0015). A contagem de vasos marcados pelo anti-SMA mostrou menos vasos no terceiro (p=0,0034) e sétimo dia (p=0,0087) no grupo experimental, confirmado pelo anti-CD34, no terceiro (p=00006) e no sétimo dia (p=0,0072). Conclusão: o VPA determinou alterações no processo de cicatrização da bexiga, em ratos, com menor densidade de colágeno e menor atividade angiogênica, mas sem comprometer a integridade do órgão.

Nintedanib, a multitarget tyrosine kinase inhibitor, suppresses postoperative peritoneal adhesion formation in a rat model

BACKGROUND

Nintedanib is an antifibrotic agent approved by the United States Food and Drug Administration for the treatment of lung fibrosis. This study aimed to evaluate the efficacy of nintedanib for the prevention of postoperative peritoneal adhesion formation in a rat model.

METHODS

Eighteen female Sprague-Dawley rats underwent peritoneal ischemic button creation to induce peritoneal adhesion formation and were randomly allocated to receive 1 mL saline, 50 mg/kg nintedanib, or 100 mg/kg nintedanib by gavage once daily for 7 days. Peritoneal adhesion evaluation and histological and immunochemical examinations were performed on postoperative day 7. Twelve additional Sprague-Dawley rats underwent ileal resection and anastomosis and were randomized to receive saline or 100 mg/kg nintedanib by gavage once daily for 7 days. Anastomotic bursting pressure was assessed on postoperative day 7.

RESULTS

All rats survived until death 7 days after surgery without complications. Peritoneal adhesion incidence, quality, and tenacity were lower in both nintedanib groups than in the saline group (P < .01), but no differences were found between the 2 nintedanib groups (P > .05). Histological and immunochemical results demonstrated less inflammation, fibrosis, collagen, and cell proliferation and fewer myofibroblasts in the ischemic buttons treated with 50 mg/kg or 100 mg/kg nintedanib than in those treated with saline (P < .01), but no difference was found between the 2 nintedanib groups (P > .05). Anastomotic bursting pressures were not significantly different between the saline and nintedanib groups (P > .05).

CONCLUSION

Nintedanib is effective for the prevention of postoperative peritoneal adhesion formation in a rat model.

Surgical adhesions in mice are derived from mesothelial cells and can be targeted by antibodies against mesothelial markers

Peritoneal adhesions are fibrous tissues that tether organs to one another or to the peritoneal wall and are a major cause of postsurgical and infectious morbidity. The primary molecular chain of events leading to the initiation of adhesions has been elusive, chiefly due to the lack of an identifiable cell of origin. Using clonal analysis and lineage tracing, we have identified injured surface mesothelium expressing podoplanin (PDPN) and mesothelin (MSLN) as a primary instigator of peritoneal adhesions after surgery in mice. We demonstrate that an anti-MSLN antibody diminished adhesion formation in a mouse model where adhesions were induced by surgical ligation to form ischemic buttons and subsequent surgical abrasion of the peritoneum. RNA sequencing and bioinformatics analyses of mouse mesothelial cells from injured mesothelium revealed aspects of the pathological mechanism of adhesion development and yielded several potential regulators of this process. Specifically, we show that PDPN+MSLN+ mesothelium responded to hypoxia by early up-regulation of hypoxia-inducible factor 1 alpha (HIF1α) that preceded adhesion development. Inhibition of HIF1α with small molecules ameliorated the injury program in damaged mesothelium and was sufficient to diminish adhesion severity in a mouse model. Analyses of human adhesion tissue suggested that similar surface markers and signaling pathways may contribute to surgical adhesions in human patients.

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

The ischaemic button model is frequently used for the induction of adhesions in laboratory rats. Male rats are often used because of the common belief that the peritesticular (intra-abdominal) fat in males facilitates adhesion formation, although this theory is not evidence based. Comparing the model’s performance in both sexes is an important aspect of refining animal experiments. The aim of this study is to compare baseline performance of the modified ischaemic button model in both male and female rats. Follow-up was 1 week and noted endpoints were intra-abdominal adhesion formation and differences in welfare assessment. A total of 192 ischaemic buttons (96 male/96 female) were created in 24 Wistar Han rats (12 male/12 female). After 1 week of follow-up, 93 buttons survived in the male group (96.9%) compared with 91 in the female group (94.8%) (p = 0.409). In the male group, 85 out of 93 (91.4%) buttons induced adhesions compared with 84 out of 91 (92.3%) in the female group (p = 0.881). All but one animal had a Zühlke score of 3. There were no clinically relevant differences in welfare scores. Male animals increased in weight significantly faster compared to females (p < 0.001), after correcting for physiological growth. The ischaemic button model resulted in equal quality and quantity of intra-abdominal adhesions in both male and female Wistar Han rats. Both male and female Wistar Han rats are suitable for the induction of experimental adhesions in the ischaemic button model.

Creation of Abdominal Adhesions in Mice

Abdominal adhesions consist of fibrotic tissue that forms in the peritoneal space in response to an inflammatory insult, typically surgery or intraabdominal infection. The precise mechanisms underlying adhesion formation are poorly understood. Many compounds and physical barriers have been tested for their ability to prevent adhesions after surgery with varying levels of success. The mouse and rat are important models for the study of abdominal adhesions. Several different techniques for the creation of adhesions in the mouse and rat exist in the literature. Here we describe a protocol utilizing abrasion of the cecum with sandpaper and sutures placed in the right abdominal sidewall. The mouse is anesthetized and the abdomen is prepped. A midline laparotomy is created and the cecum is identified. Sandpaper is used to gently abrade the surface of the cecum. Next, several figure-of-eight sutures are placed into the peritoneum of the right abdominal sidewall. The abdominal cavity is irrigated, a small amount of starch is applied, and the incision is closed. We have found that this technique produces the most consistent adhesions with the lowest mortality rate.