Comparing transforming growth factor beta-2 and fibronectin as pleurodesing agents

Evaluation of pleurodesis by poly-ε-caprolactone (PCL) gel in an animal model using New Zealand white rabbits

BACKGROUND/PURPOSE

Pleurodesis with biomaterial implant is an emerging treatment method for pleural diseases. However, the ideal biomaterial or the optimal form for the common diseases is still under investigation. In our previous study, Poly-ε-caprolactone (PCL) membrane produces significant pleurodesis in New Zealand White rabbit animal models.

METHODS

We investigate the Poly-ε-caprolactone (PCL) gel pleurodesis by animal models using New Zealand White rabbits, which were sacrificed for examination after one month. Thirty-Six New Zealand White rabbits were randomized into three groups equally to undergo procedures. Gross pleurodesis scoring was evaluated. Additionally, inflammation and fibrosis scoring were done under microscopic evaluation, as well as Western blot analysis.

RESULTS

Gross evaluation of pleurodesis score revealed that lower concentrated PCL gel (10%) produced moderate pleural adhesion, while higher concentrated PCL gel (25%) showed significantly higher pleurodesis scores. (P < 0.05) Control group with thoracostomy alone produced almost no pleurodesis (P < 0.05). Western blot showed fibronectin expression was more evident in the 25% PCL gel than 10% one.

CONCLUSION

PCL gel induced significant degree of pleurodesis in the rabbits. The 25% PCL gel produces more intensive adhesion than 10% one. Fibronectin plays an important role in the process of pleurodesis. Further study is required for the clinical application of the promising biomaterial with gel form.

Study of poly-ɛ-caprolactone membranes for pleurodesis

BACKGROUND/PURPOSE

Pleurodesis with biomaterial membrane is an emerging treatment method for pneumothorax. However, the ideal one for the common disease is still under debate.

METHODS

We investigate the Poly-ε-caprolactone (PCL) membrane pleurodesis by using New Zealand White rabbits, which was sacrificed for examination one month later. Moreover, inflammation and fibrosis scoring were done under microscopic evaluation, as well as Western blot analysis in vitro and in vivo.

RESULTS

Gross evaluation of pleurodesis score revealed that dense PCL membrane produced moderate pleural adhesion, while porous PCL membrane exhibited significantly higher pleurodesis scores.

CONCLUSION

PCL membrane induced significant degree of adhesion, both within the abdomen and chest of the rabbits. The porous PCL membrane produces more intensive adhesion than dense one. Fibronectin plays an important role in the process of pleurodesis. Further study is required for the clinical application of the promising material.

Use of a drug eluting pleural catheter for pleurodesis

PURPOSE

Repeated administration of low-dose silver nitrate (SN) has been shown to be effective in creating pleurodesis. This study aimed to determine the effectiveness of a SN-eluting pleural catheter for pleurodesis.

METHODS

Catheters with a chitosan-SN-hyaluronic acid hydrogel coating designed to release SN over 14 days, or placebo uncoated catheters, were inserted in rabbit and lamb pleurodesis models. Pleurodesis was assessed at 28 days according to a 1-8 point scoring system and pleural fibrosis and inflammation assessed histologically on a 0-4 point scale.

RESULTS

In the rabbit model, pleurodesis scores were significantly increased in both the 24 mg and 50 mg SN catheters versus control animals as well as compared to the contralateral untreated pleural space (median-treated side scores were 5, 8, and 1, respectively, median score for contralateral side was 1 in all groups). In the lamb model, pleurodesis scores were significantly increased in both the 750 mg and 1000 mg catheter groups versus control animals as well as compared to the contralateral untreated pleural space (median-treated side scores were 7, 7, and 1, respectively, median score for contralateral pleural space was 1 in all groups). Catheters appeared well tolerated, although higher than expected mortality was seen in the 50 mg catheter rabbit group.

CONCLUSIONS

A catheter designed to deliver SN to the pleural space over 14 days appears to be effective in creating pleurodesis. Further investigations to determine in-vivo catheter pharmacokinetics, toxicity, dose and optimal coating methods are warranted.

TGF-beta1 induces progressive pleural scarring and subpleural fibrosis

Pleural fibrosis is a misunderstood disorder which can cause severe restrictive lung disease with high morbidity and even mortality. The condition can develop in response to a large variety of diseases and tissue injury, among them infectious disease, asbestos, drugs, and radiation therapy. There is no efficient treatment to reverse established pleural fibrosis. TGF-beta1 is suspected, even if not proven, as a key cytokine in this process. In this study, we used adenoviral gene transfer of TGF-beta1 to the pleural mesothelium in rats. We show that local and transient TGF-beta1 overexpression induces homogenous, prolonged, and progressive pleural fibrosis without pleurodesis, associated with severe impairment of pulmonary function. We further demonstrate that pleural fibrosis can expand into the lung parenchyma from the visceral layer, but not into the muscle from the parietal layer. We provide evidence that matrix accumulation and fibrosis within the parenchyma evolved through a process involving "mesothelial-fibroblastoid transformation" and suggest that the pleural mesothelial cell may be an important player involved in the development of the subpleural distribution pattern known to be a hallmark of pulmonary fibrosis. This new model of pleural fibrosis will allow us to better understand the mechanisms of progressive fibrogenesis, and to explore novel antifibrotic therapies in the pleural cavity.

Inflammation and clinical repercussions of pleurodesis induced by intrapleural talc administration

Although reports on pleurodesis date back to the beginning of the 20th century, the search for the ideal sclerosing agent is ongoing. Several agents have been studied and used, but talc continues to be the most popular. However, potentially harmful systemic side effects have been associated with talc pleurodesis. In this article we discuss the likely mechanisms of pleural inflammation and pleurodesis with emphasis on the systemic response due to the instillation of talc into the pleural space.

Pleurodesis is inhibited by anti-vascular endothelial growth factor antibody

STUDY OBJECTIVES

The intrapleural injection of transforming growth factor (TGF)-beta2 produces pleurodesis in rabbits associated with large pleural effusions. This study investigated whether anti-vascular endothelial growth factor (VEGF) antibody has any effect on the fluid production or the pleurodesis induced by TGF-beta2.

INTERVENTIONS AND MEASUREMENTS

Three groups of seven New Zealand white rabbits were administered TGF-beta2 5.0 microg intrapleurally. Two groups received anti-VEGF antibody (10 mg/kg and 25 mg/kg) IV 24 h before TGF-beta2 injection, and the third group received no antibody. The rabbits were killed at 2 weeks, and the macroscopic pleurodesis score was determined. The degree of pleural angiogenesis was assessed by immunohistochemical staining for factor VIII.

RESULTS

The administration of anti-VEGF antibodies had no significant effect on the pleural fluid volume or the characteristics of the fluid. The mean pleurodesis score of the seven rabbits in the control group (7.71 +/- 0.76) was significantly (p < 0.05) higher than that for seven rabbits in the low-dose treatment group (4.43 +/- 2.37) and the seven rabbits in the high-dose treatment group (4.57 +/- 2.36) [+/- ]. The percentage of pleural tissue demonstrating angiogenesis in the control group (4.87 +/- 0.43%) was significantly (p < 0.05) higher than that for the low-dose (2.94 +/- 0.68%) or high-dose (2.67 +/- 0.64%) antibody groups. When all rabbits were considered, there was a highly significant correlation between the pleural vascular density scores and the pleurodesis scores (r = 0.84, p < 0.01).

CONCLUSION

VEGF and angiogenesis appear to play a pivotal role in the production of a pleurodesis.

Comparing transforming growth factor-beta2, talc and bleomycin as pleurodesing agents in sheep

BACKGROUND

Transforming growth factor (TGF)-beta2 can produce effective pleurodesis in animals, but its efficacy has not been compared with commonly used pleurodesing agents in sheep, which have a thick pleura resembling that of humans. The acute physiological effects and the level of systemic TGF-beta absorption after its intrapleural administration have not been studied. The aims of the present study were to compare: (i) the effectiveness of TGF-beta2, talc and bleomycin in producing pleurodesis in sheep; (ii) the acute side-effects and systemic TGF-beta levels following the intrapleural administration of these agents; and (iii) histological changes after intrapleural injections of these agents.

METHODOLOGY

Twelve sheep were divided into three groups and were given a single intrapleural dose of TGF-beta2 (0.25 microg/kg), talc slurry (5 g) or bleomycin (60 IU) via a chest tube. Saline or buffer was injected into the contralateral side, which served as the control. Arterial blood gases and respiratory and heart rates were monitored for the first 24 h. Plasma levels of TGF-beta1 and TGF-beta2 were measured. Pleurodesis was graded macroscopically from 1 (none) to 8 (symphysis > 50% of hemithorax) at day 14.

RESULTS

At day 14, the pleurodesis score of the TGF-beta2 group (7.7+/-0.6) was similar to that of the talc (7.0+/-1.7) group and significantly higher than that of the bleomycin group (3.3+/-2.3; P < 0.05). No significant differences were seen in arterial blood gas analysis, vital signs and plasma TGF-beta1 and TGF-beta2 concentrations among the three groups.

CONCLUSIONS

Transforming growth factor-beta2 was as effective as talc and more so than bleomycin in inducing pleurodesis in sheep. Intrapleural administration of TGF-beta2 appeared safe. No acute changes in gaseous exchange or macroscopic abnormalities were seen following intrapleural TGF-beta2. Importantly, there was no evidence of an increase in systemic TGF-beta levels following its intrapleural administration.