Efficacy of mistletoe for chemical pleurodesis in rats without malignancy

Chemical pleurodesis is an effective treatment modality to reduce recurrence of malignant effusion. Several agents have been used in chemical pleurodesis but, it is not yet clear which is better. Eighteen Sprague-Dawley rats were used and classified into three groups: a group intrapleurally injected normal saline (group A, n=6), 400mg/kg talc (group B, n=6), and 9mg/kg mistletoe extraction (ME) (group C, n=6). Autopsy was performed to evaluate the pleural adhesion, pathologic examination of pleura and lung and bronchoalveolar lavage fluid analysis 4 weeks after pleurodesis. Both group B and C showed an obvious pleural adhesion and there was no significant difference in grade of pleural adhesion between two groups (p=0.58). The parietal pleural thickness in talc group than ME group was significantly thicker (p=0.002) and the visceral pleura of talc group showed marked foreign body reaction with fibrosis and many multinucleated giant cells associated with talc crystal. This study suggests that pleurodesis using ME in condition without malignancy has comparable effect to pleurodesis using talc. However, additional experimental study in large animal or clinical trials would be required to prove a safety and an efficacy of pleurodesis using ME.