Suppressive Effects of Aspirin for Postthoracotomy Pleural Adhesion in Rats

Background: Postoperative adhesion is one of major concerns at re-thoracotomy. Aspirin has both the anti-platelet and anti-inflammatory effects, and decreases several cytokines production. Objective: We investigated that aspirin could reduce postoperative adhesion formation in a rat model. Methods: We cauterised the lung visceral pleural to make postoperative adhesion in rats. The animals were allocated to a control group and an aspirin administration group (100 mg/kg/day for 14 days). We performed re-thoracotomy and evaluated the adhesion lengths on day 14. We also investigated the cytokine expression in the adhesion region and the peripheral tissue with platelet-derived growth factor (PDGF), platelet-derived growth factor receptor (PDGFR), alpha smooth muscle actin (α-SMA), transforming growth factor beta 1 (TGF-β1), and vascular endothelial growth factor-A (VEGF-A), sequentially. Results: The adhesion lengths were significantly shorter in the aspirin group than that in the control group (8.7±2.0 mm vs 11.2±1.1 mm, p=0.024). The expressions of PDGF and PDGFR were lower in the aspirin group than that in the control group on day 3. The expression of α-SMA on fibroblasts decreased in the aspirin group on day 3. There was no significant difference in the expressions of TGF-β1 and VEGF-A with administration of aspirin. Conclusions: Aspirin could reduce postoperative pleural adhesion by inhibiting the expression of PDGF.