Beneficial effects of synthetic KL4 surfactant in experimental lung transplantation

The aim of this study was to investigate whether intratracheal administration of a new synthetic surfactant that includes the cationic, hydrophobic 21-residue peptide KLLLLKLLLLKLLLLKLLLLK (KL4), might be effective in reducing ischaemia-reperfusion injury after lung transplantation. Single left lung transplantation was performed in Landrace pigs 22 h post-harvest. KL4 surfactant at a dose of 25 mg total phospholipid.kg body weight(-1) (2.5 mL.kg body weight(-1)) was instilled at 37 degrees C to the donor left lung (n=8) prior to explantation. Saline (2.5 mL.kg body weight(-1); 37 degrees C) was instilled into the donor left lung of the untreated group (n=6). Lung function in recipients was measured during 2 h of reperfusion. Recipient left lung bronchoalveolar lavage (BAL) provided native cytometric, inflammatory marker and surfactant data. KL4 surfactant treatment recovered oxygen levels in the recipient blood (mean +/- SD arterial oxygen tension/inspiratory oxygen fraction 424 +/- 60 versus 263 +/- 101 mmHg in untreated group; p=0.01) and normalised alveolar-arterial oxygen tension difference. Surfactant biophysical function was also recovered in KL4 surfactant-treated lungs. This was associated with decreased C-reactive protein levels in BAL, and recovery of surfactant protein A content, normalised protein/phospholipid ratios, and lower levels of both lipid peroxides and protein carbonyls in large surfactant aggregates. These findings suggest an important protective role for KL4 surfactant treatment in lung transplantation.