STEEN Solution™ is a buffered extracellular solution optimally designed to perfuse the isolated donor lung during ex vivo lung perfusion. STEEN Solution™ includes human serum albumin to provide an optimal colloid osmotic pressure and dextran 40 to coat and protect the endothelium from excessive leucocyte interaction. STEEN Solution™ is intended for assessment of isolated lungs after removal from the donor body for eventual transplantation into a recipient.