Surfactant is not a new discovery in biology and medicine. In 1929, Neergard et al. suggested that physical properties of alveolar surface are an important factor that influences lung functions [1]. It quickly became clear that surfactant was constituted of a complex proteo-lipid mixture necessary to lower alveolar surface tension [Fig. 1]. Thus, surfactant replacement therapy for respiratory distress syndrome (RDS) due to its primary deficiency in preterm neonates was preclinically and clinically tested for the first time in 1972 and 1980, respectively [2,3]. At that time, RDS and acute respiratory distress syndrome (ARDS) were considered as the typical features of two different types of respiratory failures in neonates and adults, respectively.