RESUMO
Preterm infants, particularly those who born between 23 and 28 weeks' gestation, suffer from a very high incidence of respiratory distress syndrome (RDS) related to pulmonary immaturity and inability to make Pulmonary Surfactant (PS). These infants are supported by the use of oxygen, ventilators, and routine administration of surfactant replacement. The currently commercial surfactant replacement therapies do not contain hydrophilic surfactant proteins such as Surfactant Protein D (SP-D). These proteins have a key role in the innate lung host defense, thus the development of a sustained release vehicle that provides SP-D for long periods in preterm infants' lungs would exploit the therapeutic potential of SP-D and other pulmonary medications. The proposed SP-D delivery system is based on nanoparticles (NPs) composed of poly (lactic acid-co-glycolic acid) (PLGA), a biodegradable, FDA approved biopolymer. The resulted NPs were spherical with high Zeta potential value, were not toxic to A-549 lungs cells, and did not induce any inflammatory response in mouse's lungs for short and long-term periods. Moreover, SP-D released from NPs showed biological activity for several days and in vivo release experiment of SP-D loaded NPs revealed that SP-D was released from NPs in mouse lungs with different NPs delivery doses.