RESUMO
Thymosin ß4 (Tß4) is known to inhibit an inflammatory response and to increase the survival of osteoblasts on titanium (Ti) surfaces. Ti is the most widely used graft material in dentistry; however, an inflammatory response induced following implant placement results in the generation of reactive oxygen species (ROS). The oxidative stress from the production of ROS such as nitric oxide (NO) and hydrogen peroxide (H2O2) can damage surrounding cells, resulting in implant failure by decreasing cell viability. Thus, the aim of this study was to determine the biological effects of Tß4 on the oxidative stress induced to MC3T3-E1 preosteoblasts on the Ti surface. Based on an MTT assay and bromodeoxyuridine immunofluorescence staining, Tß4 was found to increase the proliferation of the H2O2-exposed MC3T3-E1 cells on Ti discs. Reverse transcription-polymerase chain reaction and western blot analyses showed that Tß4 decreased the mRNA and protein expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in H2O2-exposed MC3T3-E1 cells on the Ti discs. Tß4 inhibited the synthesis of intracellular ROS and the secretion of NO and prostaglandin E2 (PGE2) from H2O2-exposed MC3T3-E1 cells on the Ti discs. In conclusion, Tß4 inhibits H2O2-induced iNOS and COX-2 expression with a decrease in ROS, NO, and PGE2 synthesis, which leads to improved cell survival with low cytotoxicity under an oxidative stress condition in MC3T3-E1 cells on the Ti surface. This suggests that Tß4 may be a crucial molecule to reduce oxidative stress-induced cell damage or hypoxia, leading to promoted osseointegration on the Ti surface during implant placement.