Role of bone morphogenetic protein-2 in sclera remodeling of form deprivation myopic eyes in C57BL/6 mice

AIM: To identify the presence change of bone morphogenetic protein-2(BMP-2)in sclera of form deprivation myopic(FDM)eyes in C57BL/6 mice and to investigate its role in sclera remodeling. <p>METHODS: A total of 64 C57BL/6 mice which were 3～4wk were randomized into FDM-21d group(<i>n</i>=16),a normal control group(<i>n</i>=16); FDM-28d group(<i>n</i>=16)and a normal control group(<i>n</i>=16). FDM models were established by sutured 0.5mL PCR plastic caps to the skin surrounding the right eye for 21 days and 28 days in experimental group, and the fellow eyes served as the self-control eyes. Diopter and axial length of all eyes was tested by retinoscopy optometry and vernier calipers before and after the form deprivation. As the models established, the sclera of the mice were obtained and hematoxylin and eosin(H-E)staining were used for observing the morphological change in the tissue. Immunohistochemical staining and fluorescence quantificational real-time polymerase chain reaction(QRT-PCR)were applied to investigate the expression of BMP-2 protein and mRNA. <p>RESULTS: After 21 and 28d,the diopter of the deprived eyes was -1.60±1.03D and -3.10±1.19D and the axial length was prolonged by 16±12μm and 21±13μm respectively. The differences were statistically significant, compared to self-control eyes and to normal control groups(<i>P</i><0.05). After stained by H-E, the sclera from the deprived eyes became thinner and the sequence of collagenous fiber disappeared. The results from the immunohistochemical staining and QRT-PCR showed that mRNA and protein of BMP-2 decreased significantly, and the differences were statistically significant, compared to self-control eyes and to normal control groups(<i>P</i><0.05).<p>CONCLUSION: The expressions of the BMP-2 in sclera down-regulate significantly in FDM eyes,which suggests that BMP-2 may play an important role in sclera remodeling during myopia development