| Objective To construct two vectors expressing siRNA targeting DKK1 gene and to investigate the treatment effect on rat osteoporosis (OP). Methods Twelve-week-old OP rats were randomly divided into 5 groups, including control group, model group, empty vector group, DKK1-siRNA1 group, and DKK1-siRNA2 group, with 10 rats in each group. Rats in latter 4 groups were given dexamethasone for 12 weeks continuously, but rats in control group were injected normal saline. The model of osteoporosis was identified. Two vectors containing DKK1-silencing siRNA were constructed successfully. They were injected through tail vein of OP rats in therapy group, while rats in the control group and model group were injected with the same volume of PBS, and rats in empty vector group were injected with the same volume of empty vector. Bone tissue was sliced to observe if siRNA can target to bone. The expression of DKK1 mRNA in the femur was detected using RT-PCR and DKK1 protein was detected using immunohistochemistry. Serum levels of BALP, Col-I, and TRAP in each group were detected using ELISA method. Bone mineral density and the pathological changes of the femur were observed. Results (1) siRNA eukaryotic expression vectors were successfully constructed. (2) Comparing to control group, bone mineral density of the proximal femurs in model group, empty vector group, and DKK1-siRNA groups decreased significantly (P<0.05). The number of trabecular reduced and the trabecular broke in these groups, but the trabecular remained intact in control group. (3) DKK1-siRNA can target to the bone. (4) Expression of DKK1-mRNA in blood and DKK1 protein in bone were significantly decreased in therapy groups. (5) Comparing to model group and empty vector group, serum BALP and Col-I levels in therapy groups significantly decreased (P <0.05), but TRAP level increased significantly (P<0.05). (6) Bone mineral density of the proximal femur of rats between each group had no significant difference (P >0.05). (7) Formation of new trabeculae and reduction of trabecular damage were found in therapy group. Conclusion DKK1-siRNA promotes bone formation, inhibits bone resorption, and reduces the damage of bone construction. |