Establishment Of Osteoprotegerin Transgenic Mice And Its Bone Microarchitecture Study

Objective To establish the osteoprotegerin (OPG) transgenic mouse model, and to study the changes of bone microarchitecture, bone mineral density(BMD) and bone mineral content(BMC) in OPG transgenic mice for evaluating its effects on bone metabolism in vivo.Methods Expression plasmid pCI-hOPGp-mOPG containing human OPG promoter was successfully reconstructed, and micro-injected into fertilized zygotes from C57BL/6J×CBA mice to prepare transgenic mice. Progeny were screened for the presence of the transgene by PCR. 10-week-old F2 generation OPG transgenic mice(n=4) and wild-type mice(n=4) were involved in the study. The protein expression of OPG was identificated by Western Blot, the trabecular and cortical bone microarchitecture was assessed by micro-CT in proximal tibia,BMD and BMC of the femur were detected by DXA.Results 1.Out of the 69 founder generation, PCR testing revealed a total 7 transgeneic mice . Out of the 34 F4 generation, 5 OPG transgenic mice were obtained.2.Compared with wild-type mice, the OPG transgenic mice showed an increased volumetric BMD(vBMD) , tissue BMD(tBMD), trabecular thickness (Tb.Th) and trabecular number (Tb.N), with a decreased trabecular separation (Th.Sp) (P<0.05) . The cortical bone microarchitecture parameters such as cortical area (Ct.Ar) , cortical thickness (Ct.Th) , cortical BMD (Ct.BMD), cortical BMC (Ct.BMC) were also increased, with a decreased inner perimeter (Im.Pm) (P <0.05). BMD and BMC of femur were significantly increased (P <0.05 ). Conclusions 1 .OPG transgenic mice contain Flag fragment have been successfully developed.2. The bone mass of cancellous and cortical bone in OPG transgenic muse was significantly increased.