Clinical Treatment Of Bisphosphonates Associated Atypical Femoral Fractures And Investigation Of The Ginsenoside Compound K Underlying Mechanism Against Osteoporosis

Osteoporosis(Osteoporosis,OP)is characterized by bone loss and changes in microscopic structures of bone tissue,which would increase the fragility of bone,and result in fractures and some other serious diseases.Bisphosphonates had been widely used in the treatment of osteoporosis,and achieved good efficacy.However,bisphosphonates would block the metabolism of bone in long-term,increase the fragility of bone,and bone microdamage caused by daily activities gradually expanding,finally it would lead to stress fractures.This type of fractures are different with osteoporotic hip fractures different in symptoms and imaging performance,and there is no unified standard in methods and clinical efficacy for treating this type of fratures.Innovation of the anti-osteoporosis drug is a good way to improve the anti osteoporosis curative effect,reduce side effects.Therefore,it is great significance to get good clinical in the treatment of biphosphonate-associated atypical femoral fractures and develop new anti-osteoporosis drugs.The first part of this research had analyzed the clinical efficacy of intramedullary fixation in treating bisphosphonate-associated atypical femoral fractures,and it will provide a reference for clinical application.In the second part of this research,the natural product library is screened by Alpha screen technology,and it showed that ginsenoside compound K can inhibit the expression of the differentiation of osteoclasts for related gene by inhibiting mTOR activity in order to inhibit the differentiation of osteoclasts,which plays a good role in the treatment of osteoporosis.Moreover,it provides an important leading compound for the development of anti-osteoporotic drugs,and mTOR as a new target for the development of anti-osteoporotic drugs would be quickly spreaded.Part I Clinical treatment of bisphosphonates associated atypical femoral fracturesObjective: To investigate the effect of intramedullary nailing for atypical femoral fractures associated with long-term bisphosphonates use.Methods: Retrospective analysis of twenty one patients(twenty four femoral fractures)suffered from atypical femoral fractures associated with long-term bisphosphonates use,and all the fractures were treated with intramedullary nailing from February,2008 to April,2012.Nineteen females and two males were identified.The average age was 74.2 years(range,60-95 years).These fractures were occurred at an average of 58.6 months(range,37–95 months)after the using of bisphosphonates.Six fractures had no history of trauma,eighteen fractures had low-energy trauma.Eleven fractures were femoral diaphyseal fractures,thirteen fractures were subtrochanteric femoral fractures.According to AO classification,all belong to 32A2 type fractures,The union of these fractures were judged by X ray during the follow-up time,and the post-operative function of injuried limbs were assessed by Thoresen system at the final follow-up timeResults: Average follow-up was 2 years(range,1-2.5 years)All twenty four fractures healed during follow-up(mean,5.1 months;range,3-8 months),According to Thoresen system: 20 excellent results,3 good results,1 fair results,and 0 poor result,the excellent and good rate was 95.8%.without operation-related complications.Conclusions: The long term use of bisphosphonates may lead to atypical fractures of the femur.Intramedullary nailing is an effective method to treat atypical fractures associated with long-term bisphosphonates use.Part Investigation of the ginsenoside Compound K underlying ?mechanism against osteoporosisObjective: The long-term use of bisphosphonates may lead to atypical fractures,thus it is of great significance to discover new drugs against osteoporosis.The natural product ginsenoside Compound K was obtained by high throughput screening to inhibit the phosphorylation of mTOR,and its effect on osteoclast differentiation and the mechanism of anti osteoporosis was studied.Methods: Alpha-screen assay was performed in RAW264.7 cells against the natural product library,and then Compound K was founded to have the ability of mTOR inhibition,which was further confirmed by western-blot assay.The assay of osteoclast differentiation was executed to evaluate Compound K inhibited effect on osteoclast differentiation.RT-PCR assay had been carried out to investigate the influences of Compound K upon the vital protein in osteoclast differentiation such as Maf B,OSCAR,DC-STAMP.Detect the impact of Compound K for treatment of osteoporosis in ovariectomized mice.Results: Compound K significantly inhibited mTOR activity and osteoclast differentiation.Compound K decreased the transcription of OSCAR,DC-STAMP via enhancing Maf B transcription.Compound K could reverse the abnormal expression of TRACP,ALP and VD3 in ovariectomized osteoporostic mice.Compound K was able to reverse the bone mineral density of these model mice.Conclusions: Compound K inhibited mTOR activity and osteoclast differentiation through the down-regulation of OSCAR,DC-STAMP via enhancing Maf B transcription,which might be indicated in osteoporosis treatment.