Effects Of Rnai For The Targeting Pparγ On The Osteogenic Differentiation Of Mscs Of Rabbit Suppressed By Steroid

Background and ObjectiveThe steroid-induced osteonecrosis of the femoral head(ONFH) is one of the common diseases to the doctors of the orthopaedics with the using of the steroid to treat many diseases in recent years.The oseteonecrosis causes pain,disfunction of the hip joint,mostly cannot be revesed.So how to prevent it is very important.The real nosogenesis has not been revealed though many studies have done a lot of work,but they proposed several doctrines,such as doctrine of fat metabolic disorders,doctrine of embolism of fat,doctrine of bone marrow stromal cell adipogenic differentiation, doctrine of intravascular coagulation,doctrine of high pressure inside of bone, doctrine of osteoporosis,etc.Cui discovered the dexamethasone could induce anomalous proliferation of adipocyte,and the necrosis of osteocyte caused by the eposition of fatty substance in it.Li Yuebai discovered dexamethasone could upgrade the the impression of PPARγmRNA in MSCs,and degrade the impression of osteocalcin mRNA in MSCs,which may be the nosogenesis of the steroid-induced osteonecrosis of the femoral head.That indicated PPARγwas a key target gene in the steroid -induced ONFH,which played a important part in the adipogenesis of MSCs.We apply the technology of RNA interference,transfect adenovirus carrier of target siRNA to PPARγto the MSCs,meanwhile,give cells dexamethasone,then observed its expression of PPARγmRNA and osteoblast-specific transcription-activating factor-- Core-binding tactor al mRNA to explore me effect of RNA interference targeting PPARγgene to maintain osteogenic differentiation of MSCs.Methods2^ND denesty MSCs of rabbit,were selected and randomly separated by 7 groups: Group C:the cells were treated without the adenovirous and dexamethasone.Group M:the cells were treated with 10^-7 mol/L dexamethasone.Group O:the cells were treated with adenovirous 1×10⁵IU and 10^-7 mol/L dexamethasone.Group N:the cells were treated with irrelative array siRNA adenovirous 1×10⁵IU and 10^-7 mol/L dexamethasone.Group RNA interference 1,2,3(I1,I2,and I3):the cells were correspondingly treated with relative siRNA adenovirous 1×10⁵IU and with 10^-7 mol/L dexamethasone.After cutureing 7 days,The impression of the PPARγmRNA and the core binding factor al(Cbfal)mRNA were measured with RT-PCR for 7 groups.After 14 days,detect osteogenic index for each group:the content of osteocalcin in culture fluid and the alkaline phosphatase activity in cells.Results1.The impression of PPARγmRNA in cells in group M,O,and N were significantly higher than that in the group C(P＜0.05).The impression of PPAPγmRNA in cells in group I1,I2,I3 is low and approximated to the group C(P＞0.05).2.The impression of Cbfal mRNA and the alkaline phosphatase activity in cells, the content of osteocalcin in culture fluid in group M.O,and N were significantly lower than that in group C(P＜0.05).But those in group I1,I2,I3 is high and approximated to the group C(P＞0.05).Conclusion1.After cultureing with steroid,the impression of PPARγmRNA of MSCs will be upgraded,but the impression of Cbfal mRNA and the alkaline phosphatase activity in cells,the content of osteocalcin in culture fluid will be degraded.2.Transfect adenovirus carrier of target siRNA to PPARγto the MSCs could inhibit the effect of steroid to degrade the impression of PPARγmRNA,upgrade the impression of Cbfa1mRNA,and maintain the content of osteocalcin,the alkaline phosphatase activity approximated to the normal level,maintain the normal osteogenic differentiation of MSCs.The results above indicate that the effect of RNAi for the target on PPARγis very active which can inhibit the effect of steroid suppress the osteogenic differentiation of MSCs,that provided a dependable scientific evidence for the further research of prevention and cure to the steroid-induced ONFH.