Exprimental Sudy On PDGF And IGF-I Genen Expression On Bone Healing Stimulated By Low-intensity Pulsed Ultrasound

Objective: To study the changing regulation of platelet-deriverd growth factor and insulin-like growth factor-I after the stimulation by low-intensity pulsed ulrtasound.To explore the mechnaism of aceelerated bone healing atfer ultrasound stimulating at molecular level. It will provide the theoretical basis of the application of ultrasound and will be very important in the treatment of clinical delyaed union and nonunion.Methods: 40 SD rats were divided into 2 groups and tibia fractuer model were used of this experiment. Low-iniensity pulsed ultrasound were used on right tibia eveyrday after fracture for 20 minutes.The tissue or callus around fracutre site were got at 4,7,14,21d and specimen were use as histological exmaination, callus measurement. We sutdied the disrtibution of PDGF and IGF-I with monocolonal antibody respcetively by immunohistochemistry.The disrtibution of mRNA content of PDGF and IGF-I were analysed by RT-PCR. Dieffernces were compared among the 2 gropus.Results: Under the stimulating of low-intensiy pulsed ultrasound, changes at the fracurte groups were as follows:1. The callus in experimental group was significantly thicker than that of conrtol group at 14, 21d after fractrue P(<0.05).2. HE satining showed the earlier appearance and increased amount of chondrocytes and ostoblasts in experimental group than in control group.3. The expression of PDGF were much higher than that of conrtol group at 7～21d. The ulrtasound stimulated the production of PDGF.4. The expression of IGF-I were much hihger at 7, 14d than that of control group. The ulrtasound stimulated synthesis of extracellular matrix proteins in catilage.Conclusions:1. Us versatile mechano-equipment make fracture model can be a new experimental cloused fracture model.2. LIUS could increase the local content of PDGF that could pormot the mature of earlier chondrocyte and endochondral bone formration.3. LIUS increased not only the amount of chondrocytes but also the production of PDGF. The later inereased IGF-I mRNA and facilitated the endochondral bone formation.