The Effect Of Low-intensity Pulsed Ultrasound On The Formation And Invasion Of Osteochondral Junction Blood Vessels In Rabbit Knee Osteoarthritis

Objective:The study aims to observe the effect of low-intensity pulsed ultrasound(LIPUS)on parthenogenesis and vascular invasion in osteochondral junction of rabbit with osteoarthritis.Methods:Thirty-six New Zealand rabbits,between 2 to 2.5kg,were divided into three groups randomly,including early control group(EC group),early osteoarthritis group(EO group)and early osteoarthritis plus LIPUS treatment group(ET group).Twenty-four of these rabbits received anterior cruciate ligament transaction at the left behind limbs,the rest were sham-operated.ET group was exposed to LIPUS radiation after four weeks when osteoarthritis was established.EO and EC group were exposed to fake LIPUS radiation.4 weeks later,the rabbits were sacrificed and pathological changes of articular surface of femoral condyle were assessed by Safranin O-fast green cartilage staining.Western blot was used to examine the expressions of integrin?l,p-FAK(Phosphorylated Focal Adhesion Kinase),p-JNK(Phosphorylated C-Jun N-terminal Kinase),p-p38(Phosphorylated Mitogen Activated Protein Kinase38),VEGF(vascular endothelial growth factor)and ChM-1(chondromodulin-1).Results:Safranin O-fast green cartilage staining showed that compared with EC group,there were significantly more angiogenesis and vascular invasion in osteochondral junctions in EO and ET group,with more vessels at the osteochondral junction,marked disorders of tidal line broke down by vessels.Immunohistochemical test showed that compared with EC group,there were significantly up-regulation of VEGF and down-regulation of ChM-1 in EO and ET group.And there were significantly down-regulation of VEGF and up-regulation of ChM-1 in ET group compared with EO group.The Western blot test showed that the expression of integrin ?1 in EC,EO and ET group were(0.45±0.04),(0.922±0.07),(1.10±0.09)respectively,with p-FAK in EC,EO and ET group(0.18±0.03),(0.83±0.09),(1.09±0.08)respectively,p-p38 in EC,EO and ET group(0.31 ±0.04),(0.99+0.11),(0.54±0.09)respectively,p-JNK in EC,EO and ET group(0.38±0.03),(1.86±0.06),(1.29±0.08)respectively,VEGF in EC,EO and ET group(0.35±0.02),(1.02±0.10),(0.58±0.06)respectively and ChM-1 in EC,EO and ET group(1.91 ±0.08),(0.61±0.04),(1.09±0.12)respectively.Compared with EC group,integrin?1 and p-FAK was significantly up-regulated in EO(P<0.05).Moreover,Integrin ?1 and p-FAK expression was significantly up-regulated in ET group compared to the EO group(P<0.05).In comparison with the EC group,the of p-p38/p-JNK expression was significantly increased in EO group(P<0.05).Meanwhile,the p-p38/p-JNK expression was significantly decreased in ET group(P<0.05)in comparison to that of EO group.The expression of VEGF was significantly up-regulated in EO group(P<0.05),whereas compared with EO group,VEGF expression of ET group was significantly down-regulated(P<0.05).The ChM-1 expression was significantly decreased in EO group comparing to EC group(P<0.05).However,the expression of ChM-1 was significantly increased in ET group(P<0.05)in comparison to that of EO group.Conclusions:LIPUS inhibited angiogenesis and vascular invasion in osteochondral junction of rabbits with osteoarthritis,possibly,through activating integrin?1-FAK-p38/JNK-VEGF/ChM-1 pathway.