| Objective :1.To evaluate the effect of LIPUS on early healing of acute Achilles tendon injury in rats from imaging,general observation and biomechanical level.2.Gene expression was detected to observe the repair mechanism of low intensity pulsed ultrasound(LIPUS)in the early stage of acute Achilles tendon injury in rats.Methods :1.The early model of acute Achilles tendon injury in rats was established: bilateral Achilles tendon and left Achilles tendon were constructed respectively.The bone connection point of the Achilles tendon in rats was found,and 30μL(10mg/m L)of the prepared collagenase solution was slowly injected into the tendon at 30° with a micro syringe at the proximal Achilles tendon 1mm,to establish the model of acute Achilles tendon injury in rats.2.LIPUS intervention: The rat was immobilized with a cylindrical rat fixator in a prone position,exposing the left Achilles tendon of the lower limb.An appropriate amount of medical ultrasonic coupler was applied to the Achilles tendon,and the flexion of the ankle joint was 90 °.LIPUS treatment was performed with an ultrasonic probe with an effective radiation area of ERA of1cm2 perpendicular to the Achilles tendon,and continuous intervention was performed for 1-2 weeks.LIPUS parameter setting: 20%,0.5W/cm2,3MHz,1time /d,5min/ time,and ensure that the daily ultrasound time is fixed.3.Efficacy evaluation:Imaging,general observation,biomechanical examination,HE staining,immunohistochemistry,Polymerase Chain Reaction(PCR)and Western Blot(WB)were performed on rats at 1 and 2 weeks after the intervention,respectively.Results :1.Healing of Achilles tendon after LIPUS intervention:(1)Imaging results showed that compared with the normal side,the lesion area of Achilles tendon in the model side of rats was thickened in diameter,local swelling,lower echo intensity and blurred boundary;(2)The gross observation of the rats showed that the Achilles tendon tissue of the rats on the modeling side was seriously adhered to,the whole was light yellow,and the tissue was swollen,the surface was dull,and the hyperplasia was obvious.The results were consistent with the manifestations of acute Achilles tendon injury in rats,so the model was successfully established and used.(3)Biomechanical results showed that the maximum tensile breaking strength of Achilles tendon after intervention was higher than that in the model group;(4)HE staining results showed that after the intervention,the nuclei of rats were reduced and the tissue fibers were arranged in order,which were significantly improved compared with the model group.2.Changes of collagen in Achilles tendon after LIPUS intervention:(1)Immunohistochemical results: After 1 week of intervention,the positive expression of type I collagen increased slightly compared with the model group,the positive expression of type III collagen decreased slightly,and the positive expression of bone morphogenetic proteins(BMP-12)decreased slightly.After 2 weeks of intervention,the positive expression of type I collagen increased significantly,the positive expression of type III collagen decreased significantly,and the positive expression of BMP-12 protein decreased significantly,which was close to the positive expression of normal protein.(5)m RNA results: The m RNA of type III collagen decreased slightly after 1 week of intervention,and significantly decreased after 2 weeks of intervention,and gradually returned to normal level;Type I collagen m RNA increased slightly after 1 week of intervention,and gradually returned to normal level after 2 weeks.After 1 week of intervention,BMP-12 m RNA decreased slightly compared with the model group,and began to decrease significantly at2 weeks of intervention,approaching to normal BMP-12 m RNA(6)Western blot results: After 1 week of LIPUS intervention,type III collagen began to decrease,but not significantly;After 2 weeks of LIPUS intervention,the expression of type III collagen decreased significantly compared with the model group,and gradually approached the expression of normal tendon type III collagen.After LIPUS treatment for 1 week,the expression of type I collagen increased compared with the model group.After 2 weeks of LIPUS intervention,the expression level of type I collagen was significantly increased compared with that of the model group,which was close to the expression level of normal tendon type I collagen.The expression level of BMP-12 protein in the Achilles tendon tissue of rats was significantly higher than that of the normal group after LIPUS intervention for 1 week,and returned to the normal level at 2 weeks,while the protein expression level of type I collagen was significantly increased due to the high expression of BMP-12.Conclusion :1.LIPUS intervention can heal tendon in early stage.2.LIPUS can enhance the synthesis of type I collagen in the Achilles tendon of rats by up-regulating BMP-12,so as to promote the repair of acute tendon injury. |
