The Effect Of Low Intensity Pulsed Ultrasound Stimulations On The Proteomics Of The Injured Patella-patellar Tendon Junction At The Early Repairing Phase In Rabbit Model

OBJECTIVE The proteomics technology was used to obtain the two-dimensional gel electrophoresis maps of the proteins which were extracted from the tissue of the injured rabbit patella-patellar tendon (PPT) treated by LIPUS(low intensity pulsed ultrasound stimulations) and non-LIPUS sham control.The study aimed to compare the differences of protein expression profile between the LIPUS treatment group and control group.The differential proteins were analyzed to investigate the molecular mechanisms in which LIPUS accelerated the early healing of the injured bone-tendon junction.METHODS A total of16matured New Zealand white rabbits (2.5±0.5kg) were performed partial patellectomy and established the rabbit patella-patellar tendon injury model. These animals were randomly divided into the LIPUS treatment group(group T,n=8) and control group(group C,n=8).The rabbits in group T were treated with the LIPUS for20minutes a day at three days postoperatively.The rabbits in control group were prepared and treated in the same manner except keeping the LIPUS machine inactive.The animals were euthanized at1and3days after the treatment separately.There were4animals in each healing time points.The newborn complexes of PPT were harvested.The total protein was extracted using protein lysis solution and the concentration of proteins were detected.Then the proteins were separated by the two-dimensional gel electrophoresis to obtain high-resolution protein maps using Coomassie-Blue staining.The differentially expressed proteins were detected by PDQuest-8.0.1software.The peptide mass fingerprinting was obtained and analyzed using the matrix-assisted laser desorption ionization time of flight mass spectrometry(MALDI-TOF-MS) method,and retrieved to identify the differential proteins using the MascotWizard analysis software in the SWISS-PROT database. The key differential protein was verified using the Western-blot technology which might exist at the early phase of bone-tendon healing time.The primary function of the differential expressed proteins was analyzed by comparing the data with those published in the literature.RESULTS The two-dimensional gel electrophoresis maps of two groups were characterized by high resolution and good reproducibity and the differences of gel maps between two groups were significant.A total of six differentially expressed proteins were clearly identified and significantly up-expressed in the LIPUS group.These proteins were heat shock cognate71kDa protein,apolipoprotein AI,serum creatine kinase, actin serum albumin,beta hemoglobin,which was mainly related to the physiopathological functions of the protective stress protection, cytoskeleton formation and inflammatory response at the early phase of bone-tendon injury healing.CONCLUSIONS The LIPUS treatment may regulate proteins expression at the early repairing phase of bone-tendon junction.These results provide further understanding of the role of LIPUS in the recovery of injured B-T,especially in the regulation of proteomic expression potentially involved in the molecular mechanism of bone tendon junction repair.