Effects Of Two Different Platelet-rich Plasmas On The Healing Of Tendon-osseous Junction After Rotator Cuff Injury

Objective:In this study,pure platelet-rich plasma(P-PRP)and leukocyte-depleted platelet-rich plasma(L-PRP)were used to treat the healing of tendon-bone junction(BTJ)after rotator cuff injury in mice.And through histomorphology,enzyme-linked immunosorbent assay(ELISA)and biomechanical tests,observe the tissue structure characteristics of BTJ after rotator cuff injury,the changes in serum concentration of related inflammatory factors,and the recovery of biomechanical properties,and preliminarily explore platelet-rich plasma The effect of white blood cells in(PRP)on BTJ after rotator cuff injury,It provides an effective theoretical basis and practical basis for the clinical application of PRP in BTJ repair after rotator cuff inj ury in the future.Methods:Select 54 C57BL/6 mice(8 weeks old,male,20-22g).(1)Take 0.2ml each of the pre-prepared allogeneic P-PRP,L-PRP and whole blood for blood component analysis,and the remaining part for follow-up research;(2)The supraspinatus tendon was cut off the right forelimb of the mouse to establish a rotator cuff injury model.The mice were randomly divided into 3 groups,namely the control group,the L-PRP group and the P-PRP group,with 18 mice in each group.Take about 0.1ml each of the pre-prepared allogeneic L-PRP and P-PRP,And mix with 20μl 10%Cacl2 calcium chloride+lOU bovine thrombin solution,A gel was formed and filled at the injury interface of the L-PRP and P-PRP groups.The control group:filled with the same amount of normal saline;(3)At 4 and 8 weeks after surgery,blood was taken from the eyeballs and the supraspinatus-supraspinatus tendon-humeral head complex specimens were taken.Blood samples were taken(ELISA)to detect the concentrations of related inflammatory factors interleukin-1β(TL-13)and tumor necrosis factor-a(TNF-α),and the complex samples were histologically observed for the recovery of BTJ tissue structure after rotator cuffinjury;8 weeks after surgery,biomechanical testing was performed on the complex specimens to assess the recovery of its biomechanical properties.Results:(1)Analysis of blood components:P-PRP and L-PRP platelet concentrations are similar(P>0.05),and both are higher than whole blood(P<0.01);The white blood cell concentration in L-PRP was significantly higher than that in P-PRP and whole blood,and the difference was extremely significant(P<0.01).Among them,the white blood cell concentration difference between P-PRP and whole blood was statistically significant(P<0.05).(2)HE staining:4 weeks after the operation,The fusion effect of tendon and bone surface of BTJ in the two groups of L-PRP and P-PRP is better than that of the control group.The fibrocartilage layer is visible,and the number,maturity,and order of cells and fibers of chondrocytes and tendon fibers in the L-PRP group are better than those in the P-PRP group;Eight weeks after the operation,the fusion site of the L-PRP and P-PRP groups showed a four-layer transitional structure close to normal BTJ.The thickness and tightness of the fibrocartilage layer at the fusion site in the P-PRP group were better than those in the L-PRP group.In the control group,the fibrocartilage layer was well fused at the injured BTJ site,and the chondrocytes were more mature,but arranged disorderly.(3)ELISA test results:8 weeks after operation,the serum levels of IL-1β and TNF-α in each group of mice were lower than those at 4 weeks;The serum IL-1β concentration of mice in the L-PRP group was significantly higher than that in the P-PRP group(P<0.01)and the control group at 4 and 8 weeks after surgery.The concentration of IL-1β in the P-PRP group was lower than that in the control group,and the difference was extremely significant(P<0.01),The serum TNF-α concentration of mice in the L-PRP group was significantly higher than that in the P-PRP group(P<0.01)and the control group,Among them,the concentration of TNF-α in the P-PRP group was significantly lower than that in the control group,and the difference was very significant(P<0.01).(4)Biomechanical test:8 weeks after operation,the biomechanical performance indexes of the L-PRP and P-PRP groups were significantly improved compared with the control group in terms of breaking load(FL)and ultimate strength(US),Compared with the L-PRP group,the FL value in group A increased by 0.44±0.02N(P<0.01),and the US value increased by 0.78±0.28Mpa(P<0.05).Conclusion:Platelet-rich plasma can promote the healing of the tendon-osseous junction after rotator cuff injury in mice.At 8 weeks postoperatively,the healing effect of pure platelet-rich plasma is better than that of leukocyte-rich platelet-rich plasma,and the therapeutic effect of leukocyte-rich platelet-rich plasma be better at 4 weeks after the operation.