| Objective: To observe the function of platelet rich plasma (PRP) onrepairing the injury of avascular area of rabbit meniscus, and to investigate thepossible ability and mechanism of PRP on repairing meniscus injury. So thatto provide the experimental data for application of PRP in the field ofmeniscus injury therapeutic.Method: In this study, we had chosen18New Zealand white rabbitswithin3-4months old. The rabbits were randomly divided into three groups:group A, group B and group C.7-8ml arterial blood was collected from the earcenter artery of each rabbit and5ml of the blood was prepared to extract about0.5ml PRP using two-step centrifugation method (2000r/min,5min for eachstep of centrifugation). The other blood was prepared to detect plateletconcentration on blood cell analyzer. Then about0.2ml PRP was extractedfrom this part of blood and the PRP was also detected platelet concentrationon blood cell analyzer too. All rabbits were operated to build a model ofdouble knee meniscus injury which was a2mm radial tear at the avascularzone of the anterior horn of lateral meniscus. The right knee of each rabbit wasdefined to experimental group and the left was control group. In experimentalgroup,0.5ml PRP and the activator were injected into the articular while incontrol group only model building had been done. The rabbits were sacrificedby1,3,5weeks after surgery according to A, B, C group and the two lateralmeniscuses were collected from each rabbit. Every6rabbits in each groupwere divided to2groups randomly: group slice and group ELISA. Aftergeneral observation of each meniscus, the ones in group slice were prepared topathological observation while the meniscuses in group ELISA were to detectthe content of PDGF within meniscus using rabbit PDGF ELISA kit. Result:1There were no postoperative complications such as infectionhappened.2The platelet concentration in PRP extracted by two-stepcentrifugation method was as4.68times as in whole blood, which canconform to the requirements of PRP on platelet content.3General observationIn experimental group in group A, there was thin film-like tissue growbetween the injury crack but the injury crack was still obvious. In group B,the injury cracks of experimental meniscuses were partly filled with fibrousscar-like tissue, and there were no obvious cracks. While in group C,fibrillar connective tissue fully filled in the cracks of meniscuses inexperimental group.In control group, the injury cracks of meniscuses were obvious till5weeks postoperatively. Some meniscus in group C, there could be seen thatthe cracks were partly filled with a bit of fibrous scar-like tissue.Statistical analysis results showed that the healing condition ofexperimental group was significantly better than control group (P <0.05)both in group A, B and C.4Histological observationIn experimental group of group A, there were lots of cells, which wasin the majority with inflammatory cells and fibroblast, infiltrated in theedge of meniscus injury cracks. And there were little fibro-chondrocyteappeared. The reparative tissue was not obvious stained with Safranin-O.While in group B and C, reparative tissue filled in the injury cracksgradually increased and was closely connected with surrounding normalmeniscus tissue. Fibro-chondrocyte and extracellular matrix increasedgradually. And in ECM, fibrillation and neovascularization could be seen,the tissue stained with Safranin-O also expanded gradually which meanthat the composition of cartilage increased gradually.In control group of group A, the edge of meniscus injury cracks werecoarse and neither infiltrated cells nor fibro-chondrocytes could be found. In group B and C, reparative tissue partly filled in the injury cracks but notclosely connected with surrounding normal meniscus tissue. The number offibro-chondrocytes and ECM were less than which in experimental groupand fibrillation and neovascularization did not appear in the reparativetissue.Statistical analysis results showed that the healing condition ofexperimental group was significantly better than control group (P <0.05)in group B and C. While in group A, there was no significant differencebetween the two groups.5The content of PDGF in the meniscuses of group ELISAWe tested the content of PDGF in the meniscuses of group ELISAwith a rabbit PDGF ELISA kit and analyzed the result. Statistical analysisresults showed that only in group B, there can be found that the content ofPDGF of experimental group was significantly higher than of control group(P <0.05). No significant difference found in group B and C betweenexperimental and control group. In experimental group, the content ofPDGF reached the highest level at3weeks postoperatively and the lowestat5weeks.Conclusion: PRP has repair function of meniscus avascular area injuriesin the rabbit model in this study. It can induce and accelerate inflammatoryreaction; promote the meniscus of cellular proliferation and extracellularmatrix synthesis and induce cartilaginous metaplasia and vascularization. |
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