| Objective: The purpose of this experiment is to study the effectiveness and safety of human umbilical cord WJ MSCs combined with HA hydrogel in repairing rabbit knee cartilage defects,improve the animal experiment in the preclinical stage,and provide a certain theoretical basis and reference value for the future use of stem cell therapy in the treatment of human knee osteoarthritis cartilage defects.Methods: 12.0kg-2.0kg male rabbits in each side of the knee were randomly selected as the control group.A full-thickness cartilage defect model（cylindrical,diameter 4mm,depth 1.5mm）was made at the femoral trochlea of both knees of rabbits with 4mm sterile ring drill.1 ml of human umbilical cord WJ MSCs suspension（1 × 107 cells）were fully mixed with HA hydrogel with a concentration of 4% to form a complex.The complex was filled in the cartilage defect of the experimental group.The control group was only filled with HA hydrogel,and the knees were self-control.Six rabbits were randomly killed at 3 and 6 months after operation.The cartilage repair effect was evaluated from the macro and histological perspectives by gross observation,safranin O staining,Sirius red staining and type II collagen immunohistochemistry.The relevant data were statistically analyzed.Results:1)Three months after operation,gross observation: the cartilage repair area of the experimental group and the control group were defective,but the defect area of the former was significantly smaller than that of the latter,and the surface was relatively smooth.The color and integration with the surrounding were better than that of the control knee.The ICRs score of the experimental group was better than that of the control group（8.70 ± 1.16 and 2.70 ± 0.48 respectively）,with statistical difference（P < 0.05）.Pathological staining: compared with the control group,the cell structure and arrangement similar to the surrounding hyaline cartilage and extracellular matrix can be observed in the experimental group,indicating that there are some hyaline cartilage in the center of the defect,and the collagen fibers are more than those in the control group.The wakitani score of the experimental group is better than that of the control group（7.90 ± 0.74 and 9.60 ± 1.07 respectively）,with significant statistical difference（P < 0.05）.II collagen immunohistochemistry: the positive areas of type II collagen staining in the experimental group were more than those in the control group,and the immunohistochemical scores were 1.50（1.00,1.50）and 0.00（0.00,1.00）respectively.The experimental group was better than the control group,which was statistically significant（P < 0.05）.2)Six months after operation,the general observation: the surface of the cartilage repair area in the experimental group was flush with the surrounding normal cartilage,and the defect in the control group was still obvious,and the color,smoothness and integration with the surrounding of the former were better than the latter.The general view of the former was close to the surrounding normal cartilage,and the ICRs score of the experimental knee was better than that of the control knee（9.70 ± 1.34 and 3.80 ± 0.79,respectively）（P < 0.05）.Pathological staining: the cartilage repair surface of the experimental group is more smooth and flat,transparent,close to the surrounding normal cartilage,the chondrocyte structure and arrangement are good,containing more hyaline cartilage extracellular matrix,the positive staining area of collagen fibers is significantly more than that of the control group,and the arrangement is regular,which is similar to the natural cartilage structure.The wakitani score of the experimental group is better than that of the control group（4.50 ± 1.27 and 8.80 ± 1.40 respectively）,It was statistically significant（P < 0.05）.II collagen immunohistochemistry: the positive areas of type II collagen staining in the experimental group were significantly more than those in the control group,and the immunohistochemical scores were 3.00（2.50,3.00）and 1.00（0.00,1.00）respectively.The experimental group was better than the control group,which was statistically significant（P < 0.05）.Conclusion: Human umbilical cord WJ MSCs combined with HA hydrogel has certain cartilage repair ability for rabbit knee cartilage defects,and the repair ability is better than that of HA hydrogel alone. |
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