Construction Of Tissue Engineered Cartilage Based On Stromal Vascular Fraction To Repair Large Area Cartilage Defects Of Goat Knee Joint

Objective:The cartilage ECM derived particles(CEDPs)and PCL scaffolds were used as carriers to explore the Stromal Vascular Fraction(SVF)derived from autologous adipose tissue to construct the tissue engineered cartilage to repair the large area defect of cartilage in the knee joint of goats.Methods:Porous polycaprolactone(PCL)scaffolds were prepared using 3-D printing techniques.The cartilage fragments at the knee joint of the goat were scraped in a sterile environment,and extracellular matrix-derived particles derived from goat cartilage were prepared by pulverization and gradual decellularization.Microscopic morphological examination of scaffolds and extracellular matrix-derived particles was performed in vitro,and cells were combined to observe the effects of materials on cell growth and differentiation.The subcutaneous fat of the goat's neck was taken under aseptic conditions,and the SVF was obtained by enzyme digestion.It was verified in vitro to have multiple differentiation capabilities.At the time of surgery,a full-thickness cartilage defect with a diameter of 8 mm was established in the inner and outer femoral condyle of the right knee joint of the goat.The experiment was divided into 5 groups,4 goats in each group(8 defect areas),which were group A: blank control group;group B: CEDPs group;group C: CEDPs+SVF group(micro-tissue group);group D: PCL Group;Group E: PCL + micro-tissue group.The defect repair was evaluated by the International Cartilage Repair Society Visual Histological Assessment Scale,and the tissue sections were subjected to H&E,Modified Safranine O-Fast Green staining and Type II collagen staining analysis,imaging examination,biomechanical testing and glycosaminoglycan quantitative testing to evaluate the defect repair effect.Results:At 3 months of analysis,the general observations and scores of the specimens showed that the effect of group C was better than that of group AB.The results of specimen section staining showed that the proportion of hyaline cartilage in group C was higher than that in the other groups,and most of group A and group B were fibrocartilage repaired or not repaired.MRI results showed that the cartilage signal in the repaired area of group E was similar to that of normal cartilage,and the destruction of subchondral bone was lighter than the other groups.The results of nanoindentation showed that the mechanical properties of cartilage tissue in the repaired area of group E were closer to the surrounding normal cartilage.The results of quantitative analysis of glycosaminoglycan showed that the glycosaminoglycan content of newborn cartilage in group C was higher than that in group A and B.Conclusion:The combination of Adipose-drived SVF and PCL scaffolds can be used to repair cartilage defects in the weight-bearing area of goat knee joints.The results of this study indicate that SVF is a tissue engineering seed cell source with potential for differentiation,which has the advantages of being easily accessible,without culture,and can be completed in one operation.Chondrocyte extracellular matrix-derived particles provide a good carrier and microenvironment for seed cells,facilitating cell expansion and differentiation.The PCL scaffold provides good mechanical support for the defect area and creates favorable conditions for cartilage production.Therefore,the technology used in this study has a good application prospect.