Experimental Study On Repairing Rabbit Cartilage Defects With PLGA/ACECM Tissue Engineered Cartilage Scaffold By 3D Printing

Objective: Due to its special tissue structure,articular cartilage is difficult to repair itself after injury.How to realize the regeneration of articular cartilage is a huge challenge for the medical and scientific communities.The research objectives of this subject are as follows: 1.Successfully prepare poly(lactic-coglycolic acid)by low-temperature deposition 3D printing technology,improved physics,chemical decellularization method,freeze-drying and physicochemical crosslinking technology.),PLGA)scaffold,articular cartilage extracellular matrix(ACECM)scaffold and PLGA/ACECM scaffold and other three tissue engineering cartilage scaffolds to explore its physiochemical properties;2.In situ implantation of three scaffolds In the rabbit knee articular cartilage defect model,it was observed to promote cartilage regeneration.Method:1.The PLGA scaffold was prepared by low temperature deposition 3D printing technology,and the ACECM slurry was prepared by modified physical and chemical decellularization method.ACECM scaffolds were prepared by freeze-drying and physicochemical cross-linking techniques,and PLGA/ACECM scaffolds were prepared by combining ACECM slurry with PLGA scaffolds.2.Physicochemical properties of three kinds of scaffolds: macroscopic and microscopic structures were observed by scanning electron microscopy(SEM);ACECM components were qualitatively analyzed by histology and immunohistochemistry;the compressive modulus of scaffolds was detected by biomechanical machine;Three kinds of scaffolds were subcutaneously implanted in SD rats to observe the immune rejection reaction;L-929 cells were cultured in three kinds of scaffold extracts,and CCK-8 cell proliferation assay kit(CCK-8)was detected.Cell proliferation;rabbit chondrocytes were planted on three kinds of scaffolds,and the growth of chondrocytes was observed by scanning electron microscopy and laser scanning confocal microscopy.3.Three kinds of stents were implanted in situ into rabbit knee articular cartilage defect model,and were sacrificed at 3 and 6 months after operation.Gross view and imaging examination(X-RAY,Micro-CT,MRI)were used.Histological staining was used to evaluate cartilage regeneration.Results:1.Gross and SEM observations of the three scaffolds have a vertical three-dimensional orientation of the multi-porous structure;histological and immunohistochemical qualitative analysis of ACECM proved that ACECM is completely decellularized,retaining the glycosaminoglycan of the cartilage matrix(glycosa minute oglycans GAGs And type II collagen;biomechanical testing suggests that the compression modulus of PLGA stent is not statistically different from that of PLGA/ACECM stent.The compression modulus of PLGA stent and PLGA/ACECM stent is significantly higher than that of PLGA/ACECM stent.The difference in ACECM scaffolds was statistically significant.Compared with PLGA/ACECM scaffolds,PLGA scaffolds had better biomechanical properties than ACECM scaffolds.There was no obvious rejection in subcutaneous embedding of SD rats.HE staining showed ACECM.The PLGA/ACECM scaffold immunological rejection was significantly lower than that of the PLGA scaffold.The CCK-8 assay showed that the number of cells cultured in the three scaffold extracts increased with the prolongation of the culture time,which was not statistically significant compared with the control group(P >0.05);Scanning electron microscopy and laser scanning confocal microscopy showed that chondrocytes can grow on all three scaffolds.2.In situ implantation of rabbit knee articular cartilage defects showed that there was only a small amount of tissue filling in the articular cartilage defect repair area of the blank control group,partial tissue growth in the articular cartilage defect of the PLGA stent group,and most of the cartilage defect repair area in the ACECM stent group.The part of the boundary line with the normal cartilage interface is visible,and the central part of the repair defect is missing.The area of cartilage defect in the PLGA/ACECM stent group was completely filled,and the appearance was close to the normal cartilage tissue.The boundary line between the new cartilage and the surrounding normal cartilage became blurred,and the cartilage in the repaired area was continuous and flat.Histological staining and imaging examination(X-RAY,Micro-CT,MRI) showed that the PLGA/ACECM stent group was better than the PLGA stent group and the ACECM stent group in repairing rabbit knee articular cartilage defects.Conclusion:The cartilage biomimetic PLGA/ACECM oriented scaffold has a good three-dimensional oriented porous structure and has good biological and mechanical properties compared with the simple PLGA scaffold and ACECM scaffold.Rabbit knee joint stent implantation showed that the cartilage biomimetic PLGA/ACECM orientation stent can achieve complete regeneration of cartilage and prevent the occurrence of osteoarthritis.It is a good tissue engineering cartilage scaffold material.