Study On Repairing Of Osteochondral Defect Of Knee Joint In Rabbit With Rapid Prototyping Tissue Engineered Osteochondral Composite

Osteochondral defect of knee joint caused by trauma, inflammation, tumor resection and degeneration is very common in clinical practice. The repairing of articular cartilage injury is one of the problems in orthopedics, which is not solved finely today. Traditional treatment option has poor outcome, and none of these methods is a satisfied therapy for cartilage repair. At present, the research of treatment for cartilage defect focuses on tissue engineering.Early in the study of tissue engineering to repair osteochondral defect,the researchers separated from the cartilage and bone preparation, and then connect part of the cartilage and bone.However, these methods only make use of simple physical or chemical methods to connect bone - cartilage in two parts. The design of deposit in the bone - cartilage weak interface to connect the inherent instability defects may be lead to the two parts separated, and ultimately lead to failure.In this experiment, we prepare the integration of PLGA / PLGA- TCP osteochondral double scaffold coating with collagenⅠsupplemented with high-density autologous BMSCs and apply it as a single unit to treat osteochondral defect. PartⅠPreparation of the integration of rapid prototyping osteochondral scaffold and modification with collagenObjective The goal of this study is to prepare integrative PLGA/PLGA-TCP osteochondral scaffold by RP technology and support collagen modification method. Methods Prepare integrative PLGA/PLGA-TCP osteochondral scaffold by multi-spraying low-temperature manufacturing(MSLM)new technology, and modify the scaffold with collagenⅠ. Determine water absorption rate of the scaffold coating with collagenⅠand original scaffold without collagenⅠ. The microscopic structure of scaffold material were observed under scanning electron microscope (SEM).Results Higher hydrophilicity was performed in experimental group. Smooth large-scale pore and interpenetration miniature pore structure (10~500μm) can be observed under SEM. Bone and cartilage interface to connect the two parts is good. Conclusion The structure of rapid prototyping integrative PLGA/PLGA-TCP osteochondral scaffold coated with collagenⅠis consistent with the need for cartilage tissue repair.PartⅡBiocompatibility of rapid prototyping osteochondral scaffolds coated with collagen in vitroObjective The goal of present study is to investigate the biocompatibility of rapid prototyping (RP) PLGA/ PLGA-TCP scaffold coating with collagenⅠand provide a basis for in vivo experiments. Methods PLGA/ PLGA-TCP scaffold fabricated with RP technology and coated with collagen I was used as experimental group and original scaffold without collagenⅠwas used as control group. BMSCs were seeded into both groups. Adhesion and proliferation ratio were examined. Morphology of BMSCs were observed under scanning electron microscope (SEM). Results Compared with control group, the Cell adhesion ratio was increased significantly in the experimental group at 4, 8, and 12 hour after the cell seeding(P<0.05).As well, the cell proliferation of experimental group was demonstrated at higher level at 2, 4, 6, and 8 days (P<0.05). In addition, the quantity of BMSCs in experimental group was much more than control group under SEM.Conclusion This Rapid prototyping PLGA/ PLGA -TCP scaffold coated with collagenⅠpossesses good cellular biocompatibility .It can be used as a scaffold to restore osteochondral defects.PartⅢRepairing of osteochondral defect of knee joint with rapid prototyping tissue engineered osteochondral compositeObjective To prepare the PLGA/ PLGA-TCP scaffold coating with collagenⅠsupplemented with autologous BMSCs and apply it as a single unit to treat osteochondral defect. Methods PLGA/ PLGA-TCP scaffold coating with collagenⅠwas prepared according to testⅠ. Autologous BMSCs were harvested by bone aspiration of bone marrow from rabbit model, cultured and expanded in vitro and then seeded in the PLGA/ PLGA-TCP scaffold coating with collagenⅠto repair osteochondral defect of left knee in the rabbit model (experimental group);the right knee of the same rabbit was implanted with a same scaffold that was cell-free (cell-free scaffold group).The other 12 knees were left untreated as control group. Histological examination and macroscopical observation were applied to measure the repair of defect at 12th and 24th weeks after operation. Results At 12 week,the tissues newly generated in the defects of the experimental group were stained slightly positive for chondrogenesis; while on the cell-free scaffold group, both the cartilage and the subchondral bone were not regenerated; and the defects in the control group were filled with fibrous like tissue. At 24 week, the cartilage and subchondral bone of the defects on the experimental side were fully regenerated; but in the cell-free scaffold group, the defects were filled with fibrous tissue ; and the defect in the control group were not repaired. Conclusion The PLGA/ PLGA-TCP scaffold coating with collagenⅠsupplemented with autologous BMSCs can be used to treat osteochondral defect as a single unit eliminating the need of osteogenic and chondrogenic induction in vitro.