| The artilular cartilage defcets caused by injuries or degenerative events are very common in clicnic practice, yet it has a limited capacity of self-regeneration, which bring dysfunction and inferior life quality to patients. It is still a difficult problem to repair and reconstruct articular cartilage defects in orthopaedics, and it is also one of the research foci in recent years. Untill now, there have been a few methods to repair artilular cartilage defects including "microfracturing", "masaicplasty", transplantations of periosteum, periochondrium and isolated chondrocytes. Although these methods have their advantages and disadvantages respectively, they can not meet the needs of perfect reconstruction in the end. Tissue engineering that aims to "replicate tissue and organ" provide another innovative choice for repair and regeneration of articular cartilage defects.Seeding cells and 3D scaffolds are two basic bilogical elements in tissue engineering. It is an essential step to seed chondrocytes uniformly and efficiently into 3D scaffolds in order to construct tissue-engineerde cartilage in vitro, but the tissue engineering coulde not have been provided with efficient cell seeding methods. Autologous chondrocytes, lack of immunologic response, are considred to be an ideal seeding cells in tissue-engineered cattilage, but its source is limited. The allogeneic chondrocytes are obtained rather easily and may be an alternative to provide abundant seeding cells. The method of three-dimensional seeding of chondrocytes encapsulated in collagen gel into CPPf/PLLA scaffolds was evaluated whether the constructed quality of tissue-engineered cartilage can be improved. The feasibility of repair of rabbits cartilage defects with allograft chondrocytes-collagen gel-CPPf/PLLA complex was estimated. Meanwhile, articular chondrocytes by retuoviral infection using green fluorescence protein was tracked to know whether transplanted cells remain viable and contribute to repair in the host cartilage defects. Firstly, chondrocytes were liberated by sequential enzymatic digest and culture in vitro. The approach, which chondrocyte were mixed with collagen solution, and the mixture was incorporatede into a 3D CPPf/PLLA scaffold, then made into gel in the scaffold, and then culture in vitro, was evaluated whether the chondrocytes can be seeding into the 3D scaffolds evenly and efficiently and the quality of in vitro cartilage regeneration can be improved. Results showed: 1.It took 5-6 days for chodrocytes to be confluent with plating concentration of 2-4×104/cm2. 2.Chondrocytes can be seeding into CPPf/PLLA scaffolds uniformly and efficiently; 3. Chondrocytes-collagen gel-CPPf/PLLA complex can keep its original shape after long-term culture; 4. Chondrocytes-collagen gel-CPPf/PLLA complex can form mature cartilage tissue more quickly in culture; 5. The constructed quality of tissue-engineered cartilage can be improved by the method of 3D seeding of chondrocytes encapsulated in collagen gel into 3D scaffolds.Secondly, the histology morphologic characteristic of tissue-engineered cartilage allograft to repair full-thickness defects in rabbit articular cartilage was studied. Results showed: 1. Defective regions were occupied by hyaline cartilage at 4 weeks after transplantation and were baerly recongnisable with natural articular cartilage at 12 weeks. 2. Neither mononuclear cell infiltration nor vascular invasion could be seen in or around the transplanted tissue. 3. Transplanted chondrocyte marked by GFP remain viable and contribute to repair in the host cartilage defects at 4 week after surgery. Conclusions can be drawm as follows: 1. The methods presented, where chondrocytes were mixed with collagen solution ,and the mixture was incorporated into a 3D scaffolds, then made into gel in the scaffold, could serve as an efficient alternative for in vitro cartilage regeneration, also simultaneously having the advantages of both materials. 2. Combining collagen gel with CPPf/PLLA 3D scaffold can used as a good carrier to de...
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