| Intervertebral disc degeneration is the initiation factor of degenerative spinal disorders which play a pivotal role in the pathogenesis of intervertebral disc degeneration.The disorders can cause a range of spinal degenerative changes and secondary lesions, such as disc herniation, spinal segmental non-stable disease and spinal stenosis psychosis.These diseases threat to the health of the people and lead to an enormous socioeconomic impact in the world. The treatment of these diseases are mainly conservative treatment in the early stage and surgery in a later stage. In the past 30 years, decompression and fusion approach are the major surgical treatments to remove the oppression and reconstruction of spinal stability.However, with long-term follow-up,the cases continue to accumulate and integrate, especially after multi-segmental fusion.It is being increasingly recognized that the degeneration of adjacent segments and the functional damage after the fusion of spine. In the 20th century, artificial disc technology has begun to be introduced in pursuit of non-fusion of the functional reconstruction of goal. In the early cases, there have been some encouraging results.But the symptoms can not be improve and even further deteriorate followed by a part of the case. Therefore, the construction of tissue engineered nucleus which restore disc structure and function and maintain normal motor function in spinal segments is the focus of the study.In recent years, adipose-derived stem cells (adipose-derived stem cells, ADSCs) aroused the concern of researchers. ADSCs and MSCs belong to the mesoderm of adult stem cells and therefore have more similar biological characteristics. Some scholars have found that two kinds of stem cells have no significant difference in the growth kinetics, cell aging, gene transfer and cell adhesion characteristics. ADSCs have strong ability to self-renewal and mass culture accessible to a large number of cell differentiation in vitro. The cloning analysis of ADSCs showed that 52% of the cell clones have two or three directions of differentiation potential. ADSCs has been confirmed to be able to differentiate mesodermal cells including fat, cartilage, bone, muscle and other mesodermal cells under certain conditions. All these show the multiple differentiation potential of the adipose tissue. The researchers induce ADSCs to the cartilage cell differentiation with a special three-dimensional microsphere culture system simulation environment for the growth cartilage cells can detect aggrecan and theâ…¡/â…©-specific expression of collagen genes. Nucleus pulposus cells have the same phenotype which chondrocyte cells.It express the marker gene including the SOX-9, aggrecan, II collagen gene, which induce the ADSCs to provide a prerequisite for nucleus pulposus cells.The another research in intervertebral disc tissue engineering is focus on finding natural or synthetic scaffold which can be used as cell transplantation and extracellular matrix substitutes of tissue growth. The ideal scaffold material should be structurally similar with the disc matrix components and maintain cell function. It is a bottleneck restricting intervertebral disc tissue engineering to build in line with nucleus pulposus cells and extracellular matrix components with the biological characteristics of nucleus pulposus scaffold material. Chitosan is the only positively charged basic polysaccharide and the molecular structure is similar to glycosaminoglycans. Cationic properties of chitosan make it easier to capture the cartilage or intervertebral disc cells to produce a high anion proteoglycans, thus contributing to the maintenance of intervertebral disc matrix functions. Some scholars have found that the chitosan generally cause a slight foreign body rejection when implantation.The chitosan scaffolds can accelerate wound healing, which may be stimulatie the immune cells to secrete growth factors.In the repair process, it can accelerate the integration of theimplanted stent and the normal tissue.Objective:To confirm that it can slow down intervertebral disc degeneration by tissue engineeringMethods:ADSCs grown in three-dimensional chitosan scaffold were differentiated to the nucleus pulposus cells. The complex of ADSCs and Chitosan was organizated and then was used for repair a rabbit animal model of disc degeneration. The functions of nucleus pulposus of tissue engineering was final tested. Then we evaluate the biological value of nucleus pulposus of tissue engineering and provide experimental basis of the treatment of degenerative disc disease for clinical application. Results:l.The cells separated by density gradient centrifuge and adhesive property owned the characteristics of ADSCs and the third passage had a good condition. It was confirmed that the cells that were isolated and cultured were ADSCs in this experiment.2. The three-dimensional chitosan scaffolds with high porosity is ideal for disc tissue engineering scaffold material.It does not swell in water and maintain it's shape.3. The animal model of disc degeneration can be established by aspiration of lumbar nucleus pulposus of New Zealand white rabbit. The operation is simple. This method can be suitable for routine applications, because it's reliability and reproducibility. This model can provide a basis for further experimental study.4. The organized complex of ADSCs and Chitosan transplanted to degenerative discs can effectively inhibit the intervertebral stenosis. The disc degeneration can be slowed by the MRI. The biochemical tests showed that it can slow the decline in proteoglycan content and inhibit the intervertebral disc degeneration and then repaire it.Conclusion:The organized complex of ADSCs and Chitosan can effectively inhibit the disc space narrow of rabbit disc degeneration model and slow disc degeneration. This can provide the experimental evidence for degenerative disc disease by the treatments of tissue engineering. |
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