Intervertebral Disc Regeneration PDF Download

This dissertation, "Intervertebral Disc Regeneration Using Mesenchymal Stem Cells: a Mouse Model Study" by 楊帆, Fan, Yang, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled "Intervertebral disc regeneration using mesenchymal stem cells ─A mouse model study" Submitted by Fan Yang For the degree of Doctor of philosophy At the University of Hong Kong in August, 2007 Degenerative disc disease (DDD) is a common disease which affects millions of people. The causes of DDD include genetics, injury and smoking; however the underlying pathogenesis of this disease is still not very clear. Lack of the suitable animal models which can truly simulate human DDD is part of the difficulties to study the mechanism of disc degeneration. The biological therapies of DDD include protein therapy, gene therapy and cellular therapy. Compared with other traditional therapeutics, stem cell therapy is a potential regenerative method which could replace the dysfunctional disc cells and restore the function of the intervertebral discs. Some previous studies using large animals have shown that the autologous bone marrow derived mesenchymal stem cells (BMSC) could be beneficial to the degenerated disc. But the mechanism of this regeneration is still largely unknown. The scanty of molecular tools and markers hindered the research in this area. Therefore, the objective of this project is to investigate whether BMSC could be beneficial to the murine degenerative intervertebral discs. If the regenerative effect was obtained, the molecular mechanism of regeneration will be dissected using available molecular tools. In order to attain this purpose we firstly established a simple mouse tail model of DDD using a puncturing method. The caudal murine discs were punctured with 31G needle under the microscopic guidance. Disc height analysis and histology confirmed the induced degeneration was successful and progressive degenerative process was observed from 1 to 12 weeks after the puncture. The expression of Col2a1, aggrecan and Sox 9 of the whole disc decreased continuously; Col1a1 increased from 1 to 6 weeks and decreased at 12 weeks. All these data supported that this murine model had some similarities with human DDD and could be used for the evaluation of the effect of BMSC. In the next step we injected allogenic BMSC isolated from green fluorescent protein (GFP) mouse into the degenerated murine discs. The histology and the x-ray analysis showed that the injury induced degenerative process was delayed from 4 to 24 weeks after the injection of the BMSC. The expression of Col2a1, aggrecan and Sox9 increased in the regenerated disc. Type II collagen increased continuously in the regenerated nucleus pulposus. The number of GFP positive cells which express Col2a1 increased during this regeneration process, suggesting that the chondrocytic differentiation of BMSC was involved in this regeneration process. The increased expression of Col2a1 by differentiated stem cells contributes to the regeneration of the intervertebral disc. In conclusion, a simple mouse model of DDD was established to evaluate the therapeutic effect of BMSC. It was promising to observe that the progressive degeneration was delayed by the injected stem cells. The in vivo chondrocytic differentiation of the BMSC contributes to this structural restoration of the intervertebral discs. The results of this project provided further evidence that in vivo differentiation of the stem cells is an important aspect of the regenerative mechanisms. DOI: 10.5353/th_b3955697 Subjects: Interve