This dissertation, "In Vitro Chondrogenic Differentiation of Human Mesenchymal Stem Cells in Collagen Gels" by 許婷恩, Ting-yan, Hui, 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 In Vitro Chondrogenic Differentiation of Human Mesenchymal Stem Cells in Collagen Gels submitted by Hui Ting Yan for the Degree of Master of Philosophy at The University of Hong Kong in August, 2007 Articular cartilage, the load-bearing tissue of the joint, has limited potential for repair and regeneration. Given a lack of satisfactory surgical solutions, cartilage tissue engineering has been suggested as a promising approach for cartilage repair. The present study demonstrated the fabrication of cartilage-like tissue-engineered constructs by chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in collagen gels in vitro. Collagen-hMSC constructs were synthesized with 5 6 varying cell seeding densities (110 - 510 cells/ml) and initial collagen concentrations (0.5 - 3 mg/ml) to investigate the effects of the two parameters. The constructs were cultured in chondrogenic differentiation induction medium for 21 days and evaluated by histological, immunohistochemial, morphological, biochemical and biomechanical examinations. In addition, with inclusion of chondroitin sulfate (CS), collagen/CS-hMSC constructs were also fabricated and compared to their collagen-hMSC constructs counterparts. After 21 days of culture, chondrogenesis was evident in the collagen-hMSC constructs, as indicated by positive immunohistochemical staining for cartilage-specific extracellular matrix components (type II collagen and aggrecan). The meshwork of collagen fibers was remodeled into a highly ordered microstructure, characterized by thick and parallel collagen bundles. Higher cell seeding density and higher collagen concentration favored the chondrogenic differentiation of the cells, yielding an increased matrix production (glycosaminoglycans) and a higher mechanical strength (reduced elastic modulus) of the constructs. A biochemical analysis of matrix accumulation revealed no difference between the collagen/CS-hMSC and collagen-hMSC constructs. Further investigation showed that most of the CS added during fabrication was lost to the surrounding medium within the first 24 hours. To study the effects of inclusion of CS, further studies should be performed to develop a fabrication method which enables effective CS incorporation into the constructs. The current work presented a systematic study to understand the parameters in building a cartilage-like construct, and provided the groundwork for optimization of the biological and mechanical characteristics. The findings may contribute towards the development of tissue engineering solutions for cartilage injuries. DOI: 10.5353/th_b3955874 Subjects: Chondrogenesis Collagen Stem cells Mesenchyme Tissue engineering