Alternative TitleStudy on hydroxyapatite and collagen based bilayer scaffolds for osteochondral treatment
Note (General)Osteochondral injury, a simultaneous damage of articular cartilage and bone tissues, requires implantation of a bilayer scaffold (porous bodies / sponges) in which the first and second layer is optimized for cartilage and bone tissues regeneration, respectively. To promote the cartilage regeneration, the first layer is combined with cartilage tissue-engineering strategy that is a deliberate attempt to obtain in vitro cartilage by culturing and maturing stem cells. Collagen-based material is a gold standard for tissue-engineering scaffold, and commonly fabricated from the monomeric form of collagen (liquid state), owing to easiness of fabrication. Nonetheless, collagen in the native tissues exist in the fibrillar form (gel-like state), thereby the fibrillar collagen scaffold is expected to elicit more superior biological properties to the monomeric counterpart. Composite material of collagen and hydroxyapatite (HAp) is generally used as a scaffold for bone tissue. The current methods to fabricate bilayer scaffold is by knitting or gluing collagen sponge and collagen-HAp composite, which pose risk of delamination. Therefore, a continuous bilayer scaffold: collagen sponge with gradient content of HAp is desired. Electrolysis was previously used to simultaneously deposit fibrillar collagen and HAp; justifying the attempt to investigate electrolysis to fabricate continuous bilayer scaffold. Iron-oxide nanoparticle (IONP) with magnetic property has been reported to support bone cells proliferation. This thesis initially aims to elucidate the advantage of fibrillar to monomeric collagen sponges as a cartilage tissue-engineering scaffold; thereafter, the thesis focuses to construct a continuous bilayer scaffold optimized for regenerating osteochondral injury. It was discovered that collagen structure influenced the morphology of attached fibroblast, with the fibrillar collagen sponge supported higher proliferation rate to monomeric sponges. Next, electrolysis was used to prepare fibrillar collagen/HAp scaffold; chitosan was added to improve the fibril formation of collagen. Fibrillar collagen/HAp/chitosan sponges supported the faster proliferation of mesenchymal stem cells and the larger production of cartilage tissue-related extracellular matrices compared to the monomeric collagen/HAp/chitosan sponges. Next, electrolysis was used to produce fibrillar collagen-chitosan scaffolds with gradient HAp content; further addition of IONP successfully improved the proliferation rate of osteoblast (bone cells) cultured in the HAp-rich region of scaffolds. In parallel, other configuration of a continuous bilayer scaffold consisting of collagen/HAp sponge and IONP-impregnated HAp-sintered body was fabricated by simultaneously electrolyzing the latter structure in the presence of collagen/HAp solution. In conclusion, a fibrillar collagen scaffold containing IONP and gradient content of HAP is considered as an ideal scaffold to simultaneously regenerate cartilage and bone tissues in the osteochondral injury.
identifier:oai:t2r2.star.titech.ac.jp:50485935
Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2021-05-16T23:51:55+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション