Novel structured nanofibrous three dimensional bone tissue-engineered scaffolds

Tissue engineering strategies combining engineering principles and methods and biological sciences in creating implantable tissues have been viewed as the most promising technologies for tissue regeneration. Typical tissue engineered approaches include three elements: cells, bioactive molecules and three dimensional (3D) porous scaffolds, which serve as the template for cell growth and development. The understanding of the relationship between an appropriate 3D structure and the corresponding tissue response is critical in scaffolds design, particularly for bone tissue engineering application. This study first proposed a novel spiral structure design which revolutionized the conventional bulk shape design of 3D scaffolds with a hypothesis that by providing an improved mass transport mechanism, the spiral structure scaffolds would solve the problems of the conventional scaffolds such as insufficient tissue ingrowth and low regeneration rate. A series of in vitro studies both in static and dynamic cell culture conditions have demonstrated several advantages of this spiral structured scaffolds over the conventional scaffolds. At the same time, these studies show the importance of the 3D structure design to the performance of scaffolds given the same materials used for scaffolds fabrication. Furthermore, the author continues to optimize the spiral structured scaffolds in terms of appropriate fiber thickness, gap distance and wall thickness, wherein it was found that interconnected porous structure alone is not enough for an ideal scaffold due to the intrinsic diffusive mass transport mechanism. Spiral-structured scaffolds with gaps allowing fluid flow through the channels, thus promote uniform tissue regeneration throughout the whole scaffold. The author further improved the initial design by integrating the spiral structured scaffolds with an outer tubular shell which reinforced the scaffolds, particularly for bone tissue engineering applications. This design actually mimics the natural bone with non-uniform mechanical property and porosity from the outer to the inner part, thus alleviates the conflict of conventional scaffolds that the increase of high porosity to promote tissue regeneration usually lead to the inefficient mechanical strength. In order to further enhance the osteoinductive properties, the author also functionalized the scaffolds by incorporation Hydroxyapatite and BMP-2 within the scaffolds.