Anisotropic silk fibroin/gelatin scaffolds from unidirectional freezing.

Recent studies have underlined the importance of matching scaffold properties to the biological milieu. Tissue, and thus scaffold, anisotropy is one such property that is important yet sometimes overlooked. Methods that have been used to achieve anisotropic scaffolds present challenges such as complicated fabrication steps, harsh processing conditions and toxic chemicals involved. In this study, unidirectional freezing was employed to fabricate anisotropic silk fibroin/gelatin scaffolds in a simple and mild manner. Morphological, mechanical, chemical and cellular compatibility properties were investigated, as well as the effect of the addition of gelatin to certain properties of the scaffold. It was shown that scaffold properties were suitable for cell proliferation and that mesenchymal stem cells were able to align themselves along the directed fibers. The fabricated scaffolds present a platform that can be used for anisotropic tissue engineering applications such as cardiac patches.

Stem cell-derived cell-sheets for connective tissue engineering.

Cell-sheet technology involves the recovery of cells with its secreted ECM and cell-cell junctions intact, and thereby harvesting them in a single contiguous layer. Temperature changes coupled with a thermoresponsive polymer grafted culture plate surface are typically used to induce detachment of this cell-matrix layer by controlling the hydrophobicity and hydrophilicity properties of the culture surface. This review article details the genesis and development of this technique as a critical tissue-engineering tool, with a comprehensive discussion on connective tissue applications. This includes applications in the myocardial, vascular, cartilage, bone, tendon/ligament, and periodontal areas among others discussed. In particular, further focus will be given to the use of stem cells-derived cell-sheets, such as those involving bone marrow-derived and adipose tissue-derived mesenchymal stem cells. In addition, some of the associated challenges faced by approaches using stem cells-derived cell-sheets will also be discussed. Finally, recent advances pertaining to technologies forming, detaching, and manipulating cell-sheets will be covered in view of the potential impact they will have on shaping the way cell-sheet technology will be utilized in the future as a tissue-engineering technique.