Osteochondral (OC) defects are a common problem in orthopedics, affecting simultaneously the articular cartilage and underlying subchondral bone tissue. In order to repair an OC defect, the needs of cartilage, bone and bone-cartilage interface must be considered. OC tissue engineering (TE) strategies may include the use of biomaterials processed into porous scaffolds, fiber materials or hydrogels. Bilayered scaffolds, developed by combining these structures into layered and graded forms, have been receiving much attention (Chapter 1). While the ideal TE strategy has not yet been achieved, great efforts have been made in terms of pre-clinical and clinical applications of engineered biomaterials for OC regeneration, some of them overviewed in this thesis (Chapter 2). As a natural-based polymer silk fibroin (SF) has a particular interest as scaffolding material. The most recently developed biomimetic strategies and processing routes of SF-based materials aiming bone, cartilage and OC tissues regeneration, were summarized and discussed in this thesis (Chapter 3). The high processability of this protein, also motivated the use of silk in the herein developed work. Textile-based SF scaffolds were produced by a weft-knitting technology and surface modified to be modulated according to the target TE application (Chapter 5). The same textile-based technology was used to process novel weft-knitted SF spacer scaffolds for bone TE applications (Chapter 6). A monofilament of polyethylene terephthalate (PET) was used to increase the scaffolds three-dimensionality (3D), inducing structural similarities adequate for flat bone regeneration. A horseradish peroxidase (HRP)-mediated crosslinking system was used in combination with salt-leaching and freeze-drying methodologies for preparing porous SF scaffolds for cartilage TE applications (Chapter 7). Considering the stratified and hierarchical characteristics of OC tissue, bilayered scaffolds composed of a HRP-crosslinked SF layer and a composite layer combining HRP-crosslinked SF and ionic-doped (zinc and strontium) β-tricalcium phosphate (β-TCP), were proposed for OC regeneration (Chapter 8). The use of HRP-crosslinked SF hydrogels with spatial tunable properties and cell-encapsulation ability, was also proposed in this thesis as a novel strategy for the fundamental study of hydrogel-based 3D models in cancer research (Chapter 9). In summary, the presented results indicated the versatility of the proposed biomimetic strategies for improving the performance of SF as biomaterial for bone, cartilage and OC tissue engineering, or for using in 3D culture technologies to build better in vitro 3D tumor models for cancer research.
|15 May 2018
|Published - 2018