Enzymatically crosslinked scaffold with controllable cell and growth factor delivery for use in tissue engineering

UnrestrictedTissue engineering is a multidisciplinary field that applies the principles of biology and engineering to restore, improve, or maintain functions of tissue or organs. Damaged or aged tissue/organs are replaced or repaired by integrating engineered material into the body. The fundamental components used in tissue engineering can be divided into three types: cells, scaffold, and signaling molecules. Many researchers have taken each subject as a separate approach to develop new tissue-engineering strategies. In more recent developments, combinations of these subjects have been investigated to improve tissue integration and repair.; In this thesis, the aim of this study was to prepare tissue-engineered constructs composed of biopolymeric scaffolds that could be modified to enhance scaffold properties, to initiate growth factor release by bioresponsive feedback and to deliver cells in a localized manner. We presented a transglutaminase (TGase) crosslinked gelatin for use as a tissue-engineering device. Initial characterization of the crosslinked gelatin demonstrated potential as a platform base for further development. For scaffold enhancement, fragmented bovine serum albumin (BSA) was used as a linker molecule between gelatin strands and also used to increase the number of TGase reactive sites. The incorporation of BSA fragments was later shown to increase mechanical strength, and maintain biocompatibility. For growth factor release, the crosslinking mechanism of TGase conjugated gelatin to BMP-2 without significantly altering the biological structure of the protein. The conjugation introduced a novel delivery method of growth factors where growth factors were able to de-activate and re-activate through proteolytic enzymes or through physiological feedback of MMPs from the surrounding environment. For cell delivery, the non-cytoxic enzyme component enabled the use of insitu gelatin crosslinking where the cells were encapsulated in the gels and injected directly into the repair site. With the success of creating cell delivery method with gelatin TGase gel, a combination of growth factor with cell delivery system was also introduced and demonstrated