| dc.description.abstract | The human body has evolved to enable healing in most of our tissues with remarkable efficacy. This process relies on a rich and dynamic microenvironment, which coordinates a myriad of molecular and cellular processes that ultimately culminate in complete healing. Imagine being able to harness and controllably guide and amplify this regenerative environment to heal larger non-regenerating defects in tissues and organs. This project proposes a new way to think about regenerative materials by going beyond bioinspiration to establish a “bio-cooperative material”, where the patient’s own blood is transformed into living personalised devices (i.e. implants, grafts, in vitro models) that reconstruct and enhance the natural regenerative process. Self-assembling peptides were used as “supramolecular organisers” to guide the assembly of blood components, using coagulation as an active step of the fabrication technique. The project was developed along 3 main stages focused on a) understanding underlying molecular mechanisms and establishing supramolecular design rules and fabrication processes, b) understating the interaction of the materials with living cells, and c) developing personalised scaffolds that exhibit and enhance the properties of the regenerative process. A novel hydrogel was developed based on the co-assembly of peptide amphiphiles (PAs) with blood proteins. The peptide PA-K3 was used as a model to understand the molecular mechanisms behind the hydrogels assembly with blood components. It was established that negatively charged proteins (e.g. albumin and fibrinogen) interact with the positively charged peptide and trigger the gelation process and hydrogel formation. A set of different PAs (PA-K3Q, PA-Q3K3 and PA-K3Q3) were designed to interact with the blood enzyme Factor XIII by incorporating lysine and glutamine residues in the peptides sequences. From these sequences, two of the resulting hydrogels exhibited enhanced mechanical properties (PA-K3Q) and good biocompatibility (PA-K3Q and PA-Q3K3). The bio-functionality of the hydrogels was evaluated using different cell lines: fibroblasts (NIH-3T3), endothelial cells (HUVECs) and mesenchymal stem cells (hMSCs). Results showed that all cell types were able to attach and grow on the surface of the hydrogels, while hMSCs cells showed early signs of migration inside the gels. Extrusion liquid in liquid 3D printing was explored as a biofabrication method for the creation of more complex scaffolds. PA-K3 was used as a bioink and was extruded into a blood bath to create the scaffolds. Multi-layer constructs were created using this fabrication method. Further optimisation of this method in order to improve resolution and stability of the constructs will be required. In summary, this thesis highlights the potential of combining self-assembling peptide amphiphiles with blood biomolecules in order to generate bioactive tissue constructs for regenerative medicine. | en_US |
