This award by the Biomaterials program in the Division of Materials Research to University of California-Irvine is to synthesize collagen-like polymers and their mimics utilizing a novel "bottom-up" strategy using recombinant yeast system that was developed by the investigators for this project. This approach is expected to allow unprecedented flexibility in the range of independent biological and material properties that can be incorporated in the engineered biopolymers. The ability to create new artificial scaffolds that can direct the activity of cells is a critical component of furthering a number of areas such as regenerative medicine, therapies for disease, and mechanistic cell studies. Since collagen is the most abundant protein in the extracellular matrix and it dynamically interacts with cells, a collagen-based polymer could potentially mimic natural characteristics that are better than purely synthetic systems. As part of this project, investigators will introduce non-native cysteine cross-linking sites and matrix metalloproteinase proteolytic domains, and will examine their effects on collagen architecture, mechanical properties, molecular transport characteristics, and cell-based responses. The project will serve as an ideal platform to train both undergraduate and graduate students in science and engineering. Students participating in this interdisciplinary collaboration will gain an integrated perspective of the important synergies between traditionally diverse fields.
The capability to create novel materials which can mimic biological matrices and exhibit a broad range of new properties is especially critical in advancing health-related research such as regenerative medicine and therapies for disease. Collagen is an abundant, natural protein which dynamically interacts with its surrounding cells. By fabricating mimics of natural collagen, the investigators will examine the scope and applicability of new mechanical, structural, and biologically-responsive biomaterials. This can lead to a better understanding of how such materials can be used in disease treatment. The project will serve as an ideal platform to train both undergraduate and graduate students in science and engineering. Due to the interdisciplinary nature of this collaboration, students participating in this research will gain an integrated perspective of the important synergies among traditionally diverse fields that are now needed for a state-of-the-art research. In addition to hands-on training for students, the results from this proposed work will also be incorporated into graduate courses.
The most abundant protein in the extracellular matrix, collagen, has a dynamic relationship with the cells which reside within the matrix. Therefore, the ability to manipulate this biomaterial at the molecular level can lead to the ability to direct cellular processes, thus enabling and expanding the possibilities in cell-based applications. Our overall aims were to fabricate full-length biopolymers with engineered regions of unique cysteine cross-linking sites and matrix metalloproteinase (MMP) proteolytic domains, and to examine the relationships of the resulting molecular architecture, mechanical properties, and biological response. Our studies showed that the synthetic collagen variants were structurally intact, correctly assembled as triple-helices, and interacted with mammalian cells. The cysteine-collagen variants could form hydrogels, and we examined their gelation behavior. Conjugation of growth factors to these engineered sites induced myofibroblast differentiation. Collagens designed with varying numbers of MMP domains were also intact, but showed corresponding degrees of degradation when incubated with the MMP enzyme. These results are the first demonstration that it is feasible to design and fabricate full-length human collagen polymers with prescribed specialty domains, and these changes can be made to tune material properties and cellular response. The results of this work have been published in several peer-reviewed papers. Applications of the research include biomaterial development for therapeutic areas such as tissue regeneration, wound-healing, and stem-cell based technologies, as well as enabling fundamental studies in matrix-cell interactions. This project has also contributed to the education and training of several postdoctoral researchers, graduate students, and undergraduates. Members of the research team have benefitted from the interdisciplinary nature of the project, since the research has required the integration of traditionally diverse scientific disciplines such as protein engineering, materials science, rheology, and mammalian cell culture. Students and postdocs have also gained communication and team-based experience, including opportunities to work within a multi-disciplinary team, to present their work at conferences, and to write peer-reviewed manuscripts.
