Developing strategies to control cellular functions is critical in the field of tissue engineering. This is often achieved through the activation of receptor proteins on the surface of the cells, which triggers a cascade of events leading to a desired cellular response. Of interest are the cellular responses that contribute to the formation of a blood vessels network. Controlling blood vessel formation is paramount to the success of many engineered tissue substitutes, and continues to be a challenge and a barrier to progress within the field. Current strategies include the use of receptor specific growth factors, which are difficult to control, can be unstable, require high doses, and may bind to unintentional targets. There is a need to promote blood vessel formation using alternative strategies. In this proposal, the PI seeks to develop a new strategy to control cellular processes through the use of highly tunable small molecules termed, aptamers. If successful, the proposed studies will advance our understanding of the fundamental science involved in controlling cellular behavior, and have a significant impact on the field of tissue engineering. Education and outreach activities have been integrated with the proposed research and involve providing hands-on research experience to students in local middle and high school, the creation of online educator resources which will be available to K-12 teachers nationwide, as well as outreach to underrepresented minority undergraduate students.
Growth factors are used extensively in the field of tissue engineering to bind and activate cell surface receptors, with the ultimate goal to control receptor mediated process. This is particularly true for cell processes involved in angiogenesis, with the most successful approach involving the use of vascular endothelial growth factor. However, this strategy is limited due to instability of growth factors, the high doses required for efficacy, off target effects, and the lack of control of vessel development at distant sites. To address these shortcomings the investigator proposes the use of a highly tunable aptamer based platform as a strategy to engineer tissue constructs that can promote and support the formation of a vascular network. The challenge is to engineer aptamer structures to create a supramolecular aptamer assembly (SAA) that can be used to not only bind but activate target receptors and thereby control receptor mediated processes. The objective is to reveal the structural constraints that govern SAA-receptor binding and agonist behavior. Towards this goal the scientific aims set forth by this proposal are 1) characterization of supramolecular aptamer assembly (SAA) structures and target receptor interactions; and 2) correlate supramolecular aptamer assembly (SAA) structure with overall function to induce and promote angiogenesis. To successfully complete these aims, techniques established in the PI's lab will be employed for aptamer synthesis, receptor screening, and molecular evaluations of receptor interactions, including protein and gene expression changes. Structural biology and biophysical techniques will be employed to assess the structural constraints involved in aptamer-receptor interactions. Lastly, a three-dimensional model of angiogenesis will be used to quantitatively assess SAA induced angiogenesis. Completion of the tasks set forth will lay the foundation for a targeted and robust aptamer mediated neovascularization approach.
