Tissue morphogenesis is directed by the interplay of mechanical and biochemical signals in the complex weave of three-dimensional extracellular matrix. This proposal addresses the combinatorial mechanisms of matrix mechanochemical coupling in the specific context of a developing tissue that is essential for mammalian life--the lung microvasculature. This project seeks to apply soft-matter microfabrication methodologies to develop a dynamic mechanical testing platform and use it to investigate the impact of mechanical deformation on the vital steps in matrix assembly and vasculogenesis. i.e. bioblocks, or three-dimensional matrix constructs of different shapes and sizes will be produced by growing lung fibroblasts within microstructured PDMS wells and studied during static conditions or periodic stresses, with and without fluid flow in those materials. It is expected to systematically construct a body of knowledge on the effect of mechanical forces such as amplitude, frequency, matrix stiffness and flow on tissue organization and development.
The research planned represents a significant advance for biomedical engineering and developmental biology by providing a platform in which the dynamic mechanical forces exerted on three dimensional (3D) tissue-specific matrix can be accurately controlled so that the downstream consequences of mechanical perturbations can be measured as cell signaling and morphogenesis endpoints. The proposed research will provide new fundamental insights into mechanisms of mechanochemical coupling during tissue morphogenesis. In the first aim, precisely structured 3D synthetic bioblocks will be used to engineer and study the geometry and signaling of human fetal lung fibroblasts. Bioblocks with growing or decellularized natural matrices will be subjected to patterns of dynamic stretch that recapitulate fetal breathing in the second aim. The third aim will focus on endothelial signaling and morphogenesis in this dynamic 3D matrix. Together, these investigations will elucidate the developmental impact of mechanical deformation on matrix and blood vessels. This project is catalyzed by interdisciplinary synergy: PI Romer has made major contributions to the fields of matrix biology, cytoskeletal signaling, and cell adhesion, while PI Gracias has considerable expertise in the micropatterning of soft materials and microfluidic systems. The transformative features of the proposal involve the study of tissue morphogenesis in a platform that accurately mimics the 3D dynamic in vivo environment. These features are enabled by the integration of microstructured recesses coupled with surface modifications, patterned anisotropy, dynamic mechanical testing and microfluidics.
Broad Impact: Systematic dissection of the complex relationships between the mechanical and chemical stimuli that direct tissue growth and development will lead to a new body of knowledge in a number of fields ranging from developmental biology to quorum sensing. This project will solidify the collaboration of two outstanding science educators, enabling students to learn how to apply engineering tools to important problems in biology and medicine. PI Romer's work in graduate science education is exemplified by curriculum development and actuation in research ethics and molecular mechanisms of pathophysiologic processes. His website that offers free downloads of novel tools for the study of cell traction forces demonstrates his commitment to sharing the fruits of scientific investigation. In 2007, PI Gracias was awarded an education accomplishment citation from the Maryland State Board of Education (given by state senator Ulysses Currie) for K-12 outreach efforts. If this proposal is funded, it will further our efforts to expose undergraduates, K-12 students and the general public to frontiers of biology and engineering.
