Delphine Gourdon - US grants

ABSTRACT
This project will use the Surface Forces Apparatus (SFA) and various electro-optical and x-ray characterization techniques to develop a novel processing method for producing ultra-thin single-crystal films of conducting/semi-conducting organic compounds and nanoparticle films. The new method is based on preliminary results in which applying pressure, rolling and shear to confined organic-liquid films and nanoparticles dispersed in various organic solvents resulted in highly uniform well-ordered nano-thin layers over large areas. Various parameters will be investigated during this new type of mechanical processing in comparison to conventional wet (self-assembly) methods. The SFA allows one to perform simultaneous mechanical and opto-electronic characterization of thin films in situ. The aim will be to adapt this new processing method for efficient large-scale production of high area displays, organic thin film transistors (OTFT), and high area pressure-sensitive QD displays such as touch panels and new light emitting applications.
This proposal is being funded by the Chemical and Transport Systems Division
Particulate and Multiphase Processes and Interfacial, Transport and Thermodynamics Programs

The objective of the research is to characterize the mechanical properties of the fibrillar form of fibronectin, and extracellular matrix structure that is essential for development and that is upregulated in pathologies such as cancer and atherosclerosis, through the analysis of a model system of fibronectin fibers and the use of a computational model built upon the stochastic properties of fibronectin molecules. Fibronectin is assembled into a unique material in vivo with extreme extensibility, leading to speculation that its litany of binding sites for cells and cell signaling molecules may be actuated by mechanical force. This proposal is unique in that it will quantify physical properties of fibronectin fibers that define its function in vivo over a wide range of mechanical strains and attempt to connect these physical properties with the molecular architecture of the fiber. The approach will utilize a technique for quantifying the molecular structure of fibronectin molecules in model fibers that will be compared with a computational model of fibronectin fiber mechanical properties that considers both molecular unfolding and entropic spring-like behavior of fibronectin molecules.

By combining all of these efforts, we expect this interdisciplinary proposal not only to generate a fundamental understanding of the underlying mechanisms governing mechanotransduction but also to have broad ranging implications in regenerative medicine and tissue engineering due to the fundamental role of fibronectin in vivo. It is surprising that despite our vast understanding of the importance of the physical environment on the behavior of virtually every studied cell, relatively little is known about the properties of native extracellular matrix structures. This program will be transformative in its capacity to promote new approaches in mechanotransduction research, as well as to immerse undergraduate and graduate students in a broad range of technological innovation. Active participation of both women and minority students will be fostered via a collaborative relationship with the Society of Women Engineers and Minority Engineers Society. Furthermore, this project will serve as a vehicle for the development of lab modules for courses at Boston University and Cornell University that are targeted for 3rd year undergraduate students.

DESCRIPTION (provided by applicant): Increased tissue stiffness represents a hallmark of breast cancer that is mediated by physicochemical alterations of the extracellular matrix (ECM);however, the mechanisms through which enhanced ECM stiffness promotes tumor angiogenesis, and hence growth, are poorly understood. This project investigates the hypothesis that paracrine signaling by breast cancer cells increases fibronectin (Fn) matrix assembly by adipose-derived stem cells (ASCs), thereby enhancing the pro-angiogenic capability of both ASCs and endothelial cells to promote tumor vascularization. To investigate this hypothesis we propose a combination of biochemical and physical science approaches that will enable us to quantify the impact of tumor-derived soluble factor signaling on the conformation and rigidity of ASC-deposited Fn matrices. Specifically, we will use Fluorescence Resonance Energy Transfer (FRET) imaging and the Surface Forces Apparatus (SFA) to measure Fn mechanics at the macromolecular and cell/tissue level, respectively, and will assess the impact of these parameters on pro-angiogenic signaling in vitro and in vivo. This work will be accomplished in three specific aims: In Aim 1, we will evaluate Fn matrix assembly by ASCs in the presence or absence of tumor cell- conditioned media and identify signaling molecules contributing to these changes. In Aim 2, we will analyze the contributions of ASC-regulated Fn matrix characteristics towards a tumor-associated, pro-angiogenic phenotype of ASCs and endothelial cells. In Aim 3, we will determine whether ASC-regulated Fn matrix assembly promotes tumor angiogenesis, stiffness, and growth in vivo and evaluate the contributions of the signaling molecules identified in aim 1 in this pathogenesis. Transforming growth factor beta (TGF-beta) signaling will be the initial focus of the proposed studies, as this factor modulates tumorigenesis, cell contractility, and Fn assembly. Additionally, we anticipate identification of novel factors already implicated in Fn mechanics yet with an undefined role in tumor vascularization. By correlating Fn conformation and mechanics with pro-angiogenic signaling in the tumor microenvironment this work will broadly impact our understanding of the connection between tumor stiffness and vascularization and may lead to the identification of novel anti- angiogenic targets and improved therapies. While the emphasis in the proposed studies is to determine the role of ASCs in this process, a variety of other physiological and pathological situations critically rely upon ECM mechanics (e.g., organogenesis, atherosclerosis). The culture systems and mechanical testing strategies developed as part of this project introduce radically new approaches to investigate these processes. PUBLIC HEALTH RELEVANCE: Sustained angiogenesis is a hallmark of breast cancer that is influenced by extracellular matrix (ECM) mechanics;however, it remains unclear whether or not fibronectin (Fn) matrix assembly by tumor-associated adipose-derived stem cells (ASCs) may play a role in this process. This research will integrate biochemical and physical science tools to determine the effect of tumor-derived soluble factors on the rigidity of ASC-deposited Fn matrices and evaluate if these changes promote tumor vascularization. This interdisciplinary strategy has the potential to not only revolutionize our understanding of tumor angiogenesis, but also to provide widely applicable approaches to study other physiological and pathological processes that depend on Fn mechanics.

Non-Technical Section

This CAREER Award supported by the Biomaterials program in the Division of Materials Research seeks to study the structural and mechanical properties of the extracellular matrix (ECM). The extracellular matrix (ECM) is a multi-protein network used by cells to communicate with their environment. The research objectives of this Faculty Early Career Development (CAREER) project are (i) to characterize both structure and mechanics of the ECM from the protein (nanoscopic) to the cell (microscopic) level, and (ii) to exploit such fundamental understanding to engineer cell culture platforms for investigating vascularization mechanisms in functional and pathological (cancer) environments. Given the extensive interdisciplinary nature of this research, the primary educational goals of this program are to introduce students (K-12, undergraduate, and graduate) and teachers (GK-12 program) to the fields of (and the tools used in) materials and biomaterials science, biomechanics, protein physics, and cell biology. The PI will also train undergraduate and graduate students for future jobs in biomaterials science and/or engineering through (i) mentoring students from freshman to graduate level in research and (ii) integrating research into her three undergraduate and graduate level interdisciplinary courses taught across seven departments at Cornell.


Technical Section

Living cells sense and respond to their microenvironment through chemical and physical interactions determined by the adjacent cells and by the surrounding extracellular matrix (ECM) fibrillar network. The main goal of this Faculty Early Career Development (CAREER) project is to study both structural and mechanical properties of the two major building blocks of ECM structures (fibronectin and collagen) from the fiber to the cellular/tissue level. The strength of this program lies in the interdisciplinary approach that combines the PI's demonstrated expertise in (i) FRET (Fluorescence Resonance Energy Transfer) conformational mapping, and (ii) mechanical characterization of biomaterials at the nano-, and the microscopic scales. By combining these efforts, the PI will generate a fundamental understanding of the regulatory mechanisms governing ECM composition, conformation and mechanics, which will then enable the design of 2D and 3D cell culture platforms with controlled mechanobiological properties for investigating vascularization mechanisms in physiological and pathological (cancer) environments. This project has implications not only in biomaterials science but also in regenerative medicine and tissue engineering due to the fundamental role of the ECM in development and diseases such as cancer; it will also be of importance in its capacity not only to promote new approaches in cell-matrix interactions research, but also to expose K-12, undergraduate, and graduate students to a wide range of technological innovations.