Protein Printboard: Fibronectin Patterning to Control Cellular Organization Asad Moten Abstract C ells are inherently sensitive to local mesoscale and microscale patterns of chemistry and topography. Recent research has investigated how surface mechanics might dictate cell behavior, affecting both cell function and differentiation. This study professes that alterations of the underlying matrix can dictate cell behavior and function. Through micro-orienting the substrate and micro-patterning protein, we were able to engineer a structural and biological backbone to regulate cellular behavior. The techniques involved in this study to control cell behavior include the micro-orienting of the ECM, electrospinning a 3D fibrous PMMA scaffold, and micro-patterning of fibronectin(Fn) for cellular attachment, The use of microscale structuring to restore tissue architecture and dictate cell behavior has several important implications for tissue engineering, cancer treatment, and stem cell differentiation. 1 Introduction The human body consists of 10 trillion cells, which have been classified into more that 200 different cell types. Our bodies are organized in a hierarchical way: cells and extracellular matrix (ECM) form tissues, tissue form organs, and organs form complex organisms. Deciding which protein to express, when to divide, when to specialize, and when to commit suicide are all ongoing processes of the cells [1]. In addition to the intrinsic cell factors that regulate cell fate, extrinsic signals to the cell from sur- rounding ECM are essential in guiding it through distinct development paths. The difference between a clot of cells and matrix from a functional tissue is the well-defined organization of cells and ECM, which is closely associated with tissue function. The ECM is a 3D fibrous, highly oriented structure, which provides cells with numerous focal adhesion sites – points at which cells use their integrin receptors to attach to the surface. This attachment of the cell to its matrix is facilitated by fibronectin (Fn), which is an adhesive protein. The loss of this ECM architecture results in tissue malfunction and disease. Physiological processes such as development, tissue maintenance, angiogenesis, and wound healing require an orderly ECM architecture [2]. In order to intervene in any of these processes, it is necessary to have a comprehensive understanding of the molecular interactions that mediate cell motility and also of the highly complex pathways of signal transduction that regulate them. Biology and medicine are currently undergoing a paradigm shift. Up until now, cellular transformations, whether in terms of stem cell differentiation or carcinogenesis, have been discussed in terms of genetic alterations that modify or deregulate cellular growth [2]. We have focused on rigorously characterizing the molecular components that comprise life, with the hope that such classification of all the parts will lead to a greater understanding of the whole. After the sequencing of the genomes of multiple organisms, it is now clear that the approach of reductionism provides only minimum understanding of tissue behavior. Consequently, biology is moving towards the development of methods and approaches to understand how complex cell and tis- sue behaviors emerge from collective interactions among multiple molecular components. It also seeks to describe molecular processes as integrated systems rather than numerous, isolated parts [3]. There is a very close relationship between the maintenance of the specific architecture of tissues and the original construc- tion of those tissues. In morphogenesis, sets of cells are defined in the embryo by various organizer genes that in turn specify the anteroposterior axis, the dorsoventral axis, and, in Drosophila, segments and parasegments, ultimately forming blocks of cells with specific relations to each other [4]. Within these blocks, further separation and differentiation occurs, resulting in functional groups of cells in well-defined structural compartments. The fibrous extracellular matrix plays a very important role in molding the architecture of tissue as it provides support and anchorage for the cells, regulates intercellular communication, and provides necessary proteins for cellular adhesion and migration [5]. Cells maintain a characteristic morphology by adher- ing both to neighboring cells and the ECM. In vivo, the ECM is comprised of several proteins including collagen, fibronectin, NSTI-Nanotech 2009, www.nsti.org, ISBN 978-1-4398-1783-4 Vol. 2, 2009 333