Characterizing Self-Assembled Extracellular Matrix Fibrillar Films with PCA/TOF-SIMS
Christopher R. Anderton, Kiran Bhadriraju, Frank W. DelRio, and Anne L. Plant
Cell interactions with the extracellular matrix (ECM) initiate an array of biophysical and biochemical signals that drive biological processes ranging from embryonic development to cancer progression. Consequently, developing model ECMs and analytical techniques to determine their properties, as well as the resulting cellular responses, is vital to understanding how the ECM regulates cell state, and for engineering such structures as bioscaffold for tissue repair and regeneration. Adsorbed protein monolayers are often used as model ECMs, but are not analogous to what is experienced in vivo, where ECM proteins often self-assemble into higher order structures. Decellularized ECM scaffolds derived from tissue or cell cultures offer a biologically relevant model, but the complexity of these systems often makes it difficult to understand how specific components influence cell function. We have previously developed a model ECM comprised of films of fibrillar Type 1 collagen, which are robust and highly reproducible in the cell behaviors they evoke . The mechanical properties of these films strongly influence cell responses such as proliferation, cytoskeleton assembly and activation of specific signalling molecules . In this study, we employ TOF-SIMS and principal component analysis (PCA) to examine if there are chemical or orientation differences that may be responsible for differences in cell responses to mechanically compliant or mechanically rigid collagen fibril matrices. Our results establish the feasibility of this method as a label-free approach to identify chemical differences in ECM preparations, and allow us to distinguish between more complex binary and ternary self-assembled ECMs. We show that TOF-SIMS is likely to be a valuable technique in the analytical toolbox for characterizing biomanufactured ECMs.
 A. L. Plant, K. Bhadriraju, T. A. Spurlin, J. T. Elliott, BBA-Mol. Cell Res., 2009, 1793, 893-902