Biophysical Society 66th Annual Meeting Program Guide

1:30 PM – 3:00 PM Bruker

3:30 PM – 5:00 PM Curi Bio Bioengineering the Cell Environment for More Mature and Predictive 2D & 3D Models Cells in the body use a variety of cues (structural, mechanical, elec- trochemical, etc.) from the extracellular matrix (ECM) to develop and mature physiologically. These influential cues help regulate a broad spectrum of processes such as cell signaling, division, and differentia- tion. Many in vitro platforms seek to combine and incorporate these cues into the cell’s microenvironment but often fail, suffering from lack of reproducibility and incompatibility with other well-established end- point assays. Here, we demonstrate biomimetic in vitro platforms capable of reliably reproducing these essential cues. These platforms markedly improve the structural and functional development of a variety of cell types, including stem cells, cardiomyocytes, muscle cells, and more. These cutting-edge strategies can be deployed in both 2D and 3D model systems for high-throughput assessment of metabolism, electrophysiol- ogy, and contractility. We describe how the differentiation of stem cells can be enhanced by providing a more biomimetic culture environment, with a particular focus on iPSC-derived cardiomyocytes and skeletal muscle cells. Further, we highlight how an active mechanical environ- ment combined with aligned cell-nanotopography cues improves adhe- sion, signaling, and polarity across many cell applications. Finally, we demonstrate how to scale these technologies to 3D organoid systems, and how these approaches can improve the development of in vitro disease models to support the discovery of new therapies. Speaker Hamed Ghazizadeh, Product Manager, Curi Bio

Application of Large Area Mapping AFM for Automated Structural and Mechanical Analysis of Developing Cells and Tissues Active forces in biological systems define the interactions between single molecules, growing cells and developing tissues. Further develop- ment of novel biomaterials for tissue engineering is driven by the bio- mechanical and molecular cues provided to cells by their environment which are crucial parameters that influence motility, behavior, and the fate of progenitor cells. AFM can be successfully applied for comprehensive nano-mechanical characterization of single molecules, cells and tissues, under near physi- ological conditions. Currently, the trend is to extend this by studying the mechanobiology of living cells while evaluating their structure and the interaction with their cell culture substrates. In particular, it is interesting to understand how cell behavior is driven by the cytoskeletal dynamics and cell mechanics in typical cell culture scaffold scenarios. We will intro- duce the concept of automated large area multiparametric characteriza- tion of densely packed cell layers and highly corrugated tissue samples, where full automation, smart mechanical sample analysis, multiple scan- ner technology, and optical integration is critical for data throughput and reliable correlative microscopy. We will discuss how these devel- opments, in combination with advanced optical and super-resolution microscopy techniques, can overcome the inherent drawbacks of tra- ditional AFM systems for characterizing challenging biological samples. Cells adapt their shape and react to the surrounding environment by a dynamic reorganization of the F-actin cytoskeleton. We will demon- strate how cell spreading and migration in living KPG-7 fibroblasts and CHO cells, can be studied with high-speed AFM and associated with spa- tially resolved cytoskeletal reorganization events. We will further extend this with high-speed mechanical mapping of confluent cell layers, which in combination with optical tiling can be applied to automated analysis of large sample areas. External mechanical stress is known to influence cell mechanics in cor- relation to the differences in actin cytoskeleton dynamics. As a tool for analyzing the complex cellular mechanobiology, we went beyond purely elastic models, and performed sine oscillations (up to 1 kHz, amplitude 5-60 nm) in Z while in contact with the surface to probe the frequency- dependent response of living fibroblasts. We will further discuss how to calculate the viscoelastic properties, characterized by the dynamic stor- age and loss modulus (E’, E’’) distribution in such samples. In the past, investigating large and rough samples such as tissues and hydrogels using AFM was challenging due to the limited z-axis of the AFM. Using osteoarthritic cartilage as an example, we will demonstrate how a newly developed hybrid of a motorized and piezo stage enables multi-region AFM probing over a large, rough sample area while provid- ing additional correlative optical data sets. Speaker Giselle Fontes Evilsizer, AFMi Sales Applications Scientist, Bruker

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