The behavior of single mammalian cells is strongly dependent on their growth environment. For example, cells grown on plastic surfaces will have different morphologies and movement mechanisms compared to cells that are grown on softer materials designed to resemble growth substrates in vivo. This effect is particularly important in cancer research because there is a high degree of interaction between a cancer cell and its local environment during invasion into nearby tissue. Understanding how cells react in different physical environments may lead to new therapeutic strategies to combat cancer metastasis. Dr. Keng-hui Lin at Academia Sinica in Taiwan has developed a technique to produce 3D scaffolds with adjustable stiffness and dimensions which may be used as a cell culture platform to study cell behavior under more physiological conditions. The goal of the project is to learn the scaffold technique under the supervision of Dr. Lin and apply the technique to study malignant breast cancer cells. This will provide local researchers a first-hand understanding of the 3D culture technique and will foster additional international collaborations.
Recent studies using a combination of atomic force microscopy and confocal fluorescence microscopy on MDA-MB-231 breast cancer cells show a significant increase in Young's modulus as they invade into bovine collagen I hydrogels. This process is thought to be ROCK dependent, but it is unclear whether the cause is the 3D porous nature of the collagen or the act of invasion where the cells actively deform the collagen matrix. The goal of the project is to perform similar experiments on cells grown in the scaffolds to elucidate the basis of the observed cell stiffening. This NSF EAPSI award is funded in collaboration with the National Science Council of Taiwan.
The behavior of single mammalian cells is highly dependent on the physical properties of their environment. For example, cells cultured on soft materials will obtain a different phenotype, or emergent property, compared to cells cultured on rigid petri dishes. Many human diseases such as cancer may be initiated by mechanical changes in the cells’ environment. Therefore, cell culture methods must mimic an in vivo, or more physiologically relevant, environment to better understand the underlying mechanisms of how cells transmit the physical information of the environment. Keng-hui Lin’s lab at Academia Sinica in Taipei, Taiwan has developed a method to produce a soft matter 3D scaffold with spherical pores which may be used as a cell culture platform. This platform allows for the study of cells using both tunable substrate stiffness, pore size for curvature, and cell adhesive mechanism. In this project, MDA-MB-231 metastatic breast cancer cells were cultured on gelatin scaffolds prepared in the Lin lab. The actin cytoskeleton of the cell, which provides cell rigidity and is heavily linked to the cell’s ability to mechanically transduce signals, was fluorescently labeled allowing researchers to visualize the cell’s actin cytoskeleton as the MDA-MB-231 cells are grown in different environments (gelatin scaffolds, collagen I matrices, and glass). The morphology of the cells grown in different environments are compared to determine the cell’s response to environment mechanics and topography. To test the mechanical integrity and rigidity of the cell’s cytoskeleton, indentation-based rheology methods such as atomic force microscopy are widely used whereby the sample is gently indented and the force response from the sample is measured. Protocols for indentation-based sample hardness testing of soft materials were established in the Lin lab using bulk rheometers, as well as computer programs designed to analyze raw data from atomic force microscopes and the bulk rheometers. The results of this project may be used as a basis to further study the influences of substrate topography in the behavior of single cells. Additionally, the project allowed for a cultural exchange of scientific ideas between the Lin lab at Academia Sinica and Robert Ros lab at Arizona State University and introduced an international collaborative link.
