Probing cellular microenvironments and tissue remodeling by atomic force microscopy

Abstract

The function of cells is strongly determined by the properties of their extracellular microenvironment. Biophysical parameters like environmental stiffness and fiber orientation in the surrounding matrix are important determinants of cell adhesion and migration. Processes like tissue maintenance, wound repair, cancer cell invasion, and morphogenesis depend critically on the ability of cells to actively sense and remodel their surroundings. Pericellular proteolytic activity and adaptation of migration tactics to the environment are strategies to achieve this aim. Little is known about the distinct regulatory mechanisms that are involved in these processes. The system's critical biophysical and biochemical determinants are well accessible by atomic force microscopy (AFM), a unique tool for functional, nanoscale probing and morphometric, highresolution imaging of processes in live cells. This review highlights common principles of tissue remodeling and focuses on application examples of different AFM techniques, for example elasticity mapping, the combination of AFM and fluorescence microscopy, the morphometric imaging of proteolytic activity, and force spectroscopy applications of single molecules or individual cells. To achieve a more complete understanding of the processes underlying the interaction of cells with their environments, the combination of AFM force spectroscopy experiments will be essential.

2B4 Engagement Mediates Rapid LFA-1 and Actin-Dependent NK Cell Adhesion to Tumor Cells as Measured by Single Cell Force Spectroscopy

“…The basic mode of function of AFM and SCFS have been explained in detail elsewhere (15,17). The data presented in this study were acquired with a NanoWizard II AFM equipped with a CellHesion stage (JPK Instruments, Berlin, Germany).…”

“…In the past, this has been hampered at least in part by the availability of suitable high resolution methods, which would enable the investigation of these parameters on the single-cell level under physiological conditions in real time. With atomic force microscopy (AFM)-driven single cell force spectroscopy (SCFS) a method became available that fulfills these requirements (14)(15)(16). The instrumentation is based on a flexible tip, the cantilever, with a reflective coating on its back from which a laser beam is deflected onto a photosensitive diode.…”

Force-controlled spatial manipulation of viable mammalian cells and micro-organisms by means of FluidFM technology

“…With respect to the manipulation of organisms, it is already widely employed for a bright spectrum of adhesion experiments. [18][19][20][21][22][23] So far AFM has not been used for displacement experiments because organisms are readily attached to the underside of the AFM cantilever preventing their release onto another position of the substrate. The development of the FluidFM technology 24 combining the precise AFM force feedback with nanofluidics via an incorporated microchannel directly in the cantilever opens novel strategies for the spatial manipulation of biological objects.…”

Measuring cell adhesion forces during the cell cycle by force spectroscopy

“…18 AFM was originally developed for high-resolution imaging but it has also become a powerful tool to manipulate biomolecules 19,20 or cells 21,22 and to investigate forces in the piconewton range. 23,24 In AFM force spectroscopy, the cantilever is moved toward a sample or a surface until it is in contact with it and then retracted while the interaction forces between the cantilever and surface are measured. Force spectroscopy allows direct measurement of the adhesive and mechanical properties of individual cells.…”