Optical Microscopy System Observes, Stimulates Multiple Living Cells

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A new optical microscope uses holographic techniques to stimulate multiple cells simultaneously and monitor cell activity after stimulation. Developed by researchers at Kobe University and called SIFOM for three-dimensional (3D) Stimulation and Imaging-based Functional Optical Microscopy, the system consists of two subfunctions: 3D observation of cells and 3D stimulation of cells based on digital holography. SIFOM can precisely stimulate user-defined targeted cells and simultaneously record the volumetric fluorescence distribution in a single acquisition.

SIFOM 3D optical microscopy system, Kobe University.

his is a concept drawing of the SIFOM system for cell manipulation technology combining 3D fluorescence observation and 3D stimulation. Courtesy of Kobe University.

SIFOM achieves precise, simultaneous stimulation of fluorescent-labeled cells by using multiple 3D spots generated by digital holograms displayed on a phase-mode spatial light modulator. Single-shot 3D acquisition of the fluorescence distribution is accomplished by digital holographic microscopy. The system uses high-speed scanless photography to obtain information about multiple events occurring in 3D space within a short time frame.

To validate the system, the researchers from Kyoto Institute of Technology and Utsunomiya as well as Kobe University used lung cancer cells and fluorescent beads about 10 μm in size. They recorded a fluorescent hologram in a defocused state from the focal position in the direction of depth and achieved reconstruction of both the cells and the fluorescent beads.

SIFOM 3D optical microscopy system, Kobe University.

3D recording of lung cancer cells: (a) 2D fluorescent observation, (b) a fluorescent hologram when one cell is selectively extracted, (c) a hologram when moved to a depth of 80 μm, (d) a reconstruction of (c), (e) after extracting two cells and exposing to light stimulation, (f) a hologram when moved to a depth of 80 um, (g) reconstruction of (f). Courtesy of Kobe University.

During the verification experiment, the researchers were able to observe light stimulation for a maximum of five cells at one time. The number of cells that could be stimulated was limited by the amount of light power available for stimulation. In 2D space, the team expects that simultaneous light stimulation will be possible for more than 100 cells. In the future, the team plans to expand the stimulation depth to a few hundred μm using two-photon stimulation.

To avoid damage to living cells, the amount of fluorescence used to observe them must be controlled, the researchers said, adding that high-sensitivity measurements are therefore required. The team plans to overcome this challenge and prepare the new optical microscopy system for practical use.

SIFOM could be used as a tool for the reconstruction of lost nerve pathways, the construction of artificial neural networks, and the development of food resources. It could also be used for manipulating the states of cells in optogenetics, potentially increasing the level of cell manipulation beyond what is currently possible.

SIFOM 3D optical microscopy system, Kobe University.
This is an illustration of optical stimulation of cell activity in human brain and plant cells by holographic optogenetics. Courtesy of Kobe University.

Professor Osamu Matoba said, “We have a research grant from JST CREST Grant Number JPMJCR1755, Japan, to fabricate a SIFOM and then apply it to further development of neuroscience. We will collaborate with companies to introduce the new optical microscope into the commercial market.” 

The research was published in Optics Letters, a publication of OSA, The Optical Society (   

Published: January 2019
A discipline that combines optics and genetics to enable the use of light to stimulate and control cells in living tissue, typically neurons, which have been genetically modified to respond to light. Only the cells that have been modified to include light-sensitive proteins will be under control of the light. The ability to selectively target cells gives researchers precise control. Using light to control the excitation, inhibition and signaling pathways of specific cells or groups of...
Holography is a technique used to capture and reconstruct three-dimensional images using the principles of interference and diffraction of light. Unlike conventional photography, which records only the intensity of light, holography records both the intensity and phase information of light waves scattered from an object. This allows the faithful reproduction of the object's three-dimensional structure, including its depth, shape, and texture. The process of holography typically involves the...
Fluorescence is a type of luminescence, which is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Specifically, fluorescence involves the absorption of light at one wavelength and the subsequent re-emission of light at a longer wavelength. The emitted light occurs almost instantaneously and ceases when the excitation light source is removed. Key characteristics of fluorescence include: Excitation and emission wavelengths: Fluorescent materials...
Research & TechnologyeducationKobe UniversityAsia-PacificImagingLight SourcesMicroscopyOpticsoptogeneticsBiophotonicsmedicalindustrialholographyfluorescence3D imagingoptical microscopyBioScan

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