New imaging technique uses sheets of light to study live cells

Bengaluru: Limitations of conventional imaging flow cytometry (IFC) in the study of cell biology could be addressed with a new technique developed at the Indian Institute of Science (IISc)’s Department of Instrumentation and Applied Physics (IAP).

IFC employs the features of two techniques — flow cytometry, to measure parameters of cells like size and morphology, and microscopy, which helps generate high-resolution images of individual cells and organelles, the structures within cells that perform specific functions.

IISc said traditional IFC methods involved the lighting up of specific regions within the cell, the cumbersome point-based illumination technique that does not allow volume interrogation and estimation of biophysical parameters on the go.

Prof Partha Pratim Mondal’s group at IAP has pitched an alternative with a new system called M3IC (Multichannel, Multi-sheet, and Multicolour light sheet Imaging flow Cytometry). The technique involves the use of a sheet of light to illuminate the cell’s inner structures.

The M3IC system uses a vertically aligned multi-sheet array (VAMSA) illumination to study, at high resolution, cells flowing simultaneously through multiple microfluidic channels. The technique demonstrated organelle-level resolution. Its multicolour imaging feature enables multi-organelle investigation, determination of critical biophysical parameters, and drug treatment studies on cancer cells.

Closer look, wider range

In their paper published recently in Nature’s Communications Physics journal, the researchers concluded that the M3IC system has the “distinct advantage” of cross-sectional imaging and simultaneous interrogation of several cells in parallel. They underlined VAMSA’s versatility in its ability to adaptively alter the number of light sheets used in the interrogation.

Working with the new system, the researchers were able to visualise differences in the shape and distribution of mitochondria (membrane-bound organelles) in normal cells and cancer cells treated with a chemotherapy drug.

The researchers said the technique was in line with future diagnostic needs that call for a single-platform system to image, count, and analyse multiple organelles and visualise cell volume with organelle-level resolution at high throughput. They also anticipated M3IC to significantly aid the fields of fluorescence microscopy, bio-instrumentation, and optical physics.