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Tissues consist of a heterogeneous mixture of different cell types, complicating our understanding of their biological functions and studies of disease.

Now, a multi-institutional team led by the University of Osaka has developed and provided proof-of-concept of a new technology to visualize the distribution of components within a single cell, paving the way for a much greater understanding of disease in complex biological samples.

The work is in the journal Communications Chemistry.

t-SPESI (tapping-mode scanning probe electrospray ionization) is a technique that allows analysis of the spatial layout of molecules in a sample. Multiple micro-samples of different regions of a cell are taken and transferred for analysis by a technique called mass spectrometry, which can determine the exact chemical components in that region.

"We have developed a new t-SPESI unit that allows us to visualize the microscopy sample in multiple modes," explains lead author Yoichi Otsuka. "We can also directly observe the sampling process as the micro-samples are taken for mass spectrometry analysis."

By modifying their previously developed t-SPESI technology, the team enabled the analytical unit to be positioned above an inverted fluorescence microscope. This allows observation of the sampling process, as well as direct observation of the sample itself.

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The sample can be imaged in various modes, allowing the detection of any fluorescently tagged target molecules, determination of the distribution of features on the cell surface, and imaging of the locations of the chemical components of the cell.

This technology can visualize the distribution of intracellular lipids, fatty compounds that play key roles in metabolic processes. Abnormal distributions and functions of lipids are known to be linked to disease.

"When we applied our technology to model cells, we were able to observe the lipids within each individual cell using mass spectrometry imaging, directly visualize the cell by fluorescence microscopy, and also determine the surface shape of the cell," explains senior author Michisato Toyoda. They were also able to detect distinctions between different types of cells with different cellular compositions.

"This allows an understanding of the multidimensional molecular information of individual cells within a sample of diseased tissue," says Otsuka.

This exciting new technology will have a great impact on our ability to understand the processes underlying the development of disease in complex biological samples, allowing us to understand the complex mixtures and interactions of cells present in tissue samples. This will contribute to the development of advanced therapies and diagnostic techniques for a wide variety of diseases.