Profiling of sweet-fatty molecules on cell surfaces.

New method enables measurement of glycolipids; now, for example, the relevance in cancer will be investigated

So-called glycolipids, or "sweet-fatty" molecules, are a relatively unknown group among the body’s diverse lipids. A method developed by an Austrian team led by chemist Evelyn Rampler of the University of Vienna has now provided deeper insights into the functioning of certain glycolipids, which are located, among other things, on the surfaces of stem cells. The researchers from the University of Vienna, BOKU Vienna and the University of Graz presented the method, which can be applied to a wide range of glycolipid groups, in the open access "Journal of the American Chemical Society Au".

Pioneering method development in glyco-research, i.e. for determining the function of sugar structures on cell surfaces, recently received great recognition with the award of the Nobel Prize in Chemistry to Carolyn Bertozzi. Research into the class of sweet-fatty molecules known as glycolipids, on the other hand, is a relatively new, emerging field of research. With their new study, chemist Evelyn Rampler of the University of Vienna and her colleagues are providing valuable basic research. Building on highly sensitive methods such as mass spectrometry (a method for measuring the mass of atoms or molecules), the necessary structural elucidation for glycolipids can now be carried out.

Poorly measurable so far

The aim of the current study was to develop a method and data analysis for a specific class of glycolipids that has not been well measured so far: so-called gangliosides, whose composition changes on the cell membrane during stem cell differentiation.

"With previous approaches, it was not possible to elucidate the multiple functions of gangliosides in Alzheimer’s disease, dementia or cancer because they lacked the necessary sensitivity. With our new method, we now provide a tool for the comprehensive analysis of gangliosides," says Evelyn Rampler, group leader at the Institute of Analytical Chemistry at the University of Vienna.

A research consortium at MedUni Vienna and the University of Vienna will now investigate the relevance of gangliosides and other sweet-fatty molecules in cancer. It is also conceivable that the method could be combined with Nobel Prize winner Carolyn Bertozzi’s bioorthogonal labeling to investigate sugar structures on cells in even greater detail.

Human stem cell study

"Our study on human stem cells has shown that the existing patterns of gangliosides change massively depending on which cells or tissues arise from the stem cells. It was therefore possible to identify new markers for different cell types, which now still need to be confirmed in independent studies with larger samples," says Evelyn Rampler.

"Using our new method based on mass spectrometry, we were able to measure and describe the molecular diversity of gangliosides in an unprecedented level of detail," said first author and chemist Katharina Hohenwallner of the University of Vienna.

Experiments with stem cells, conducted by Dominik Egger from the Institute of Cell and Tissue Culture Technologies at BOKU Vienna, also contributed to the success. In addition, the "Lipid Data Analyzer" software for gangliosides was adapted together with researchers from the University of Graz (Institute of Pharmaceutical Sciences).

Surgical tissue waste as samples

For the analysis, the team used tissue samples that accumulate as medical waste during operations. First, the so-called mesenchymal stem cells were isolated from the tissue and allowed to differentiate into, for example, bone cells, cartilage cells or fat cells. During the study, the largest number of gangliosides to date was found and these were identified as potential markers to distinguish the different cell types at the chemical level. Using automated data analysis, the researchers developed a method to comprehensively measure and structurally describe the gangliosides for the first time (e.g. which fatty acid is attached to the molecule).

Publication in "JACS Au:

Decoding Distinct Ganglioside Patterns of Native and Differentiated Mesenchymal Stem Cells by a Novel Glycolipidomics Profiling Strategy; Katharina Hohenwallner, Nina Troppmair, Lisa Panzenboeck, Cornelia Kasper, Yasin El Abiead, Gunda Koellensperger, Leonida M. Lamp, Jürgen Hartler, Dominik Egger, and Evelyn Rampler, Open Access Journal of the American Chemical Society / JACS Au, 2022,

DOI: 10.1021/jacsau.2c00230

Illustrations:

Fig. 1: Human mesenchymal stem cells were differentiated into fat cells and the fat vacuoles were stained: The stem cells and their differentiation products contain specific sweet-fatty surface structures (glycolipids) that can be used to distinguish them. C: Institute for Cell and Tissue Culture Technologies, BOKU Vienna