Joseph Kennedy (Presenter)
Prosolia, Inc
Authorship: Joseph H Kennedy, Jeffrey S. Patrick, Mariam ElNaggar, Justin Wiseman
Prosolia, Inc. Indianapolis, IN
| Short Abstract The determination of the distribution of lipids and metabolites in tissue samples is of seminal importance to understanding disease and biochemistry. DESI imaging is important for its ability to provide objective molecular information in histological context without perturbing the integrity of the tissue. The majority of the experiments done using DESI have provided nominal mass information. Both lipids and small molecule metabolites have many nominal mass isobars including phosphatidylserines, cholines, and sulfatides which can differ by less than 50 mDa. Here the need for accurate mass (< 3 ppm), high mass resolution (> 40,000) information are demonstrated. Examples showing differential tissue distribution of isobaric metabolites and lipids differing by < 50 mDa are provided in a variety of tissues and the benefits to understanding disease and fundamental biochemistry are discussed. |
Long Abstract
The analysis of the distribution of lipids and metabolites in tissue samples is of seminal importance to understanding disease and biochemistry. DESI imaging is important for its ability to provide objective molecular information in histological context without perturbing the integrity of the tissue. The majority of the experiments done using DESI have provided nominal mass information. Both lipids and small molecule metabolites have many nominal mass isobars including phosphatidylserines (PS), cholines (PC), and sulfatides which can differ by less than 50 mDa. Here the advantages of accurate mass (< 3 ppm), high mass resolution (> 40,000) information are demonstrated in conveying the distribution of lipids and small molecule metabolites. Examples are provided in a variety of tissues and the benefits to understanding disease and fundamental biochemistry are discussed. Rat and mouse tissues from animals having model disease including diabetes, kidney dysfunction, neurological disease (i.e. ADHD), and others are examined. Tissue thin sections (10-20 micron) from frozen samples are mounted on glass slides and interrogated using DESI (desorption electrospray ionization). The DESI is interfaced to a Thermo QExactive Focus (orbitrap) mass spectrometer operated at 70,000 resolving power in both positive and negative modes. Mass spectral images are processed using Firefly and MSIReader, among others. Comparative results using mass windows of 1 Da down to <5 mDa are provided which show significantly different spatial distribution of analytes from one another and from chemical background. The benefit of high mass resolving power is demonstrated in: 1) unique identification of analyte formulas; 2) discrimination in space of isobaric metabolites and lipids (e.g. PS, PC and Sulfatides); 3) discrimination of metabolite signal from chemical background for improved images. The more discrete distribution allows for better discrimination of biochemical pathways active in different tissue regions and improves the biochemical information content of MS images and provides a tool to better understand fundamental biochemistry in localized disease.
References & Acknowledgements:
| Description | Y/N | Source |
| Grants | no | |
| Salary | yes | Prosolia |
| Board Member | no | |
| Stock | no | |
| Expenses | no |
IP Royalty: no
| Planning to mention or discuss specific products or technology of the company(ies) listed above: | yes |