Desorption electrospray ionization mass spectrometry (DESI-MS) is the pioneer ambient ionization technique (Science. 2004 Oct 15;306(5695):471-3). It involves direct analysis of unmodified samples by a spray of charged solvent droplets directed to the sample. Primary droplets hit the sample surface forming a thin film from which secondary droplets containing charged analytes are formed and directed to the mass spectrometer inlet. DESI-MS can be coupled to any mass spectrometer designed for ESI ionization. DESI-MS profiling and imaging modes have been applied in a number of valuable models for differentiating cells and tissues metabolic states, such as cancer (Proc Natl Acad Sci U S A. 2013 Jan 29;110(5):1611-6), embryological development and cellular stemness evaluation (PLoS One. 2013 Sep 20;8(9):e74981) based on the small molecules’ profiles (lipids and other metabolites). As examples, in brain cancer samples, tumor type, tumor staging and tumor cell concentration have been matched by DESI-MS. The analysis of lipid profiles in individual microscopic preimplantation embryos avoided sample pooling and detected fatty acid and cholesterol disturbances in metabolism due to the impact of in vitro culture conditions. We present herein an overview of our current efforts on DESI-MS medical applications. Brain and prostate tumor sections and fresh tissue are profiled and imaged in operating rooms at Harvard and Indiana Universities during tissue removal in order to correlate and support surgery decisions and patient prognosis. In collaboration with the Purdue Veterinary School, bladder cancer staging and propensity are evaluated in the canine model, which presents similar features to the human bladder cancer. Cellular development in embryos is followed in pure totipotent conditions (i.e. during preimplantation development in mouse and bovine species) in a joint work with the Friedrich-Loeffler-Institut in Germany. For all these studies, the use of appropriate and powerful multivariate statistical approaches such as principal component analysis in ion images and data fusion of positive and negative mass spectral information is becoming crucial for straightforward biological interpretation of the high amount of chemical information acquired by DESI-MS and for the development of statistical tools that can provide the chemical diagnosis in almost real-time condition with sample analysis.
Medical Applications and Data Analysis of in situ Metabolomics by Desorption Electrospray Ionization (DESI) Mass Spectrometry
PIRRO, VALENTINA;
2013-01-01
Abstract
Desorption electrospray ionization mass spectrometry (DESI-MS) is the pioneer ambient ionization technique (Science. 2004 Oct 15;306(5695):471-3). It involves direct analysis of unmodified samples by a spray of charged solvent droplets directed to the sample. Primary droplets hit the sample surface forming a thin film from which secondary droplets containing charged analytes are formed and directed to the mass spectrometer inlet. DESI-MS can be coupled to any mass spectrometer designed for ESI ionization. DESI-MS profiling and imaging modes have been applied in a number of valuable models for differentiating cells and tissues metabolic states, such as cancer (Proc Natl Acad Sci U S A. 2013 Jan 29;110(5):1611-6), embryological development and cellular stemness evaluation (PLoS One. 2013 Sep 20;8(9):e74981) based on the small molecules’ profiles (lipids and other metabolites). As examples, in brain cancer samples, tumor type, tumor staging and tumor cell concentration have been matched by DESI-MS. The analysis of lipid profiles in individual microscopic preimplantation embryos avoided sample pooling and detected fatty acid and cholesterol disturbances in metabolism due to the impact of in vitro culture conditions. We present herein an overview of our current efforts on DESI-MS medical applications. Brain and prostate tumor sections and fresh tissue are profiled and imaged in operating rooms at Harvard and Indiana Universities during tissue removal in order to correlate and support surgery decisions and patient prognosis. In collaboration with the Purdue Veterinary School, bladder cancer staging and propensity are evaluated in the canine model, which presents similar features to the human bladder cancer. Cellular development in embryos is followed in pure totipotent conditions (i.e. during preimplantation development in mouse and bovine species) in a joint work with the Friedrich-Loeffler-Institut in Germany. For all these studies, the use of appropriate and powerful multivariate statistical approaches such as principal component analysis in ion images and data fusion of positive and negative mass spectral information is becoming crucial for straightforward biological interpretation of the high amount of chemical information acquired by DESI-MS and for the development of statistical tools that can provide the chemical diagnosis in almost real-time condition with sample analysis.
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