Kaija Schaepe oral presentation (OB3-Wed2-1-6)
Detection of lipids in native human bone sections by ToF-SIMS and AP-SMALDI Orbitrap MSI
1 Justus Liebig University of Giessen - Institute of Physical Chemistry, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
2 Justus Liebig University of Giessen - Institute of Veterinary Anatomy, -Histology and -Embryology, Frankfurter Str. 98, 35392 Giessen, Germany
3 Justus Liebig University of Giessen - Institute of Inorganic and Analytical Chemistry, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
Lipids play an important role in human diseases such as cancer, diabetes, and osteoporosis. Even though in osteoporosis, the mechanisms and molecular controls remain unclear, there is the hypothesis that “osteoporosis might be considered the obesity of bone” as exemplarily discussed by E. A. Greco et al. .
To get a mass spectrometric insight into this bone-fat relationship, the first goal of this study was to adapt sample preparation, measurement parameters and procedures for mass spectrometric imaging analysis of lipids in human bone sections via time-of-flight secondary ion mass spectrometry (ToF-SIMS) and atmospheric pressure scanning microprobe matrix-assisted laser desorption/ionization (AP-SMALDI) Orbitrap mass spectrometry imaging. For this purpose, a cryosectioning protocol consisting of freeze-embedding and -cryosectioning with a tape was successfully optimized from T. Kawamoto et al. . Mounting of the so-obtained sections was optimized to fit the specific sample holders for the different instrumental set-ups. This enables consecutive imaging of the same section with ToF-SIMS followed by AP-SMALDI MS to investigate lipidomics and lipid-localization in osseous tissue.
The so-established method was applied to several osteoporotic and control/non-osteoporotic bone samples from human donors. AP-SMALDI data were compared by exploitation of the novel Metaspace tool  for high-mass-resolution datasets that offers a false discovery rate-controlled metabolite annotation in combination with several databases such as lipid maps. Preliminary results reveal specific localization of various lipids such as phosphatidylcholines and phosphatidylethanolamines in human osteoporotic and control bone samples.
 E. A. Greco, A. Lenzi, S. Migliaccio, Therapeutic Advances in Endocrinology and Metabolism 6(6), 2015, 273–286.
 T. Kawamoto, M. Shimizu, Histochemistry and Cell Biology 113(5), 2000, 331–339.
 Palmer, A. et al. FDR-controlled metabolite annotation for high-resolution imaging mass spectrometry. Nature methods 14(1), 2017, 57–60.