title: Lipid changes within the epidermis of living skin equivalents observed across a time-course by MALDI-MS imaging and profiling.
abstract: BACKGROUND
  Mass spectrometry imaging (MSI) is a powerful tool for the study of intact tissue sections. Here, its application to the study of the distribution of lipids in sections of reconstructed living skin equivalents during their development and maturation is described.
  
  
  METHODS
  Living skin equivalent (LSE) samples were obtained at 14 days development, re-suspended in maintenance medium and incubated for 24 h after delivery. The medium was then changed, the LSE re-incubated and samples taken at 4, 6 and 24 h time points. Mass spectra and mass spectral images were recorded from 12 μm sections of the LSE taken at each time point for comparison using matrix assisted laser desorption ionisation mass spectrometry.
  
  
  RESULTS
  A large number of lipid species were identified in the LSE via accurate mass-measurement MS and MSMS experiments carried out directly on the tissue sections. MS images acquired at a spatial resolution of 50 μm × 50 μm showed the distribution of identified lipids within the developing LSE and changes in their distribution with time. In particular development of an epidermal layer was observable as a compaction of the distribution of phosphatidylcholine species.
  
  
  CONCLUSIONS
  MSI can be used to study changes in lipid composition in LSE. Determination of the changes in lipid distribution during the maturation of the LSE will assist in the identification of treatment responses in future investigations.
authors.affiliation: Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK. c.mitchell@surrey.ac.uk.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Mitchell
authors.affiliation: Stiefel A GSK Company, GlaxoSmithKline, Stockley Park West, Uxbridge, Middlesex, UB1 1BT, UK. heather.long@stiefel.com.
authors.forename: Heather
authors.initials: H
authors.lastname: Long
authors.affiliation: Stiefel A GSK Company, GlaxoSmithKline, Stockley Park West, Uxbridge, Middlesex, UB1 1BT, UK. michael.x.donaldson@stiefel.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Donaldson
authors.affiliation: Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK. s.francese@shu.ac.uk.
authors.forename: Simona
authors.initials: S
authors.lastname: Francese
authors.affiliation: Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK. m.r.clench@shu.ac.uk.
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Clench
mesh_terms: D004817:Epidermis / Q000737:chemistry*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008055:Lipids / Q000737:chemistry*; D015999:Multivariate Analysis; D025341:Principal Component Analysis; D017768:Skin, Artificial; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013109:Sphingomyelins / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D013997:Time Factors
chemical_list: D008055:Lipids; D013109:Sphingomyelins