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Lipid changes within the epidermis of living skin equivalents observed across a time-course by MALDI-MS imaging and profiling.

Mitchell CA, Long H, Donaldson M, Francese S, Clench MR - Lipids Health Dis (2015)

Bottom Line: In particular development of an epidermal layer was observable as a compaction of the distribution of phosphatidylcholine species.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.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK. c.mitchell@surrey.ac.uk.

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.

No MeSH data available.


a MALDI-MSI-IMS image mapping the in-source fragment m/z ion species for SM (d18:1/16:0) in tissue and within a SM (d18:1/16:0) lipid standard. Particularly m/z 520.5024 is likely to be the N-paltimitoylsphingosine unit of the structure following neutral loss of cyclophosphane [H (HO)P (O) (OCH2CH2O)] m/z 183. The ion m/z 644.4309 correspond to a loss of trimethylamineN (Ch3) m/z 59 from the M + H adduct. Ion map for m/z 256.2599 represents the d18 side chain of the SM lipid structure. The approximate fragment conformations are depicted in the structural diagram. b. MALDI-MSI-IMS of commonly occurring fragment ions found within tissue and lipid standards representative of fatty acyl side chains
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Fig3: a MALDI-MSI-IMS image mapping the in-source fragment m/z ion species for SM (d18:1/16:0) in tissue and within a SM (d18:1/16:0) lipid standard. Particularly m/z 520.5024 is likely to be the N-paltimitoylsphingosine unit of the structure following neutral loss of cyclophosphane [H (HO)P (O) (OCH2CH2O)] m/z 183. The ion m/z 644.4309 correspond to a loss of trimethylamineN (Ch3) m/z 59 from the M + H adduct. Ion map for m/z 256.2599 represents the d18 side chain of the SM lipid structure. The approximate fragment conformations are depicted in the structural diagram. b. MALDI-MSI-IMS of commonly occurring fragment ions found within tissue and lipid standards representative of fatty acyl side chains

Mentions: In the imaging experiments it was possible to gain further information using spotted lipid standards in the image path but just off the tissue. Figure 3a shows that some of the ions detected are fragment ions of larger species e.g. SM (d18:1/16:0). Here, m/z 520.5024 detected in tissue at a drift-time value of 51.98 is also observed as a fragment ion of the SM (d18:1/16:0) lipid standard. It can be assigned to loss of cyclophosphane [H (HO) P (O) (OCH2CH2O)] m/z 183, from the protonated SM species, forming N-paltimitoylsphingosphine. Similarly the m/z 644.4309 ion corresponds to a loss of trimethylamine N (CH3) m/z 59. The fragment ion m/z 256.2599 corresponds to the d18 side chain within the sphingolipid structure. When the images of the fragment species (e.g. m/z 520.5024 and 644.4309) were compared with the protonated and sodium adduct ion images (m/z 703.5669 and 725.5487) a similar distribution of signal was observed between images; the main difference being intensities as expected.Fig. 3


Lipid changes within the epidermis of living skin equivalents observed across a time-course by MALDI-MS imaging and profiling.

Mitchell CA, Long H, Donaldson M, Francese S, Clench MR - Lipids Health Dis (2015)

a MALDI-MSI-IMS image mapping the in-source fragment m/z ion species for SM (d18:1/16:0) in tissue and within a SM (d18:1/16:0) lipid standard. Particularly m/z 520.5024 is likely to be the N-paltimitoylsphingosine unit of the structure following neutral loss of cyclophosphane [H (HO)P (O) (OCH2CH2O)] m/z 183. The ion m/z 644.4309 correspond to a loss of trimethylamineN (Ch3) m/z 59 from the M + H adduct. Ion map for m/z 256.2599 represents the d18 side chain of the SM lipid structure. The approximate fragment conformations are depicted in the structural diagram. b. MALDI-MSI-IMS of commonly occurring fragment ions found within tissue and lipid standards representative of fatty acyl side chains
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4525729&req=5

Fig3: a MALDI-MSI-IMS image mapping the in-source fragment m/z ion species for SM (d18:1/16:0) in tissue and within a SM (d18:1/16:0) lipid standard. Particularly m/z 520.5024 is likely to be the N-paltimitoylsphingosine unit of the structure following neutral loss of cyclophosphane [H (HO)P (O) (OCH2CH2O)] m/z 183. The ion m/z 644.4309 correspond to a loss of trimethylamineN (Ch3) m/z 59 from the M + H adduct. Ion map for m/z 256.2599 represents the d18 side chain of the SM lipid structure. The approximate fragment conformations are depicted in the structural diagram. b. MALDI-MSI-IMS of commonly occurring fragment ions found within tissue and lipid standards representative of fatty acyl side chains
Mentions: In the imaging experiments it was possible to gain further information using spotted lipid standards in the image path but just off the tissue. Figure 3a shows that some of the ions detected are fragment ions of larger species e.g. SM (d18:1/16:0). Here, m/z 520.5024 detected in tissue at a drift-time value of 51.98 is also observed as a fragment ion of the SM (d18:1/16:0) lipid standard. It can be assigned to loss of cyclophosphane [H (HO) P (O) (OCH2CH2O)] m/z 183, from the protonated SM species, forming N-paltimitoylsphingosphine. Similarly the m/z 644.4309 ion corresponds to a loss of trimethylamine N (CH3) m/z 59. The fragment ion m/z 256.2599 corresponds to the d18 side chain within the sphingolipid structure. When the images of the fragment species (e.g. m/z 520.5024 and 644.4309) were compared with the protonated and sodium adduct ion images (m/z 703.5669 and 725.5487) a similar distribution of signal was observed between images; the main difference being intensities as expected.Fig. 3

Bottom Line: In particular development of an epidermal layer was observable as a compaction of the distribution of phosphatidylcholine species.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.

View Article: PubMed Central - PubMed

Affiliation: Biomedical Research Centre, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB, UK. c.mitchell@surrey.ac.uk.

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.

No MeSH data available.