Biomarker Mapping on Skin Tape Strips Using MALDI Mass Spectrometry Imaging
Keratinocyte organization and biochemistry are important in forming the skin’s protective barrier. Intrinsic and extrinsic factors can affect skin barrier function at the cellular and molecular levels. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometric imaging, a technique which combines both molecular aspects and histological details, has proven to be a valuable method in various disciplines including pharmacology, dermatology and cosmetology. It typically requires ex vivo samples, prepared following frozen tissue sectioning. This paper demonstrates the feasibility of performing MALDI analysis on tape strips collected non-invasively on skin. The aim is to obtain molecular imaging of corneocytes on tapes towards novel biological insights. Tapes were collected from two skin sites (volar forearm and cheek) of human volunteers. Ten molecules relating to skin barrier function were detected with a single mode of acquisition at high spatial resolution with a 7 T MALDI-Fourier transform ion cyclotron resonance (FTICR) instrument. The method sensitivity was adequate to create molecular maps which could be overlaid on transmission microscopy images of the same area of the tape. Analysis of the molecular distributions from tapes at the two skin sites was consistent with the known skin properties of the two sites, confirming the validity of the observations. Hierarchical clustering analysis was used to differentiate corneocyte populations based on their molecular profiles. Furthermore, morphological analysis provided a new way of considering statistical populations of corneocytes on the same tape, rather than measuring a single averaged value, providing additional useful information relating to their structure-function relationship.
KeywordsMolecular mapping Corneocytes MALDI-FTICR mass spectrometry imaging Skin barrier
Desorption electrospray ionization
Fourier transform ion cyclotron resonance
Liquid chromatography/mass spectrometry tandem
Matrix-assisted laser desorption/ionization
Mass spectrometry Imaging
Natural moisturization factor
Pyrrolidine carboxylic acid
Root mean square
Region of interest
Time-of-flight secondary ion mass spectrometry
The authors would like to thank Gaël Picard de Müller and Fabien Pamelard for their contribution to the morphologic and statistical approaches.
Compliance with Ethical Standards
Conflict of Interest
GNS is employee of Johnson & Johnson Santé Beauté France, a manufacturer of skin care products. GH, DB, and JS are employees of ImaBiotech, SAS a provider of analytical services including MALDI-MSI. The authors of the manuscript declare no competing commercial/financial interests.
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