title: In vivo coherent Raman imaging of the melanomagenesis-associated pigment pheomelanin.
abstract: Melanoma is the most deadly form of skin cancer with a yearly global incidence over 232,000 patients. Individuals with fair skin and red hair exhibit the highest risk for developing melanoma, with evidence suggesting the red/blond pigment known as pheomelanin may elevate melanoma risk through both UV radiation-dependent and -independent mechanisms. Although the ability to identify, characterize, and monitor pheomelanin within skin is vital for improving our understanding of the underlying biology of these lesions, no tools exist for real-time, in vivo detection of the pigment. Here we show that the distribution of pheomelanin in cells and tissues can be visually characterized non-destructively and noninvasively in vivo with coherent anti-Stokes Raman scattering (CARS) microscopy, a label-free vibrational imaging technique. We validated our CARS imaging strategy in vitro to in vivo with synthetic pheomelanin, isolated melanocytes, and the Mc1re/e, red-haired mouse model. Nests of pheomelanotic melanocytes were observed in the red-haired animals, but not in the genetically matched Mc1re/e; Tyrc/c("albino-red-haired") mice. Importantly, samples from human amelanotic melanomas subjected to CARS imaging exhibited strong pheomelanotic signals. This is the first time, to our knowledge, that pheomelanin has been visualized and spatially localized in melanocytes, skin, and human amelanotic melanomas.
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Hequn
authors.initials: H
authors.lastname: Wang
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.|Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue E25-519, Cambridge, Massachusetts 02139, USA.
authors.forename: Sam
authors.initials: S
authors.lastname: Osseiran
authors.affiliation: Cutaneous Biology Research Center, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Vivien
authors.initials: V
authors.lastname: Igras
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.|Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue E25-519, Cambridge, Massachusetts 02139, USA.|Harvard University Program in Biophysics, Building C2 Room 112, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Nichols
authors.affiliation: Cutaneous Biology Research Center, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Elisabeth M
authors.initials: EM
authors.lastname: Roider
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Joachim
authors.initials: J
authors.lastname: Pruessner
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: Hensin
authors.initials: H
authors.lastname: Tsao
authors.affiliation: Cutaneous Biology Research Center, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Fisher
authors.affiliation: Wellman Center for Photomedicine, Harvard Medical School, Massachusetts General Hospital, 149 13th Street, Charlestown, Massachusetts 02129, USA.|Harvard University Program in Biophysics, Building C2 Room 112, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.|Ludwig Center at Harvard, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Conor L
authors.initials: CL
authors.lastname: Evans
mesh_terms: D000818:Animals; D004423:Ear / Q000000981:diagnostic imaging; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D008543:Melanins / Q000032:analysis* / Q000378:metabolism; D008544:Melanocytes / Q000378:metabolism*; D018328:Melanoma, Amelanotic / Q000378:metabolism*; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D018613:Microscopy, Confocal / Q000295:instrumentation / Q000379:methods; D057054:Molecular Imaging / Q000379:methods*; D044102:Receptor, Melanocortin, Type 1 / Q000235:genetics; D012867:Skin / Q000000981:diagnostic imaging / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D008543:Melanins; D044102:Receptor, Melanocortin, Type 1; C018362:pheomelanin