title: A quantitative approach to histopathological dissection of elastin-related disorders using multiphoton microscopy.
abstract: BACKGROUND
  Multiphoton microscopy (MPM) is a novel imaging technology that has recently become applicable for diagnostic purposes. The use of (near) infrared light in MPM allows for deep tissue imaging. In addition, this modality exploits the autofluorescent nature of extracellular matrix fibres within the skin.
  
  
  OBJECTIVE
  To quantitate the structure and abundance of elastic fibres in human dermis in three dimensions utilizing autofluorescent signals generated by MPM for the objective examination of elastin-related skin disorders.
  
  
  METHODS
  Cross-sections of skin samples from elastin-related disorders were analysed by MPM and correlated to histopathology. In situ visualization of elastic fibres by MPM was conducted by en face imaging of ex vivo skin samples through the intact epidermis. Image analysis software was used to quantify elastic fibres in three dimensions.
  
  
  RESULTS
  Based on the MPM-detected elastin-specific autofluorescence, we developed the Dermal Elastin Morphology Index (DEMI), calculated as the ratio of elastic fibre surface area and volume. This enabled objective three-dimensional quantification of elastic fibres. Quantitative scoring of sun-damaged skin using DEMI correlated with qualitative histopathological grading of the severity of solar elastosis. Furthermore, this approach was applied to changes in elastic fibre architecture in other disorders, such as pseudoxanthoma elasticum (PXE), PXE-like syndrome, elastofibroma, focal dermal elastosis, anetoderma, mid-dermal elastolysis and striae distensae. We imaged elastic fibres in intact ex vivo skin imaged en face through the epidermis, indicating that this approach could be used in vivo.
  
  
  CONCLUSIONS
  MPM has the potential for noninvasive in vivo visualization of elastic fibres in the dermis with near histological resolution. DEMI allows objective assessment of elastic fibres to support diagnosis and monitoring of disease progress or therapy of elastin-related skin disorders.
authors.affiliation: Centenary Institute, Newtown, NSW, Australia; Discipline of Dermatology, University of Sydney, Camperdown, NSW, Australia; Department of Dermatology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
authors.forename: P L
authors.initials: PL
authors.lastname: Tong
authors.forename: J
authors.initials: J
authors.lastname: Qin
authors.forename: C L
authors.initials: CL
authors.lastname: Cooper
authors.forename: P M
authors.initials: PM
authors.lastname: Lowe
authors.forename: D F
authors.initials: DF
authors.lastname: Murrell
authors.forename: S
authors.initials: S
authors.lastname: Kossard
authors.forename: L G
authors.initials: LG
authors.lastname: Ng
authors.forename: B
authors.initials: B
authors.lastname: Roediger
authors.forename: W
authors.initials: W
authors.lastname: Weninger
authors.forename: N K
authors.initials: NK
authors.lastname: Haass
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004549:Elastin / Q000378:metabolism*; D006801:Humans; D021621:Imaging, Three-Dimensional; D036641:Microscopy, Fluorescence, Multiphoton; D008875:Middle Aged; D011561:Pseudoxanthoma Elasticum / Q000473:pathology; D012871:Skin Diseases / Q000473:pathology*
chemical_list: D004549:Elastin