Interest of polarized FT-IR imaging to characterize the collagen network in human skin

BACKGROUND: During pathological and/or physiological processes, such as tumoral progression or aging, human skin undergoes molecular and structural changes mainly due to alterations of dermal structural proteins such as type I collagen. These modifications in dermis are probably due to collagen fibers rearrangement and reorientation which have not been thoroughly studied up to now. FT-IR (Fourier transform infrared) microspectroscopy associated to polarization measurement appears as an interesting method to determine in situ the alignment of type I collagen fibers.

OBJECTIVE: In this paper, two different clustering algorithms were applied to determine different layers in human skin. Besides, we used polarized FT-IR imaging to evaluate the molecular organization of dermal collagen.

METHODS: To do this, a cryosection of skin from 48-year-old woman was analyzed. Acquired FT-IR images were firstly processed using K-means and fuzzy C-means (FCM). FCM was chosen on polarized FT-IR images in order to highlight the molecular orientation of dermal collagen fibrils. The ratio of Amide I/Amide II bands integrated intensities was computed in order to assess the orientation of collagen fibrils.

RESULTS AND CONCLUSION: This methodology permitted to reveal the potential of polarized FT-IR microspectroscopy for the characterization of type I collagen network in human skin. Our approach could help to find innovative applications in dermatology as well as in cosmetics.