title: Infrared spectroscopy reveals both qualitative and quantitative differences in equine subchondral bone during maturation.
abstract: The collagen phase in bone is known to undergo major changes during growth and maturation. The objective of this study is to clarify whether Fourier transform infrared (FTIR) microspectroscopy, coupled with cluster analysis, can detect quantitative and qualitative changes in the collagen matrix of subchondral bone in horses during maturation and growth. Equine subchondral bone samples (n = 29) from the proximal joint surface of the first phalanx are prepared from two sites subjected to different loading conditions. Three age groups are studied: newborn (0 days old), immature (5 to 11 months old), and adult (6 to 10 years old) horses. Spatial collagen content and collagen cross-link ratio are quantified from the spectra. Additionally, normalized second derivative spectra of samples are clustered using the k-means clustering algorithm. In quantitative analysis, collagen content in the subchondral bone increases rapidly between the newborn and immature horses. The collagen cross-link ratio increases significantly with age. In qualitative analysis, clustering is able to separate newborn and adult samples into two different groups. The immature samples display some nonhomogeneity. In conclusion, this is the first study showing that FTIR spectral imaging combined with clustering techniques can detect quantitative and qualitative changes in the collagen matrix of subchondral bone during growth and maturation.
authors.affiliation: University of Eastern Finland, Department of Physics and Mathematics, Kuopio, Finland.
authors.forename: Yevgeniya
authors.initials: Y
authors.lastname: Kobrina
authors.forename: Hanna
authors.initials: H
authors.lastname: Isaksson
authors.forename: Miikka
authors.initials: M
authors.lastname: Sinisaari
authors.forename: Lassi
authors.initials: L
authors.lastname: Rieppo
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Brama
authors.forename: Rene
authors.initials: R
authors.lastname: van Weeren
authors.forename: Heikki J
authors.initials: HJ
authors.lastname: Helminen
authors.forename: Jukka S
authors.initials: JS
authors.lastname: Jurvelin
authors.forename: Simo
authors.initials: S
authors.lastname: Saarakkala
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001842:Bone and Bones / Q000502:physiology*; D006736:Horses; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*