Combining μX-ray fluorescence, μXANES and μXRD to shed light on Zn2+ cations in cartilage and meniscus calcifications

• Published in: Journal of trace elements in medicine and biology 2013-10, Vol.27 (4), p.326-333
• Main Authors: Dessombz, Arnaud, Nguyen, Christelle, Ea, Hang-Korng, Rouzière, Stephan, Foy, Eddy, Hannouche, Didier, Réguer, Solene, Picca, Frederic-Emmanuel, Thiaudière, Dominique, Lioté, Frédéric, Daudon, Michel, Bazin, Dominique
• Format: Article
• Language: English
• Subjects: Aged; Ca phosphate apatites; Ca pyrophosphate; Cartilage, Articular - chemistry; Cartilage, Articular - pathology; Cations - analysis; Chemical Sciences; Humans; Knee Joint - chemistry; Knee Joint - pathology; Light; Male; Material chemistry; Menisci, Tibial - chemistry; Menisci, Tibial - pathology; Osteoarthritis; Osteoarthritis - pathology; Spectrometry, X-Ray Emission; X-Ray Absorption Spectroscopy; X-Ray Diffraction; Zinc - analysis; Zn environment; μX-ray absorption spectroscopy
• ISSN: 0946-672X; 1878-3252
• DOI: 10.1016/j.jtemb.2013.02.001

We aimed to examine the presence of Zn, a trace element, in osteoarthritis (OA) cartilage and meniscus from patients undergoing total knee joint replacement for primary OA. We mapped Ca2+ and Zn2+ at the mesoscopic scale by X-ray fluorescence microanalysis (μX-ray) to determine the spatial distribution of the 2 elements in cartilage, μX-ray absorption near edge structure spectroscopy to identify the Zn species, and μX-ray diffraction to determine the chemical nature of the calcification. Fourier transform infrared spectroscopy was used to determine the chemical composition of cartilage and meniscus. Ca2+ showed a heterogeneous spatial distribution corresponding to the calcifications within cartilage (or meniscus) or at their surface. At least 2 Zn2+ species were present: the first may correspond to Zn embedded in protein (different Zn metalloproteins are known to prevent calcification in biological tissues), and the second may be associated with a Zn trap in or at the surface of the calcification. Calcification present in OA cartilage may significantly modify the spatial distribution of Zn; part of the Zn may be trapped in the calcification and may alter the associated biological function of Zn metalloproteins.