Infrared microspectroscopic determination of collagen cross-links in articular cartilage

Abstract

, "Infrared microspectroscopic determination of collagen cross-links in articular cartilage," J. Biomed. Opt. 22(3), 035007 (2017), doi: 10.1117/1.JBO.22.3.035007. Abstract. Collagen forms an organized network in articular cartilage to give tensile stiffness to the tissue. Due to its long half-life, collagen is susceptible to cross-links caused by advanced glycation end-products. The current standard method for determination of cross-link concentrations in tissues is the destructive high-performance liquid chromatography (HPLC). The aim of this study was to analyze the cross-link concentrations nondestructively from standard unstained histological articular cartilage sections by using Fourier transform infrared (FTIR) microspectroscopy. Half of the bovine articular cartilage samples (n ¼ 27) were treated with threose to increase the collagen cross-linking while the other half (n ¼ 27) served as a control group. Partial least squares (PLS) regression with variable selection algorithms was used to predict the cross-link concentrations from the measured average FTIR spectra of the samples, and HPLC was used as the reference method for cross-link concentrations. The correlation coefficients between the PLS regression models and the biochemical reference values were r ¼ 0.84 (p < 0.001), r ¼ 0.87 (p < 0.001) and r ¼ 0.92 (p < 0.001) for hydroxylysyl pyridinoline (HP), lysyl pyridinoline (LP), and pentosidine (Pent) cross-links, respectively. The study demonstrated that FTIR microspectroscopy is a feasible method for investigating cross-link concentrations in articular cartilage.

Effects of human articular cartilage constituents on simultaneous diffusion of cationic and nonionic contrast agents

“…Histological analyses showed that PG and amide I concentrations predominantly increased while water content decreased as a function of cartilage depth (Figure 3). 30,33‐35 The differences between the distributions of collagen (amide I) and PG concentration between more (Mankin score > 5) and less degenerated samples (Mankin score ≤ 5) were not statistically significant.…”

“…To (Figure 3). 30,[33][34][35] The differences between the distributions of collagen (amide I) and PG concentration between more (Mankin score > 5) and less degenerated samples (Mankin score ≤ 5) were not statistically significant.…”

“…The pixel size of 5.5 ×5.5 µm, spectral resolution 8 cm −1 , and eight repeated scans were selected to measure the spatially resolved infrared spectra of the cartilage. The infrared light absorption spectrum in each pixel was collected within the wavelength range of 3800 to 750 cm −1 and, amide I concentration was measured from the peak area ranging from 1720 cm −1 to 1595 cm −1 30 . The depth‐wise amide I concentration profiles were averaged from three sections per sample.…”

Infrared attenuated total reflection spectroscopic surface analysis of bovine‐tail intervertebral discs after UV‐light‐activated riboflavin‐induced collagen cross‐linking

“…Conventional methods for the determination of the degree of cross-linking in tissues include highperformance liquid chromatography (HPLC) and diffusion scanning calorimetry after enzymatic digestion of collected samples. However, both methods are time consuming, require sample blocks for analysis and are destructive preventing subsequent analysis with alternative techniques [8][9][10][11].…”