Raman analysis of proteoglycans simultaneously in bone and cartilage

Abstract

Bone and cartilage are connective tissues with distinct organic matrix (collagen and non‐collagenous proteins) composition facilitating their biological function. Proteoglycans (PGs), a member of the non‐collagenous proteins fulfill functions that are determined by both their core protein and their glycosaminoglycan chains. The purpose of the present study was to identify Raman bands that are representative of PG concentration and may be used in both bone and cartilage tissues. To achieve this goal, we analyzed a series of reference PGs and collagens, as well as turkey leg tendon to verify the laser polarization independency of the identified bands. Additionally, the applicability of these bands in both cartilage and bone tissue simultaneously was tested in a healthy femoral head by Raman imaging and hierarchical cluster analysis to describe the distribution of PGs at the micron level from articular cartilage to subchondral bone. The results of the study show that the Raman band ~1375 cm−1 can be used as a PGs marker band in both cartilage and bone. Moreover, articular cartilage has a lower content of organic matrix (mostly type II collagen), while the middle and deep transitional zone haves a higher concentration of PGs. The calcified cartilage is characterized by a lower content of PGs and total organic matrix (estimated from the integrated area of the amide III band). Copyright © 2014 John Wiley & Sons, Ltd.

Raman Spectroscopy Reveals New Insights into the Zonal Organization of Native and Tissue-Engineered Articular Cartilage

“…With that in mind, we found that the bands near ∼1410 cm –1 (ν s (COO – ) of GAG provided a better contrast than the commonly used (ν s (S=O) peak near 1061 cm –1 . 23 This univariate analysis of the Raman spectroscopy data allows a localization of the main components of articular cartilage, namely, collagen, GAG, water, chondrocytes, and their nuclei.…”

“…The residual spectral variance of 10.75% was mainly associated with the chondrocyte spectral signature (i.e., cytoplasmic biomolecules and DNA) and other minor ECM biomolecules. 23 Of note, we took into account the anisotropic Raman scattering in the biochemical analysis of collagen by using the total collagen content, which was calculated as the sum of collagen fibers aligned perpendicular and parallel to the tissue surface (see Figure S3). …”

Label-Free Raman Spectroscopy Detects Stromal Adaptations in Premetastatic Lungs Primed by Breast Cancer

“…Another pertinent peak was observed at ca. 1061 cm −1 in the MCL and MDL PCs, which is known to be a key spectral marker for proteoglycans (41,42). This finding offers an intriguing insight into the nature of molecular modifications in the pre-metastatic niche, particularly in light of the study of Gao et al .…”

Vibrational spectroscopy of articular cartilage

“…Therefore, the CH 3 symmetric deformation peak at 1,375 cm ¡1 may be a better choice for glycosaminoglycans if calcified cartilage is included in the analyses (68).…”