Characterization of Degraded Cartilage Using Confocal Raman Microscopy

Abstract

Osteoarthritis is a degenerative disease with pathological changes at the molecular level. Moreover, the damage to articular cartilage is irreversible. Early detection and the ability to follow the progression of osteoarthritis are essential to anticipate management. To characterize degraded human articular cartilage and to identify cellular changes that are precursors of phenotypic matrix changes in osteoarthritis, normal and degraded articular cartilage explants were harvested from the same patient’s knee after informed consent. The blocks were washed several times (four times) with phosphate-buffered saline (often abbreviated to PBS) and then fixed on CaF2 slides using Cell-Tak® (an adhesive glue), and the whole set was placed in different Petri dishes containing PBS for Raman measurements. The analysis of the spectroscopic data allowed to differentiate degraded cartilage from normal cartilage by applying intensity ratios of some Raman bands and/or spectral regions. In addition, peaks at 864, 929, 945, 1107, 1386, and 2887 cm−1 were identified as characteristic Raman markers of degraded cartilage. The use of confocal Raman microscopy (CRM) has proven to be relevant in providing biochemical information necessary to characterize OA cartilage. CRM appears to be a powerful tool for the diagnosis and therapeutic evaluation of osteoarthritis in both early and late stages.