Raman spectroscopy detection of molecular changes associated with two experimental models of osteoarthritis in rats

The aim of the present study was to evaluate the feasibility of applying Raman spectroscopy in probing the molecular changes in terms of collagen deposition and tissue remodeling associated with two well-established experimental models of osteoarthritis (OA) in knee of rats. In order to evaluate alterations in the articular surface area, the menisci-covered tibial region was assessed into three groups as follows: control (joint preserved) and two models of experimental knee OA: collagenase-induced model (n = 8) and treadmill exercise-induced model (n = 8). Each group was examined for molecular changes using spectral parameters related to cartilage, subchondral bone, and bone tissues. A significant increase of Raman ratios related to mineralization and tissue remodeling was found (p < 0.05), suggesting that both models were successful for inducing OA in rats. The significantly lower phenylalanine content and higher crystallinity in the treadmill exercise-induced model of OA than collagenase-induced model of OA (p < 0.05) indicated that the OA pathogenesis was model-dependent. Thus, this work suggests that the Raman spectroscopy technique has potential for the diagnosis and detection of cartilage damage and monitoring of subchondral bone and bone in OA pathogenesis at the molecular level.