Degradation of cartilage, occurring in osteoarthritis and other conditions leads to pain and reduced mobility. Current treatments beyond anti-inflammatories include intra-articular injections of hyaluronan or preparations based on adult mesenchymal stem cells (MSC), the latter shown to aid cartilage regeneration which requires the assessment of the cartilage, best on a molecular level and in a minimally invasive way. However, the conventional methods are invasive, destroying and can only provide a snapshot of a tissue structure and functional state on a sample-by-sample basis, while the continuous monitoring and high-throughput assays require low-invasive biopsy-free approach. As a first step to address this problem, in current work, we explored the potential of label-free multispectral imaging of endogenous tissue fluorescence to characterise the molecular composition, structure and functional status of ex vivo healthy bovine and osteoarthritic (OA) human knee articular cartilage followed by monitoring the effects of experimental treatment of OA cartilage performed ex vivo.
However, strong autofluorescence of collagens (especially from collagen type II, which is the structural backbone of collagen fibrils) from various cartilage layers presents a challenge, because this signal tends to overpower the fluorescence from chondrocytes. We have managed to use Robust Dependent Component Analysis (RoDECA) to observe the detailed metabolic information with a proper account of intrinsic cellular heterogeneity, which signifies the sophisticated quantitative biochemical analysis. This work reports on the “signatures” of the healthy articular cartilage for superficial and transitional layer, define the “healthy range” of each fluorophore’s abundance and localization of chondrocytes non-invasively as well as identify the changes of the signatures in OA cartilage of real patients and observe the reaction of the OA cartilage on 2 types of experimental treatments.