Imaging joint cartilage at a molecular level

Australian scientists have reported an advanced imaging technique that allows the condition of joint cartilage to be examined — right down to a molecular level. Described in the journal Scientific Reports, the technique has potential for diagnostics and treatment planning of cartilage disease and impairment, including for osteoarthritis.

“Damage and degradation of cartilage around joints leads to severe pain and loss of mobility,” said Dr Saabah Mahbub, Research Fellow at the ARC Centre of Excellence for Nanoscale BioPhotonics (CNBP) and lead author of the study.

“We need a tool to help us to determine, objectively, the degree of problem that the joint cartilage is exhibiting. We then need a way to be able to monitor the effectiveness of any cartilage regeneration therapies that are able to be undertaken.

“Ideally, we need to be able to do this monitoring at a molecular level and in a minimally invasive way.”

Together with other researchers from CNBP, as well as Macquarie University, UNSW Sydney, Quantitative and Regeneus, Dr Mahbub investigated a cutting-edge technique termed hyperspectral imaging, which combines the power of an advanced optical microscope together with high-powered data analysis to measure and image the electromagnetic light-waves being given off by the cartilage tissue and cartilage cells known as chondrocytes.

“In this study, we applied our advanced hyperspectral microscopy to osteoarthritic human cartilage — to investigate its capacity to generate molecular data and to help us characterise the cartilage disease-state, as well as to examine potential treatment effects,” Dr Mahbub said.

“Using this approach, we were able to identify types and amounts of collagen (collagen I and collagen II) in the cartilage tissue as well as to test for the specific co-enzymes FAD and NADH in the chondrocytes.”

The hyperspectral-based study was also capable of detecting effects related to cartilage treatments (in this case, the use of secretions from stem cells). This was indicated by hyperspectral imagery indicating changes in the composition of the cartilage — ratios of collagen I to collagen II — when comparing pre- and post-cartilage treatment activity.

“We believe that levels of collagen I, collagen II and associated proteins may be sensitive to improvements in cartilage health and could be used to monitor patient progression and to discern between effects of different osteoarthritis therapies,” Dr Mahbub said.

It is envisaged that, in the future, the imaging technique will be available to patients in a clinical setting where it would be deployed endoscopically through small incisions in targeted areas of the body. Meanwhile, Dr Mahbub and the research team are to further investigate the molecular underpinnings of the progression of cartilage deterioration as well as regeneration.

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