Detection of cartilage degradation by autofluorescence lifetime

Cartilage is a vital organ to maintain joint function. Upon arthritis, proteolytic enzymes initiate degradation of cartilage extracellular matrix (ECM) resulting in eventual loss of joint function.However, there are only limited ways of non-invasively monitoring early chemical changes in cartilage matrix.

In collaboration with Professor Paul French and Dr Chris Dunsby at Imperial College London, we found that the autofluorescence decay profiles of cartilage tissue are significantly affected by proteolytic degradation of cartilage ECM and can be characterised by measurements of the autofluorescence lifetime (AFL). This methodology may provide a novel tool to help early diagnosis of Osteoarthritis.

Image: Detection of cartilage degradation by autofluorescence lifetime. Autofluorescence lifetime images of cartilage pieces. A cartilage piece was halved and one piece was soaked in the buffer containing with or without human active MMP-1 (collagenase) for 48 h at 37 °C. The other piece of cartilage was either frozen down immediately (buffer control) or incubated with buffer without enzymes for the same length of time as the other piece. Two paired pieces of cartilages were then put together, and interface of cartilages were imaged using the wide-field FLIM microscope. Note that MMP-1-treated cartilage piece showed significantly shorter fluorescence lifetime.