Imaging early molecular changes in osteoarthritic (OA) joints is instrumental for the development of disease-modifying drugs. To this end, a ﬂuorescent resonance energy transfer-based peptide probe that is cleavable by matrix metalloproteinase 13 (MMP-13) has been developed. This protease degrades type II collagen, a major matrix component of cartilage. The probe exhibits high catalytic efﬁciency (kcat/KM = 6.5 × 105 M−1 s−1) and high selectivity for MMP-13 over a set of nine MMPs. To achieve optimal in vivo pharmacoki-netics and tissue penetration, the probe has been further conjugated to a linear L-polyglutamate chain of 30 kDa. The conjugate detects early bio-chemical events that occur in a surgically induced murine model of OA before major histological changes. The nanometric probe is suitable for the moni-toring of in vivo efﬁcacy of an orally bioavailable MMP-13 inhibitor, which effectively blocks cartilage degradation during the development of OA. This new polymer-probe can therefore be a useful tool in detecting early OA, disease progression, and in developing MMP-13-based disease-modifying drugs for OA.
Advanced functional materials