Derivatization Strategies for the Detection of Triamcinolone Acetonide in Cartilage by Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Osteoarthritis (OA), characterized by degeneration of the cartilaginous tissue in articular joints, severely impairs mobility in many people worldwide. The degeneration is thought to be mediated by inflammatory processes occurring in the tissue of the joint, including the cartilage. Intra-articular administered triamcinolone acetonide (TAA) is one of the drug treatments employed to ameliorate the inflammation and pain that characterizes OA. However, the penetration and distribution of TAA into the avascular cartilage is not well understood. We employed matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), which has been previously used to directly monitor the distribution of drugs in biological tissues, to evaluate the distribution of TAA in human cartilage after in vitro incubation. Unfortunately, TAA is not easily ionized by regular electrospray ionization (ESI) or MALDI. To overcome this problem, we developed an on-tissue derivatization method with Girard's reagent T (GirT) in human incubated cartilage being able to study its distribution and quantify the drug abundance (up to 3.3 ng/μL). Our results demonstrate the depth of penetration of a corticosteroid drug in human OA cartilage using MALDI-MSI.