Time-of-flight secondary ion mass spectrometry-based molecular distribution distinguishing healthy and osteoarthritic human cartilage

TL;DR

This study uses TOF-SIMS imaging to identify molecular distribution differences in healthy versus osteoarthritic human cartilage, revealing specific lipid and mineral alterations associated with OA.

Contribution

First application of TOF-SIMS to map lipid and mineral distributions in human cartilage, distinguishing healthy from osteoarthritic tissue at high spatial resolution.

Findings

Cholesterol-related peaks differ between healthy and OA cartilage.

Higher oleic acid and fatty acids in OA cartilage.

Calcium and phosphate accumulate around chondrocytes in OA.

Abstract

Osteoarthritis (OA) is a pathology that ultimately causes joint destruction. The cartilage is one of the principal affected tissues. Alterations in the lipid mediators and an imbalance in the metabolism of cells that form the cartilage (chondrocytes) have been described as contributors to the OA development. In this study, we have studied the distribution of lipids and chemical elements in healthy and OA human cartilage. Time of flight-secondary ion mass spectrometry (TOF-SIMS) allows us to study the spatial distribution of molecules at a high resolution on a tissue section. TOF-SIMS revealed a specific peak profile that distinguishes healthy from OA cartilages. The spatial distribution of cholesterol-related peaks exhibited a remarkable difference between healthy and OA cartilages. A distinctive colocalization of cholesterol and other lipids in the superficial area of the cartilage was found. A higher intensity of oleic acid and other fatty acids in the OA cartilages exhibited a similar localization. On the other hand, CN(-) was observed with a higher intensity in the healthy samples. Finally, we observed an accumulation of calcium and phosphate ions exclusively in areas surrounding the chondrocyte in OA tissues. To our knowledge, this is the first time that TOF-SIMS revealed combined changes in the molecular distribution in the OA human cartilage.