Extracellular vesicles — new tool for joint repair and regeneration

Extracellular vesicles (EVs) are a heterogeneous group of membrane-enclosed particles involved in a multitude of biological processes, including the development and homeostasis of cartilage tissue. In this Perspectives article, the authors describe the current knowledge of the functions of EVs in joint physiology and explore the therapeutic potential of EVs as tools to deliver biologically-active therapeutic agents to joints. Cell-derived extracellular vesicles (EVs), present in synovial fluid and cartilage extracellular matrix (ECM), are involved in joint development and in the regulation of joint homeostasis. Although the exact function of EVs in these processes remains incompletely defined, the knowledge already acquired in this field suggests a role for these EVs as biomarkers of joint disease, and as a new tool to restore joint homeostasis and enhance articular tissue regeneration. In addition to direct injection of therapeutic EVs into the target site, surface coating of scaffolds and embedding of EVs in hydrogels might also lead to novel therapeutic possibilities. Based on the existing literature of EVs in synovial fluid and articular tissues, and investigation of the molecular factors (including microRNAs) active in joint homeostasis (or during its disturbance), we postulate novel perspectives for the implementation of EVs as a regenerative medicine approach in joint repair.