The invention provides compositions comprising mesenchymal stem cell (MSC) derived exosomes, and methods of their use in subjects having certain lung diseases including inflammatory lung disease.L'invention concerne des compositions qui comportent des exosomes issus de cellules souches mésenchymateuses (MSC), et leurs procédés d'utilisation chez des sujets présentant certaines maladies pulmonaires, comprenant la maladie pulmonaire inflammatoire.