We describe the use of exosome such as mesenchymal stem cell exosomes in a method of promoting, restoring or enhancing homeostasis in an individual suffering from graft versus host disease (GVHD) or epidermolysis bullosa (EB). The homeostasis may comprise immune homeostasis such as maintenance of an immune response. The method may comprise administering a therapeutically effective amount of exosome to the individual.
