**9.1. Stem cell**

Stem cells are unique in that they possess the capacity to self-renew and capable of differentiation into many cell types hence leading to the regeneration of injured organs. In lung injury, stem cells have been shown to promote endothelial and epithelial repair by engrafting into tissue and interacting with neighboring cells. Furthermore, stem cells beneficially influence the host's immune response by reducing harmful inflammatory reactions. Paracrine mediators and mitochondria-containing micro-vesicles released by stem cells appear responsible for the beneficial effects on immune responses and cellular functions [81].
