Mesenchymal stem cells in the treatment of chronic lung disease.

Mesenchymal stem cells (MSCs) are a populace of non-haematopoietic multipotent stromal cells, which have the ability to differentiate into tissue derived from a single germ layer. MSCs have been isolated from various sites, including adipose tissue, skeletal muscle, synovium, spleen, thymus, lung and amniotic fluid, but are most often isolated from bone marrow. MSCs have several valuable functions that make them a promising therapeutic option in the field of regenerative medicine, including the secretion of anti-inflammatory cytokines and growth factors, the migration of cells to the site of injury when administered and the ability to 'rescue' cells through the transfer of functional mitochondria. They also offer the possibility of autologous cell transplantation, circumventing immune rejection. These properties, among others, make MSCs a promising potential therapeutic agent in the treatment of chronic lung diseases with high rates of morbidity and mortality, such as idiopathic pulmonary fibrosis (IPF), COPD and obstructive bronchiolitis (OB). Numerous animal models have shown the protective and reparative effects of MSCs in models of experimental lung injury. There are currently several clinical trials underway to evaluate the safety and efficacy of MSCs in the treatment of IPF, COPD and OB. While early results are encouraging, a considerable amount of research must be done concerning the safety MSCs, as well as their optimal dosage, time and route of administration. In addition, much is still unknown about the pathogenesis of these chronic lung diseases, as well as the mechanisms MSCs utilize to assist in their repair.