Muse Cells and Ischemia-Reperfusion Lung Injury.

Ischemia-reperfusion injury (IRI) is one of the main causes of primary graft dysfunction that accounts for 25% of mortality after lung transplantation. Disruption of blood supply and subsequent reperfusion result in organ damage with activating innate and adaptive immune response, leading to inflammatory insults. The IRI after lung transplantation is primarily manifested by permeability pulmonary edema on the basis of pulmonary vascular endothelial cell injury as seen in acute respiratory distress syndrome (ARDS). Stem cells have potent anti-inflammatory and immunomodulatory properties through local paracrine mechanisms. The application of mesenchymal stem cells (MSCs) for ARDS as well as IRI in various organs, therefore, has been interested and extensively investigated in animal models with promising results. Furthermore, two recent clinical randomized, placebo-controlled pilot studies demonstrated that treatment of ARDS with MSCs appears to be safe and feasible.Muse cells are stress-tolerant and non-tumorigenic endogenous pluripotent-like stem cells. They comprise small proportions of cultured fibroblasts and MSCs and can be isolated from these populations. Muse cells are known to migrate to the damaged tissue after local or systemic administration, spontaneously differentiate into the tissue-compatible cells, and also secrete factors related to immunomodulation and tissue repair. We have recently shown the effect of Muse cells on ameliorating lung IRI in a rat model. With 2 h of warm ischemia and subsequent reperfusion on the left lung, the lung showed severe pulmonary edema. Administration of Muse cell through the left pulmonary artery immediately after reperfusion more significantly improved lung oxygenation capacity, compliance, and histological damage on days 1 and 3 after reperfusion compared with MSCs, and this was associated with higher expression levels of proteins related with anti-inflammation and tissue repair in the lung. Encouraging results of this study advocate further investigation of the ability of Muse cells to prevent and treat IRI after lung transplantation.