Stem cells for mesothelial repair: an understudied modality.

Adhesions are bands of fibrous tissue that form between opposing organs and the peritoneum, restricting vital intrapleural and abdominal movement. They remain a major problem in abdominal surgery, occurring in more than three fourths of patients following laparotomy. Adhesions result when injury to the mesothelium is not repaired by mesothelial cells and can be viewed as scar tissue formation. The mechanism of mesothelial healing suggested the involvement of stem cells in the process. It has long been known that peritoneal wounds heal in the same amount of time regardless of size. Therefore, the mesothelium could not regenerate solely by proliferation and centripetal migration of cells at the wound edge as occurs in the healing of skin epithelium. Several studies suggest the presence of i) mesothelial stem cells that can differentiate into mesothelial cells and a few other phenotypes and/or ii) that mesothelial cells are themselves stem cells. Other studies have suggested that adult stem cells in the muscle underlying the peritoneum can differentiate into mesothelial cells and contribute to healing. Prevention of abdominal adhesions have been accomplished by delivery of autologous mesothelial cells and multipotent adult stem cells isolated from skeletal muscle. Adult stem cells from sources other than the serosal tissue offer an alternative treatment modality to prevent the formation of abdominal adhesions.