Endothelial damage and stem cell repair in atherosclerosis.

Atherosclerosis is a slowly progressing and multifactorial disease, in which endothelial dysfunction and damage play an initial role. Many risk factors for atherosclerosis can lead to endothelial damage of the vessel, especially in the areas where blood flow is disturbed. In the presence of hyperlipidemia, disturbed blood flow results in increased endothelial turnover in the arterial wall. It was demonstrated that disturbed blood flow activates endoplasmic reticulum stress initiating a signal pathway leading to endothelial apoptosis. Following endothelial death, the neighboring mature endothelial cells actively proliferate and migrate to heal the wound. However, stem cell repairing may be needed if endothelial damage is severe. As rapid development of stem cell research, it is expected that stem/progenitor cells may serve as a new source for vascular repair. In this review, we aim at examining key elements of endothelial turnover in atherosclerosis, i.e. damage and repair. We will also discuss the mechanisms of the process repaired by mature endothelial as well as stem cells, and highlight recent reciprocal stem cell application, which may provide a new hope to the treatment of severe atherosclerotic complications.