Systemic lupus erythematosus (SLE) is associated with a high prevalence of cardiovascular disease. Circulating endothelial progenitor cells (EPCs) contribute to vascular regeneration and repair, thereby protecting against atherosclerotic disease. EPCs are derived from CD34+ haematopoietic stem cells (HSCs), which have an increased propensity for apoptosis in the bone marrow of patients with SLE.