CD34 and anti-neutrophil cytoplasmic antibody-associated vasculitis: Impaired eEOCs regeneration and activity have been shown in different types of noninflammatory and inflammatory vascular diseases: patients with ANCA-associated vasculitis (AAV) showed increased numbers of circulating CD34+ hematopoietic progenitor cells (HPCs) and endothelial progenitor cells (EPCs) after the institution of immunosuppressive therapy and disease remission [13].