Recent researches indicate that impairment of vascular and endothelial homeostasis plays a major role in the initiation and development of IPAH.We have recently reported the safety and feasibility data for autologous endothelial progenitor cells (EPCs) injection in patients with IPAH. Yet many questions remain unanswered: what is the ideal quantity of EPCs for therapy, the duration of the therapeutic effect, and moreover, the potential toxicity of such therapy. To help answer these questions, we designed the one year follow-up to investigate the safety and efficacy of autologous EPCs injection in patients with IPAH.

Inclusion Criteria:

• The inclusion criteria included a base-line six minute walking distance between 100 and 450 m
• A resting mean pulmonary-artery pressure greater than 30 mm Hg
• A pulmonarycapillary wedge pressure of less than 15 mm Hg
• Pulmonary vascular resistance greater than 240 dyn•sec•cm-5
• 18-60 years old

Exclusion Criteria:

• The exclusion criteria included secondary pulmonary hypertension as a result of heart disease
• Pulmonary disease
• Sleep-associated disorders
• Chronic thromboembolic disease
• Autoimmune or collagen vascular disease
• HIV infection
• Liver disease
• New York Heart Association functional class IV
• Major bleeding requiring blood transfusion
• Diabetes
• Renal dysfunction
• Evidence for malignant diseases were excluded