The goal of this study was to investigate the feasibility, safety, and initial clinical outcome of intravenous infusion of autologous endothelial progenitor cells (EPCs) in patients with idiopathic pulmonary arterial hypertension (IPAH).

Experimental data suggest that transplantation of EPCs attenuates monocrotaline-induced pulmonary hypertension in rats and dogs. In addition, clinical studies suggest that autologous progenitor cell transplantation is feasible and safe in patients with ischemic diseases.

We conducted a prospective, randomized trial comparing the effects of EPC transplantation plus conventional therapy with those of conventional therapy alone in patients with IPAH. The primary end point was change in the 6-min walk distance using a standardized protocol. The secondary end points were changes in hemodynamic variables as assessed by right heart catheterization.

After 12 weeks of follow-up, the mean distance walked in 6 min increased by 48.2 m in the cell infusion group (from 263 ± 42 m to 312 ± 34 m), and an increase of 5.7 m occurred in the conventional therapy group (from 264 ± 42 m to 270 ± 44 m). The mean difference between the 2 groups was 42.5 m (95% confidence interval 28.7 to 56.3 m, p < 0.001). The patients in the cell infusion group also had significant improvement in mean pulmonary artery pressure, pulmonary vascular resistance, and cardiac output. There were no severe adverse events with cell infusion.

This preliminary study showed that intravenous infusion of autologous EPCs seemed to be feasible and safe, and might have beneficial effects on exercise capacity and pulmonary hemodynamics in patients with IPAH. (Safety and Efficacy Study of Transplantation of EPCs to Treat Idiopathic Pulmonary Arterial Hypertension; http://www.clinicaltrials.gov/ct/show/NCT00257413?order=1; NCT00257413).