Summary
The pulmonary endothelium plays a significant role in the pathobiology of Primary
Pulmonary Hypertension. A number of diseases, related by a history of vascular injury,
are associated with increased numbers of circulating endothelial cells (CECs). We
hypothesized that patients with pulmonary hypertension would also have an increased
number of circulating endothelial cells due to the high pressures and increased shear
stress present within the pulmonary vasculature. We isolated the CECs from 14 patients
with pulmonary hypertension, (5 primary and 11 secondary) and compared them to the
cells from 12 normal controls. There was a significant increase in the number of CECs
in peripheral blood in patients with both PPH and secondary pulmonary hypertension
(SPH) when compared to normal volunteers (33.1 +/- 1.9 {PPH} and 27.2 +/- 6.9 {SPH}
vs. 3.5 +/- 1.3 {controls}, p < 0.001). The number of circulating endothelial cells
in the patient’s peripheral blood correlated significantly with the systolic, diastolic
and mean pulmonary artery pressures of the individual. Approximately 50% of the CECs
from patients with pulmonary hypertension expressed CD36, a marker of microvascular
origin and 25% expressed E-selectin, a marker of endothelial cell activation. Although
the origin of the CECs in patients with PH requires further investigation, one possible
source is the pulmonary vasculature, and in patients with plexogenic pulmonary hypertension,
the plexiform lesions. CECs may provide a non-invasive mean of accessing cells important
to the pathobiology of severe pulmonary hypertension.
Keywords
Circulating endothelial cells - plexiform lesion - angiogenesis - primary pulmonary
hypertension
