Imbalance between platelet vascular endothelial growth factor and platelet-derived growth factor in pulmonary hypertension - Effect of prostacyclin therapy

Focal vascular injury and impaired endothelial function are features of pul monary hypertension (PH) that lead to enhanced platelet endothelial cell in teractions. Vascular endothelial growth factor (VEGF) is contained in plate lets and released at sites of vascular injury to promote endothelial repair and wound healing in combination with platelet-derived nonspecific mitogen s such as platelet-derived growth factor (PDGF). The overall balance betwee n platelet VEGF and PDGF was investigated in 21 patients with primary PH, 8 with secondary PH, and 27 with chronic hypoxemic lung disease (CHLD), as w ell as in 29 control subjects. Platelet VEGF content was increased in patie nts with primary and secondary PH as compared with control subjects (518 +/ - 89, 675 +/- 156, and 166 +/- 29 fg/10(5) platelets, respectively; p < 0.0 1), whereas platelet PDGF content was similar in the three groups (31 +/- 2 , 36 +/- 4, and 33 +/- 3 pg/10(5) platelets, respectively; NS). Patients tr eated with a continuous prostacyclin infusion had a higher platelet VEGF bu t a similar platelet PDGF content as compared with untreated patients. Mode rate increases in platelet VEGF and PDGF contents were observed in the CHLD patients. We conclude that patients with primary or secondary PH have an i ncrease in platelet VEGF content, but not in platelet PDGF content, and tha t their platelet VEGF content increases further in response to prostacyclin infusion. We suggest that imbalance between platelet VEGF and PDGF is bene ficial to patients with PH.