Angiostatic Factors in the Pulmonary Endarterectomy Material from Chronic Thromboembolic Pulmonary Hypertension Patients Cause Endothelial Dysfunction

Diana Zabini,Andrea Olschewski,Irene M Lang,Elvira Stacher,Zoltán Bálint,Horst Olschewski,Walter Klepetko,Akos Heinemann,Chandran Nagaraj,Patrick Nierlich,Rory Edward Morty

doi:10.1371/journal.pone.0043793

Abstract

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease with persistent thrombotic occlusion or stenosis of the large pulmonary arteries resulting in pulmonary hypertension. Surgical removal of the neointimal layer of these vessels together with the non-resolved thrombus consisting of organized collagen-rich fibrotic areas with partly recanalized regions is the treatment of choice (pulmonary endarterectomy, PEA). The present study investigates endothelial cells isolated from such material as well as factors present in the surgical PEA material, which may contribute to impairment of recanalization and thrombus non-resolution. We observed muscularized vessels and non-muscularized vessels in the PEA material. The isolated endothelial cells from the PEA material showed significantly different calcium homeostasis as compared to pulmonary artery endothelial cells (hPAECs) from normal controls. In the supernatant (ELISA) as well as on the tissue level (histochemical staining) of the PEA material, platelet factor 4 (PF4), collagen type I and interferon-gamma-inducible 10 kD protein (IP-10) were detected. CXCR3, the receptor for PF4 and IP-10, was particularly elevated in the distal parts of the PEA material as compared to human control lung (RT-PCR). PF4, collagen type I and IP-10 caused significant changes in calcium homeostasis and affected the cell proliferation, migration and vessel formation in hPAECs. The presence of angiostatic factors like PF4, collagen type I and IP-10, as recovered from the surgical PEA material from CTEPH patients, may lead to changes in calcium homeostasis and endothelial dysfunction.

Highlights

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and late complication of venous thromboembolism [1,2] leading to occluded pulmonary arteries and vascular remodelling [3]
Vessels are present in surgical pulmonary endarterectomy (PEA) material of chronic thromboembolic pulmonary hypertension (CTEPH) patients
The purified CTEPHhECs were positively stained for von Willebrand factor (vWF) and vascular endothelial (VE) cadherin, but were negative for sma-actin, showing the purity of the culture (Figure S1)

Summary

Introduction

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare and late complication of venous thromboembolism [1,2] leading to occluded pulmonary arteries and vascular remodelling [3]. The reason for the incomplete resolution of the clot is currently unknown, but an increased resistance to endogenous thrombolysis due to a polymorphism affecting the fibrinogen a-a chain crosslinkage could be one explanation [11,12]. Another hypothesis suggests that the differentiation of adventitial fibroblasts or mesenchymal progenitor cells present in the neointima of the occluded vessels of CTEPH patients might be triggered by factors present in the microenvironment of the clot [13]. Collagen-secreting cells were detected in PEA material participating in formation of this microenvironment [18]

Methods

Results

Conclusion