Blood outgrowth endothelial cells from Hereditary Haemorrhagic Telangiectasia patients reveal abnormalities compatible with vascular lesions.
OBJECTIVE
Hereditary haemorrhagic telangiectasia (HHT) is originated by mutations in endoglin (HHT1) and ALK1 (HHT2) genes. The purpose of this work was to isolate and characterize circulating endothelial cells from HHT patients.


METHODS
Pure primary cultures of blood outgrowth endothelial cells (BOECs) were obtained from 50 ml of peripheral blood by selection on collagen plates with endothelial medium.


RESULTS
The amount of endoglin in HHT1-BOECs is half the controls, but HHT2-BOECs are also endoglin-deficient. Since the TGF-beta/ALK1 pathway activates the endoglin promoter activity, these results suggest the involvement of ALK1 in endoglin gene expression. Endothelial TGF-beta pathways, mediated by ALK1 and ALK5, are impaired in HHT cells. HHT-BOECs show disorganized and depolymerized actin fibers, as compared to the organized stress fibers of healthy-BOECs. Functionally, HHT-BOECs have impaired tube formation, in contrast with the cord-like structures derived from normal donors.


CONCLUSIONS
Decreased endoglin expression, impaired TGF-beta signalling, disorganized cytoskeleton, and failure to form cord-like structures are common characteristics of endothelial cells from HHT patients. These features may lead to fragility of small vessels and bleeding characteristic of the HHT vascular dysplasia and to a disrupted and abnormal angiogenesis, which may explain the clinical symptoms associated with this disease.
Fernandez-L
Africa
A
Centro de Investigaciones Biologicas, CSIC, Ramiro de Maeztu, 9. Madrid, Spain.
Sanz-Rodriguez
Francisco
F
Zarrabeitia
Roberto
R
Pérez-Molino
Alfonso
A
Hebbel
Robert P
RP
Nguyen
Julia
J
Bernabéu
Carmelo
C
Botella
Luisa-Maria
LM
D030201:Activin Receptors, Type I / Q000235:genetics / Q000378:metabolism; D015703:Antigens, CD; D015153:Blotting, Western / Q000379:methods; D016022:Case-Control Studies; D018929:Cell Culture Techniques; D002469:Cell Separation / Q000379:methods; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000473:pathology; D000071063:Endoglin; D042783:Endothelial Cells / Q000378:metabolism / Q000473:pathology*; D005434:Flow Cytometry; D006801:Humans; D008856:Microscopy, Fluorescence; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D018919:Neovascularization, Physiologic; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013683:Telangiectasia, Hereditary Hemorrhagic / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000032:analysis / Q000235:genetics
D015703:Antigens, CD; C064206:ENG protein, human; D000071063:Endoglin; D011956:Receptors, Cell Surface; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D019010:Vascular Cell Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human