Rapamycin improves TIE2-mutated venous malformation in murine model and human subjects
Elisa Boscolo, … , Joyce Bischoff, Laurence M. Boon
Elisa Boscolo, … , Joyce Bischoff, Laurence M. Boon
Published August 10, 2015
Citation Information: J Clin Invest. 2015;125(9):3491-3504. https://doi.org/10.1172/JCI76004.
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Research Article Genetics

Rapamycin improves TIE2-mutated venous malformation in murine model and human subjects

Abstract

Venous malformations (VMs) are composed of ectatic veins with scarce smooth muscle cell coverage. Activating mutations in the endothelial cell tyrosine kinase receptor TIE2 are a common cause of these lesions. VMs cause deformity, pain, and local intravascular coagulopathy, and they expand with time. Targeted pharmacological therapies are not available for this condition. Here, we generated a model of VMs by injecting HUVECs expressing the most frequent VM-causing TIE2 mutation, TIE2-L914F, into immune-deficient mice. TIE2-L914F–expressing HUVECs formed VMs with ectatic blood-filled channels that enlarged over time. We tested both rapamycin and a TIE2 tyrosine kinase inhibitor (TIE2-TKI) for their effects on murine VM expansion and for their ability to inhibit mutant TIE2 signaling. Rapamycin prevented VM growth, while TIE2-TKI had no effect. In cultured TIE2-L914F–expressing HUVECs, rapamycin effectively reduced mutant TIE2-induced AKT signaling and, though TIE2-TKI did target the WT receptor, it only weakly suppressed mutant-induced AKT signaling. In a prospective clinical pilot study, we analyzed the effects of rapamycin in 6 patients with difficult–to-treat venous anomalies. Rapamycin reduced pain, bleeding, lesion size, functional and esthetic impairment, and intravascular coagulopathy. This study provides a VM model that allows evaluation of potential therapeutic strategies and demonstrates that rapamycin provides clinical improvement in patients with venous malformation.

Authors

Elisa Boscolo, Nisha Limaye, Lan Huang, Kyu-Tae Kang, Julie Soblet, Melanie Uebelhoer, Antonella Mendola, Marjut Natynki, Emmanuel Seront, Sophie Dupont, Jennifer Hammer, Catherine Legrand, Carlo Brugnara, Lauri Eklund, Miikka Vikkula, Joyce Bischoff, Laurence M. Boon

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Figure 1

HUVEC-TIE2-L914F formed VM lesions in immune-deficient mice.

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HUVEC-TIE2-L914F formed VM lesions in immune-deficient mice. (A) Western...
(A) Western blot of p-TIE2 in HUVECs transfected with TIE2-WT or with mutant TIE2 (L914F). Tubulin served as loading control. (B) Representative nude mouse 7 days after injection of HUVEC-TIE2-WT (left flank) or HUVEC-TIE2-L914F (right flank) and Matrigel explants from each injected mouse (n = 8) (bottom panel). (C) Matrigel explants with HUVEC-TIE2-WT (left) or HUVEC-TIE2-L914F (middle) sectioned and stained with specific anti-human CD31 (hu-CD31), representative images (n = 4). Murine lung tissue (right) is shown as negative control for anti-human CD31 staining. Scale bar: 100 μm. (D) HUVEC-TIE2-WT and HUVEC-TIE2-L914F tissue sections stained for H&E (top panel) and UEA-I and αSMA (bottom panel). Patient-derived VM and infantile hemangioma are shown for comparison. Representative images (n = 4 WT, L914F; n = 2 patients with VM; n = 3 patients with infantile hemangioma). UEA-I (red) and αSMA (green); arrows point to areas with perivascular αSMA+ cell coverage in VM vessels. Scale bars: 100 μm. (E) Quantification of human CD31–stained blood vessels (vessels/mm2) and luminal area occupied by human CD31–stained blood vessels (μm2) in HUVEC-TIE2-WT or HUVEC-TIE2-L914F mid-explant sections. Data expressed as mean ± SEM, t test (n = 8).