RNAi knockdown of ACVRL1 in the endothelial cell line HMEC-1 mimics disturbances in angiogenesis as observed in patients with hereditary hemorrhagic telangiectasia (HHT) type 2

Background Hereditary hemorrhagic telangiectasia (HHT) type 2 occurs with a prevalence of 1:5,000; making it one of the more common rare diseases. HHT type 2 is an autosomal dominant inherited disease, with one allele of the ACVRL1 gene mutated. Patients present with severe disturbances of angiogenesis and very often exhibit clinically severe nosebleeds and impaired quality of life. The aim of our study was to observe how downregulation of ACVRL1 in the endothelial cell line HMEC-1 affects angiogenesis.

Methods RNAi knockdown was performed with a pool of four siRNAs directed against the ACVRL1 gene (NM_000020.3; cat#: L-005302-02-0020, siRNA ON-TARGET plus SMARTpool, Dharmacon) using various transfection methods, such as electroporation and lipofection. Quantitative RT-PCR was deployed to verify efficient RNAi knockdown at the transcript level. The effects of ACVRL1 knockdown on angiogenesis were monitored by a matrigel-based endothelial tube formation assay and evaluated using the Angiogenesis Analyzer software (ImageJ, Fiji).

Results ACVRL1 knockdown in the HMEC-1 cell line was achieved at the nucleic acid level and was confirmed by RT-qPCR. Angiogenesis analysis after ACVRL1 knockdown revealed a higher number of junctions, greater segment length and fewer isolated segments then observed in control cells consitent with pathologic proangiogenic effects as reported for ACVRL1 mutant endothelial cells.

Conclusion ACVRL1 RNAi knockdown of HMEC-1 cells appears to be a suitable method for in vitro studies of HHT type 2 related angiogenesis.

Verein zur Förderung der Diagnostik und Therapie von Tumoren und Gefäßfehlbildungen im Kopf-Halsbereich e.V. Marburg

Publication History

Article published online:
12 May 2023