Age-dependent lethality in novel transgenic mouse models of central nervous system arteriovenous malformations

Background and Purpose-The lack of an appropriate animal model has been a limitation in studying hemorrhage from arteriovenous malformations (AVMs) in the central nervous system. Methods-Novel mouse central nervous system AVM models were generated by conditionally deleting the activin receptor-like kinase (Alk1; Acvrl1) gene with the SM22-Cre transgene. All mice developed AVMs in their brain and/or spinal cord, and >80% of them showed a paralysis or lethality phenotype due to internal hemorrhages during the first 10 to 15 weeks of life. The mice that survived this early lethal period, however, showed significantly reduced lethality rates even though they carried multiple AVMs. Results-The age-dependent change in hemorrhage rates allowed us to identify molecular factors uniquely upregulated in the rupture-prone AVM lesions. Conclusions-Upregulation of angiopoietin 2 and a few inflammatory genes were identified in the hemorrhage-prone lesions, which may be comparable with human pathology. These models will be an exceptional tool to study pathophysiology of AVM hemorrhage.