Novel hemorrhage models of cerebral cavernous malformations

Abstract

Cerebral cavernous malformations (CCMs) are ectatic capillary-venous malformations that develop in approximately 0.5% of the population. Patients with CCMs may develop headaches, focal neurologic deficits, seizures, and hemorrhages. While symptomatic CCMs, depending upon the anatomic location, can be surgically removed, there is currently no pharmaceutical therapy to treat CCMs. Several mouse models have been developed to better understand CCM pathogenesis and test therapeutics. The most common mouse models induce a large CCM burden that is anatomically restricted to the cerebellum and contributes to lethality in the early days of life. These inducible models thus have a relatively short period for drug administration. We developed an inducible CCM3 mouse model that develops CCMs after weaning and provides a longer period for potential therapeutic intervention. Using this new model, three recently proposed CCM therapies -fasudil, tempol, vitamin D3, and a combination of the three drugs failed to substantially reduce CCM formation when treatment was administered for five weeks, from postnatal day 21 (P21) to P56. We next restricted Ccm3 deletion to the brain vasculature and provided greater time (121 days) for CCMs to develop chronic hemorrhage, recapitulating the human lesions. We also developed the first model of acute CCM hemorrhage by injecting mice harboring CCMs with lipopolysaccharide. These efficient models will enable future drug studies to more precisely target clinically relevant features of CCM disease: CCM formation, chronic hemorrhage, and acute hemorrhage.

mPR-Specific Actions Influence Maintenance of the Blood–Brain Barrier (BBB)

“…It has been proven that falling below the threshold of haploinsufficiency for CCMs in microvascular ECs is an essential first step for the pathogenesis of CCM lesions in vivo, generated from both zebrafish [ 26 , 28 ] and mice Ccms mutant models [ 29 ], while the genetic “two-hit” mechanism is just the most extreme end (null) at the spectrum of haploinsufficiency. Approximately 60% of patients with CCMs have the sporadic form of the disease [ 30 ], which is difficult to be explained by the current dominant “two-hit” model [ 31 ] even though clonal expansion data provided some degree of support for this “two-hit” model [ 32 ]. Therefore, there must be a “trigger” to initiate the hemorrhagic events of CCM lesions which is also suggested by our in vitro data.…”