Periodic Reporting for period 3 - Damocles (Modelling brain aneurysm to elucidate the role of platelets)
Periodo di rendicontazione: 2021-06-01 al 2022-11-30
Intracranial aneurysms (IA) with and without subarachnoid hemorrhage (SAH) linger as a potentially devastating clinical problem with a prevalence of 3%1, 2 and an annual risk of rupture around 1%3 . The mortality rate with conservative treatment within the first months is 50-60%. About one-third of patients left with an untreated aneurysm will die from recurrent bleeding within 6 months after recovering from the first bleeding episode. The IA rupture event is ominous and lingers as a clinical quandary. No safe and effective non-invasive therapies have been identified and implemented in clinical practice mainly because of a lack of knowledge of the underlying mechanisms. Increasing evidence points to inflammation as one of the leading factors in the pathogenesis of IA. Intrasaccular clot formation is a common feature of IA occurring unruptured and ruptured IA. I hypothesize that platelet signaling pathways are instrumental in aneurysm formation and the fate of aneurysm rupture. To answer these questions, I designed an interdisciplinary proposal, which gathers biophysical, pharmacologic, biochemical and in vivo approaches, with the following objectives:
- Aim 1 will investigate platelet activation status in peripheral blood and within the aneurysmal sac from patients with unruptured IA.
- Aim 2 will decipher platelet mechanisms and responses in artificial aneurysm-like vessels.
- Aim3 will evaluate platelet mechanisms in in-vivo intracranial aneurysm mouse model and test anti-platelet therapies with the ultimate goal of generating targeted therapies that result in the stabilization or regression of intracranial aneurysm
- Aim 1 will investigate platelet activation status in peripheral blood and within the aneurysmal sac from patients with unruptured IA.
- Aim 2 will decipher platelet mechanisms and responses in artificial aneurysm-like vessels.
- Aim3 will evaluate platelet mechanisms in in-vivo intracranial aneurysm mouse model and test anti-platelet therapies with the ultimate goal of generating targeted therapies that result in the stabilization or regression of intracranial aneurysm
Based on the 3 objectives described above, we got during the first midterm period the following results:
Aim 1: To test the platelet activation status in patients with IA, we recruited over 70 patients with IA. Blood was drawn within or upstream of the aneurysm sac and in the peripheral blood. We measured several specific platelet activation markers by flow cytometry and ELISA (P-selectin exposure, integrin activation, soluble PF4). We observed that platelets from patients with IA are in a pre-activated state in the peripheral blood and in the aneurysm sac.
Aim2: To study the impact of the aneurysm geometry on platelet activation, we have access thanks to a collaboration with Dr. Boujeltia-Zouaoui at the University of Brussels, microfluidic chambers that mimic the aneurysm sac. We perfused whole blood through this chamber at a high shear rate and observed that platelet are more activated in the aneurysm sac.
Aim3: To investigate the role of platelets in an-vivo models of brain aneurysm, we had to develop 2 reliable mouse models of aneurysm: one for aneurysm formation and one for aneurysm rupture. In the rupture model, we observed mice that lack platelets develop more aneurysm rupture than mice with normal platelet count suggesting that platelets are necessary to prevent the rupture.
Aim 1: To test the platelet activation status in patients with IA, we recruited over 70 patients with IA. Blood was drawn within or upstream of the aneurysm sac and in the peripheral blood. We measured several specific platelet activation markers by flow cytometry and ELISA (P-selectin exposure, integrin activation, soluble PF4). We observed that platelets from patients with IA are in a pre-activated state in the peripheral blood and in the aneurysm sac.
Aim2: To study the impact of the aneurysm geometry on platelet activation, we have access thanks to a collaboration with Dr. Boujeltia-Zouaoui at the University of Brussels, microfluidic chambers that mimic the aneurysm sac. We perfused whole blood through this chamber at a high shear rate and observed that platelet are more activated in the aneurysm sac.
Aim3: To investigate the role of platelets in an-vivo models of brain aneurysm, we had to develop 2 reliable mouse models of aneurysm: one for aneurysm formation and one for aneurysm rupture. In the rupture model, we observed mice that lack platelets develop more aneurysm rupture than mice with normal platelet count suggesting that platelets are necessary to prevent the rupture.
Until now, the role of platelets in brain aneurysm has not been addressed despite the medical need for therapies. In our project, we combine several approaches to tackle this question.
Our data obtained during this first midterm period suggest that platelets have an ambivalent role in brain aneurysm disease: they prevent the rupture but, platelet activation can also contribute to the aneurysm evolution.
We expect until the end of the project to tease apart which platelet mechanisms contribute to the aneurysm formation and rupture.
Our data obtained during this first midterm period suggest that platelets have an ambivalent role in brain aneurysm disease: they prevent the rupture but, platelet activation can also contribute to the aneurysm evolution.
We expect until the end of the project to tease apart which platelet mechanisms contribute to the aneurysm formation and rupture.