Introduction: Aneurysmal subarachnoid hemorrhage is a devastating medical condition with a high morbidity and mortality. Matrix metalloproteinases (MMPs) are a family of proteins that have been implicated in the pathogenesis of intracranial aneurysms via a mechanism of proteolysis of the vascular extracellular matrix (ECM). The purpose of this study is to determine the differences in MMP levels in blood coming from patients spanning the entire spectrum of aneurysmal vascular pathology.
Methods: Intra-aneurysmal and peripheral arterial blood samples were collected from five patients with ruptured intracranial aneurysms, six patients with unruptured intracranial aneurysms and three patients with non-aneurysmal sub-arachnoid hemorrhage. Peripheral arterial blood samples were collected from a six-month follow-up cerebral angiogram for four patients with coiled unruptured aneurysms. MSD electrochemiluminescent detection arrays were used to determine the levels of MMP-1, MMP-3 and MMP-9 in plasma.
Results: MMP-1 levels were significantly decreased in intra-aneurysmal blood as well as peripheral arterial blood from patients with ruptured aneurysms as compared with those who had unruptured aneurysms (p=0.02 and p=0.03 respectively). There were no significant differences between the intra-aneurysmal blood and the peripheral arterial blood of the same patient (p=0.39). There were no significant differences between MMP-1 levels in patients with ruptured aneurysms compared to those with non-aneurysmal subarachnoid hemorrhage (p=0.54). MMP-3 levels did not show any significant differences between the different groups (p=0.33). MMP-9 was significantly increased in patients with ruptured aneurysms from both intra-aneurysmal and peripheral arterial blood compared to patients with non-aneurysmal subarachnoid hemorrhages (p=0.036). There was a milder increase of MMP-9 in unruptured aneurysms that did not reach statistical significance.
Conclusions: MMPs are very promising biomarkers that could be potentially used to understand the natural history of an aneurysm, predict its potential for rupture and monitor vascular recovery after intervention.
Patient Care: MMPs could be used in the future as biomarkers in the diagnosis and treatment of aneurysms
Learning Objectives: 1- Understand the role of MMPs in the natural history of ruptured vs. unruptured aneurysms
2- Evaluate MMPs as biomarkers for the diagnosis and treatment of aneurysms