Participants undergoing standard of care microsurgical clipping of unruptured cerebral aneurysm will be treated with 2 mg Sirolimus daily for 14-18 consecutive days prior to surgery.

Participants undergoing standard of care endovascular treatment of unruptured cerebral aneurysm procedure will be treated with 2 mg Sirolimus daily for 14-18 consecutive days prior to procedure.

Standard of care microsurgical clipping of an unruptured cerebral artery aneurysm.

Change in gene expressions will be reported as fold change from control arteries: superficial temporal artery from the same patient and the intracerebral temporal lobe artery from a different patient. Genes to be evaluated are endothelial cell marker genes such as Cluster of Differentiation (CD) 34, CD31, Von Willebrand Factor (vWF), E-selectin, Vascular Endothelial (VE)-cadherin and Endothelial Nitric Oxide Synthase (eNOS) and pro-inflammatory-matrix remodeling proliferation genes such as Matrix Metallopeptidase (MMP)3 and MMP9, Vascular Cell Adhesion Molecule (VCAM)-1, Intercellular Adhesion Molecule (ICAM), Inducible Nitric Oxide Synthase (iNOS), Membrane Cofactor Protein (MCP) and Interleukin (IL)-1ß.

Change in gene expressions will be reported as fold change of intra-aneurysmal blood to peripheral blood from the same patient. Genes to be evaluated are endothelial cell marker genes (CD34, CD31, vWF, E-selectin, VE-cadherin, and eNOS) and pro-inflammatory-matrix remodeling proliferation genes (MMP3, MMP9, VCAM-1, ICAM, iNOS, MCP, and IL-1ß).

Fold change of IL-2 expression and expression of endothelial cell marker genes (CD34, CD31, vWF, E-selectin, VE-cadherin, and eNOS) and pro-inflammatory-matrix remodeling proliferation genes (MMP3, MMP9, VCAM-1, ICAM, iNOS, MCP, and IL-1ß) will be evaluated between sirolimus treated to non-treated patients.