Experimental investigation of the microstructure and mechanics of human middle cerebral arteries

A detailed understanding of cerebral artery biomechanics is essential for advancing cerebrovascular research and neurovascular device development. Yet, despite the clinical relevance of these vessels, high-fidelity experimental data remains extremely limited. As a result, current device development is often informed by data from non-cerebral vessels or animals. To address this gap, this study characterized the mechanical behavior and structural composition of human middle cerebral arteries obtained from six donors. Ring-extension testing was used to quantify elastin- and collagen-dominant region stiffnesses, while histological staining was used to assess elastin, collagen, and smooth muscle cell (SMC) content. Histology revealed that, unlike large elastic arteries, cerebral arteries are dominated by SMCs, contain sparse elastin, and lack a distinct external elastic lamina. Comparative analysis showed that mechanical behavior could not be inferred from composition alone, highlighting the importance of considering tissue integrity and organization when assessing structure. To explore clinically relevant differences, samples were grouped by cardiovascular disease (CVD) status and arterial branch type (M1 vs. M2). CVD-affected arteries exhibited significantly higher elastin-dominant region stiffness and reduced medial SMC content (p < 0.05). M2 branches showed significantly lower collagen-dominant region stiffness, internal elastic lamina fraction, and adventitial collagen content compared to M1 branches (p < 0.05). These findings highlight the structural and mechanical heterogeneity of human cerebral arteries and suggest that neurovascular device design and deployment strategies might benefit from considering both disease state and anatomical location. By jointly evaluating mechanics and composition, this study provides a foundational dataset to guide future cerebrovascular research and device development.