Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, Georgia, United States.
Georgia Institute of Technology, Wallace H. Coulter Department of Biomedical Engineering, Atlanta, Georgia, United States.
J Biomed Opt. 2023 Sep;28(9):096501. doi: 10.1117/1.JBO.28.9.096501. Epub 2023 Sep 9.
Although the molecular origins of sickle cell disease (SCD) have been extensively studied, the effects of SCD on the vasculature-which can influence blood clotting mechanisms, pain crises, and strokes-are not well understood. Improving this understanding can yield insight into the mechanisms and wide-ranging effects of this devastating disease.
We aim to demonstrate the ability of a label-free 3D quantitative phase imaging technology, called quantitative oblique back-illumination microscopy (qOBM), to provide insight into the effects of SCD on brain vasculature.
Using qOBM, we quantitatively analyze the vasculature of freshly excised, but otherwise unaltered, whole mouse brains. We use Townes sickle transgenic mice, which closely recapitulate the pathophysiology of human SCD, and sickle cell trait mice as controls. Two developmental time points are studied: 6-week-old mice and 20-week-old mice. Quantitative structural and biophysical parameters of the vessels (including the refractive index (RI), which is linearly proportional to dry mass) are extracted from the high-resolution images and analyzed.
qOBM reveals structural differences in the brain blood vessel thickness (thinner for SCD in particular brain regions) and the RI of the vessel wall (higher and containing a larger variation throughout the brain for SCD). These changes were only significant in 20-week-old mice. Further, vessel breakages are observed in SCD mice at both time points. The vessel wall RI distribution near these breaks, up to away from the breaking point, shows an erratic behavior characterized by wide RI variations. Vessel diameter, tortuosity, texture within the vessel, and structural fractal patterns are found to not be statistically different. As with vessel breaks, we also observe blood vessel blockages only in mice brains with SCD.
qOBM provides insight into the biophysical and structural composition of brain blood vessels in mice with SCD. Data suggest that the RI may be an indirect indicator of vessel rigidity, vessel strength, and/or tensions, which change with SCD. Future and studies with qOBM could improve our understanding of SCD.
尽管镰状细胞病 (SCD) 的分子起源已得到广泛研究，但 SCD 对血管的影响（会影响血液凝结机制、疼痛危机和中风）尚未得到很好的理解。深入了解这一点可以深入了解这种破坏性疾病的机制和广泛影响。
我们旨在展示一种无标记的 3D 定量相位成像技术，称为定量斜向背照显微镜 (qOBM)，能够深入了解 SCD 对大脑血管的影响。
使用 qOBM，我们定量分析了新鲜取出的、但未改变的全鼠脑的血管。我们使用 Townes 镰状转基因小鼠，该模型紧密模拟了人类 SCD 的病理生理学，并用镰状细胞特征小鼠作为对照。研究了两个发育时间点：6 周龄小鼠和 20 周龄小鼠。从高分辨率图像中提取并分析血管的定量结构和生物物理参数（包括折射率 (RI)，RI 与干质量呈线性比例）。
qOBM 揭示了大脑血管厚度的结构差异（特别是在某些大脑区域，SCD 较薄）和血管壁 RI 的变化（SCD 更高，整个大脑的变化更大）。这些变化仅在 20 周龄小鼠中显著。此外，在两个时间点都观察到 SCD 小鼠的血管破裂。在离破裂点 处，靠近这些破裂点的血管壁 RI 分布表现出不稳定的行为，其特征是 RI 变化较大。血管直径、曲折度、血管内纹理和结构分形图案没有表现出统计学差异。与血管破裂一样，我们也仅在 SCD 小鼠的大脑中观察到血管阻塞。
qOBM 提供了对 SCD 小鼠大脑血管生物物理和结构组成的深入了解。数据表明，RI 可能是血管刚性、血管强度和/或张力的间接指标，这些指标随 SCD 而变化。未来的 qOBM 研究可以增进我们对 SCD 的理解。
