Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, USA.
NTT-Hi Tech Institute, Nguyen Tat Thanh University, Ho Chi Minh, Vietnam.
J Biophotonics. 2021 May;14(5):e202000458. doi: 10.1002/jbio.202000458. Epub 2021 Feb 11.
Photoacoustic microscopy (PAM) has great potential for visualization of the microvasculature with high spatial resolution and contrast. Early detection and differentiation of newly developed blood vessels named choroidal neovascularization (CNV) from normal vasculature remains a challenge in ophthalmology. Exogenous contrast agents can assist with improving PAM sensitivity, leading to differentiation of CNV. Here, an FDA-approved indocyanine green (ICG) was utilized as a PAM contrast agent. ICG was conjugated with RGD peptides, allowing the ICG to bind to the integrin expressed in CNV. Molecular PAM imaging showed that ICG-RGD can target CNV for up to 5 days post intravenous administration in living rabbits with a model of CNV. The PAM image sensitivity and image contrast were significantly enhanced by 15-fold at 24 h post-injection. Overall, the presented approach demonstrates the possibility of targeted ICG to be employed in PAM molecular imaging, allowing more precise evaluation of neovascularization.
光声显微镜（PAM）具有高空间分辨率和对比度的微血管可视化的巨大潜力。从正常脉管系统中早期检测和区分新形成的血管，即脉络膜新生血管（CNV），仍然是眼科领域的一个挑战。外源性对比剂可以提高 PAM 的灵敏度，从而实现 CNV 的区分。在这里，一种获得 FDA 批准的吲哚菁绿（ICG）被用作 PAM 对比剂。ICG 与 RGD 肽缀合，使 ICG 能够与 CNV 中表达的整合素结合。分子 PAM 成像显示，在 CNV 模型的活兔中，静脉注射后长达 5 天，ICG-RGD 可靶向 CNV。注射后 24 小时，PAM 图像的灵敏度和图像对比度显著增强了 15 倍。总的来说，所提出的方法证明了靶向 ICG 用于 PAM 分子成像的可能性，从而可以更精确地评估新生血管。
