Department of Cardiology, Fujian Medical University Union Hospital, Fujian Institute of Coronary Heart Disease, Fuzhou, Fujian 350001, P.R. China.
Department of Ultrasonography, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, P.R. China.
Mol Med Rep. 2017 Nov;16(5):5986-5996. doi: 10.3892/mmr.2017.7314. Epub 2017 Aug 22.
The aim of the present study was to investigate the feasibility of using ultrasonography (US) and magnetic resonance (MR) for bimodal molecular imaging of atherosclerotic neovasculature with liquid perfluorocarbon magnetic nanocapsules (NCs) targeted to vascular endothelial growth factor receptor 2 (VEGFR‑2). By incorporating perfluorooctyl bromide (PFOB) and superparamagnetic iron oxide (SPIO) into polylactic acid, a SPIO‑embedded PFOB NC was constructed; subsequently, a VEGFR‑2‑targeted NC (VTNC) containing dual detectable probes was created by covalently linking a VEGFR‑2 antibody onto the surface of the SPIO‑embedded PFOB NC. Target specificity was verified in vitro by incubating VTNC with VEGFR‑2+ or VEGFR‑2‑ endothelial cells. Rats with vulnerable plaques were assigned to receive either an injection of VTNC (Targeted group; n=8) or an injection of NC (Nontargeted group; n=8); control rats also received an injection of VTNC (Control group; n=8). US and MR imaging of the abdominal aorta were performed to detect VTNC by measuring of the ultrasonic grayscale intensity (GSI) and MR contrast‑to‑noise ratio (CNR) prior to and at successive time points following VTNC and NC injections. The percent positive area (PPA) of CD31+ (PPACD31+) or VEGFR‑2+ (PPAVEGFR‑2+) expression was quantified by immunohistochemical staining. CD31 was used to verify the existence of endothelial cells as it is widely expressed on the surface of endothelial cells whether activated or not. The results demonstrated that VTNC was able to highly and selectively detect VEGFR‑2+ endothelial cells, and GSI, CNR, PPACD31+ and PPAVEGFR‑2+ were significantly increased in the targeted group compared with the nontargeted and control groups. In the control group, no atherosclerotic plaques or angiogenesis was identified, thus no expression of PPACD31+ and PPAVEGFR‑2 (data not shown). There were strong correlations among GSI, CNR, PPACD31+ and PPAVEGFR‑2+. In conclusion, two‑probe VTNC is feasible for bimodal US and MR molecular imaging of atherosclerotic neovasculature, which may offer complementary information for the more reliable prediction of plaque vulnerability.
本研究旨在探讨使用超声（US）和磁共振（MR）对靶向血管内皮生长因子受体 2（VEGFR-2）的液态全氟碳磁性纳米囊（NCs）进行双模式分子成像检测动脉粥样硬化新生血管的可行性。通过将全氟辛基溴（PFOB）和超顺磁性氧化铁（SPIO）掺入聚乳酸中，构建了一种 SPIO 嵌入 PFOB NC；随后，通过将 VEGFR-2 抗体共价连接到 SPIO 嵌入 PFOB NC 的表面，制备了一种含有双重可检测探针的 VEGFR-2 靶向 NC（VTNC）。通过将 VTNC 与 VEGFR-2+或 VEGFR-2-内皮细胞孵育，在体外验证了靶特异性。将易损斑块大鼠分为接受 VTNC 注射（靶向组；n=8）或 NC 注射（非靶向组；n=8）；对照组大鼠也接受 VTNC 注射（对照组；n=8）。在注射 VTNC 和 NC 前后，通过测量超声灰度强度（GSI）和 MR 对比噪声比（CNR），对腹主动脉进行 US 和 MR 成像，以检测 VTNC。通过免疫组织化学染色定量 CD31+（PPACD31+）或 VEGFR-2+（PPAVEGFR-2+）表达的阳性面积百分比（PPA）。CD31 被用来验证内皮细胞的存在，因为它广泛表达在内皮细胞的表面，无论是否被激活。结果表明，VTNC 能够高度且选择性地检测 VEGFR-2+内皮细胞，与非靶向组和对照组相比，靶向组的 GSI、CNR、PPACD31+和 PPAVEGFR-2+显著增加。在对照组中，未发现动脉粥样硬化斑块或血管生成，因此未检测到 PPACD31+和 PPAVEGFR-2（未显示数据）。GSI、CNR、PPACD31+和 PPAVEGFR-2 之间存在强相关性。总之，双探针 VTNC 可用于动脉粥样硬化新生血管的双模式 US 和 MR 分子成像，可为更可靠地预测斑块易损性提供补充信息。
