利用光学/顺磁纳米探针经血脑屏障实现脑肿瘤的两阶靶向成像。
Two-order targeted brain tumor imaging by using an optical/paramagnetic nanoprobe across the blood brain barrier.
机构信息
Department of Gastroenterology, Zhongshan Hospital affiliated with Fudan University, 180 Fenglin Road, Shanghai 200032, China.
出版信息
ACS Nano. 2012 Jan 24;6(1):410-20. doi: 10.1021/nn203749v. Epub 2011 Dec 22.
Surgical resection is a mainstay of brain tumor treatments. However, the completed excision of malignant brain tumor is challenged by its infiltrative nature. Contrast enhanced magnetic resonance imaging is widely used for defining brain tumor in clinic. However its ability in tumor visualization is hindered by the transient circulation lifetime, nontargeting specificity, and poor blood brain barrier (BBB) permeability of the commercially available MR contrast agents. In this work, we developed a two-order targeted nanoprobe in which MR/optical imaging reporters, tumor vasculature targeted cyclic [RGDyK] peptides, and BBB-permeable Angiopep-2 peptides are labeled on the PAMAM-G5 dendrimer. This nanoprobe is supposed to first target the α(V)β(3) integrin on tumor vasculatures. Increased local concentration of nanoprobe facilitates the association between BBB-permeable peptides and the low-density lipoprotein receptor-related protein (LRP) receptors on the vascular endothelial cells, which further accelerates BBB transverse of the nanoprobe via LRP receptor-mediated endocytosis. The nanoprobes that have penetrated the BBB secondly target the brain tumor because both α(V)β(3) integrin and LRP receptor are highly expressed on the tumor cells. In vivo imaging studies demonstrated that this nanoprobe not only efficiently crossed intact BBB in normal mice, but also precisely delineated the boundary of the orthotropic U87MG human glioblastoma xenograft with high target to background signal ratio. Overall, this two-order targeted nanoprobe holds the promise to noninvasively visualize brain tumors with uncompromised BBB and provides the possibility for real-time optical-image-guided brain tumor resection during surgery.
手术切除是脑肿瘤治疗的主要手段。然而,由于脑肿瘤具有浸润性,恶性脑肿瘤的完全切除仍具有挑战性。对比增强磁共振成像在临床上广泛用于定义脑肿瘤。然而,其肿瘤可视化能力受到商业上可用的磁共振对比剂的瞬态循环寿命、非靶向特异性和差的血脑屏障(BBB)通透性的限制。在这项工作中,我们开发了一种二级靶向纳米探针,其中磁共振/光学成像报告分子、肿瘤血管靶向环[RGDyK]肽和 BBB 通透性的 Angiopep-2 肽标记在 PAMAM-G5 树枝状大分子上。这种纳米探针首先应该靶向肿瘤血管上的α(V)β(3)整合素。纳米探针的局部浓度增加有助于 BBB 通透性肽与血管内皮细胞上的低密度脂蛋白受体相关蛋白 (LRP)受体之间的结合,这进一步通过 LRP 受体介导的内吞作用加速了纳米探针的 BBB 横向转运。已经穿透 BBB 的纳米探针其次靶向脑肿瘤,因为α(V)β(3)整合素和 LRP 受体在肿瘤细胞上均高度表达。体内成像研究表明,这种纳米探针不仅能有效地穿过正常小鼠完整的 BBB,而且能以高靶背比精确描绘出同源 U87MG 人胶质母细胞瘤异种移植的边界。总的来说,这种二级靶向纳米探针有望无创可视化 BBB 未受损的脑肿瘤,并为手术期间实时光学图像引导脑肿瘤切除提供了可能性。