Purpose

Targeted delivery in vivo remains an immense roadblock for the translation of nanomaterials into the clinic. The greatest obstacle is the mononuclear phagocyte system (MPS), which sequesters foreign substances from general circulation and causes accumulation in organs such as the liver and spleen. The purpose of this study was to determine whether attaching an active targeting antibody, 5B1, to the surface of gold nanoparticles and using clodronate liposomes to deplete liver and splenic macrophages could help to minimize uptake by MPS organs, increase targeted delivery to CA19.9-positive pancreatic tumors, and enhance pancreatic tumor delineation.

Procedures

To produce the antibody-gold nanoparticle conjugate (Ab-AuNP), the Ab was conjugated to p-isothiocyanatobenzyl-desferrioxamine (p-SCN-DFO) and subsequently conjugated to NHS-activated gold nanoparticles. The Ab-AuNP was characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Modified Lindmo assay was performed to assess binding affinity and internalization potential in vitro. The Ab-AuNP was radiolabeled with ⁸⁹Zr and injected into CA19.9-positive BxPc-3 pancreatic orthotopic tumor-bearing mice pretreated with or without clodronate liposomes for PET imaging and biodistribution studies. Inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis was used to confirm delivery of gold nanoparticles to BxPc-3 pancreatic subcutaneous xenografts.

Results

Mice pretreated with clodronate liposomes in an orthotopic setting demonstrated decreased liver uptake at early time points (12.2 ± 2.3 % ID/g vs. 22.8 ± 3.8 % ID/g at 24 h) and increased tumor uptake at 120 h (13.8 ± 8.0 % ID/g vs. 6.0 ± 1.2 % ID/g). This allowed for delineation of orthotopic pancreatic xenografts in significantly more mice treated with clodronate (6/6) than in mice not treated with clodronate (2/6) or mice injected with gold nanoparticles labeled with a nonspecific antibody (0/5).

Conclusions

The combination of clodronate liposomes and an active targeting antibody on the surface of gold nanoparticles allowed for PET/CT imaging of subcutaneous and orthotopic pancreatic xenografts in mice.

中文翻译：

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使用 89Zr 标记的金纳米颗粒抗体偶联物对胰腺肿瘤进行免疫 PET 成像。

 目的

体内靶向递送仍然是纳米材料转化为临床的巨大障碍。最大的障碍是单核吞噬细胞系统（MPS），它将外来物质从全身循环中隔离出来，并导致肝脏和脾脏等器官积聚。本研究的目的是确定将主动靶向抗体 5B1 附着到金纳米粒子的表面并使用氯膦酸盐脂质体消耗肝脏和脾脏巨噬细胞是否有助于最大限度地减少 MPS 器官的摄取，增加对 CA19.9- 的靶向递送阳性胰腺肿瘤，并增强胰腺肿瘤的勾画。

 程序

为了生产抗体-金纳米粒子缀合物 (Ab-AuNP)，将 Ab 与对异硫氰酸苄基去铁胺 ( p -SCN-DFO) 缀合，然后与 NHS 激活的金纳米粒子缀合。 Ab-AuNP 通过透射电子显微镜 (TEM) 和原子力显微镜 (AFM) 进行表征。进行改良的 Lindmo 测定以评估体外结合亲和力和内化潜力。 Ab-AuNP 用⁸⁹ Zr 进行放射性标记，并注射到经过或未经过氯膦酸盐脂质体预处理的 CA19.9 阳性 BxPc-3 胰腺原位肿瘤小鼠中，用于 PET 成像和生物分布研究。使用电感耦合等离子体光发射光谱 (ICP-OES) 分析来确认金纳米粒子向 BxPc-3 胰腺皮下异种移植物的递送。

 结果

在原位环境中用氯膦酸盐脂质体预处理的小鼠表现出早期时间点肝脏摄取减少（24小时时为12.2±2.3％ID/g vs. 22.8±3.8％ID/g），并且在120小时时肿瘤摄取增加（13.8±8.0％） ID/g与6.0 ± 1.2 % ID/g)。这使得用氯膦酸盐治疗的小鼠（6/6）比未用氯膦酸盐治疗的小鼠（2/6）或注射了非特异性抗体标记的金纳米颗粒的小鼠（0/5）显着更多的小鼠中描绘出原位胰腺异种移植物。

 结论

氯膦酸盐脂质体和金纳米粒子表面的主动靶向抗体的组合允许对小鼠皮下和原位胰腺异种移植物进行 PET/CT 成像。