Kobayashi H, Wu C, Kim M K, Paik C H, Carrasquillo J A, Brechbiel M W
Department of Nuclear Medicine, National Institutes of Health Bethesda,Maryland 20892, USA.
Bioconjug Chem. 1999 Jan-Feb;10(1):103-11. doi: 10.1021/bc980091d.
We evaluated the in vivo biodistribution of indium- and yttrium-labeled second-generation polyamidoamine dendrimer (PAMAM) conjugated with 2-(p-isothiocyanatobenzyl)-6-methyl-diethylenetriaminepentaacetic acid (1B4M), a derivative of DTPA. In addition, we conjugated PAMAM-1B4M to humanized anti-Tac IgG (HuTac) and evaluated its in vitro and in vivo properties. PAMAM-1B4M was labeled with 111In at 37-48 MBq/mg (1.0-1.3 mCi/mg) or with 88Y at 3.7-4.8 MBq/mg (0.1-0. 13 mCi/mg), and an aliquot of radiolabeled conjugate was saturated with the corresponding stable yttrium or indium. Nontumor-bearing nude mice were injected intravenously with 55.5-66.6 kBq (1.5-1.8 microCi) of 88Y-labeled PAMAM-1B4M or with 185 kBq (5 microCi) of 111In-labeled PAMAM-1B4M. The mice were then sacrificed at 15 min, 90 min, 1 day, and 4 days postinjection. Then the PAMAM-1B4M was conjugated with HuTac and labeled with 111In at 111-259 MBq/mg (3-7 mCi/mg). Another preparation of 111In-labeled HuTac-PAMAM-1B4M was saturated with stable indium. Immunoreactivity of both preparations and biodistribution in normal mice 1 h after injection and in ATAC4 and A431 tumor-bearing mice 18 h after injection were evaluated and compared with those of 111In-labeled 1B4M-HuTac. We noted significantly higher accumulations (p < 0.05) of 111In-labeled and 88Y-labeled unsaturated PAMAM-1B4M than saturated preparations in the liver, kidney, spleen, and bone at most time points. The whole-body clearance times of unsaturated preparations were significantly slower than those of saturated preparations at all time points, with the exception of 168 h for 111In-labeled PAMAM-1B4M. The saturated preparation of 111In-labeled HuTac-PAMAM-1B4M showed lower hepatic uptake (27 +/- 2%ID/g) than the unsaturated (32 +/- 2%ID/g), but greater than the HuTac-1B4M control (10 +/- 0%ID/g). The splenic uptake showed 15 +/- 1, 38 +/- 5, and 8 +/- 1%ID/g for the saturated, unsaturated, and control, respectively. The biodistribution of the dendrimer conjugated HuTac in normal organs of tumor-bearing mice was similar to nontumor-bearing mice. Specific tumor (ATAC4) uptake was higher than that in nonspecific tumor (A431). In conclusion, we evaluated the biodistribution of radiolabeled PAMAM-1B4M. We noted high accumulation in the liver, kidney, and spleen, which significantly decreased when the chelates were saturated with the stable element. A similar phenomenon was observed between unsaturated and saturated 111In-labeled HuTac-PAMAM-1B4M, indicating that the PAMAM dendrimer had a detrimental effect on biodistribution.
我们评估了与二乙三胺五乙酸（DTPA）的衍生物2-(对异硫氰酸苄基)-6-甲基二乙三胺五乙酸（1B4M）共轭的铟和钇标记的第二代聚酰胺-胺树枝状大分子（PAMAM）的体内生物分布。此外，我们将PAMAM-1B4M与人性化抗Tac IgG（HuTac）共轭，并评估了其体外和体内特性。PAMAM-1B4M用111In以37 - 48 MBq/mg（1.0 - 1.3 mCi/mg）或用88Y以3.7 - 4.8 MBq/mg（0.1 - 0.13 mCi/mg）进行标记，并且放射性标记的共轭物的一份用相应的稳定钇或铟饱和。给无瘤裸鼠静脉注射55.5 - 66.6 kBq（1.5 - 1.8微居里）的88Y标记的PAMAM-1B4M或185 kBq（5微居里）的111In标记的PAMAM-1B4M。然后在注射后15分钟、90分钟、1天和4天处死小鼠。接着将PAMAM-1B4M与HuTac共轭并用111In以111 - 259 MBq/mg（3 - 7 mCi/mg）进行标记。另一种111In标记的HuTac-PAMAM-1B4M制剂用稳定铟饱和。评估了两种制剂的免疫反应性以及在正常小鼠注射后1小时和荷ATAC4和A431瘤小鼠注射后18小时的生物分布，并与111In标记的1B4M-HuTac的生物分布进行比较。我们注意到，在大多数时间点，111In标记和88Y标记的不饱和PAMAM-1B4M在肝脏、肾脏和脾脏以及骨骼中的蓄积显著高于饱和制剂（p < 0.05）。除了111In标记的PAMAM-1B4M在168小时外，不饱和制剂在所有时间点的全身清除时间均显著慢于饱和制剂。111In标记的HuTac-PAMAM-1B4M的饱和制剂显示肝脏摄取（27±2%ID/g）低于不饱和制剂（32±2%ID/g），但高于HuTac-1B4M对照（10±0%ID/g）。脾脏摄取分别为饱和制剂15±1%ID/g、不饱和制剂38±5%ID/g和对照8±1%ID/g。共轭HuTac的树枝状大分子在荷瘤小鼠正常器官中的生物分布与无瘤小鼠相似。特异性肿瘤（ATAC4）摄取高于非特异性肿瘤（A431）。总之，我们评估了放射性标记的PAMAM-1B4M的生物分布。我们注意到在肝脏、肾脏和脾脏中有高蓄积，当螯合物用稳定元素饱和时蓄积显著降低。在不饱和和饱和的111In标记的HuTac-PAMAM-1B4M之间观察到类似现象，表明PAMAM树枝状大分子对生物分布有不利影响。
