Institute of Diagnostic and Interventional Radiology, Jena University Hospital-Friedrich Schiller University Jena, Erlanger Allee 101, D-07747 Jena, Germany.
Nanotechnology. 2011 Dec 16;22(50):505102. doi: 10.1088/0957-4484/22/50/505102. Epub 2011 Nov 23.
Localized magnetic heating treatments (hyperthermia, thermal ablation) using superparamagnetic iron oxide nanoparticles (MNPs) continue to be an active area of cancer research. For generating the appropriate heat to sufficiently target cell destruction, adequate MNP concentrations need to be accumulated into tumors. Furthermore, the knowledge of MNP bio-distribution after application and additionally after heating is significant, firstly because of the possibility of repeated heating treatments if MNPs remain at the target region and secondly to study potential adverse effects dealing with MNP dilution from the target region over time. In this context, little is known about the behavior of MNPs after intra-tumoral application and magnetic heating. Therefore, the present in vivo study on the bio-distribution of intra-tumorally injected MNPs in mice focused on MNP long term monitoring of pre and post therapy over seven days using multi-channel magnetorelaxometry (MRX). Subsequently, single-channel MRX was adopted to study the bio-distribution of MNPs in internal organs and tumors of sacrificed animals. We found no distinct change of total MNP amounts in vivo during long term monitoring. Most of the MNP amounts remained in the tumors; only a few MNPs were detected in liver and spleen and less than 1% of totally injected MNPs were excreted. Apparently, the application of magnetic heating and the induction of apoptosis did not affect MNP accumulation. Our results indicate that MNP mainly remained within the injection side after magnetic heating over a seven-days-observation and therefore not affecting healthy tissue. As a consequence, localized magnetic heating therapy of tumors might be applied periodically for a better therapeutic outcome.
局部磁热治疗（热疗、热消融）使用超顺磁氧化铁纳米颗粒（MNPs）仍然是癌症研究的一个活跃领域。为了产生足够的热量以充分靶向细胞破坏，需要将足够浓度的 MNP 积聚到肿瘤中。此外，了解应用 MNP 后的生物分布以及加热后的生物分布非常重要，一方面是因为如果 MNPs 留在靶区，则有可能进行重复加热治疗，另一方面是研究随着时间的推移从靶区稀释 MNP 所涉及的潜在不良反应。在这方面，关于 MNP 瘤内应用和磁热后的行为知之甚少。因此，本研究通过多通道磁弛豫测量（MRX）对小鼠瘤内注射 MNPs 的生物分布进行了体内研究，重点关注治疗前和治疗后七天的 MNP 长期监测。随后，采用单通道 MRX 研究了牺牲动物的内部器官和肿瘤中的 MNP 生物分布。我们发现，在长期监测过程中，体内总 MNP 量没有明显变化。大多数 MNP 量仍留在肿瘤中; 只有少量 MNP 在肝脏和脾脏中检测到，不到总注射 MNP 的 1%被排泄。显然，磁热应用和细胞凋亡诱导没有影响 MNP 的积聚。我们的结果表明，在七天观察期内进行磁热治疗后，MNP 主要保留在注射侧，因此不会影响健康组织。因此，肿瘤的局部磁热治疗可能会定期进行，以获得更好的治疗效果。
