Biodistribution and Toxicity Assessment of Superparamagnetic Iron Oxide Nanoparticles In Vitro and In Vivo.

Biodistribution and toxicity assessment are critical for safe clinical use of newly developed medicines. Superparamagnetic iron oxide nanoparticles (SPION) are effective carriers for targeted drug delivery. This study aimed to examine the toxicity and biodistribution of SPION coated with polyethylenimine (PEI) (SPION-PEI) designed for small interfering RNA (siRNA) delivery both in vitro and in vivo. SPION-PEI/siRNA complexes were prepared at different weight ratios. Cytotoxic effects of SPION-PEI/siRNA on HSC-T6 cell viability were determined by using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT). Rats were divided into three groups: a control group, a normal-saline group and a SPION-PEI/siRNA group. After a single intravenous injection, in vivo nanoparticle biodistribution and accumulation were evaluated by Prussian blue staining in the heart, liver, spleen, lung and kidney 8 h, 24 h, and 7 days after the injection. Their distribution was histologically studied at the three time points by measuring ironpositive areas (µm2) in organ sections stained with Prussian blue. The same organs were analyzed by H&E staining for any possible histopathological changes. Furthermore, biochemical indexes such as alanine amino transaminase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN) and creatinine (CREA) were also assessed at all experimental time points. Electrophoresis exhibited that the SPION-PEI could retard siRNA altogether at weight ratios above 4. MTT assay showed that SPION-PEI loaded with siRNA had low cytotoxicity. In vivo study revealed that the liver and spleen were the major sites of SPION-PEI/siRNA deposition. The iron content was significantly increased in the liver and spleen, peaking 24 h after intravenous injection and then declining gradually. No evidence was found of irreversible histopathological damage to any of the organs tested. These results suggested that most SPION-PEI/siRNA complexes were distributed in the liver and spleen, which might be the target organs of SPION-PEI/siRNA complexes. SPIONPEI/siRNA may serve as in vivo carrier for biomedical medicines.

[In vivo and in vitro research study of the influence on placenta angiogenesis by gene silencing of netrin-1].

OBJECTIVE: To study influence on angiogenesis of placenta by gene silencing of netrin-1. METHODS: Netrin-1 gene in human umbilical vein endothelial cells (HUVEC) and placenta of pregnant rats were silenced by RNA interference. The following methods were used in this study, including the phenytetrazoliumromide (MTT) for viability, clone formation for proliferation, transwell for migration, and tube formation for angiogenesis in vitro. The change of fetal growth was recorded. Placental microvessel density in pregnant rats was measured by immunohistochemical CD(34) staining in vivo. RESULTS: (1) HUVEC: viability and proliferation of HUVEC were remarkably inhibited by gene silencing of netrin-1, which number of clone formation, migration cell, tube formation were from (69 ± 6)%, 86 ± 17, 37 ± 9 decreased to (46 ± 5)%, 46 ± 13 and 17 ± 5 (P < 0.05) respectively. (2) Placenta of pregnant rats: after netrin-1 gene silenced, fetal weight were decreased from (2.39 ± 0.17) g to (2.12 ± 0.10) g (P < 0.05). Placental microvessel density was decreased from (258 ± 38)/mm(2) to (197 ± 32)/mm(2) in vivo (P < 0.05). CONCLUSIONS: Gene silencing of netrin-1 could inhibit viability, proliferation, migration, tubal formation of HUVEC and angiogenesis of placenta. Netrin-1 plays an important role in regulating angiogenesis in placenta.