Delivery of siRNA in vitro and in vivo using PEI-capped porous silicon nanoparticles to silence MRP1 and inhibit proliferation in glioblastoma

Abstract

BackgroundMultidrug resistance-associated protein 1 (MRP1) overexpression plays a major role in chemoresistance in glioblastoma multiforme (GBM) contributing to its notorious deadly nature. Although MRP1-siRNA transfection to GBM in vitro has been shown to sensitise the cells to drug, MRP1 silencing in vivo and the phenotypic influence on the tumour and normal tissues upon MRP1 down-regulation have not been established. Here, porous silicon nanoparticles (pSiNPs) that enable high-capacity loading and delivery of siRNA are applied in vitro and in vivo.ResultWe established pSiNPs with polyethyleneimine (PEI) capping that enables high-capacity loading of siRNA (92 µg of siRNA/mg PEI-pSiNPs), and optimised release profile (70% released between 24 and 48 h). These pSiNPs are biocompatible, and demonstrate cellular uptake and effective knockdown of MRP1 expression in GBM by 30%. Also, siRNA delivery was found to significantly reduce GBM proliferation as an associated effect. This effect is likely mediated by the attenuation of MRP1 transmembrane transport, followed by cell cycle arrest. MRP1 silencing in GBM tumour using MRP1-siRNA loaded pSiNPs was demonstrated in mice (82% reduction at the protein level 48 h post-injection), and it also produced antiproliferative effect in GBM by reducing the population of proliferative cells. These results indicate that in vitro observations are translatable in vivo. No histopathological signs of acute damage were observed in other MRP1-expressing organs despite collateral downregulations.ConclusionsThis study proposes the potential of efficient MRP1-siRNA delivery by using PEI-capped pSiNPs in achieving a dual therapeutic role of directly attenuating the growth of GBM while sensitising residual tumour cells to the effects of chemotherapy post-resection.Electronic supplementary materialThe online version of this article (10.1186/s12951-018-0365-y) contains supplementary material, which is available to authorized users.

Transferrin-targeted porous silicon nanoparticles reduce glioblastoma cell migration across tight extracellular space

“…Deriving therapeutic counter measures against aforementioned infiltrative migration mechanisms employed by a cancer cell (such as the use of small molecules 11 , peptides 12 , RNA interference 13 ) has been an obvious approach to intervene cancer progression 14 . Despite those discoveries, the pharmacokinetic challenges such as rapid degradation, clearance of those small molecules, and off-target adverse effects are still problematic in clinical translation.…”

In vivo gene delivery mediated by non-viral vectors for cancer therapy

“…They loaded NPs with the MRP1-siRNA with the release rate of 70% between 24 to 48 h and injected them into the mice bearing GBM (U87 cell). The release profile of NPs between 24 to 48 h was 70% [100]. PEI-Si NP-MRP1-siRNA showed significantly higher loading and cellular uptake in U87 cells as compared to the non-PEI NPs due to the higher positive charge.…”

“…Noteworthy, the knock-down of the multidrug transporter P-glycoprotein (Pgp) induces G2/M arrest in leukemia cells [223]. The investigation of MRP1 silencing in CD-1 nude mice bearing U87 cells showed that PEI-Si NP-MRP1-siRNA significantly decrease the level of MRP1 mRNA and protein compared to the non-siRNA cargo [100]. It seems that the release profile of siRNA between 24 to 48 h has critical role in gene delivery efficiency.…”

Rekindling RNAi Therapy: Materials Design Requirements for In Vivo siRNA Delivery

“…That work demonstrated >90% transfection efficiency in vitro, as well as a demonstrable phenotypic outcome (e.g., neovascularization) in vivo . At the smaller scale, the Voelcker group developed PEI‐functionalized pSi nanoparticles for systemic administration, attaining 30–63% gene silencing effect in vitro and up to 82% in vivo . While the use of PEI raises the abovementioned concerns regarding dose‐dependent cytotoxicity, silicon is amenable to other condenser chemistries.…”