Exceedingly Small Gadolinium Oxide Nanoparticles with Remarkable Relaxivities for Magnetic Resonance Imaging of Tumors.

Gd chelates have occupied most of the market of magnetic resonance imaging (MRI) contrast agents for decades. However, there have been some problems (nephrotoxicity, non-specificity, and low r1 ) that limit their applications. Herein, a wet-chemical method is proposed for facile synthesis of poly(acrylic acid) (PAA) stabilized exceedingly small gadolinium oxide nanoparticles (ES-GON-PAA) with an excellent water dispersibility and a size smaller than 2.0 nm, which is a powerful T1 -weighted MRI contrast agent for diagnosis of diseases due to its remarkable relaxivities (r1 = 70.2 ± 1.8 mM-1 s-1 , and r2 /r1 = 1.02 ± 0.03, at 1.5 T). The r1 is much higher and the r2 /r1 is lower than that of the commercial Gd chelates and reported gadolinium oxide nanoparticles (GONs). Further ES-GON-PAA is developed with conjugation of RGD2 (RGD dimer) (i.e., ES-GON-PAA@RGD2) for T1 -weighted MRI of tumors that overexpress RGD receptors (i.e., integrin αv ß3 ). The maximum signal enhancement (ΔSNR) for T1 -weighted MRI of tumors reaches up to 372 ± 56% at 2 h post-injection of ES-GON-PAA@RGD2, which is much higher than commercial Gd-chelates (<80%). Due to the high biocompatibility and high tumor accumulation, ES-GON-PAA@RGD2 with remarkable relaxivities is a promising and powerful T1 -weighted MRI contrast agent.

Lipid Nanoparticles Composed of Quaternary Amine-Tertiary Amine Cationic Lipid Combination (QTsome) for Therapeutic Delivery of AntimiR-21 for Lung Cancer.

MicroRNA-21 (miR-21) is an oncomiR that is frequently upregulated in human cancers. AntimiR-21 (AM-21) is an oligonucleotide complementary to miR-21 that is designed to inhibit its gene silencing activities. To facilitate efficient delivery of AM-21, a novel lipid nanoparticle formulation called QTsome, based on a combination of quaternary amine and tertiary amine cationic lipids, with a distinctive pH-responsive profile, was developed. QTsome/AM-21 comprising DODMA/DOTAP/DOPC/CHOL/mPEG-DPPE and AM-21 oligonucleotide exhibited a mean particle diameter of below 150 nm, moderate zeta potential (+13.2 mV), excellent colloidal stability, and high drug loading efficiency (above 80%). In vitro study showed QTsome/AM-21 induced upregulation of miR-21 targets, including PTEN and DDAH1, in A549 cells while increasing their sensitivity toward paclitaxel (PTX). Finally, tumor regression, prolonged survival, and miR-21 target upregulation were demonstrated in an A549 xenograft mouse model. These data suggest that QTsome/AM-21 warrants further evaluation as an anticancer agent.

CD33-Targeted Lipid Nanoparticles (aCD33LNs) for Therapeutic Delivery of GTI-2040 to Acute Myelogenous Leukemia.

CD33-targeted lipid nanoparticles (aCD33LNs) were synthesized for delivery of GTI-2040, an antisense oligonucleotide (ASO) against the R2 subunit of ribonucleotide reductase, to acute myelogenous leukemia (AML). These LNs incorporated a deoxycholate-polyethylenimine (DOC-PEI) conjugate, which has shown significant activity to facilitate oligonucleotide delivery. Anti-CD33 scFv (aCD33) was added as a targeting ligand. The delivery efficiency of this system was investigated both in vitro and in vivo. When cells were treated with aCD33LN/GTI-2040, significant uptake was observed in CD33 positive Kasumi-1 cells. aCD33LNs loaded with GTI-2040 induced significant down-regulation of R2 mRNA and protein levels in AML cells. Moreover, aCD33LN/GTI-2040 showed a 15-fold reduction in the IC50 of antileukemic drug Ara-C in Kasumi-1 cells. In Kasumi-1 xenograft model, aCD33LN/GTI-2040 showed significant R2 downregulation compared to LN/GTI-2040. Furthermore, aCD33LN/GTI-2040 coadministered with Ara-C was shown to be highly effective in tumor growth inhibition and to greatly increase survival time of mice bearing Kasumi-1 xenograft tumors. The conjugate DOC-PEI has shown an ability to include calcein release from lipid nanoparticles, suggesting a potential mechanism contributing to efficient endosome release by DOC-PEI2K. These results indicate that aCD33LNs are a highly effective vehicle for the therapeutic delivery of antisense agents to AML.

Improving long-term subcutaneous drug delivery by regulating material-bioenvironment interaction.

Subcutaneous long-acting release (LAR) formulations have been extensively developed in the clinic to increase patient compliance and reduce treatment cost. Despite preliminary success for some LAR systems, a major obstacle limiting the therapeutic effect remains on their interaction with surrounding tissues. In this review, we summarize how living bodies respond to injected or implanted materials, and highlight some typical strategies based on smart material design, which may significantly improve long-term subcutaneous drug delivery. Moreover, possible strategies to achieve ultra-long (months, years) subcutaneous drug delivery systems are proposed. Based on these discussions, we believe the well-designed subcutaneous long-acting formulations will hold great promise to improve patient quality of life in the clinic.

In Situ shRNA Synthesis on DNA-Polylactide Nanoparticles to Treat Multidrug Resistant Breast Cancer.

Nanomedicine has shown unprecedented potential for cancer theranostics. Nucleic acid (e.g., DNA and RNA) nanomedicines are of particular interest for combination therapy with chemotherapeutics. However, current nanotechnologies to construct such nucleic acid nanomedicines, which rely on chemical conjugation or physical complexation of nucleic acids with chemotherapeutics, have restrained their clinical translation due to limitations such as low drug loading efficiency and poor biostability. Herein, in situ rolling circle transcription (RCT) is applied to synthesize short hairpin RNA (shRNA) on amphiphilic DNA-polylactide (PLA) micelles. Core-shell PLA@poly-shRNA structures that codeliver a high payload of doxorubicin (Dox) and multidrug resistance protein 1 (MDR1) targeted shRNA for MDR breast cancer (BC) therapy are developed. DNA-PLA conjugates are first synthesized, which then self-assemble into amphiphilic DNA-PLA micelles; next, using the conjugated DNA as a promoter, poly-shRNA is synthesized on DNA-PLA micelles via RCT, generating PLA@poly-shRNA microflowers; and finally, microflowers are electrostatically condensed into nanoparticles using biocompatible and multifunctional poly(ethylene glycol)-grafted polypeptides (PPT-g-PEG). These PLA@poly-shRNA@PPT-g-PEG nanoparticles are efficiently delivered into MDR breast cancer cells and accumulated in xenograft tumors, leading to MDR1 silencing, intracellular Dox accumulation, potentiated apoptosis, and enhanced tumor therapeutic efficacy. Overall, this nanomedicine platform is promising to codeliver anticancer nucleic acid therapeutics and chemotherapeutics.

Polyrotaxane-based supramolecular theranostics.

The development of smart theranostic systems with favourable biocompatibility, high loading efficiency, excellent circulation stability, potent anti-tumour activity, and multimodal diagnostic functionalities is of importance for future clinical application. The premature burst release and poor degradation kinetics indicative of polymer-based nanomedicines remain the major obstacles for clinical translation. Herein we prepare theranostic shell-crosslinked nanoparticles (SCNPs) using a ß-cyclodextrin-based polyrotaxane (PDI-PCL-b-PEG-RGD⊃ß-CD-NH2) to avoid premature drug leakage and achieve precisely controllable release, enhancing the maximum tolerated dose of the supramolecular nanomedicines. cRGDfK and perylene diimide are chosen as the stoppers of PDI-PCL-b-PEG-RGD⊃ß-CD-NH2, endowing the resultant SCNPs with excellent integrin targeting ability, photothermal effect, and photoacoustic capability. In vivo anti-tumour studies demonstrate that drug-loaded SCNPs completely eliminate the subcutaneous tumours without recurrence after a single-dose injection combining chemotherapy and photothermal therapy. These supramolecular nanomedicines also exhibit excellent anti-tumour performance against orthotopic breast cancer and prevent lung metastasis with negligible systemic toxicity.

Impact of Semiconducting Perylene Diimide Nanoparticle Size on Lymph Node Mapping and Cancer Imaging.

Semiconducting molecules of perylene diimide (PDI) with strong light absorption properties in the near-infrared region and good biocompatibility have received increasing attention in the field of theranostics, especially as photoacoustic (PA) imaging agents. Herein, we report a series of [64Cu]-labeled PDI nanoparticles (NPs) of different sizes (30, 60, 100, and 200 nm) as dual positron emission tomography (PET) and PA imaging probes and photothermal therapy agents. The precise size control of the PDI NPs can be achieved by adjusting the initial concentration of PDI molecules in the self-assembly process, and the photophysical property of different sized PDI NPs was studied in detail. Furthermore, we systematically investigated the size-dependent accumulation of the PDI NPs in the lymphatic system after local administration and in tumors after intravenous injection by PA and PET imaging. The results revealed that 100 nm is the best size for differentiating popliteal and sciatic LNs since the interval is around 60 min for the NPs to migrate from popliteal LNs to sciatic LNs, which is an ideal time window to facilitate surgical sentinel LN biopsy and pathological examination. Furthermore, different migration times of the different-sized PDI NPs will provide more choices for surgeons to map the specific tumor relevant LNs. PDI NP theranostics can also be applied to imaging-guided cancer therapy. The NPs with a size of 60 nm appear to be the best for tumor imaging and photothermal cancer therapy due to the maximum tumor accumulation efficiency. Thus, our study not only presents organic PDI NP theranostics but also introduces different-sized NPs for multiple bioapplications.

Preparation and evaluation of a novel liposomal formulation of cisplatin.

A novel liposomal formulation of cisplatin (L-CDDP) was synthesized and characterized. The L-CDDP was formed by conjugating CDDP to the carboxyl of oleic acid incorporated into empty liposomes. Particle size (155.4±16.1nm) and zeta potential (-50.92±1.19mV) of the L-CDDP were determined. In addition, pharmacokinetic properties and antitumor activity in vitro and in vivo were evaluated. Pharmacokinetic study demonstrated that L-CDDP had markedly prolonged circulation time relative to the free drug. Furthermore, L-CDDP showed significantly enhanced in vitro cytotoxicity in comparison to free CDDP. A549-engrafted mice treated with L-CDDP had a higher survival rate compared to those treated with free CDDP. Finally, A549-engrafted mice treated with L-CDDP showed no significant loss of body weight, whereas free CDDP treatment at the same dose caused significant loss of body weight. These results suggest further evaluation of the in vivo antitumor efficacy of the novel L-CDDP formulation is warranted.

Proteinase K-containing lipid nanoparticles for therapeutic delivery of siRNA LOR-1284.

BACKGROUND: The objective of the present study was to develop an efficient delivery vehicle for siRNA LOR-1284 through incorporation of proteinase K (PrK) as a means of preventing siRNA degradation by serum nucleases. Lipid nanoparticle-PrK-siRNA (LN-PrK-siRNA) complexes were synthesized and characterized. MATERIALS AND METHODS: siRNA complexed with PrK and liposomes composed of dimethyldioctadecyl ammonium bromide/cholesterol/Tween 80 (60:35:5 molar ratio) were investigated for down-regulation of R2 mRNA activity in KB human carcinoma cells. RESULTS: Treatment with LN-PrK-siRNA (30:0.3:1 molar ratio) significantly reduced levels of R2 mRNA compared to siRNA-liposomes without PrK in serum-containing medium. LN-PrK-siRNA complexes showed increased stability in serum and reduced toxicity in KB cells relative to LN-siRNA complexes. CONCLUSION: LN-PrK-siRNA complexes are promising delivery vehicles for siRNA.

Nonionic surfactant vesicles for delivery of RNAi therapeutics.

RNAi is a promising potential therapeutic approach for many diseases. A major barrier to its clinical translation is the lack of efficient delivery systems for siRNA. Among nonviral vectors, nonionic surfactant vesicles (niosomes) have shown a great deal of promise in terms of their efficacy and toxicity profiles. Nonionic surfactants have been shown to be a superior alternative to phospholipids in several studies. There is a large selection of surfactants with various properties that have been incorporated into niosomes. Therefore, there is great potential for innovation in terms of nisome composition. This article summarizes recent advancements in niosome technology for the delivery of siRNA.

A polyethylenimine-linoleic acid conjugate for antisense oligonucleotide delivery.

A novel antisense oligonucleotide (ASO) carrier, polyethylenimine conjugated to linoleic acid (PEI-LA), was synthesized and evaluated for delivery of LOR-2501 to tumor cells. LOR-2501 is an ASO targeting ribonucleotide reductase R1 subunit (RRM1). In this study, PEI-LA was synthesized by reacting PEI (Mw ~ 800) with linoleoyl chloride. Gel retardation assay showed complete complexation between PEI-LA and LOR-2501 at N/P ratio above 8. No significant cytotoxicity was observed with these complexes at the tested dosage levels. Interestingly, at N/P ratio of >6, levels of cellular uptake of PEI-LA/LOR-2501 were double that of PEI/LOR-2501 complexes of the same N/P ratio. PEI-LA/LOR-2501 induced downregulation of 64% and 70% of RRM1 at mRNA and protein levels, respectively. The highest transfection activity was shown by PEI-LA/LOR-2501 complexes at N/P ratio of 10. Finally, using pathway specific inhibitors, clathrin-mediated endocytosis was shown to be the principle mechanism of cellular internalization of these complexes. In conclusion, PEI-LA is a promising agent for the delivery of ASOs and warrants further investigation.

Delivery of calf thymus DNA to tumor by folate receptor targeted cationic liposomes.

Calf thymus DNA (ctDNA) has been shown to stimulate macrophages to produce cytokines both in vitro and in vivo when complexed with cationic liposomes. In addition, direct cytotoxicity of ctDNA has been found in tissue culture and in mice. In this study, ctDNA and folate receptor targeted cationic liposome complexes (ctDNA-F-CLs) were prepared and evaluated in FR (+) tumors. In addition, the underlying mechanism for the anti-cancer activity of ctDNA-F-CLs was investigated. Selective uptake of ctDNA-F-CLs was observed in FR (+) KB and L1210JF cells using flow cytometry. In RAW264.7 cells and DBA/2 mice, ctDNA-F-CLs and ctDNA-N-CLs significantly induced TNF-α and IL-6 production compared to free ctDNA. However, no significant difference in cytokine production was observed between ctDNA-N-CLs and ctDNA-F-CLs. In tumor bearing DBA/2 mice, ctDNA-F-CLs significantly increased INF-γ and IL-6 production compared to ctDNA-N-CLs. Furthermore in L1210JF cells, ctDNA-F-CLs had significantly increased cytotoxicity compared to ctDNA-N-CLs. Tumor cell apoptosis was also found in co-culture of RAW264.7 cells and ctDNA-F-CLs treated L1210JF cells. In L1210JF tumor bearing mice, ctDNA-F-CLs were found to significantly inhibit tumor growth and prolong the median survival time (MeST). In contrast, ctDNA-N-CLs and free ctDNA showed similar activities for tumor inhibition and animal survival. Moreover, the anti-cancer effect of ctDNA-F-CL was further enhanced by combination with anti-cancer drug doxorubicin. These results suggest that ctDNA-F-CLs are a promising agent for treatment of FR-positive tumors.