Chenguang Zhou

Lactosylated liposomes for targeted delivery of doxorubicin to hepatocellular carcinoma

Background N-lactosyl-dioleoylphosphatidylethanolamine (Lac-DOPE) was synthesized and evaluated as a liver-specific targeting ligand via asialoglycoprotein receptors for liposomal delivery of doxorubicin. Methods Lactosylated liposomes encapsulating calcein (Lac-L-calcein) or doxorubicin (Lac-L-DOX) composed of egg phosphatidylcholine, cholesterol, monomethoxy polyethylene glycol 2000-distearoyl phosphatidylethanolamine, and Lac-DOPE at 50:35:5:10 (mol/mol) were prepared by polycarbonate membrane extrusion and evaluated in human hepatocellular carcinoma HepG2 cells. Cellular uptake of Lac-L-calcein was monitored by confocal microscopy and by flow cytometry. The cytotoxicity of Lac-L-DOX was evaluated by MTT assay. The pharmacokinetic properties of Lac-L-DOX were studied in normal mice, and its biodistribution and antitumor activity were studied in nude mice with HepG2 xenografts. Results The size of Lac-L-DOX was less than 100 nm and the liposomes demonstrated excellent colloidal stability. In vitro uptake of Lac-L-calcein by HepG2 cells was four times greater than that of non-targeted L-calcein. In the presence of 20 mM lactose, the uptake of Lac-L-calcein was inhibited, suggesting that asialoglycoprotein receptors mediated the observed cellular uptake. Lac-L-DOX exhibited enhanced in vivo cytotoxicity compared with the nontargeted liposomal doxorubicin (L-DOX), and its pharmacokinetic parameters indicate that Lac-L-DOX has a long blood circulation time (t1/2 8.73 hours). Tissue distribution and therapeutic efficacy studies in nude mice bearing HepG2 xenografts show that Lac-L-DOX had significantly stronger tumor inhibitory activity compared with L-DOX and free doxorubicin, along with a higher accumulation of drug within the tumor site and greater cellular uptake by tumor cells. Conclusion These data suggest that lactosylated liposomes are promising drug delivery vehicles for hepatocellular carcinoma.

Lipid-coated nano-calcium-phosphate (LNCP) for gene delivery

While calcium-phosphate has been used to deliver plasmid DNA (pDNA) for decades, the method is typically characterized by low and irreproducible transfection efficiency relative to the other non-viral approaches, such as liposomes and polymers. Here we report a novel gene transfer vector comprising lipid-coated nano-calcium-phosphate (LNCP) that provides consistently efficient and satisfactory pDNA delivery. It is based on core-shell nanoparticles comprising a calcium-phosphate core and a cationic lipid shell. This method, in contrast to the solution precipitation methods used in the past, yields colloidally stable calcium-phosphate nanoparticles inside the cationic liposomes. Our results indicate that the particle size and the size distribution of the LNCP remain virtually unchanged even after 21 days of storage. Atomic force microscopy measurements reveal that the LNCP have a 5-fold higher rigidity than common cationic liposomes. The LNCP transfected pDNA 24 times greater than the naked pDNA and 10-fold greater relative to the standard calcium-phosphate precipitation preparations, suggesting that the LNCP may have potential as a novel transfection agent for gene therapy.

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.

Insight into Mechanisms of Cellular Uptake of Lipid Nanoparticles and Intracellular Release of Small RNAs

PurposeUnderstanding mechanisms of cellular uptake and intracellular release would enable better design of nanocarriers for delivery of nucleic acids such as siRNA and microRNA (miRNA).MethodIn this study, we investigated cellular pharmacokinetics of siRNA by co-encapsulating fluorescently labeled siRNA and molecular beacon (MB) in four different formulations of cationic lipid nanoparticles (LNPs). A miRNA mimic was also used as a probe for investigating cellular pharmacokinetics, which correlated well with RNAi activities.ResultsWe tried to find the best LNP formulation based on the combination of DOTMA and DODMA. When the DOTMA/DODMA ratio was at 5/40, the LNP containing a luciferase siRNA produced the highest gene silencing activity. The superior potency of DOTMA/DODMA could be attributed to higher uptake and improved ability to facilitate siRNA release from endosomes subsequent to uptake.ConclusionsOur findings may provide new insights into RNAi transfection pathways and have implications on cationic LNP design.

Efficient siRNA Delivery Using a Polyamidoamine Dendrimer with a Modified Pentaerythritol Core

PurposeDelivery of siRNA into cells remains a critical challenge. Our lab has shown a novel polyamidoamine (PAMAM) dendrimer with modified pentaerythritol derivative core (PD dendrimer) to exhibit high plasmid DNA transfection efficiency and low cytotoxicity. Here, we evaluate PD dendrimer as a siRNA carrier.MethodsAgarose gel electrophoresis and AFM were used to confirm formation of generation 5 (G5)-PD dendrimer/siRNA nanoparticles (NPs). G5 PD dendrimer/anti-luciferase siRNA NPs were used to transfect SK Hep-1 cells with stable luciferase expression. Effects of various endocytic pathway inhibitors on uptake of G5 PD dendrimer/siRNA NPs in SK Hep-1 cells were also investigated.ResultsAgarose gel electrophoresis indicated that G5 PD dendrimer and siRNA formed NPs at weight ratios >0.5:1. G5 PD dendrimer showed effective luciferase gene silencing when weight ratio was 3.0:1 and above. Treatment with endocytosis inhibitors showed that clathrin-mediated endocytosis was the main endocytic pathway by which G5-PD dendrimer/siRNA NPs enter the cell.ConclusionsThese results show that the novel G5 PD dendrimer has high siRNA delivery activity and is promising as a delivery agent for its therapeutic application.

SPANosomes as delivery vehicles for small interfering RNA (siRNA)

Nonionic surfactant vesicles, or SPANosomes (SPs), comprised of cationic lipid and sorbitan monooleate (Span 80) were synthesized and evaluated as small interfering RNA (siRNA) vectors. The SPs had a mean diameter of less than 100 nm and exhibited excellent colloidal stability. The SP/siRNA complexes possessed a slightly positive zeta potential of 12 mV and demonstrated a high siRNA incorporation efficiency of greater than 80%. Cryogenic transmission electron microscopy (cryo-TEM) imaging of the SP/siRNA indicated a predominantly core-shell structure. The SP/siRNA complexes were shown to efficiently and specifically silence expression of both green fluorescent protein (GFP) (66% knockdown) and aromatase (77% knockdown) genes in breast cancer cell lines. In addition, the cellular trafficking pathway of the SP/siRNA was investigated by confocal microscopy using molecular beacons as probes for cytosolic delivery. The results showed efficient endosomal escape and cytosolic delivery of the siRNA cargo following internalization of the SP/siRNA complexes. In conclusion, Span 80 is a potent helper lipid, and the SPs are promising vehicles for siRNA delivery.

Nanotechnology for the delivery of phytochemicals in cancer therapy.

The aim of this review is to summarize advances that have been made in the delivery of phytochemicals for cancer therapy by the use of nanotechnology. Over recent decades, much research effort has been invested in developing phytochemicals as cancer therapeutic agents. However, several impediments to their wide spread use as drugs still have to be overcome. Among these are low solubility, poor penetration into cells, high hepatic disposition, and narrow therapeutic index. Rapid clearance or uptake by normal tissues and wide tissue distribution result in low drug accumulation in the target tumor sites can result in undesired drug exposure in normal tissues. Association with or encapsulation in nanoscale drug carriers is a potential strategy to address these problems. This review discussed lessons learned on the use of nanotechnology for delivery of phytochemicals that been tested in clinical trials or are moving towards the clinic.

Comparative cellular pharmacokinetics and pharmacodynamics of siRNA delivery by SPANosomes and by cationic liposomes

UNLABELLED Mechanistic understanding of intracellular trafficking is important for the development of small interfering RNA (siRNA) delivery vehicles. Here, we describe a novel methodology to quantitatively analyze nanocarrier-mediated disposition of siRNA. Cellular uptake and cytoplasmic release of siRNA over time were quantified by measuring the fluorescence intensities of fluorescently-labeled siRNAs and molecular beacons using flow cytometry. This method was used to investigate the cellular pharmacokinetics (PK) of siRNA delivery by SPANosomes (SP) and by cationic liposomes (CL). The results showed that the superior pharmacodynamic (PD) response of SP was because it enhanced transport of siRNA into the cytoplasm compared to the CL. The divergent cellular pharmacokinetic profiles of the two formulations were associated with different cellular entry pathways. These findings can facilitate the rational design of more efficient siRNA delivery vehicles in the future. FROM THE CLINICAL EDITOR In this paper the authors describe a novel methodology to quantitatively analyze nanocarrier-mediated disposition of small interfering RNA, comparing SPANosomes with cationic liposomes as delivery systems with different entry pathways.

A Covalently Stabilized Lipid−Polycation−DNA (sLPD) Vector for Antisense Oligonucleotide Delivery

Antisense oligonucleotide G3139 is designed for Bcl-2 downregulation and is known to induce toll-like receptor activation. Novel stabilized lipid-polycation-DNA (sLPD) nanoparticles were constructed and evaluated for the delivery of G3139 to human carcinoma KB cells and for bioactivity in vivo. Polyethylenimine (PEI) was incorporated as a DNA condensing agent. The lipid composition used was DOTAP/DDAB/Chol/TPGS/linoleic acid/hexadecenal at molar ratios of 30/30/34/1/5/0.2. The nanoparticles were stabilized by the formation of a reversible covalent bond between the aldehyde group on the cis-11-hexadecenal and amines on the PEI. When sLPDs were used to transfect KB cells, 90.4% Bcl-2 downregulation was observed, compared to no significant downregulation by free G3139 and 54.6% downregulation by nonstabilized LPD-G3139. The sLPDs were then evaluated for therapeutic efficacy in mice bearing KB subcutaneous tumors and were found to trigger a strong antitumor response, inhibiting tumor growth and prolonging survival with 72% increase in lifespan (ILS). Consistent with previous reports on other G3139 nanoparticles, the increased antitumor activities of sLPDs in vivo were found to be associated with increased cytokine induction rather than Bcl-2 downregulation, suggesting an immunological mechanism.

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.