Leukemia-specific siRNA delivery by immunonanoplexes consisting of anti-JL1 minibody conjugated to oligo-9 Arg-peptides

Noninvasive imaging of c(RGD)2 -9R as a potential delivery carrier for transfection of siRNA in malignant tumors

The purpose of our study was to develop and evaluate a novel integrin α_v β₃ -specific delivery carrier for transfection of siRNA in malignant tumors. We adopted arginine-glycine-aspartate (RGD) motif as a tissue target for specific recognition of integrin α_ν β₃ . A chimaeric peptide was synthesized by adding nonamer arginine residues (9-arginine [9R]) at the carboxy terminus of cyclic-RGD dimer, designated as c(RGD)₂ -9R, to enable small interfering RNA (siRNA) binding. To test the applicability of the delivery carrier in vivo, c(RGD)₂ -9R was labeled with radionuclide of technetium-99m. Biodistribution and γ-camera imaging studies were performed in HepG2 xenograft-bearing nude mice. As results, an optimal 10:1 molar ratio of ^99m Tc-c(RGD)₂ -9R to siRNA was indicated by the electrophoresis on agarose gels. ^99m Tc-c(RGD)₂ -9R/siRNA remained stable under a set of conditions in vitro. For in vivo study, tumor radioactivity uptake of ^99m Tc-c(RGD)₂ -9R/siRNA in nude mice bearing HepG2 xenografts was significantly higher than that of control probe (P < .05). The xenografts were clearly visualized at 4 hours till 6 hours noninvasively after intravenous injection of ^99m Tc-c(RGD)₂ -9R/siRNA, while the xenografts were not visualized at any time after injection of control probe. It was concluded that c(RGD)₂ -9R could be an effective siRNA delivery carrier. Technetium-99m radiolabeled-delivery carrier represents a potential imaging strategy for RNAi-based therapy.

Current Progress in Non-viral RNAi-Based Delivery Strategies to Lymphocytes

RNAi-based therapy holds great promise, as it can be utilized for the treatment of multiple conditions in an accurate manner via sequence-specific manipulation of gene expression. To date, RNAi therapeutics have advanced into clinical trials for liver diseases and solid tumors; however, delivery of RNAi to leukocytes in general and to lymphocytes in particular remains a challenge. Lymphocytes are notoriously hard to transduce with RNAi payloads and are disseminated throughout the body, often located in deep tissues; therefore, developing an efficient systemic delivery system directed to lymphocytes is not a trivial task. Successful manipulation of lymphocyte function with RNAi possesses immense therapeutic potential, as it will enable researchers to resolve lymphocyte-implicated diseases such as inflammation, autoimmunity, transplant rejection, viral infections, and blood cancers. This potential has propelled the development of novel targeted delivery systems relying on the accumulating research knowledge from multiple disciplines, including materials science and engineering, immunology, and genetics. Here, we will discuss the recent progress in non-viral delivery strategies of RNAi payloads to lymphocytes. Special emphasis will be made on the challenges and potential opportunities in manipulating lymphocyte function with RNAi. These approaches might ultimately become a novel therapeutic modality to treat leukocyte-related diseases.

Construction and Biological Evaluation of a Novel Integrin ανβ₃-Specific Carrier for Targeted siRNA Delivery In Vitro

(1) Background: The great potential of RNA interference (RNAi)-based gene therapy is premised on the effective delivery of small interfering RNAs (siRNAs) to target tissues and cells. Hence, we aimed at developing and examining a novel integrin α_vβ₃-specific delivery carrier for targeted transfection of siRNA to malignant tumor cells; (2) Methods: Arginine-glycine-aspartate motif (RGD) was adopted as a tissue target for specific recognition of integrin α_vβ₃. To enable siRNA binding, a chimeric peptide was synthesized by adding nonamer arginine residues (9R) at the carboxy terminus of cyclic-RGD dimer, designated as c(RGD)₂-9R. The efficiency of 9R peptide transferring siRNA was biologically evaluated in vitro by flow cytometry, confocal microscopy, and Western blot; (3) Results: An optimal 10:1 molar ratio of c(RGD)₂-9R to siRNA was confirmed by the electrophoresis on agarose gels. Both the flow cytometry and confocal microscopy results testified that transfection of c(RGD)₂-9R as an siRNA delivery carrier was obviously higher than the naked-siRNA group. The results of Western blot demonstrated that these 9R peptides were able to transduce siRNA to HepG2 cells in vitro, resulting in efficient gene silencing; and (4) Conclusion: The chimeric peptide of c(RGD)₂-9R can be developed as an effective siRNA delivery carrier and shows potential as a new strategy for RNAi-based gene therapy.

Advances in siRNA delivery to T-cells: potential clinical applications for inflammatory disease, cancer and infection

The specificity of RNAi and its ability to silence ‘undruggable’ targets has made inhibition of gene expression in T-cells with siRNAs an attractive potential therapeutic strategy for the treatment of inflammatory disease, cancer and infection. However, delivery of siRNAs into primary T-cells represents a major hurdle to their use as potential therapeutic agents. Recent advances in siRNA delivery through the use of electroporation/nucleofection, viral vectors, peptides/proteins, nanoparticles, aptamers and other agents have now enabled efficient gene silencing in primary T-cells both in vitro and in vivo. Overcoming such barriers in siRNA delivery offers exciting new prospects for directly targeting T-cells systemically with siRNAs, or adoptively transferring T-cells back into patients following ex vivo manipulation with siRNAs. In the present review, we outline the challenges in delivering siRNAs into primary T-cells and discuss the mechanism and therapeutic opportunities of each delivery method. We emphasize studies that have exploited RNAi-mediated gene silencing in T-cells for the treatment of inflammatory disease, cancer and infection using mouse models. We also discuss the potential therapeutic benefits of manipulating T-cells using siRNAs for the treatment of human diseases.

Sendai F/HN viroplexes for efficient transfection of leukemic T cells

PURPOSE

Most chemical transfection reagents are ineffective for the transfection of cells in suspension, such as leukemic cell and stem cell lineages. We developed two different types of viroplexes, cationic Sendai F/HN viroplexes (CSVs) and protamine sulfate-condensed cationic Sendai F/HN viroplexes (PCSVs) for the efficient transfection of T-leukemic cells.

MATERIALS AND METHODS

The viroplex systems were prepared by reconstitution of fusogenic Sendai F/HN proteins in DMKE (O,O'-dimyristyl-N-lysyl glutamate) cationic liposomes. The viroplexes were further optimized for plasmid DNA and siRNA delivery to suspension cells. The particle size and surface charge of the viroplexes were analyzed with a ζ-sizer. Transfection of plasmid DNA (pDNA) and small interfering RNA (siRNA) by CSVs or PCSV was evaluated by measurement of transgene expression, confocal microscopy, FACS, and RT-PCR.

RESULTS

The optimized CSVs and PCSVs exhibited enhanced gene and siRNA delivery in the tested suspension cell lines (Jurkat cells and CEM cells), compared with conventional cationic liposomes. In the case of pDNA transfection, the CSVs and PCSVs show at least 10-fold and 100-fold higher transgene expression compared with DMKE lipoplexes (or lipofectamine 2000), respectively. The CSVs showed more effective siRNA delivery to the suspension cells than cationic liposomes, as assessed by confocal microscopy, FACS, and RT-PCR. The effective transfection by the CSVs and PCSVs is presumably due to fusogenic activity of F/HN proteins resulting in facilitated internalization of pDNA and siRNA.

CONCLUSION

This study suggests that Sendai F/HN viroplexes can be widely applicable for the transfection of pDNA and siRNA to suspension cell lines.

Novel protein transduction domain mimics as nonviral delivery vectors for siRNA targeting NOTCH1 in primary human T cells

RNA interference technology has recently been highlighted as a powerful research method as well as a potential therapeutic treatment for several diseases. However, the delivery of small interfering RNA (siRNA) into T cell lines and primary blood cells is exceedingly challenging, as they are resistant to transfection by conventional reagents. As a result, there is an unmet need for nonviral, efficient, and easily prepared carriers for siRNA delivery into hard-to-transfect cell types. Here, we report a novel system based on protein transduction domain mimics (PTDMs), generated by ring opening metathesis polymerization, for intracellular delivery of siRNA molecules. PTDM-based siRNA delivery induced efficient NOTCH1 knockdown in Jurkat T cells and human peripheral blood mononuclear cells without any measured toxicity. Furthermore, delivering siRNA to NOTCH1 in human peripheral blood cells modulated cell proliferation and differentiation of T cells into T(H)1 cells.

Nanomedicines based on recombinant fusion proteins for targeting therapeutic siRNA oligonucleotides

The enormous promise of siRNA technology for rational and targeted therapy can only be realized if the inherent problems in terms of pharmaceutical development are overcome. Besides liposomal and polymeric nanoparticles, fusion proteins hold great potential for cell-type specific delivery of siRNA. Consisting of a protein binder and an oligonucleotide complexing domain, fusion proteins are designed for targeted delivery to a certain tissue or organ and subsequent release of the siRNA after cellular uptake. This article focuses on the possibilities and importance of targeting and complexing domains, including polymers and dendrimers. In vitro and in vivo evaluations are discussed with an in-depth view on pharmacokinetic properties. Remaining challenges concerning specificity on the tissue and molecular levels are highlighted.

Expression of JL1 in Burkitt lymphoma is associated with improved overall survival

JL1 is a novel molecule expressed in the surface of hematopoietic precursor cells, but not on any other mature human tissue. Accordingly, JL1 is expressed in acute lymphoblastic leukemia (ALL) cells and can be used both for specific diagnosis and as a target for treatment. However, expression of JL1 by lymphomas has not been thoroughly assessed. Burkitt lymphoma is a potentially curable aggressive lymphoma, but prognostic markers that stratify risk have not been established. We therefore assayed JL1 expression in Burkitt lymphoma patients to assess its value as a prognostic marker for this disease. Tissue microarray blocks of formalin-fixed paraffin-embedded tissue samples from patients with Burkitt lymphoma and other B-cell lymphomas, at the Asan Medical Center and Seoul National University Hospital from January 1998 to December 2008 were immunohistochemically assayed using a mouse monoclonal antibody against JL1. We found that 30.2% of Burkitt lymphoma samples, but no other lymphoma samples, were positive for JL1. JL-1 expression was significantly correlated with patient survival (P = 0.022), but not with other clinical manifestations of the disease, with 91.6% of JL1-positive patients achieving complete remission in response to chemotherapy and 6.25% experiencing disease recurrence. JL1 positivity was significantly correlated with prolonged overall survival by both Kaplan-Meier survival (P = 0.035) and Cox proportional hazard model (P = 0.043) analysis. JL1 expression in Burkitt lymphoma was positively correlated with overall survival and better response to chemotherapy, suggesting that JL1 may be a prognostic marker for risk stratification in these patients.