Jianliang Shen

An injectable nanoparticle generator enhances delivery of cancer therapeutics

The efficacy of cancer drugs is often limited because only a small fraction of the administered dose accumulates in tumors. Here we report an injectable nanoparticle generator (iNPG) that overcomes multiple biological barriers to cancer drug delivery. The iNPG is a discoidal micrometer-sized particle that can be loaded with chemotherapeutics. We conjugate doxorubicin to poly(L-glutamic acid) by means of a pH-sensitive cleavable linker, and load the polymeric drug (pDox) into iNPG to assemble iNPG-pDox. Once released from iNPG, pDox spontaneously forms nanometer-sized particles in aqueous solution. Intravenously injected iNPG-pDox accumulates at tumors due to natural tropism and enhanced vascular dynamics and releases pDox nanoparticles that are internalized by tumor cells. Intracellularly, pDox nanoparticles are transported to the perinuclear region and cleaved into Dox, thereby avoiding excretion by drug efflux pumps. Compared to its individual components or current therapeutic formulations, iNPG-pDox shows enhanced efficacy in MDA-MB-231 and 4T1 mouse models of metastatic breast cancer, including functional cures in 40–50% of treated mice.

Cyclodextrin and polyethylenimine functionalized mesoporous silica nanoparticles for delivery of siRNA cancer therapeutics

Effective delivery holds the key to successful in vivo application of therapeutic small interfering RNA (siRNA). In this work, we have developed a universal siRNA carrier consisting of a mesoporous silica nanoparticle (MSNP) functionalized with cyclodextrin-grafted polyethylenimine (CP). CP provides positive charge for loading of siRNA through electrostatic interaction and enables effective endosomal escape of siRNA. Using intravital microscopy we were able to monitor tumor enrichment of CP-MSNP/siRNA particles in live mice bearing orthotopic MDA-MB-231 xenograft tumors. CP-MSNP delivery of siRNA targeting the M2 isoform of the glycolytic enzyme pyruvate kinase (PKM2) resulted in effective knockdown of gene expression in vitro and in vivo. Suppression of PKM2 led to inhibition of tumor cell growth, invasion, and migration.

The nano-plasma interface: implications of the protein corona

The interactions between nanoparticles and macromolecules in the blood plasma dictate the biocompatibility and efficacy of nanotherapeutics. Accordingly, the properties of nanoparticles and endogenous biomolecules change at the nano-plasma interface. Here, we review the implications of such changes including toxicity, immunological recognition, molecular targeting, biodistribution, intracellular uptake, and drug release. Although this interface poses several challenges for nanomedicine, it also presents opportunities for exploiting nanoparticle-protein interactions.

High Capacity Nanoporous Silicon Carrier for Systemic Delivery of Gene Silencing Therapeutics

Gene silencing agents such as small interfering RNA (siRNA) and microRNA offer the promise to modulate expression of almost every gene for the treatment of human diseases including cancer. However, lack of vehicles for effective systemic delivery to the disease organs has greatly limited their in vivo applications. In this study, we developed a high capacity polycation-functionalized nanoporous silicon (PCPS) platform comprised of nanoporous silicon microparticles functionalized with arginine-polyethyleneimine inside the nanopores for effective delivery of gene silencing agents. Incubation of MDA-MB-231 human breast cancer cells with PCPS loaded with STAT3 siRNA (PCPS/STAT3) or GRP78 siRNA (PCPS/GRP78) resulted in 91 and 83% reduction of STAT3 and GRP78 gene expression in vitro. Treatment of cells with a microRNA-18a mimic in PCPS (PCPS/miR-18) knocked down 90% expression of the microRNA-18a target gene ATM. Systemic delivery of PCPS/STAT3 siRNA in murine model of MDA-MB-231 breast cancer enriched particles in tumor tissues and reduced STAT3 expression in cancer cells, causing significant reduction of cancer stem cells in the residual tumor tissue. At the therapeutic dosage, PCPS/STAT3 siRNA did not trigger acute immune response in FVB mice, including changes in serum cytokines, chemokines, and colony-stimulating factors. In addition, weekly dosing of PCPS/STAT3 siRNA for four weeks did not cause signs of subacute toxicity based on changes in body weight, hematology, blood chemistry, and major organ histology. Collectively, the results suggest that we have developed a safe vehicle for effective delivery of gene silencing agents.

Multifunctional gold nanorods for siRNA gene silencing and photothermal therapy

Cancer is a complex disease that usually requires several treatment modalities. A multifunctional nanotherapeutic system is designed, incorporating small interfering RNA (siRNA) and gold nanorods (Au NRs) for photothermal therapy. Surface-engineered Au NRs with polyethylenimine are synthesized using a layer-by-layer assembly and siRNA is absorbed on the surface. The siRNA is efficiently delivered into breast cancer cells, resulting in subsequent gene silencing. Cells are then irradiated with near-infrared (NIR) light, causing heat-induced anticancer activity. The combination of gene silencing and photothermal therapy results in effective inhibition of cell proliferation.

Safety of Nanoparticles in Medicine

Nanomedicine involves the use of nanoparticles for therapeutic and diagnostic purposes. During the past two decades, a growing number of nanomedicines have received regulatory approval and many more show promise for future clinical translation. In this context, it is important to evaluate the safety of nanoparticles in order to achieve biocompatibility and desired activity. However, it is unwarranted to make generalized statements regarding the safety of nanoparticles, since the field of nanomedicine comprises a multitude of different manufactured nanoparticles made from various materials. Indeed, several nanotherapeutics that are currently approved, such as Doxil and Abraxane, exhibit fewer side effects than their small molecule counterparts, while other nanoparticles (e.g. metallic and carbon-based particles) tend to display toxicity. However, the hazardous nature of certain nanomedicines could be exploited for the ablation of diseased tissue, if selective targeting can be achieved. This review discusses the mechanisms for molecular, cellular, organ, and immune system toxicity, which can be observed with a subset of nanoparticles. Strategies for improving the safety of nanoparticles by surface modification and pretreatment with immunomodulators are also discussed. Additionally, important considerations for nanoparticle safety assessment are reviewed. In regards to clinical application, stricter regulations for the approval of nanomedicines might not be required. Rather, safety evaluation assays should be adjusted to be more appropriate for engineered nanoparticles.

Co-Delivery of Cisplatin Prodrug and Chlorin e6 by Mesoporous Silica Nanoparticles for Chemo-Photodynamic Combination Therapy to Combat Drug Resistance.

Combination therapy shows great promise in circumventing cisplatin resistance. We report herein the development of a novel nanoscale drug delivery system (nDDS) based nanotherapeutic that combines chemotherapy and photodynamic therapy (PDT) into one single platform to achieve synergistic anticancer capacity to conquer cisplatin resistance. Mesoporous silica nanoparticle (MSNs) was used as the drug delivery vector to conjugate cisplatin prodrug and to load photosensitizer chlorin e6 (Ce6) to afford the dual drug loaded delivery system MSNs/Ce6/Pt. The hybrid nanoparticles have an average diameter of about 100 nm and slightly positive surface charge of about 18.2 mV. The MSNs/Ce6/Pt nanoparticles can be efficiently internalized by cells through endocytosis, thereby achieving much higher cellular Pt uptake than cisplatin in cisplatin-resistant A549R lung cancer cells. After 660 nm light irradiation (10 mW/cm(2)), the cellular reactive oxygen species (ROS) level in MSNs/Ce6/Pt treated cells was elevated dramatically. As a result of these properties, MSNs/Ce6/Pt exhibited very potent anticancer activity against A549R cells, giving a half-maximal inhibitory concentration (IC50) value for the combination therapy of 0.53 μM, much lower than that of cisplatin (25.1 μM). This study suggests the great potential of nDDS-based nanotherapeutic for combined chemo-photodynamic therapy to circumvent cisplatin resistance.

Shrinkage of pegylated and non-pegylated liposomes in serum

An essential requisite for the design of nanodelivery systems is the ability to characterize the size, homogeneity and zeta potential of nanoparticles. Such properties can be tailored in order to create the most efficient drug delivery platforms. An important question is whether these characteristics change upon systemic injection. Here, we have studied the behavior of phosphatidylcholine/cholesterol liposomes exposed to serum proteins. The results reveal a serum-induced reduction in the size and homogeneity of both pegylated and non-pegylated liposomes, implicating the possible role of osmotic forces. In addition, changes to zeta-potential were observed upon exposing liposomes to serum. The liposomes with polyethylene glycol expressed different characteristics than their non-polymeric counterparts, suggesting the potential formation of a denser protein corona around the non-pegylated liposomes.

Porous silicon microparticles for delivery of siRNA therapeutics

Small interfering RNA (siRNA) can be used to suppress gene expression, thereby providing a new avenue for the treatment of various diseases. However, the successful implementation of siRNA therapy requires the use of delivery platforms that can overcome the major challenges of siRNA delivery, such as enzymatic degradation, low intracellular uptake and lysosomal entrapment. Here, a protocol for the preparation and use of a biocompatible and effective siRNA delivery system is presented. This platform consists of polyethylenimine (PEI) and arginine (Arg)-grafted porous silicon microparticles, which can be loaded with siRNA by performing a simple mixing step. The silicon particles are gradually degraded over time, thereby triggering the formation of Arg-PEI/siRNA nanoparticles. This delivery vehicle provides a means for protecting and internalizing siRNA, without causing cytotoxicity. The major steps of polycation functionalization, particle characterization, and siRNA loading are outlined in detail. In addition, the procedures for determining particle uptake, cytotoxicity, and transfection efficacy are also described.

A Liposome Encapsulated Ruthenium Polypyridine Complex as a Theranostic Platform for Triple-Negative Breast Cancer

Ruthenium coordination complexes have the potential to serve as novel theranostic agents for cancer. However, a major limitation in their clinical implementation is effective tumor accumulation. In this study, we have developed a liposome-based theranostic nanodelivery system for [Ru(phen)2dppz](ClO4)2 (Lipo-Ru). This ruthenium polypyridine complex emits a strong fluorescent signal when incorporated in the hydrophobic lipid bilayer of the delivery vehicle or in the DNA helix, enabling visualization of the therapeutic agent in tumor tissues. Incubation of MDA-MB-231 breast cancer cells with Lipo-Ru induced double-strand DNA breaks and triggers apoptosis. In a mouse model of triple-negative breast cancer, treatment with Lipo-Ru dramatically reduced tumor growth. Biodistribution studies of Lipo-Ru revealed that more than 20% of the injected dose accumulated in the tumor. These results suggest that Lipo-Ru could serve as a promising theranostic platform for cancer.