Rong Tong

Photoswitchable nanoparticles for triggered tissue penetration and drug delivery.

We report a novel nanoparticulate drug delivery system that undergoes reversible volume change from 150 to 40 nm upon phototriggering with UV light. The volume change of these monodisperse nanoparticles comprising spiropyran, which undergoes reversible photoisomerization, and PEGylated lipid enables repetitive dosing from a single administration and enhances tissue penetration. The photoswitching allows particles to fluoresce and release drugs inside cells when illuminated with UV light. The mechanism of the light-induced size switching and triggered-release is studied. These particles provide spatiotemporal control of drug release and enhanced tissue penetration, useful properties in many disease states including cancer.

Reversible Cell‐Specific Drug Delivery with Aptamer‐Functionalized Liposomes

cis-Diamminedichloroplatinum(II) (cisplatin) is a potent chemotherapeutic agent for the treatment of a broad range of cancerous tumors. 2] Despite its excellent antitumor efficacy, the major drawbacks of cisplatin include its lack of tumor specificity and severe side effects. In addition, certain tumor-cell types develop resistance to cisplatin from exposure to the drug. Strategies that allow the delivery of cisplatin specifically to tumor cells are highly desirable. Several strategies have been reported for the delivery of cisplatin specifically to tumor sites, the most common of which is to use antibody (Ab) recognition against different cell-surface targets. The binding of Abs to the cell-membrane receptors triggers receptor-mediated endocytosis, with the result of improved therapeutic efficacy. Despite this success, the use of Abs as cell-specific homing agents poses significant challenges. Ab conjugations are difficult to control and typically show poor site specificity for the conjugation and inconsistent binding affinity. The antibody-based drugdelivery system also tends to be immunogenic, so it requires extra humanization steps, which make it more difficult for clinical application. Nucleic acid based aptamers provide excellent alternatives to antibodies as cell-specific agents. They are singlestranded oligonucleotides identified through an in vitro selection process, termed system evolution of ligands by exponential enrichment (SELEX), to bind the target molecules selectively. 12] Many aptamers identified by SELEX have nearly identical binding affinity and specificity to those of Abs. Aptamers are much easier to prepare and to scale up. They are generally considered nonimmunogenic and can be gradually degraded by nucleases and cleared from the blood to cause minimal system toxicity. Functionalizations of aptamers to facilitate site-specific conjugation are also straightforward. Thus, aptamers are promising targeting ligands and have been used in targeted drug-delivery systems, most of which are block-copolymer nanoparticles. Although these new nanotechnology-based platforms look promising, the clinical benefit of nanoparticles for targeted cancer therapy is yet to be demonstrated. Liposomes are by far the most successful drug-delivery systems; a number of liposome-based systems have been approved by the US Food and Drug Administration for disease treatment in the clinic. Liposomes have been shown to increase the plasma residence time of aptamers. Previous efforts on liposomal drug delivery have focused on developing long-circulating liposomes that target cancerous tumor tissues through the enhanced permeation and retention (EPR) effect, 34] a passive targeting mechanism. However, cancer targeting entirely based on EPR still has undesirable systemic side effects and suboptimal antitumor efficacy: clinical studies of a cisplatin-containing liposome showed only poor to moderate therapeutic efficacy. 38] Delivery vehicles with active tumor-targeting capability could, in principle, improve this significantly. Personalized chemotherapy is an unmet challenge in cancer treatment. Despite the existence of rough empirical dosage guidelines, the individual patient response can deviate strongly from average behavior. This problem is especially acute for chemotherapy agents, for which drug overdosage can have severe consequences. At present, once an initial dosage is administered, the side effects and drug effectiveness can no longer be modulated if there are no “antidotes” to the treatment. However, the discovery of good antidotes or neutralizers for each individual drug molecule is not an easy task, if even practical. Moreover, there are no known ways to “multiplex” different antidotes to control complex treatment profiles with multiple drugs. We report here the controlled formulation of aptamerconjugated, cisplatin-encapsulating multifunctional liposomes. Cancer-cell-specific targeting and drug delivery are demonstrated by using this delivery platform. Furthermore, we also show for the first time that a complementary DNA (cDNA) of the aptamer can function as an antidote to disrupt [*] R. Tong, A. Mishra, Prof. G. C. L. Wong, Prof. J. Cheng, Prof. Y. Lu Department of Materials Science and Engineering University of Illinois at Urbana-Champaign 1304 W. Green Street, Urbana, IL 61801 (USA) Fax: (+ 1)217-333-2736 E-mail: gclwong@illinois.edu jianjunc@illinois.edu Homepage: http://www.matse.illinois.edu/faculty/wong/profile.html http://www.matse.illinois.edu/faculty/cheng/profile.html Dr. Z. Cao, W. Xu, Prof. Y. Lu Department of Chemistry University of Illinois at Urbana-Champaign 600 S. Mathews Avenue, Urbana, IL 61801 (USA) Fax: (+ 1)217-244-3186 E-mail: yi-lu@illinois.eduyi-lu@illinois.edu Homepage: http://www.chemistry.illinois.edu/faculty/Yi_Lu.html [] Z.C. and R.T. contributed equally to this work.

Anticancer Polymeric Nanomedicines

Polymers play important roles in the design of delivery nanocarriers for cancer therapies. Polymeric nanocarriers with anticancer drugs conjugated or encapsulated, also known as polymeric nanomedicines, form a variety of different architectures including polymer‐drug conjugates, micelles, nanospheres, nanogels, vesicles, and dendrimers. This review focuses on the current state of the preclinical and clinical investigations of polymer‐drug conjugates and polymeric micelles. Recent progress achieved in some promising fields, such as site‐specific protein conjugation, pH‐sensitive polymer‐drug conjugates, polymer nanoparticles for targeted cancer therapy, stimuli‐responsive polymeric micelles, polymeric vesicles, and dendrimer‐based anticancer nanomedicines, will be highlighted.

Translocation of HIV TAT peptide and analogues induced by multiplexed membrane and cytoskeletal interactions

Cell-penetrating peptides (CPPs), such as the HIV TAT peptide, are able to translocate across cellular membranes efficiently. A number of mechanisms, from direct entry to various endocytotic mechanisms (both receptor independent and receptor dependent), have been observed but how these specific amino acid sequences accomplish these effects is unknown. We show how CPP sequences can multiplex interactions with the membrane, the actin cytoskeleton, and cell-surface receptors to facilitate different translocation pathways under different conditions. Using “nunchuck” CPPs, we demonstrate that CPPs permeabilize membranes by generating topologically active saddle-splay (“negative Gaussian”) membrane curvature through multidentate hydrogen bonding of lipid head groups. This requirement for negative Gaussian curvature constrains but underdetermines the amino acid content of CPPs. We observe that in most CPP sequences decreasing arginine content is offset by a simultaneous increase in lysine and hydrophobic content. Moreover, by densely organizing cationic residues while satisfying the above constraint, TAT peptide is able to combine cytoskeletal remodeling activity with membrane translocation activity. We show that the TAT peptide can induce structural changes reminiscent of macropinocytosis in actin-encapsulated giant vesicles without receptors.

Spatiotemporal controlled delivery of nanoparticles to injured vasculature.

There are a number of challenges associated with designing nanoparticles for medical applications. We define two challenges here: (i) conventional targeting against up-regulated cell surface antigens is limited by heterogeneity in expression, and (ii) previous studies suggest that the optimal size of nanoparticles designed for systemic delivery is approximately 50–150 nm, yet this size range confers a high surface area-to-volume ratio, which results in fast diffusive drug release. Here, we achieve spatial control by biopanning a phage library to discover materials that target abundant vascular antigens exposed in disease. Next, we achieve temporal control by designing 60-nm hybrid nanoparticles with a lipid shell interface surrounding a polymer core, which is loaded with slow-eluting conjugates of paclitaxel for controlled ester hydrolysis and drug release over approximately 12 days. The nanoparticles inhibited human aortic smooth muscle cell proliferation in vitro and showed greater in vivo vascular retention during percutaneous angioplasty over nontargeted controls. This nanoparticle technology may potentially be used toward the treatment of injured vasculature, a clinical problem of primary importance.

Photoswitchable nanoparticles for in vivo cancer chemotherapy

Significance The importance of this research is in the demonstration of the effectiveness and improved safety of a nanoparticulate chemotherapeutic formulation that can be phototriggered to shrink in size at the tumor site. That shrinkage enhanced nanoparticle penetration into tumors and also triggered local drug release. The result was increased efficacy and reduced systemic toxicity. The phototriggered formulation also relieved the compression of tumor blood vessels, which is a recognized barrier to nanoparticle accumulation in tumors. There are many obstacles to effective cancer chemotherapy, including drug penetration and accumulation in tumors and drug systemic toxicity. The penetration of therapies into tumors is limited by the dense tumor matrix and by compression of the tumor vasculature. We have developed spiropyran-based nanoparticles that shrink from 103 to 49 nm upon irradiation at 365 nm. That shrinkage enhanced tissue penetration and drug release. Irradiation of s.c. HT-1080 tumors in nude mice administered i.v. docetaxel-containing nanoparticles was more effective treatment than free docetaxel or encapsulated docetaxel without irradiation. Irradiation at the tumor site also resulted in less systemic toxicity than if the nanoparticles were irradiated before injection, presumably because of less systemically distributed free drug. The enhanced efficacy of nanoparticles in irradiated tumors may have been related to the observed enhanced tumor penetration by nanoparticles and decompression of tumor blood vessels, which may also increase nanoparticle delivery into tumors.

The formulation of aptamer-coated paclitaxel―polylactide nanoconjugates and their targeting to cancer cells

Paclitaxel-polylactide (Ptxl-PLA) conjugate nanoparticles, termed as nanoconjugates (NCs), were prepared through Ptxl/(BDI)ZnN(TMS)(2) (BDI = 2-((2,6-diisopropylphenyl)-amido)-4-((2,6-diisopropylphenyl)-imino)-2-pentene)-mediated controlled polymerization of lactide (LA) followed by nanoprecipitation. Nanoprecipitation of Ptxl-PLA resulted in sub-100 nm NCs with monomodal particle distributions and low polydispersities. The sizes of Ptxl-PLA NCs could be precisely controlled by using appropriate water-miscible solvents and by controlling the concentration of Ptxl-PLA during nanoprecipitation. Co-precipitation of a mixture of PLA-PEG-PLA (PLA = 14 kDa; PEG = 5 kDa) and Ptxl-PLA in PBS resulted in NCs that could stay non-aggregated in PBS for an extended period of time. To develop solid formulations of NCs, we evaluated a series of lyoprotectants, aiming to identify candidates that could effectively reduce or eliminate NC aggregation during lyophilization. Albumin was found to be an excellent lyoprotectant for the preparation of NCs in solid form, allowing lyophilized NCs to be readily dispersed in PBS without noticeable aggregates. Aptamer-NCs bioconjugates were prepared and found to be able to effectively target prostate-specific membrane antigen in a cell-specific manner.

Polylactide-cyclosporin A nanoparticles for targeted immunosuppression

Polymeric nanoparticles (NPs), prepared via coprecipitation of drugs and polymers, are promising drug delivery vehicles for treating diseases with improved efficacy and reduced toxicity. Here, we report an unprecedented strategy for preparing polylactide‐cyclosporine A (PLA‐CsA) NPs (termed CsA‐NPs) through CsA‐initiated ring‐opening polymerization of lactide (LA) followed by nanoprecipitation. The resulting CsA‐NPs have sub‐100 nm sizes and narrow particle size distributions, and release CsA in a sustained manner without a “burst”‐release effect. Both free CsA and CsA‐NPs displayed comparable suppression of T‐cell proliferation and production of inflammatory cytokines in various T‐cell assays in a dose‐dependent manner. The IC50 values for CsA and CsA‐NPs were 27.5 and 72.0 ng/ml, respectively. As lymph nodes are the main loci for T‐cell activation, we coupled dendritic cells (DCs) with CsA‐NPs and successfully delivered CsA selectively to the lymph nodes. Our studies indicated that CsA‐NPs could be internalized in the DCs with a sustained release of CsA to the culture medium, suppressing alloreactive T‐cell proliferation. Allogeneic DCs loaded with CsA‐NPs were able to migrate to the draining lymph nodes where the T‐cell priming was significantly reduced without any systemic release. This innovative nanoparticulate CsA delivery technology constitutes a strong basis for future targeted delivery of immunosuppressive drugs with improved efficiency and reduced toxicity.—Azzi, J., Tang, L., Tong, R., El Haddad, N., Akiyoshi, T., Mfarrej, B., Moore, R., Yang, S., Jurewicz, M., Ichimura, T., Lindeman, N., Cheng, J., Abdi, R. Polylactide‐cyclosporin A nanoparticles for targeted immunosuppression. FASEB J. 24, 3927–3938 (2010). www.fasebj.org

Shedding light on nanomedicine

Light is an electromagnetic radiation that can convert its energy into different forms (e.g., heat, chemical energy, and acoustic waves). This property has been exploited in phototherapy (e.g., photothermal therapy and photodynamic therapy (PDT)) and optical imaging (e.g., fluorescence imaging) for therapeutic and diagnostic purposes. Light-controlled therapies can provide minimally- or noninvasive spatiotemporal control as well as deep tissue penetration. Nanotechnology provides numerous advantages, including selective targeting of tissues, prolongation of therapeutic effect, protection of active payloads, and improved therapeutic indices. This review explores the advances that nanotechnology can bring to light-based therapies and diagnostics, and vice versa, including photo-triggered systems, nanoparticles containing photoactive molecules, and nanoparticles that are themselves photoactive. Limitations of light-based therapies such as photic injury and phototoxicity are discussed.

Targeting tumor vasculature with aptamer-functionalized doxorubicin-polylactide nanoconjugates for enhanced cancer therapy

An A10 aptamer (Apt)-functionalized, sub-100 nm doxorubicin-polylactide (Doxo-PLA) nanoconjugate (NC) with controlled release profile was developed as an intravenous therapeutic strategy to effectively target and cytoreduce canine hemangiosarcoma (cHSA), a naturally occurring solid tumor malignancy composed solely of tumor-associated endothelium. cHSA consists of a pure population of malignant endothelial cells expressing prostate-specific membrane antigen (PSMA) and is an ideal comparative tumor model system for evaluating the specificity and feasibility of tumor-associated endothelial cell targeting by A10 Apt-functionalized NC (A10 NC). In vitro, A10 NCs were selectively internalized across a panel of PSMA-expressing cancer cell lines, and when incorporating Doxo, A10 Doxo-PLA NCs exerted greater cytotoxic effects compared to nonfunctionalized Doxo-PLA NCs and free Doxo. Importantly, intravenously delivered A10 NCs selectively targeted PSMA-expressing tumor-associated endothelial cells at a cellular level in tumor-bearing mice and dramatically increased the uptake of NCs by endothelial cells within the local tumor microenvironment. By virtue of controlled drug release kinetics and selective tumor-associated endothelial cell targeting, A10 Doxo-PLA NCs possess a desirable safety profile in vivo, being well-tolerated following high-dose intravenous infusion in mice, as supported by the absence of any histologic organ toxicity. In cHSA-implanted mice, two consecutive intravenous infusions of A10 Doxo-PLA NCs exerted rapid and substantial cytoreductive activities within a period of 7 days, resulting in greater than 70% reduction in macroscopic tumor-associated endothelial cell burden as a consequence of enhanced cell death and necrosis.