Nanoparticle-aptamer Bioconjugates Research Articles

Abstract IA18: Targeted polymeric nanoparticles: From academic innovations to clinical trials and lessons learned

Abstract A variety of organic and inorganic materials have been utilized to generate nanoparticles for drug delivery applications, including polymeric nanoparticles, dendrimers, nanoshells, liposomes, nucleic acid based nanoparticles, magnetic nanoparticles, and virus nanoparticles. The two most commonly used systems are polymeric nanoparticles and liposomes [1, 2]. Controlled release polymer technology has impacted virtually every branch of medicine, including ophthalmology, pulmonary, pain medicine, endocrinology, cardiology, orthopedics, immunology, neurology and dentistry, with several of these systems in clinical practice today such as Atridox, Lupron Depot, Gliadel, Zoladex, Trelstart Depot, Risperidol Consta and Sandostatin LAR. The annual worldwide market of controlled release polymer systems which extends beyond drug delivery is now estimated at $100 billion and these systems are used by over 100 million people each year. Polymeric nanoparticles can deliver drugs in the optimum dosage over time, thus increasing the efficacy of the drug, maximizing patient compliance and enhancing the ability to use highly toxic, poorly soluble, or relatively unstable drugs. These systems can also be used to co-deliver two or more drugs for combination therapy [3]. The surface engineering of these nanoparticles may yield them “stealth” to prolong their residence in blood [4] and the functionalization of these particles with targeting ligands can differentially target their delivery or uptake by a subset of cells [5], further increasing their specificity and efficacy [6]. The successful clinical translation of therapeutic nanoparticles requires optimization of many distinct parameters including: variation in the composition of the carrier system, drug loading efficiency, surface hydrophilicity, surface charge, particle size, density of possible ligands for targeting, etc., resulting in a large number of potential variables for optimization which is impractical to achieve using a low throughput approach. More recently combinatorial approaches have been developed to precisely engineer nanoparticles and screen multiple nanoparticle characteristics simultaneously with the goal of identifying formulations with the desired physical and biochemical properties for each specific application [7]. The goal of this talk is to review our efforts in the design and optimization of polymeric nanoparticles for medical applications, which formed the foundation for the clinical translation of the first-in-human targeted and controlled-release nanoparticles, BIND-014 and SEL-068 [8, 9].

Polydopamine-Based Surface Modification of Novel Nanoparticle-Aptamer Bioconjugates for In Vivo Breast Cancer Targeting and Enhanced Therapeutic Effects.

In this study, we reported a simple polydopamine (pD)-based surface modification method to prepare novel nanoparticle-aptamer bioconjugates (Apt-pD-DTX/NPs) for in vivo tumor targeting and enhanced therapeutic effects of breast cancer. With simple preparation procedures, the new functionalized Apt-pD-DTX/NPs could maximumly increase the local effective drug concentration on tumor sites, achieving enhanced treatment effectiveness and minimizing side effects. The dopamine polymerization and aptamer conjugation barely changed the characters of NPs. Both in vitro cell experiments (i.e. endocytosis of fluorescent NPs, in vitro cellular targeting and cytotoxicity assays) and in vivo animal studies (i.e. in vivo imaging, biodistribution and antitumor effects of NPs) demonstrated that the Apt-pD-DTX/NPs could achieve significantly high targeting efficiency and enhanced therapeutic effects compared with clinical Taxotere® and NPs without functional modification. Above all, the Apt-pD-DTX/NPs showed great potential as a promising nanoformulation for in vivo breast cancer therapy and the construction of pD-modified NP-aptamer bioconjugates could be of great value in medical use.

A cancer cell-activatable aptamer-reporter system for one-step assay of circulating tumor cells.

The current antibody-mediated numeration assays of circulating tumor cells (CTCs) require multiple steps and are time-consuming. To overcome these technical limitations, a cancer cell-activatable aptamer-reporter was formulated by conjugating a biomarker-specific aptamer sequence with paired fluorochrome-quencher molecules. In contrast to the antibody probes, the intact aptamer-reporter was optically silent in the absence of cells of interest. However, when used in an assay, the aptamer selectively targeted cancer cells through interaction with a specific surface biomarker, which triggered internalization of the aptamer-reporter and, subsequently, into cell lysosomes. Rapid lysosomal degradation of the aptamer-reporter resulted in separation of the paired fluorochrome-quencher molecules. The released fluorochrome emitted bright fluorescent signals exclusively within the targeted cancer cells, with no background noise in the assay. Thus, the assays could be completed in a single step within minutes. By using this one-step assay, CTCs in whole blood and marrow aspirate samples of patients with lymphoma tumors were selectively highlighted and rapidly detected with no off-target signals from background blood cells. The development of the cancer cell-activatable aptamer-reporter system allows for the possibility of a simple and robust point-of-care test for CTC detection, which is currently unavailable.

Targeted cancer therapies: an overview

Cancer medically known as malignant neoplasm is a group of different diseases all involving unregulated cell growth due to defects in the genetic makeup of two types of genes, i.e. oncogene, which drive the growth of cancer cells and tumor suppressor genes which prevent cancer from developing. Cancer is detected in a number of ways, including symptoms, screening tests, medical imaging and is usually treated with chemotherapy, radiation therapy and surgery. With the advancement in medical sciences, targeted cancer therapy has got lot of importance which has many benefits, comforts and patient friendly as compared to conventional therapies. This review gives an insight of the various targeted therapies, their role and impact in treatment of various types of cancers. Targeted cancer therapies like monoclonal antibodies, nanoparticle-aptamer bioconjugates, oligopeptide-based, folate-based, AdNectins, microfluidics and nanotechnology approaches have led to deliver target- oriented toxic drugs to specific cancer cells.DOI: http://dx.doi.org/10.3126/ijls.v6i1.6085

Selective Prostate Cancer Thermal Ablation With Laser Activated Gold Nanoshells

Laser activated gold nanoshell thermal ablation represents a new, minimally invasive technology that offers benign tissue sparing thermal ablation of malignant tumors. We evaluated the efficacy of this technology for eradicating prostate cancer in a subcutaneous tumor model. The 110 nm gold nanoshells with a 10 nm gold shell are designed to act as intense near infrared absorbers. PC-3 cells were injected on the dorsum of nude mice in 3 groups, including 1-gold nanoshell plus near infrared laser, 2-saline alone and 3-near infrared laser alone. Animals received 7.0 ml/gm body weight (low dose) or 8.5 ml/gm body weight (high dose) nanoshells via tail vein injection. Control animals received saline. A 810 nm near infrared laser with a 200 mu laser fiber and an energy setting of 4 W/cm(2) was aimed at the tumor bed for 3 minutes. Tumors were measured at days 0, 7, 14 and 21. Tissue temperature was monitored during laser activation. Tumors were harvested at day 21 and stained with hematoxylin and eosin, and for nicotinamide adenine dinucleotide diaphorase activity. We observed 93% tumor necrosis and regression in the high dose treated group. Nicotinamide adenine dinucleotide staining corroborated this finding. The ablation zone was sharply limited to the laser spot size. There was no difference in the size or tumor histology in control groups, indicating a benign course for near infrared laser treatment alone. Temperatures up to 65.4C were attained in the treated group. Laser activated gold nanoshell ablation is an effective and selective technique for prostate cancer ablation in an ectopic murine tumor model.

Co‐Delivery of Hydrophobic and Hydrophilic Drugs from Nanoparticle–Aptamer Bioconjugates

Apromisingapplicationofnanoparticle(NP)drugdeliverysystemsisthetargeteddeliveryoftherapeuticagentsinacell-,tissue-,ordisease-specificmanner.Thisgoalmaybeachieved by the surface-modification of NPs with antibodies,nucleic acid ligands (aptamers; Apt), peptides, or small mole-cules that bind to antigens present on the target cells or tis-sues.

Application of Nanotechnology in Cancer Research: Review of Progress in the National Cancer Institute's Alliance for Nanotechnology

Application of Nanotechnology in Cancer Research: Review of Progress in the National Cancer Institute's Alliance for Nanotechnology

Targeted nanoparticle-aptamer bioconjugates for cancer chemotherapy in vivo

Targeted uptake of therapeutic nanoparticles in a cell-, tissue-, or disease-specific manner represents a potentially powerful technology. Using prostate cancer as a model, we report docetaxel (Dtxl)-encapsulated nanoparticles formulated with biocompatible and biodegradable poly(D,L-lactic-co-glycolic acid)-block-poly(ethylene glycol) (PLGA-b-PEG) copolymer and surface functionalized with the A10 2'-fluoropyrimidine RNA aptamers that recognize the extracellular domain of the prostate-specific membrane antigen (PSMA), a well characterized antigen expressed on the surface of prostate cancer cells. These Dtxl-encapsulated nanoparticle-aptamer bioconjugates (Dtxl-NP-Apt) bind to the PSMA protein expressed on the surface of LNCaP prostate epithelial cells and get taken up by these cells resulting in significantly enhanced in vitro cellular toxicity as compared with nontargeted nanoparticles that lack the PSMA aptamer (Dtxl-NP) (P < 0.0004). The Dtxl-NP-Apt bioconjugates also exhibit remarkable efficacy and reduced toxicity as measured by mean body weight loss (BWL) in vivo [body weight loss of 7.7 +/- 4% vs. 18 +/- 5% for Dtxl-NP-Apt vs. Dtxl-NP at nadir, respectively (mean +/- SD); n = 7]. After a single intratumoral injection of Dtxl-NP-Apt bioconjugates, complete tumor reduction was observed in five of seven LNCaP xenograft nude mice (initial tumor volume of approximately 300 mm3), and 100% of these animals survived our 109-day study. In contrast, two of seven mice in the Dtxl-NP group had complete tumor reduction with 109-day survivability of only 57%. Dtxl alone had a survivability of only 14%. Saline and nanoparticles without drug were similarly nonefficacious. This report demonstrates the potential utility of nanoparticle-aptamer bioconjugates for a therapeutic application.

Nanoparticle-Aptamer Bioconjugates for Targeted Antineoplastic Drug Delivery

Targeted drug delivery technologies can provide physicians with new approaches to treat and manage patients with cancer. Nucleic acid ligands (aptamers) are a novel class of targeting molecules that can be used in a similar manner to antibodies. Beyond use as drugs themselves, aptamers have the potential to serve as targeting ligands to deliver drugs, imaging agents, or other bioactive agents to the intended site of action. Bioconjugates of nanoparticles and aptamers can selectively bind and be taken up by cancer cells. In this article we review progress to date for antineoplastic drug delivery using nanoparticle-aptamer bioconjugates.Aptamers are isolated through a process of in vitro selection, also referred to as systematic evolution of ligands by exponential enrichment (SELEX). There is an increasing numbers of aptamers for cancer targeting being reported in the literature. These aptamers often interact with antigens that are overexpressed exclusively, or preferentially, on cancer cells or in the cancer microenvironment. As novel drug delivery vehicles, nanoparticle-aptamer bioconjugates may be developed to target a myriad of diseases including many cancers by delivering a variety of therapeutic agents specifically to the site of interest.The first in vivo study of antineoplastic drug delivery by a bioconjugate employed nanoparticle encapsulating docetaxel and aptamers that bind certain prostate cancer cells. In this study using a xenograft murine model of prostate cancer, these bioconjugates were shown to significantly improve tumor reduction after intratumoral injection compared with all controls. Furthermore, the docetaxel-loaded nanoparticle-aptamer bioconjugates demonstrated reduced toxicity in terms of acute bodyweight loss compared with the controls. In vitro, the efficacy of the docetaxel-loaded nanoparticle-aptamer bioconjugate was shown to be due to intracellular delivery of the drug to the cancer cells, and the bioconjugate without the drug had no cytotoxicity.Nanoparticle-aptamer bioconjugates may prove to be useful not only for management of cancer but also various other indications. New aptamers, multivalent targeting strategies, and multimodal treatments such as simultaneous radio- and chemotherapy may further increase the efficacy of these bioconjugates and facilitate their clinical translation for therapeutic and diagnostic applications.

804 ORAL Cancer nanotechnology: drug encapsulated nanoparticle-aptamer bioconjugates for targeted delivery to prostate cancer cells

804 ORAL Cancer nanotechnology: drug encapsulated nanoparticle-aptamer bioconjugates for targeted delivery to prostate cancer cells

Nanoparticle-Aptamer Bioconjugates

Nucleic acid ligands (aptamers) are potentially well suited for the therapeutic targeting of drug encapsulated controlled release polymer particles in a cell- or tissue-specific manner. We synthesized a bioconjugate composed of controlled release polymer nanoparticles and aptamers and examined its efficacy for targeted delivery to prostate cancer cells. Specifically, we synthesized poly(lactic acid)-block-polyethylene glycol (PEG) copolymer with a terminal carboxylic acid functional group (PLA-PEG-COOH), and encapsulated rhodamine-labeled dextran (as a model drug) within PLA-PEG-COOH nanoparticles. These nanoparticles have the following desirable characteristics: (a) negative surface charge (-50 +/- 3 mV, mean +/- SD, n = 3), which may minimize nonspecific interaction with the negatively charged nucleic acid aptamers; (b) carboxylic acid groups on the particle surface for potential modification and covalent conjugation to amine-modified aptamers; and (c) presence of PEG on particle surface, which enhances circulating half-life while contributing to decreased uptake in nontargeted cells. Next, we generated nanoparticle-aptamer bioconjugates with RNA aptamers that bind to the prostate-specific membrane antigen, a well-known prostate cancer tumor marker that is overexpressed on prostate acinar epithelial cells. We demonstrated that these bioconjugates can efficiently target and get taken up by the prostate LNCaP epithelial cells, which express the prostate-specific membrane antigen protein (77-fold increase in binding versus control, n = 150 cells per group). In contrast to LNCaP cells, the uptake of these particles is not enhanced in cells that do not express the prostate-specific membrane antigen protein. To our knowledge, this represents the first report of targeted drug delivery with nanoparticle-aptamer bioconjugates.