Jinming Gao

Nanonization strategies for poorly water-soluble drugs.

Poor water solubility for many drugs and drug candidates remains a major obstacle to their development and clinical application. Conventional formulations to improve solubility suffer from low bioavailability and poor pharmacokinetics, with some carriers rendering systemic toxicities (e.g. Cremophor(®) EL). In this review, several major nanonization techniques that seek to overcome these limitations for drug solubilization are presented. Strategies including drug nanocrystals, nanoemulsions and polymeric micelles are reviewed. Finally, perspectives on existing challenges and future opportunities are highlighted.

Surface hydrolysis of poly(glycolic acid) meshes increases the seeding density of vascular smooth muscle cells

A procedure for surface hydrolysis of poly(glycolic acid) (PGA) meshes was developed to increase cell seeding density and improve attachment of vascular smooth muscle cells. Hydrolysis of PGA in 1N NaOH transformed ester groups on the surface of PGA fibers to carboxylic acid and hydroxyl groups. After hydrolysis, the polymer scaffold retained its original gross appearance and dimensions while the fiber diameter decreased. A plot of fiber diameter versus the hydrolysis time showed a linear relationship, with a rate of decrease in fiber diameter of 0.65 microm/min. The molecular weight and thermal properties of the polymer did not change significantly following surface hydrolysis. In cell seeding experiments, surface-hydrolyzed mesh was seeded with more than twice as many cells as unmodified PGA mesh. Vascular smooth muscle cells attached to the surface-hydrolyzed PGA mesh both as individual cells and as cell aggregates while only cell aggregates were observed on the unmodified mesh. Control experiments indicated that adsorption of serum proteins onto the surface-hydrolyzed PGA fibers was correlated with the increase in cell seeding density. These results demonstrate that optimization of biomaterial-cell interactions provides a strategy for increasing the initial cell seeding density for the engineering of tissues of high cell density.

Theranostic nanomedicine for cancer

Baran Sumer1, Jinming Gao2† †Author for correspondence 1Department of Otolaryngology, Head and Neck Surgery, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA Tel.: +1 214 648 3102; Fax: +1 214 648 2246; E-mail: baran.sumer@ utsouthwestern.edu 2Department of Pharmacology, Harold C Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75093, USA Tel.: +1 214 645 6370; Fax: +1 214 645 6347; E-mail: jinming.gao@ utsouthwestern.edu ‘Over recent decades, there has been explosive development of a variety of nanotechnology platforms to diagnose and treat cancer.’

A nanoparticle-based strategy for the imaging of a broad range of tumours by nonlinear amplification of microenvironment signals

Stimuli-responsive nanomaterials are increasingly important in a variety of applications such as biosensing, molecular imaging, drug delivery and tissue engineering. For cancer detection, a paramount challenge still exists in search of methods that can illuminate tumors universally regardless of their genotypes and phenotypes. Here we capitalized on the acidic, angiogenic tumor microenvironment to achieve broad detection of tumor tissues in a wide variety of mouse cancer models. This was accomplished using ultra-pH sensitive fluorescent nanoprobes that have tunable, exponential fluorescence activation upon encountering subtle, physiologically relevant pH transitions. These nanoprobes were silent in the circulation, then dramatically activated (>300 fold) in response to neovasculature or to the low extracellular pH in tumors. Thus, we have established non-toxic, fluorescent nanoreporters that can non-linearly amplify tumor microenvironmental signals, permitting identification of tumor tissue independently of histological type or driver mutation, and detection of acute treatment responses much more rapidly than conventional imaging approaches.

Tunable, Ultrasensitive pH-Responsive Nanoparticles Targeting Specific Endocytic Organelles in Living Cells†

In recent years, multifunctional nanoparticles have received considerable attention in many applications such as biosensors, diagnostic nanoprobes and targeted drug delivery.[1] These efforts have been driven to a large extent by the need to improve biological specificity in diagnosis and therapy through the precise, spatio-temporal control of agent delivery. In order to achieve this goal, continuous efforts have been dedicated to develop stimuli-responsive nanoplatforms.[2] Environmental stimuli that were exploited include pH,[3] temperature,[4] enzymatic expression,[5] redox reaction[6] and light induction.[7] Among these activating signals, pH trigger is one of the most extensively studied stimuli based on two types of pH differences: (a) pathological (e.g. tumor) vs. normal tissues and (b) acidic intracellular compartments.[8] For example, due to the unusual acidity of the tumor extracellular microenvironment (pHe ≈ 6.5), several pHe-responsive nanosystems were reported to increase the sensitivity of tumor imaging or the efficacy of therapy.[9]

Multifunctional micellar nanomedicine for cancer therapy.

Polymeric micelles are supramolecular, core-shell nanoparticles that offer considerable advantages for cancer diagnosis and therapy. Their relatively small size (10–100 nm), ability to solubilize hydrophobic drugs as well as imaging agents, and improved pharmacokinetics provide a useful bioengineering platform for cancer applications. Several polymeric micelle formulations are currently undergoing phase I/II clinical trials, which have shown improved antitumor efficacy and reduced systemic toxicity. This minireview will focus on recent advancements in the multifunctional design of micellar nanomedicine with tumor targeting, stimulated drug release, and cancer imaging capabilities. Such functionalization strategies result in enhanced micellar accumulation at tumor sites, higher drug bioavailability, as well as improved tumor diagnosis and visualization of therapy. Ultimately, integrated nanotherapeutic systems (e.g., theranostic nanomedicine) may prove essential to address the challenges of tumor heterogeneity and adaptive resistance to achieve efficacious treatment of cancer.

An NQO1- and PARP-1-mediated cell death pathway induced in non-small-cell lung cancer cells by β-lapachone

Lung cancer is the number one cause of cancer-related deaths in the world. Patients treated with current chemotherapies for non-small-cell lung cancers (NSCLCs) have a survival rate of ≈15% after 5 years. Novel approaches are needed to treat this disease. We show elevated NAD(P)H:quinone oxidoreductase-1 (NQO1) levels in tumors from NSCLC patients. β-Lapachone, an effective chemotherapeutic and radiosensitizing agent, selectively killed NSCLC cells that expressed high levels of NQO1. Isogenic H596 NSCLC cells that lacked or expressed NQO1 along with A549 NSCLC cells treated with or without dicoumarol, were used to elucidate the mechanism of action and optimal therapeutic window of β-lapachone. NSCLC cells were killed in an NQO1-dependent manner by β-lapachone (LD50, ≈4 μM) with a minimum 2-h exposure. Kinetically, β-lapachone-induced cell death was characterized by the following: (i) dramatic reactive oxygen species (ROS) formation, eliciting extensive DNA damage; (ii) hyperactivation of poly(ADP-ribose)polymerase-1 (PARP-1); (iii) depletion of NAD+/ATP levels; and (iv) proteolytic cleavage of p53/PARP-1, indicating μ-calpain activation and apoptosis. β-Lapachone-induced PARP-1 hyperactivation, nucleotide depletion, and apoptosis were blocked by 3-aminobenzamide, a PARP-1 inhibitor, and 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid acetoxymethyl ester (BAPTA-AM), a Ca2+ chelator. NQO1− cells (H596, IMR-90) or dicoumarol-exposed NQO1+ A549 cells were resistant (LD50, >40 μM) to ROS formation and all cytotoxic effects of β-lapachone. Our data indicate that the most efficacious strategy using β-lapachone in chemotherapy was to deliver the drug in short pulses, greatly reducing cytotoxicity to NQO1− “normal” cells. β-Lapachone killed cells in a tumorselective manner and is indicated for use against NQO1+ NSCLC cancers.

The synergistic effect of hierarchical assemblies of siRNA and chemotherapeutic drugs co-delivered into hepatic cancer cells.

Diblock copolymers (PEI-PCL) of poly(ε-caprolactone) (PCL) and linear poly(ethylene imine) (PEI) were synthesized and assembled to biodegradable nano-carriers for co-delivery of BCL-2 siRNA and doxorubicin (DOX). Folic acid as a tumor-targeting ligand was conjugated to the polyanion, poly(ethylene glycol)-block-poly(glutamic acid) (FA-PEG-PGA). Driven by the electrostatic interaction, FA-PEG-PGA was coated onto the surface of the cationic PEI-PCL nanoparticles pre-loaded with siRNA and DOX, potentiating a ligand-directed delivery to human hepatic cancer cells Bel-7402. At certain N/P and C/N ratios (N/P: PEI-PCL nitrogen to siRNA phosphate; C/N: FA-PEG-PGA carboxyl to PEI-PCL amine), the nanoparticles exhibited not only high transfection efficiency but also ideally controlled release of drug. Compared to non-specific delivery, the folate-targeted delivery of BCL-2 siRNA resulted in more significant gene suppression at both the BCL-2 mRNA and protein expression levels, inducing cancer cell apoptosis and improving the therapeutic efficacy of the co-administered DOX. Herein we demonstrated that co-loading siRNA and small molecular drug in a multifunctional hierarchical nano-assembly enabled simultaneously delivering siRNA and drug into the same cancer cells, yielding synergistic effect of RNA interference and chemotherapy in cancer.

MRI-Visible Micellar Nanomedicine for Targeted Drug Delivery to Lung Cancer Cells

Polymeric micelles are emerging as a highly integrated nanoplatform for cancer targeting, drug delivery and tumor imaging applications. In this study, we describe a multifunctional micelle (MFM) system that is encoded with a lung cancer-targeting peptide (LCP), and encapsulated with superparamagnetic iron oxide (SPIO) and doxorubicin (Doxo) for MR imaging and therapeutic delivery, respectively. The LCP-encoded MFM showed significantly increased alpha(v)beta(6)-dependent cell targeting in H2009 lung cancer cells over a scrambled peptide (SP)-encoded MFM control as well as in an alpha(v)beta(6)-negative H460 cell control. (3)H-Labeled MFM nanoparticles were used to quantify the time- and dose-dependent cell uptake of MFM nanoparticles with different peptide encoding (LCP vs SP) and surface densities (20% and 40%) in H2009 cells. LCP functionalization of the micelle surface increased uptake of the MFM by more than 3-fold compared to the SP control. These results were confirmed by confocal laser scanning microscopy, which further demonstrated the successful Doxo release from MFM and accumulation in the nucleus. SPIO clustering inside the micelle core resulted in high T(2) relaxivity (>400 Fe mM(-1) s(-1)) of the resulting MFM nanoparticles. T(2)-weighted MRI images showed clear contrast differences between H2009 cells incubated with LCP-encoded MFM over the SP-encoded MFM control. An ATP activity assay showed increased cytotoxicity of LCP-encoded MFM over SP-encoded MFM in H2009 cells (IC(50) values were 28.3 +/- 6.4 nM and 73.6 +/- 6.3 nM, respectively; p < 0.005). The integrated diagnostic and therapeutic design of MFM nanomedicine potentially allows for image-guided, target-specific treatment of lung cancer.

Polymeric nanomedicine for cancer MR imaging and drug delivery

Multifunctional nanomedicine is emerging as a highly integrated platform that allows for molecular diagnosis, targeted drug delivery, and simultaneous monitoring and treatment of cancer. Advances in polymer and materials science are critical for the successful development of these multi-component nanocomposites in one particulate system with such a small size confinement (<200 nm). Currently, several nanoscopic therapeutic and diagnostic systems have been translated into clinical practice. In this feature article, we will provide an up-to-date review on the development and biomedical applications of nanocomposite materials for cancer diagnosis and therapy. An overview of each functional component, i.e. polymer carriers, MR imaging agents, and therapeutic drugs, will be presented. Integration of different functional components will be illustrated in several highlighted examples to demonstrate the synergy of the multifunctional nanomedicine design.