Multimodality imaging in vivo for preclinical assessment of tumor-targeted doxorubicin nanoparticles

Adenovirus-Derived Nano-Capsid Platforms for Targeted Delivery and Penetration of Macromolecules into Resistant and Metastatic Tumors

Macromolecular therapeutics such as nucleic acids, peptides, and proteins have the potential to overcome treatment barriers for cancer. For example, nucleic acid or peptide biologics may offer an alternative strategy for attacking otherwise undruggable therapeutic targets such as transcription factors and similar oncologic drivers. Delivery of biological therapeutics into tumor cells requires a robust system of cell penetration to access therapeutic targets within the cell interior. A highly effective means of accomplishing this may be borrowed from cell-penetrating pathogens such as viruses. In particular, the cell entry function of the adenovirus penton base capsid protein has been effective at penetrating tumor cells for the intracellular deposition of macromolecular therapies and membrane-impermeable drugs. Here, we provide an overview describing the evolution of tumor-targeted penton-base-derived nano-capsids as a framework for discussing the requirements for overcoming key barriers to macromolecular delivery. The development and pre-clinical testing of these proteins for therapeutic delivery has begun to also uncover the elusive mechanism underlying the membrane-penetrating function of the penton base. An understanding of this mechanism may unlock the potential for macromolecular therapeutics to be effectively delivered into cancer cells and to provide a treatment option for tumors resisting current clinical therapies.

Types of spectroscopy and microscopy techniques for cancer diagnosis: a review

Cancer is a life-threatening disease that has claimed the lives of many people worldwide. With the current diagnostic methods, it is hard to determine cancer at an early stage, due to its versatile nature and lack of genomic biomarkers. The rapid development of biophotonics has emerged as a potential tool in cancer detection and diagnosis. Using the fluorescence, scattering, and absorption characteristics of cells and tissues, it is possible to detect cancer at an early stage. The diagnostic techniques addressed in this review are highly sensitive to the chemical and morphological changes in the cell and tissue during disease progression. These changes alter the fluorescence signal of the cell/tissue and are detected using spectroscopy and microscopy techniques including confocal and two-photon fluorescence (TPF). Further, second harmonic generation (SHG) microscopy reveals the morphological changes that occurred in non-centrosymmetric structures in the tissue, such as collagen. Again, Raman spectroscopy is a non-destructive method that provides a fingerprinting technique to differentiate benign and malignant tissue based on Raman signal. Photoacoustic microscopy and spectroscopy of tissue allow molecule-specific detection with high spatial resolution and penetration depth. In addition, terahertz spectroscopic studies reveal the variation of tissue water content during disease progression. In this review, we address the applications of spectroscopic and microscopic techniques for cancer detection based on the optical properties of the tissue. The discussed state-of-the-art techniques successfully determines malignancy to its rapid diagnosis.

Biomedical Applications of Translational Optical Imaging: From Molecules to Humans

Light is a powerful investigational tool in biomedicine, at all levels of structural organization. Its multitude of features (intensity, wavelength, polarization, interference, coherence, timing, non-linear absorption, and even interactions with itself) able to create contrast, and thus images that detail the makeup and functioning of the living state can and should be combined for maximum effect, especially if one seeks simultaneously high spatiotemporal resolution and discrimination ability within a living organism. The resulting high relevance should be directed towards a better understanding, detection of abnormalities, and ultimately cogent, precise, and effective intervention. The new optical methods and their combinations needed to address modern surgery in the operating room of the future, and major diseases such as cancer and neurodegeneration are reviewed here, with emphasis on our own work and highlighting selected applications focusing on quantitation, early detection, treatment assessment, and clinical relevance, and more generally matching the quality of the optical detection approach to the complexity of the disease. This should provide guidance for future advanced theranostics, emphasizing a tighter coupling-spatially and temporally-between detection, diagnosis, and treatment, in the hope that technologic sophistication such as that of a Mars rover can be translationally deployed in the clinic, for saving and improving lives.

Rapid and label-free cancer theranostics via in situ bio-self-assembled DNA-gold nanostructures loaded exosomes

Chemically engineered nanomaterials have been extensively used in early tumor detection and cancer therapy. Despite the promise shown, their chemical or exogenous nature hinders their application due to their unknown adverse effects. Herein, using a cancer cell environment, fluorescent DNA-gold nanostructures were bio-self-assembled through simple incubation of DNA and Au solutions with cancer cells. In situ, ex vivo, bio-responsive self-assembly of ring-shaped DNA-Au nanostructures is reported for the first time. Subsequently, the exosomes released by the above-mentioned cancer cells were found to carry the self-assembled DNA-Au nanostructures, exhibiting strong in vivo dual fluorescence properties. Interestingly, these exosomes could be immediately taken up in vitro by their parent cells, reaching the nucleus within 10 min after incubation. Taking advantage of the unique endogenous properties of exosomes, and their advanced cargo delivery capacity, we further exploited the DNA-Au nanostructure loaded exosomes with mitoxantrone for accurate cancer theranostics. The in vitro and in vivo results showed that the exosomes could effectively deliver the drug cargo to cancerous cells, hence, displaying an enhanced targeting effect towards parent cancer cells, and a synergistic tumor inhibition effect, while showing great biocompatibility towards normal cells and vital organs. Hence, exosomes carrying the in situ bio-self-assembled DNA-Au nanostructures could be an outstanding delivery system for dye-free targeted cancer detection and therapy.

Development of an embedded multimodality imaging platform for onco-pharmacology using a smart anticancer prodrug as an example

Increasingly, in vivo imaging holds a strategic position in bio-pharmaceutical innovation. We will present the implementation of an integrated multimodal imaging setup enabling the assessment of multiple, complementary parameters. The system allows the fusion of information provided by: Near infrared fluorescent biomarkers, bioluminescence (for tumor proliferation status), Photoacoustic and Ultrasound imaging. We will study representative applications to the development of a smart prodrug, delivering a highly cytotoxic chemotherapeutic agent to cancer tumors. The results realized the ability of this embedded, multimodality imaging platform to firstly detect bioluminescent and fluorescent signals, and secondly, record ultrasound and photoacoustic data from the same animal. This study demonstrated that the prodrug was effective in three different models of hypoxia in human cancers compared to the parental cytotoxic agent and the vehicle groups. Monitoring by photoacoustic imaging during the treatments revealed that the prodrug exhibits an intrinsic capability to prevent the progression of tumor hypoxia. It is essential for onco-pharmacology studies to precisely document the hypoxic status of tumors both before and during the time course of treatments. This approach opens new perspectives for exploitation of preclinical mouse models of cancer, especially when considering associations between hypoxia, neoangiogenesis and antitumor activity.

Doxorubicin-loaded quaternary ammonium palmitoyl glycol chitosan polymeric nanoformulation: uptake by cells and organs

PURPOSE

This study was aimed to develop doxorubicin-loaded quaternary ammonium palmitoyl glycol chitosan (DOX-GCPQ) nanoformulation that could enable DOX delivery and noninvasive monitoring of drug accumulation and biodistribution at tumor site utilizing self-florescent property of doxorubicin.

MATERIALS AND METHODS

DOX-GCPQ amphiphilic polymeric nanoformulations were prepared and optimized using artificial neural network (ANN) and characterized for surface morphology by atomic force microscopy, particle size with polydispersity index (PDI), and zeta potential by dynamic light scattering. Fourier transformed infrared (FTIR) and X-ray diffractometer studies were performed to examine drug polymer interaction. The ANN-optimized nanoformulation was investigated for in vitro release, cellular, tumor, and tissue uptake.

RESULTS

The optimized DOX-GCPQ nanoformulation was anionic spherical micelles with the hydrodynamic particle size of 97.8±1.5 nm, the PDI of <0.3, the zeta potential of 28±2 mV, and the encapsulation efficiency of 80%±1.5%. Nanoformulation demonstrated a sustained release pattern over 48 h, assuming Weibull model. Fluorescence microscopy revealed higher uptake of DOX-GCPQ in human rhabdomyosarcoma (RD) cells as compared to free DOX. In vitro cytotoxicity assay indicated a significant cytotoxicity of DOX-GCPQ against RD cells as compared to DOX and blank GCPQ (P<0.05). DOX-GCPQ exhibited low IC50 (1.7±0.404 µmol) when compared to that of DOX (3.0±0.968 µmol). In skin tumor xenografts, optical imaging revealed significantly lower DOX-GCPQ in heart and liver (P<0.05) and accumulated mainly in tumor (P<0.05) as compared to other tissues.

CONCLUSION

The features of nanoformulation, ie, small particle size, sustained drug release, and enhanced cellular uptake, potential to target tumor passively coupled with the possibility of monitoring of tumor localization by optical imaging may make DOX-GCPQ an efficient nanotheranostic system.

Real-Time Multimodal Bioimaging of Cancer Cells and Exosomes through Biosynthesized Iridium and Iron Nanoclusters

Multimodal bioimaging is a powerful tool for visualizing the abnormal state at the target site of the related disease. In this study, we used multimodal imaging techniques such as computed tomography, fluorescence, and magnetic resonance imaging to improve early and precise diagnosis of tumor. Herein, we reported the facile in situ biosynthesis of iridium and iron oxide nanoclusters (NCs) in cancer cells or tumor tissue. These NCs are used as a multimodal bioimaging probe to improve the image sensitivity and specificity toward the tumor. These NCs are applied for the in vivo multimodal imaging in the form of an imaging probe capable of enhancing the sensitivity of the image and specificity toward the tumor tissue. Our observation demonstrates that highly luminescent and magnetic NCs are not only biocompatible but also tumor-targeted because NC formation does not take place in normal cells and tissues. In addition, we isolated exosomes and the biosynthesized NCs internalized within exosomes, and these exosomes can be used as cancer biomarkers.

Detecting the functional complexities between high-density lipoprotein mimetics

High-density lipoprotein (HDL) is a key regulator of lipid homeostasis through its native roles like reverse cholesterol transport. The reconstitution of this natural nanoparticle (NP) has become a nexus between nanomedicine and multi-disease therapies, for which a major portion of HDL functionality is attributed to its primary scaffolding protein, apolipoprotein A1 (apoA1). ApoA1-mimetic peptides were formulated as cost-effective alternatives to apoA1-based therapies; reverse-4F (r4F) is one such peptide used as part of a nanoparticle platform. While similarities between r4F- and apoA1-based HDL-mimetic nanoparticles have been identified, key functional differences native to HDL have remained undetected. In the present study, we executed a multidisciplinary approach to uncover these differences by exploring the form, function, and medical applicability of engineered HDL-mimetic NPs (eHNPs) made from r4F (eHNP-r4F) and from apoA1 (eHNP-A1). Comparative analyses of the eHNPs through computational molecular dynamics (MD), advanced microfluidic NP synthesis and screening technologies, and in vivo animal model studies extracted distinguishable eHNP characteristics: the eHNPs share identical structural and compositional characteristics with distinct differences in NP stability and organization; eHNP-A1 could more significantly stimulate anti-inflammatory responses characteristic of the scavenger receptor class B type 1 (SR-B1) mediated pathways; and eHNP-A1 could outperform eHNP-r4F in the delivery of a model hydrophobic drug to an in vivo tumor. The biomimetic microfluidic technologies and MD simulations uniquely enabled our comparative analysis through which we determined that while eHNP-r4F is a capable NP with properties mimicking natural eHNP-A1, challenges remain in reconstituting the full functionality of NPs naturally derived from humans.

Ultrasonic RF time series for early assessment of the tumor response to chemotherapy

Ultrasound radio-frequency (RF) time series have been shown to carry tissue typing information. To evaluate the potential of RF time series for early prediction of tumor response to chemotherapy, 50MCF-7 breast cancer-bearing nude mice were randomized to receive cisplatin and paclitaxel (treatment group; n = 26) or sterile saline (control group; n = 24). Sequential ultrasound imaging was performed on days 0, 3, 6, and 8 of treatment to simultaneously collect B-mode images and RF data. Six RF time series features, slope, intercept, S1, S2, S3, and S4, were extracted during RF data analysis and contrasted with microstructural tumor changes on histopathology. Chemotherapy administration reduced tumor growth relative to control on days 6 and 8. Compared with day 0, intercept, S1, and S2 were increased while slope was decreased on days 3, 6, and 8 in the treatment group. Compared with the control group, intercept, S1, S2, S3, and S4 were increased, and slope was decreased, on days 3, 6, and 8 in the treatment group. Tumor cell density decreased significantly in the latter on day 3. We conclude that ultrasonic RF time series analysis provides a simple way to noninvasively assess the early tumor response to chemotherapy.

A Multimodal Biomicroscopic System based on High-frequency Acoustic Radiation Force Impulse and Multispectral Imaging Techniques for Tumor Characterization Ex vivo

We report a multimodal biomicroscopic system which offers high-frequency ultrasound B-mode, acoustic radiation force impulse (ARFI), and multispectral imaging for qualitative tumor characterization ex vivo. Examinations of resected tissues from diseased regions such as tumors are crucial procedures during surgical operations to treat cancer. Particularly, if tiny tumors remain at surgical sites after tumor resection, such tumors can result in unwanted outcomes, such as cancer recurrence or metastasis to other organs. To avoid this, accurate characterizations of tumors resected during surgery are necessary. To this end, we devised a multimodal biomicroscopic system including high-frequency ultrasound B-mode, ARFI, and multispectral imaging modalities to examine resected tumors with high levels of accuracy. This system was evaluated with tissue-mimicking phantoms with different mechanical properties. In addition, colorectal tumors excised from cancer patients were examined. The proposed system offers highly resolved anatomical, mechanical, chemical information pertaining to tumors, thus allowing the detection of tumor regions from the surface to deep inside tissues. These results therefore suggest that the multimodal biomicroscopic system has the potential to undertake qualitative characterizations of excised tumors ex vivo.

CXCR-4 Targeted, Short Wave Infrared (SWIR) Emitting Nanoprobes for Enhanced Deep Tissue Imaging and Micrometastatic Cancer Lesion Detection

Realizing the promise of precision medicine in cancer therapy depends on identifying and tracking cancerous growths to maximize treatment options and improve patient outcomes. This goal of early detection remains unfulfilled by current clinical imaging techniques that fail to detect lesions due to their small size and suborgan localization. With proper probes, optical imaging techniques can overcome this by identifying the molecular phenotype of tumors at both macroscopic and microscopic scales. In this study, the first use of nanophotonic short wave infrared technology is proposed to molecularly phenotype small lesions for more sensitive detection. Here, human serum albumin encapsulated rare-earth nanoparticles (ReANCs) with ligands for targeted lesion imaging are designed. AMD3100, an antagonist to CXCR4 (a classic marker of cancer metastasis) is adsorbed onto ReANCs to form functionalized ReANCs (fReANCs). fReANCs are able to preferentially accumulate in receptor positive lesions when injected intraperitoneally in a subcutaneous tumor model. fReANCs can also target subtissue microlesions at a maximum depth of 10.5 mm in a lung metastatic model of breast cancer. Internal lesions identified with fReANCs are 2.25 times smaller than those detected with ReANCs. Thus, an integrated nanoprobe detection platform is presented, which allows target-specific identification of subtissue cancerous lesions.

On the horizon: Optical imaging for cutaneous squamous cell carcinoma

BACKGROUND

Surgical resection with negative margins remains the standard of care for high-risk cutaneous squamous cell carcinoma (SCC). However, surgical management is often limited by poor intraoperative tumor visualization and inability to detect occult nodal metastasis. The inability to intraoperatively detect microscopic disease can lead to additional surgery, tumor recurrence, and decreased survival.

METHODS

A comprehensive literature review was conducted to identify studies incorporating optical imaging technology in the management of cutaneous SCC (January 1, 2000-December 1, 2014).

RESULTS

Several innovative optical imaging techniques, Raman spectroscopy, confocal microscopy, and fluorescence imaging, have been developed for intraoperative surgical guidance. Fifty-seven studies review the ability of these techniques to improve cutaneous SCC localization at the gross and microscopic level.

CONCLUSION

Significant advances have been achieved with real-time optical imaging strategies for intraoperative cutaneous SCC margin assessment and tumor detection. Optical imaging holds promise in improving the percentage of negative surgical margins and in the early detection of micrometastatic disease. © 2015 Wiley Periodicals, Inc. Head Neck 38: E2204-E2213, 2016.

Cellular uptake and intracellular trafficking of oligonucleotides: implications for oligonucleotide pharmacology

One of the major constraints on the therapeutic use of oligonucleotides is inefficient delivery to their sites of action in the cytosol or nucleus. Recently it has become evident that the pathways of cellular uptake and intracellular trafficking of oligonucleotides can strongly influence their pharmacological actions. Here we provide background information on the basic processes of endocytosis and trafficking and then review recent literature on targeted delivery and subcellular trafficking of oligonucleotides in that context. A variety of approaches including molecular scale ligand-oligonucleotide conjugates, ligand-targeted nanocarriers, and the use of small molecules to enhance oligonucleotide effects are discussed.

pH-Responsive Theranostic Polymer-Caged Nanobins (PCNs): Enhanced Cytotoxicity and T1 MRI Contrast by Her2-Targeting

A PCN theranostic platform comprises a doxorubicin (DXR)-loaded liposomal core and an acid-sensitive polymer shell that is functionalized with Herceptin and Gd^III-based MRI contrast agents. In vitro testing reveals a 14-fold increase in DXR-based cytotoxicity versus a non-targeted analogue and an 120-fold improvement in cellular Gd^III-uptake in comparison with clinically approved DOTA-Gd^III, leading to significant T₁ MRI contrast enhancement.

Ultrasonic spectrum analysis for in vivo characterization of tumor microstructural changes in the evaluation of tumor response to chemotherapy using diagnostic ultrasound

Background

There is a strong need for early assessment of tumor response to chemotherapy in order to avoid the adverse effects of unnecessary chemotherapy and to allow early transition to second-line therapy. The purpose of this study was to determine the feasibility of ultrasonic spectral analysis for the in vivo characterization of changes in tumor microstructure in the evaluation of tumor response to chemotherapy using diagnostic ultrasound.

Methods

Experiments were approved by the regional animal care committee. Twenty-four MCF-7 breast cancer bearing nude mice were treated with adriamycin or sterile saline administered by intraperitoneal injection. Ultrasonic radio-frequency (RF) data was collected using a clinically available ultrasound scanner (6-MHz linear transducer). Linear regression parameters (spectral slope and midband-fit) regarding the calibrated power spectra from the RF signals were tested to monitor tumor response to treatment. The section equivalent to the ultrasound imaging plane was stained with hematoxylin and eosin to allow for assessment of the density of tumor cell nuclei.

Results

Treatment with adriamycin significantly reduced tumor growth in comparison with the control group (p = 0.003). Significant changes were observed in the ultrasonic parameters of the treated relative to the untreated tumors (p < 0.05). The spectral slope increased by 48.5%, from −10.66 ± 2.96 to −5.49 ± 2.69; the midband-fit increased by 12.8%, from −57.10 ± 7.68 to −49.81 ± 5.40. Treated tumors were associated with a significant decrease in the density of tumor cell nuclei as compared with control tumors (p < 0.001).

Conclusions

Ultrasonic spectral analysis can detect changes in tumor microstructure after chemotherapy, and this will be helpful in the early evaluation tumor response to chemotherapy.

Analysis of targeted viral protein nanoparticles delivered to HER2+ tumors

The HER2+ tumor-targeted nanoparticle, HerDox, exhibits tumor-preferential accumulation and tumor-growth ablation in an animal model of HER2+ cancer. HerDox is formed by non-covalent self-assembly of a tumor targeted cell penetration protein with the chemotherapy agent, doxorubicin, via a small nucleic acid linker. A combination of electrophilic, intercalation, and oligomerization interactions facilitate self-assembly into round 10-20 nm particles. HerDox exhibits stability in blood as well as in extended storage at different temperatures. Systemic delivery of HerDox in tumor-bearing mice results in tumor-cell death with no detectable adverse effects to non-tumor tissue, including the heart and liver (which undergo marked damage by untargeted doxorubicin). HER2 elevation facilitates targeting to cells expressing the human epidermal growth factor receptor, hence tumors displaying elevated HER2 levels exhibit greater accumulation of HerDox compared to cells expressing lower levels, both in vitro and in vivo. Fluorescence intensity imaging combined with in situ confocal and spectral analysis has allowed us to verify in vivo tumor targeting and tumor cell penetration of HerDox after systemic delivery. Here we detail our methods for assessing tumor targeting via multimode imaging after systemic delivery.

Evaluation of ¹⁸F-FDG and ¹⁸F-FLT for monitoring therapeutic responses of colorectal cancer cells to radiotherapy

In order to compare the efficacy of (18)F-fluorothymidine (FLT) and (18)F-fluorodeoxyglucose (FDG) for monitoring early responses to irradiation, two human colorectal cancer (CRC) cell lines SW480 and SW620, which were derived from the primary lesions and the metastatic lymph node, underwent X-ray irradiation of 0, 10, or 20 Gy and were examined at 0, 24 and 72 h After irradiation, reduced proliferation of both SW480 and SW620 cells was observed in a dose-dependent manner (P<0.001), G0-G1 arrest was also noted in both cell types after 72 h in the 20 Gy group (P<0.001). Although increased apoptosis was observed in both cell lines after irradiation (P<0.001), a greater percentage of SW480 cells underwent apoptosis in response to irradiation than SW620 cells. Increased Hsp27 and decreased integrin β3, Ki67 and VEGFR2 expression was observed over time via immunocytochemistry and Western blot analysis (P<0.001), however, no significant changes were noted in response to irradiation. Finally, reduced uptake of (18)F-FLT by SW480 or SW620 cells was observed at 24-h post-irradiation, however, reduced (18)F-FDG uptake was only observed after 72 h. Therefore, we conclude that (18)F-FLT is a more suitable positron emission tomography (PET) tracer for monitoring early responses to irradiation in primary and metastatic lymph node CRC cells.

Development of adenovirus capsid proteins for targeted therapeutic delivery

The outer shell of the adenovirus capsid comprises three major types of protein (hexon, penton base and fiber) that perform the majority of functions facilitating the early stages of adenovirus infection. These stages include initial cell-surface binding followed by receptor-mediated endocytosis, endosomal penetration and cytosolic entry, and intracellular trafficking toward the nucleus. Numerous studies have shown that the penton base contributes to several of these steps and have supported the development of this protein into a delivery agent for therapeutic molecules. Studies revealing that the fiber and hexon bear unexpected properties of cell entry and/or nuclear homing have supported the development of these capsid proteins, as well into potential delivery vehicles. This review summarizes the findings to date of the protein-cell activities of these capsid proteins in the absence of the whole virus and their potential for therapeutic application with regard to the delivery of foreign molecules.

A novel self-assembly albumin nanocarrier for reducing doxorubicin-mediated cardiotoxicity

Doxorubicin is an antitumor drug commonly used against a wide spectrum of tumors. However, the clinical application of DOX is restricted by its cardiotoxicity. To reduce the cardiotoxicity, we develop an albumin-based nanocarrier via a new molecular switch method for DOX delivery. Spherically shaped DOX-loaded HSA nanoparticles (NPs-DOX) are prepared with a drug-loading capacity and particle size of 4.3% and 120.1 ± 26 nm, respectively. In vivo studies demonstrate that NPs-DOX is able to preferentially accumulate in tumor and show great tumor inhibition on H22 hepatocellular-carcinoma-bearing mice. As for the toxicity, compared with free DOX, the maximum tolerated dose of NPs-DOX is increased from 10 to over 30 mg/kg, indicating the reduced systematic toxicity. More importantly, the cardiotoxicity induced by NPs-DOX is also significantly reduced because both left ventricular ejection fraction and left ventricular fractional shortening are almost not changed and other cardiotoxicity markers such as serum creatine kinase-MB, lactate dehydrogenase, superoxide dismutase, and malonaldehyde are kept constant. The reduced cardiotoxicity of NPs-DOX is also confirmed by nonhistological changes in the heart tissue. Therefore, such albumin-based nanocarrier can be one of the most promising strategies for the delivery of DOX.

Receptors, endocytosis, and trafficking: the biological basis of targeted delivery of antisense and siRNA oligonucleotides

The problem of targeted delivery of antisense and siRNA oligonucleotides can be resolved into two distinct aspects. The first concerns devising ligand-oligonucleotide or ligand-carrier moieties that bind with high selectivity to receptors on the cell type of interest and that are efficiently internalized by endocytosis. The second concerns releasing oligonucleotides from pharmacologically inert endomembrane compartments so that they can access RNA in the cytosol or nucleus. In this review, we will address both of these aspects. Thus, we present information on three important receptor families, the integrins, the receptor tyrosine kinases, and the G protein-coupled receptors in terms of their suitability for targeted delivery of oligonucleotides. This includes discussion of receptor abundance, internalization and trafficking pathways, and the availability of suitable high affinity ligands. We also consider the process of oligonucleotide uptake and intracellular trafficking and discuss approaches to modulating these processes in a pharmacologically productive manner. Hopefully, the basic information presented in this review will be of value to investigators involved in designing delivery approaches for oligonucleotides.