Second-generation aptamer-conjugated PSMA-targeted delivery system for prostate cancer therapy

Structure-activity relationship study of mesyl and busyl phosphoramidate antisense oligonucleotides for unaided and PSMA-mediated uptake into prostate cancer cells

Phosphorothioate (PS) group is a key component of a majority of FDA approved oligonucleotide drugs that increase stability to nucleases whilst maintaining interactions with many proteins, including RNase H in the case of antisense oligonucleotides (ASOs). At the same time, uniform PS modification increases nonspecific protein binding that can trigger toxicity and pro-inflammatory effects, so discovery and characterization of alternative phosphate mimics for RNA therapeutics is an actual task. Here we evaluated the effects of the introduction of several N-alkane sulfonyl phosphoramidate groups such as mesyl (methanesulfonyl) or busyl (1-butanesulfonyl) phosphoramidates into gapmer ASOs on the efficiency and pattern of RNase H cleavage, cellular uptake in vitro, and intracellular localization. Using Malat1 lncRNA as a target, we have identified patterns of mesyl or busyl modifications in the ASOs for optimal knockdown in vitro. Combination of the PSMA ligand-mediated delivery with optimized mesyl and busyl ASOs resulted in the efficient target depletion in the prostate cancer cells. Our study demonstrated that other N-alkanesulfonyl phosphoramidate groups apart from a known mesyl phosphoramidate can serve as an essential component of mixed backbone gapmer ASOs to reduce drawbacks of uniformly PS-modified gapmers, and deserve further investigation in RNA therapeutics.

Therapeutic potential of targeting mirnas to prostate cancer tumors: using psma as an active target

Prostate cancer (PC) is a commonly diagnosed malignancy in men and is associated with high mortality rates. Current treatments for PC include surgery, chemotherapy, and radiation therapy. However, recent advances in targeted delivery systems have yielded promising new approaches to PC treatment. As PC epithelial cells express high levels of prostate-specific membrane antigen (PSMA) on the cell surface, new drug conjugates focused on PSMA targeting have been developed. microRNAs (miRNAs) are small noncoding RNAs that regulate posttranscriptional gene expression in cells and show excellent possibilities for use in developing new therapeutics for PC. PSMA-targeted therapies based on a miRNA payload and that selectively target PC cells enhances therapeutic efficacy without eliciting damage to normal surrounding tissue. This review discusses the rationale for utilizing miRNAs to target PSMA, revealing their potential in therapeutic approaches to PC treatment. Different delivery systems for miRNAs and challenges to miRNA therapy are also explored.

siAKR1C3@PPA complex nucleic acid nanoparticles inhibit castration-resistant prostate cancer in vitro

Introduction

AKR1C3, as a crucial androgenic enzyme, implicates the androgen biosynthesis and promoting prostate cancer cell growth in vitro. This study provides a new gene therapy strategy for targeting AKR1C3 to treat castration-resistant prostate cancer.

Methods

siAKR1C3@PPA is assembled from PEG3500, PAMAM, Aptamer-PSMA, and siRNA for AKR1C3. We analyzed the relationship between AKR1C3 expression and the survival rate of prostate cancer patients based on the GEPIA online database to perform disease-free survival, and found that AKR1C3 may be an important factor leading to poor prognosis in prostate cancer. Considering AKR1C3 as a therapeutic target for castration-resistant prostate cancer, we constructed a complex nucleic acid nanoparticle, siAKR1C3@PPA to investigate the inhibitory effect on castration-resistant prostate cancer.

Results

Aptamer-PSMA acts as a target to guide siAKR1C3@PPA into PSMA-positive prostate cancer cells and specifically down regulate AKR1C3. Cyclin D1 was decreased as a result of siAKR1C3@PPA treatment. Changes in Cyclin D1 were consistent with decreased expression of AKR1C3 in LNCaP-AKR1C3 cells and 22RV1 cells. Furthermore, in the LNCaP-AKR1C3 group, 1070 proteins were upregulated and 1015 proteins were downregulated compared to the LNCaP group according to quantitative 4D label-free proteomics. We found 42 proteins involved in cell cycle regulation. In a validated experiment, we demonstrated that PCNP and CINP were up-regulated, and TERF2 and TP53 were down-regulated by western blotting.

Conclusion

We concluded that siAKR1C3@PPA may arrest the cell cycle and affect cell proliferation.

Aptamer-Enabled Nanomaterials for Therapeutics, Drug Targeting and Imaging

A wide variety of nanomaterials have emerged in recent years with advantageous properties for a plethora of therapeutic and diagnostic applications. Such applications include drug delivery, imaging, anti-cancer therapy and radiotherapy. There is a critical need for further components which can facilitate therapeutic targeting, augment their physicochemical properties, or broaden their theranostic applications. Aptamers are single-stranded nucleic acids which have been selected or evolved to bind specifically to molecules, surfaces, or cells. Aptamers can also act as direct biologic therapeutics, or in imaging and diagnostics. There is a rich field of discovery at the interdisciplinary interface between nanomaterials and aptamer science that has significant potential across biomedicine. Herein, we review recent progress in aptamer-enabled materials and discuss pending challenges for their future biomedical application.

Prostate-Specific Membrane Antigen and Esterase Dual Responsive Camptothecin-Oligopeptide Self-Assembled Nanoparticles for Efficient Anticancer Drug Delivery

Background

The clinical utility of camptothecin (CPT) is restricted by poor aqueous solubility, high lipophilicity, active lactone ring instability, and off-targeted toxicities. We report here a prostate-specific membrane antigen (PSMA) and esterase dual responsive self-assembled nanoparticles (CPT-WT-H NPs) for highly efficient CPT delivery and effective cancer therapy.

Methods and Results

In this study, smart self-assembled nanoparticles CPT-WT-H NPs were elaborately designed and synthesized by combing hydrophobic CPT with hydrophilic PSMA-responsive penta-peptide via a cleavable ester bond. This dual responsive nanoparticle with negatively charged surface first respond to the extracellular PSMA and then to the intracellular esterase, achieving a programmable release of CPT at the tumor site and producing the byproducts of biocompatible glutamic acid and aspartic acid. Our data demonstrated that CPT-WT-H NPs exhibited greatly improved water solubility and stability. Results from MTT and flow cytometry showed CPT-WT-H NPs exhibited significantly higher cytotoxicity as well as apoptosis-inducing activity against PSMA-expressing LNCaP-FGC cells than the non-PSMA-expressing cancer cells, showing excellent cytotoxic selectivity. Moreover, the unique nanostructure provided the efficient transportation of CPT to tumor site, which resulted in the effective inhibition of tumor growth and low systemic toxicity in vivo.

Conclusion

CPT-WT-H NPs exhibited excellent in vitro PSMA-response ability and in vivo antitumor activity and safety, holding the promise to become a new and potent anticancer drug. The current research presents a promising strategy for efficient drug delivery.

PSMA-Targeting Reduction-Cleavable Hyperbranched Polyamide-Amine Gene Delivery System to Treat the Bone Metastases of Prostate Cancer

Objective

This study aimed to develop aptamer-anchored hyperbranched poly(amido amine) (HPAA) for the systemic delivery of miRNA-133a-3p and to evaluate its therapeutic potential against bone metastasis of prostate cancer in vivo and in vitro.

Methods

A glutathione (GSH)-responsive cationic HPAA was prepared by the Michael addition reaction. Furthermore, HPAA-PEG was produced by PEGylation, and then the aptamer targeted to prostate-specific membrane antigen (PSMA) was conjugated to the HPAA-PEG. The obtained HPAA-PEG-APT could form nanocomplexes with miRNA-133a-3p through electrostatic adsorption.

Results

The results of immunocytochemistry indicated that the complexes could target PSMA-expressing LNCaP cells. The ability of HPAA-PEG-APT to facilitate the delivery of miRNA-133a-3p into LNCaP cells was proven, and HPAA-PEG-APT/miRNA-133a-3p demonstrated enhanced antitumor activity, lower cytotoxicity and better biocompatibility in vitro. Moreover, in a mouse tibial injection tumor model, the intravenous injection of the HPAA-PEG-APT/miRNA-133a-3p complex significantly inhibited cancer growth and extended the survival time.

Conclusion

This study provided an aptamer-anchored HPAA-loaded gene system to deliver miRNA-133a-3p for better therapeutic efficacy of bone metastasis of prostate cancer.

Metal-Labeled Aptamers as Novel Nanoprobes for Imaging Mass Cytometry Analysis

Imaging mass cytometry (IMC) is an emerging imaging technology that exploits the multiplexed analysis capabilities of the CyTOF mass cytometer to make spatially resolved measurements for tissue sections. In a comprehensive view of tissue composition and marker distribution, recent developments of IMC require highly sensitive, multiplexed assays. Approaching the sensitivity of the IMC technique, we designed a novel type of biocompatible metal-labeled aptamer nanoprobe (MAP), named ¹⁶⁷Er-A10-3.2. The small molecular probe was synthesized by conjugating ¹⁶⁷Er-polymeric pentetic acid (¹⁶⁷Er-DTPA) with an RNA aptamer A10-3.2. For demonstration, ¹⁶⁷Er-A10-3.2 was applied for observing protein spatial distribution on prostatic epithelium cell of paraffin embedded Prostatic adenocarcinoma (PaC) tissue sections by IMC technology. The ¹⁶⁷Er-A10-3.2 capitalizes on the ability of the aptamer to specifically bind target cancer cells as well as the small size of ¹⁶⁷Er-A10-3.2 can accommodate multiple aptamer binding antigen labeled at high density. The detection signal of ¹⁶⁷Er-A10-3.2 probe was 3-fold higher than that of PSMA antibody probe for a targeted cell under lower temperature epitope retrieval (37 °C) of PaC tissue. Furthermore, we successfully demonstrated the simultaneously staining ability of aptamer probes in IMC analysis. The successful imaging acquisition using aptamers probes in IMC technology may offer opportunity for the diagnosis of malignancies in the future.

Aptamers, the Nucleic Acid Antibodies, in Cancer Therapy

The arrival of the monoclonal antibody (mAb) technology in the 1970s brought with it the hope of conquering cancers to the medical community. However, mAbs, on the whole, did not achieve the expected wonder in cancer therapy although they do have demonstrated successfulness in the treatment of a few types of cancers. In 1990, another technology of making biomolecules capable of specific binding appeared. This technique, systematic evolution of ligands by exponential enrichment (SELEX), can make aptamers, single-stranded DNAs or RNAs that bind targets with high specificity and affinity. Aptamers have some advantages over mAbs in therapeutic uses particularly because they have little or no immunogenicity, which means the feasibility of repeated use and fewer side effects. In this review, the general properties of the aptamer, the advantages and limitations of aptamers, the principle and procedure of aptamer production with SELEX, particularly the undergoing studies in aptamers for cancer therapy, and selected anticancer aptamers that have entered clinical trials or are under active investigations are summarized.

Aptamers Chemistry: Chemical Modifications and Conjugation Strategies

Soon after they were first described in 1990, aptamers were largely recognized as a new class of biological ligands that can rival antibodies in various analytical, diagnostic, and therapeutic applications. Aptamers are short single-stranded RNA or DNA oligonucleotides capable of folding into complex 3D structures, enabling them to bind to a large variety of targets ranging from small ions to an entire organism. Their high binding specificity and affinity make them comparable to antibodies, but they are superior regarding a longer shelf life, simple production and chemical modification, in addition to low toxicity and immunogenicity. In the past three decades, aptamers have been used in a plethora of therapeutics and drug delivery systems that involve innovative delivery mechanisms and carrying various types of drug cargos. However, the successful translation of aptamer research from bench to bedside has been challenged by several limitations that slow down the realization of promising aptamer applications as therapeutics at the clinical level. The main limitations include the susceptibility to degradation by nucleases, fast renal clearance, low thermal stability, and the limited functional group diversity. The solution to overcome such limitations lies in the chemistry of aptamers. The current review will focus on the recent arts of aptamer chemistry that have been evolved to refine the pharmacological properties of aptamers. Moreover, this review will analyze the advantages and disadvantages of such chemical modifications and how they impact the pharmacological properties of aptamers. Finally, this review will summarize the conjugation strategies of aptamers to nanocarriers for developing targeted drug delivery systems.

Aptamers as Delivery Agents of siRNA and Chimeric Formulations for the Treatment of Cancer

Both aptamers and siRNA technologies have now reached maturity, and both have been validated with a product in the market. However, although pegaptanib reached the market some time ago, there has been a slow process for new aptamers to follow. Today, some 40 aptamers are in the market, but many in combination with siRNAs, in the form of specific delivery agents. This combination offers the potential to explore the high affinity and specificity of aptamers, the silencing power of siRNA, and, at times, the cytotoxicity of chemotherapy molecules in powerful combinations that promise to delivery new and potent therapies. In this review, we report new developments in the field, following up from our previous work, more specifically on the use of aptamers as delivery agents of siRNA in nanoparticle formulations, alone or in combination with chemotherapy, for the treatment of cancer.

Potential and Challenges of Aptamers as Specific Carriers of Therapeutic Oligonucleotides for Precision Medicine in Cancer

Due to the progress made in the area of precision and personalized medicine in the field of cancer therapy, strategies to selectively and specifically identify target molecules causative of the diseases are urgently needed. Efforts are being made by a number of different laboratories, companies, and researchers to develop therapeutic molecules that selectively recognize the tissues and the cells of interest, exhibit few or no off-target and side effects, are non-immunogenic, and have a strong action. Aptamers, artificially selected single-stranded DNA or RNA oligonucleotides, are promising molecules satisfying many of the requirements needed for diagnosis and precision medicine. Aptamers can also couple to their native mechanism of action the delivery of additional molecules (oligonucleotides, siRNAs, miRNAs) to target cells. In this review, we summarize recent progress in the aptamer-mediated strategy for the specific delivery of therapeutic oligonucleotides.

Dendritic cells pulsed with prostate-specific membrane antigen in metastatic castration-resistant prostate cancer patients: a systematic review and meta-analysis

BACKGROUND

Dendritic cells (DCs) are used in many malignancies as vaccines to induce immunity against specific cancer antigens. The role of DCs in metastatic castration-resistant prostate cancer (mCRPC) is not determined. In this study, the proportion of mCRPC patients with clinically significant response to targeted therapy by DCs pulsed with prostate-specific membrane antigen was evaluated, and the possible adverse effects of this modality were investigated.

METHODS

Major databases were searched up to Feb 2017, to identify studies in which the antitumor efficacy of DCs pulsed with the extracellular portion of PSMA was studied for the treatment of mCRPC. Data were collected by two reviewers and analyzed using Comprehensive Meta-Analysis software, version 2.0.

FINDINGS

Our study consisted of 6 nonrandomized prospective (cohort) trials, overall reporting on 153 mCRPC patients. The event rate that is the representative of fraction of patients showing antitumor response was 0.43 (95% confidence interval = 0.355-0.512; P = 0.097). No significant between-study heterogeneity or inconsistency was detected (I2 = 5.47; Q = 5; P = 0.382). Our study failed to demonstrate a significant therapeutic efficacy for DCs in mCRPC. However, no significant adverse effects were seen.

Aptamer-miR-34c Conjugate Affects Cell Proliferation of Non-Small-Cell Lung Cancer Cells

MicroRNAs (miRNAs) are key regulators of different human processes that represent a new promising class of cancer therapeutics or therapeutic targets. Indeed, in several tumor types, including non-small-cell lung carcinoma (NSCLC), the deregulated expression of specific miRNAs has been implicated in cell malignancy. As expression levels of the oncosuppressor miR-34c-3p are decreased in NSCLC compared to normal lung, we show that reintroduction of miR-34c-3p reduces NSCLC cell survival in vitro. Further, in order to deliver the miR-34c-based therapeutic selectively to tumor cells, we took advantage of a reported nucleic acid aptamer (GL21.T) that binds and inhibits the AXL transmembrane receptor and is rapidly internalized in the target cells. By applying methods successfully used in our laboratory, we conjugated miR-34c to the GL21.T aptamer as targeting moiety for the selective delivery to AXL-expressing NSCLC cells. We demonstrate that miR-34c-3p and the GL21.T/miR-34c chimera affect NSCLC cell proliferation and are able to overcome acquired RTK-inhibitor resistance by targeting AXL receptor. Thus, the GL21.T/miR-34c chimera exerts dual inhibition of AXL at functional and transcriptional levels and represents a novel therapeutic tool for the treatment of NSCLC.

Circulating Tumor Cell Phenotyping via High-Throughput Acoustic Separation

The study of circulating tumor cells (CTCs) offers pathways to develop new diagnostic and prognostic biomarkers that benefit cancer treatments. In order to fully exploit and interpret the information provided by CTCs, the development of a platform is reported that integrates acoustics and microfluidics to isolate rare CTCs from peripheral blood in high throughput while preserving their structural, biological, and functional integrity. Cancer cells are first isolated from leukocytes with a throughput of 7.5 mL h-1 , achieving a recovery rate of at least 86% while maintaining the cells' ability to proliferate. High-throughput acoustic separation enables statistical analysis of isolated CTCs from prostate cancer patients to be performed to determine their size distribution and phenotypic heterogeneity for a range of biomarkers, including the visualization of CTCs with a loss of expression for the prostate specific membrane antigen. The method also enables the isolation of even rarer, but clinically important, CTC clusters.

Hyaluronic acid-modified polyamidoamine dendrimer G5-entrapped gold nanoparticles delivering METase gene inhibits gastric tumor growth via targeting CD44+ gastric cancer cells

BACKGROUND

Gastric cancer (GC) is the second most common leading cause of cancer-related death. Cancer stem cell (CSC) with the mark of CD44 played an important role in GC. rMETase was wildly exploited as chemotherapeutic option for GC. Polymers synthetic nanoparticle drug delivery systems have been commonly used for cancer therapy. With the decorating of Hyaluronic acid (HA), a receptor of CD44, nanoparticles exhibit with good biocompatibility and aqueous solubility.

METHODS

The characteristic of nanoparticles (NPs) was analyzed by TEM and DLS. The viability and proliferation of GC cells were examined by MTT assays. The levels of CD44, Cyt C, and c-caspase 3 were examined by Western blot. The level of ROS was measured by DCFH-DA assays. The morphology of tissues was detected using hematoxylin-eosin (H&E) stain. Nude mice xenograft models were used to evaluate the effect of HA-PAMAM-Au-METase on GC.

RESULTS

The transfection of rMETase carried by HA-G5 PAMAM-Au visibly inhibited the proliferation and tumorsphere formation of GC cells through obviously enhancing METase activity. Elevation of METase activity suppressed the proliferation of CD44(+) GC cells through down-regulating MET in cellular supernatant that resulted in the increase of Cyc C and ROS levels. The number of CD44(+) GC cells in nude mice injected with G5 PAMAM-Au-METase decorated by HA was markly declined resulting in the inhibition of tumor growth.

CONCLUSION

HA-G5 PAMAM-Au-METase significantly suppressed tumor growth of GC by targeted damaging the mitochondrial function of CD44(+) gastric CSCs.

Nanoparticle-based targeted cancer strategies for non-invasive prostate cancer intervention

Prostate cancer is screened by testing circulating levels of the prostate-specific antigen (PSA) biomarker, monitoring changes over time, or a digital rectal exam. Abnormal results often lead to prostate biopsy. Prostate cancer positive patients are stratified into very low-risk, low-risk, intermediate-risk, and high-risk, based on clinical classification parameters, to assess therapy options. However, there remains a gap in our knowledge and a compelling need for improved risk stratification to inform clinical decisions and reduce both over-diagnosis and over-treatment. Further, current strategies for clinical intervention do not distinguish clinically aggressive prostate cancer from indolent disease. This mini-review takes advantage of a large number of functionally characterized microRNAs (miRNA), epigenetic regulators of prostate cancer, that define prostate cancer cell activity, tumor stage, and circulate as biomarkers to monitor disease progression. Nanoparticles provide an effective platform for targeted delivery of miRNA inhibitors or mimics specifically to prostate tumor cells to inhibit cancer progression. Several prostate-specific transmembrane proteins expressed at elevated levels in prostate tumors are under investigation for targeting therapeutic agents to prostate cancer cells. Given that prostate cancer progresses slowly, circulating miRNAs can be monitored to identify tumor progression in indolent disease, allowing identification of miRNAs for nanoparticle intervention before the crucial point of transition to aggressive disease. Here, we describe clinically significant and non-invasive intervention nanoparticle strategies being used in clinical trials for drug and nucleic acid delivery. The advantages of mesoporous silica-based nanoparticles and a number of candidate miRNAs for inhibition of prostate cancer are discussed.

Tumor characterization by ultrasound-release of multiple protein and microRNA biomarkers, preclinical and clinical evidence

We have previously shown that low frequency ultrasound can release biomarkers from cells into the murine circulation enabling an amplification and localization of the released biomarker that could be used as a blood-based method to detect cancer earlier and monitor therapy. In this study, we further demonstrate that this technique could be used for characterization of tumors and/or identification of cellular masses of unknown origin due to the release of multiple protein and nucleic acid biomarkers in cells in culture, mice and patients. We sonicated colon (LS174T) and prostate (LNCaP) cancer cell lines in culture at a low frequency of 1 MHz and show that there were several-fold changes in multiple protein and microRNA (miRNA) abundance with treatment at various intensities and time. This release was dependent on the duration and intensity of the sonication for both cell lines. Significant increased release in biomarkers was also observed following tumor sonication in living mice bearing subcutaneous LS174T cell line xenografts (for proteins and nucleic acids) and in an experimental LS174T liver tumor model (for proteins only). Finally, we demonstrated this methodology of multiple biomarker release in patients undergoing ablation of uterine fibroids using MR guided high intensity focused ultrasound. Two protein biomarkers significantly increased in the plasma after the ultrasound treatment in 21 samples tested. This proof that ultrasound-amplification method works in soft tissue tumor models together with biomarker multiplexing, could allow for an effective non-invasive method for identification, characterization and localization of incidental lesions, cancer and other disease. Pre-treatment quantification of the biomarkers, allows for individualization of quantitative comparisons. This individualization of normal marker levels in this method allows for specificity of the biomarker-increase to each patient, tumor or organ being studied.

Aptamer-conjugated multi-walled carbon nanotubes as a new targeted ultrasound contrast agent for the diagnosis of prostate cancer

Early diagnosis is primarily important for the therapeutic and prognostic outcomes of malignancies including prostate cancer (PCa). However, the visuality and veracity of ultrasound imaging for the diagnosis and prognostic prediction of PCa remains poor at present. In this study, we developed a new nanoultrasound contrast agent by modifying multi-walled carbon nanotubes (MWCNTs) with polyethylene glycol (PEG) and anti-PSMA aptamer. The result showed that the modified MWCNTs offered better visuality and veracity and were able to target PCa cells more effectively as compared with the traditional contrast agent. The zeta potential was about - 38 mv. The length of this contrast agent was about 400 nm and the diameter of it was about 30 nm. The zeta potential, TEM, and FT-IR all proved the successful preparation of the agent. The vitro cytological study revealed good cell uptake and biocompatibility of the new contrast agent. The minimum detection concentration in vitro is 10 μg/ml. The earliest stage of the detection was under the parameters of frequency = 6.0 MHz and medical index = 0.06. Both in vitro and in vivo ultrasound imaging demonstrated that the new nanoultrasound contrast agent had a good development effect, distribution, and metabolism, and may prove to be a good targeted ultrasound contrast agent, especially for PCa.

Aptamer Cell-Based Selection: Overview and Advances

Aptamers are high affinity single-stranded DNA/RNA molecules, produced by a combinatorial procedure named SELEX (Systematic Evolution of Ligands by Exponential enrichment), that are emerging as promising diagnostic and therapeutic tools. Among selection strategies, procedures using living cells as complex targets (referred as "cell-SELEX") have been developed as an effective mean to generate aptamers for heavily modified cell surface proteins, assuring the binding of the target in its native conformation. Here we give an up-to-date overview on cell-SELEX technology, discussing the most recent advances with a particular focus on cancer cell targeting. Examples of the different protocol applications and post-SELEX strategies will be briefly outlined.

MicroRNA-16-1 Inhibits Tumor Cell Proliferation and Induces Apoptosis in A549 Non-Small Cell Lung Carcinoma Cells

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. Plenty of microRNAs (miRs), except miR-16-1, have been reported to be associated with the initiation and progression of NSCLC. This study was aimed to explore the impacts of miR-16-1 on NSCLC cells. Human NSCLC cell line A549 was used, and the expression of miR-16-1 was up- or downregulated by transfecting with miR-16-1 mimics or inhibitors. Afterward, cell proliferation and apoptosis were detected using MTT assay, BrdU assay, and Annexin V/FITC Apoptosis Detection Kit. The expression changes of proliferation- and apoptosis-related factors were measured by Western blot. Results showed that miR-16-1 overexpression significantly inhibited cell proliferation and induced apoptosis when compared with the control group. Besides, miR-16-1 overexpression significantly upregulated the protein expressions of p27, Bax, procaspase 3, and cleaved caspase 3, whereas it downregulated Bcl-2. Conversely, miR-16-1 suppression affected NSCLC cell proliferation and apoptosis, and these protein expressions resulted in completely opposite impacts. In conclusion, miR-16-1 overexpression could inhibit cell proliferation and induce apoptosis via regulating the expression of p27, Bcl-2, Bax, and caspase 3 in NSCLC cells.

Application of aptamers in diagnostics, drug-delivery and imaging

Aptamers are small, single-stranded oligonucleotides (DNA or RNA) that bind to their target with high specificity and affinity. Although aptamers are analogous to antibodies for a wide range of target recognition and variety of applications, they have significant advantages over antibodies. Since aptamers have recently emerged as a class of biomolecules with an application in a wide array of fields, we need to summarize the latest developments herein. In this review we will discuss about the latest developments in using aptamers in diagnostics, drug delivery and imaging. We begin with diagnostics, discussing the application of aptamers for the detection of infective agents itself, antigens/ toxins (bacteria), biomarkers (cancer), or a combination. The ease of conjugation and labelling of aptamers makes them a potential tool for diagnostics. Also, due to the reduced off-target effects of aptamers, their use as a potential drug delivery tool is emerging rapidly. Hence, we discuss their use in targeted delivery in conjugation with siRNAs, nanoparticles, liposomes, drugs and antibodies. Finally, we discuss about the conjugation strategies applicable for RNA and DNA aptamers for imaging. Their stability and self-assembly after heating makes them superior over protein-based binding molecules in terms of labelling and conjugation strategies.

The therapeutic and diagnostic potential of the prostate specific membrane antigen/glutamate carboxypeptidase II (PSMA/GCPII) in cancer and neurological disease

Prostate specific membrane antigen (PSMA) otherwise known as glutamate carboxypeptidase II (GCPII) is a membrane bound protein that is highly expressed in prostate cancer and in the neovasculature of a wide variety of tumours including glioblastomas, breast and bladder cancers. This protein is also involved in a variety of neurological diseases including schizophrenia and ALS. In recent years, there has been a surge in the development of both diagnostics and therapeutics that take advantage of the expression and activity of PSMA/GCPII. These include gene therapy, immunotherapy, chemotherapy and radiotherapy. In this review, we discuss the biological roles that PSMA/GCPII plays, both in normal and diseased tissues, and the current therapies exploiting its activity that are at the preclinical stage. We conclude by giving an expert opinion on the future direction of PSMA/GCPII based therapies and diagnostics and hurdles that need to be overcome to make them effective and viable.

Diagnosis of prostate cancer using anti-PSMA aptamer A10-3.2-oriented lipid nanobubbles

In this study, the lipid targeted nanobubble carrying the A10-3.2 aptamer against prostate specific membrane antigen was fabricated, and its effect in the ultrasound imaging of prostate cancer was investigated. Materials including 2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dipalmitoyl-sn-glycero-3-phosphatidic acid, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine, 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol, carboxyl-modified 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, and polyethyleneglycol-2000 were for mechanical oscillation, and nanobubbles were obtained through the centrifugal flotation method. After mice were injected with nanobubbles, abdominal color Doppler blood flow imaging significantly improved. Through left ventricular perfusion with normal saline to empty the circulating nanobubbles, nanobubbles still existed in tumor tissue sections, which demonstrated that nanobubbles could enter tissue spaces via the permeability and retention effect. Fluorinated A10-3.2 aptamers obtained by chemical synthesis had good specificity for PSMA-positive cells, and were linked with carboxyl-modified 1,2-distearoyl-sn-glycero-3-phosphoethanolamine lipid molecules from the outer shell of nanobubbles via amide reaction to construct targeted nanobubbles. Gel electrophoresis and immunofluorescence confirmed that targeted nanobubbles were fabricated successfully. Next, targeted nanobubbles could bind with PSMA-positive cells (C4-2 cells), while not with PSMA-negative cells (PC-3 cells), using in vitro binding experiments and flow cytometry at the cellular level. Finally, C4-2 and PC-3 xenografts in mice were used to observe changes in parameters of targeted and non-targeted nanobubbles in the contrast-enhanced ultrasound mode, and the distribution of Cy5.5-labeled targeted nanobubbles in fluorescent imaging of live small animals. Comparison of ultrasound indicators between targeted and non-targeted nanobubbles in C4-2 xenografts showed that they had similar peak times (P>0.05), while the peak intensity, half time of peak intensity, and area under the curve of ½ peak intensity were significantly different (P<0.05). In PC-3 xenografts, there were no differences in these four indicators. Fluorescent imaging indicated that targeted nanobubbles had an aggregation ability in C4-2 xenograft tumors. In conclusion, targeted nanobubbles carrying the anti-PSMA A10-3.2 aptamer have a targeted imaging effect in prostate cancer.

Specific Delivery of MiRNA for High Efficient Inhibition of Prostate Cancer by RNA Nanotechnology

Both siRNA and miRNA can serve as powerful gene-silencing reagents but their specific delivery to cancer cells in vivo without collateral damage to healthy cells remains challenging. We report here the application of RNA nanotechnology for specific and efficient delivery of anti-miRNA seed-targeting sequence to block the growth of prostate cancer in mouse models. Utilizing the thermodynamically ultra-stable three-way junction of the pRNA of phi29 DNA packaging motor, RNA nanoparticles were constructed by bottom-up self-assembly containing the anti-prostate-specific membrane antigen (PSMA) RNA aptamer as a targeting ligand and anti-miR17 or anti-miR21 as therapeutic modules. The 16 nm RNase-resistant and thermodynamically stable RNA nanoparticles remained intact after systemic injection in mice and strongly bound to tumors with little or no accumulation in healthy organs 8 hours postinjection, and subsequently repressed tumor growth at low doses with high efficiency.

Aptamer-miRNA-212 Conjugate Sensitizes NSCLC Cells to TRAIL

TNF-related apoptosis-inducing ligand (TRAIL) is a promising antitumor agent for its remarkable ability to selectively induce apoptosis in cancer cells, without affecting the viability of healthy bystander cells. The TRAIL tumor suppressor pathway is deregulated in many human malignancies including lung cancer. In human non-small cell lung cancer (NSCLC) cells, sensitization to TRAIL therapy can be restored by increasing the expression levels of the tumor suppressor microRNA-212 (miR-212) leading to inhibition of the anti-apoptotic protein PED/PEA-15 implicated in treatment resistance. In this study, we exploited a previously described RNA aptamer inhibitor of the tyrosine kinase receptor Axl (GL21.T) expressed on lung cancer cells, as a means to deliver miR-212 into human NSCLC cells expressing Axl. We demonstrate efficient delivery of miR-212 following conjugation of the miR to GL21.T (GL21.T-miR212 chimera). We show that the chimera downregulates PED and restores TRAIL-mediate cytotoxicity in cancer cells. Importantly, treatment of Axl+ lung cancer cells with the chimera resulted in (i) an increase in caspase activation and (ii) a reduction of cell viability in combination with TRAIL therapy. In conclusion, we demonstrate that the GL21.T-miR212 chimera can be employed as an adjuvant to TRAIL therapy for the treatment of lung cancer.

A specific aptamer-cell penetrating peptides complex delivered siRNA efficiently and suppressed prostate tumor growth in vivo

Specific and efficient delivery of siRNA into intended tumor cells remains as a challenge, even though RNAi has been exploited as a new strategy for prostate cancer therapy. This work aims to address both specificity and efficiency of SURVIVIN-siRNA delivery by constructing a therapeutic complex using combinatorial strategies. A fusion protein STD was first expressed to serve as a backbone, consisting of streptavidin, a cell-penetrating peptide called Trans-Activator of Transcription (TAT) and a double-stranded RNA binding domain. A biotinylated Prostate Specific Membrane Antigen (PSMA) specific aptamer A10 and SURVIVIN-siRNA were then linked to STD protein to form the therapeutic complex. This complex could specifically targeted PSMA(+) tumor cells. Compared to lipofectamine and A10-siRNA chimera, it demonstrated higher efficiency in delivering siRNA into target cells by 19.2% and 59.9%, and increased apoptosis by 16.8% and 26.1% respectively. Upon systemic administration, this complex also showed significant efficacy in suppressing tumor growth in athymic mice (p <0.001). We conclude that this therapeutic complex could specifically and efficiently deliver SURVIVIN-siRNA to target cells and suppressed tumor growth in vivo, which indicates its potential to be used as a new strategy in prostate cancer therapy.

Smart functional nucleic acid chimeras: enabling tissue specific RNA targeting therapy

A major obstacle for effective utilization of therapeutic oligonucleotides such as siRNA, antisense, antimiRs etc. is to deliver them specifically to the target tissues. Toward this goal, nucleic acid aptamers are re-emerging as a prominent class of biomolecules capable of delivering target specific therapy and therapeutic monitoring by various molecular imaging modalities. This class of short oligonucleotide ligands with high affinity and specificity are selected from a large nucleic acid pool against a molecular target of choice. Poor cellular uptake of therapeutic oligonucleotides impedes gene-targeting efficacy in vitro and in vivo. In contrast, aptamer-oligonucleotide chimeras have shown the capacity to deliver siRNA, antimiRs, small molecule drugs etc. toward various targets and showed very promising results in various studies on different diseases models. However, to further improve the bio-stability of such chimeric conjugates, it is important to introduce chemically-modified nucleic acid analogs. In this review, we highlight the applications of nucleic acid aptamers for target specific delivery of therapeutic oligonucleotides.

Diagnosis of prostate cancer via nanotechnological approach

Prostate cancer is one of the leading causes of cancer-related deaths among the Caucasian adult males in Europe and the USA. Currently available diagnostic strategies for patients with prostate cancer are invasive and unpleasant and have poor accuracy. Many patients have been overly or underly treated resulting in a controversy regarding the reliability of current conventional diagnostic approaches. This review discusses the state-of-the-art research in the development of novel noninvasive prostate cancer diagnostics using nanotechnology coupled with suggested diagnostic strategies for their clinical implication.

Study on the prostate cancer-targeting mechanism of aptamer-modified nanoparticles and their potential anticancer effect in vivo

Ligand-mediated prostate cancer (PCa)-targeting gene delivery is one of the focuses of research in recent years. Our previous study reported the successful preparation of aptamer-modified nanoparticles (APT-NPs) in our laboratory and demonstrated their PCa-targeting ability in vitro. However, the mechanism underlying this PCa-targeting effect and their anticancer ability in vivo have not yet been elucidated. The objective of this study was to assess the feasibility of using APT-NPs to deliver micro RNA (miRNA) systemically to PCa cells, to testify their tumor-targeting efficiency, and to observe their biodistribution after systemic administration to a xenograft mouse model of PCa. In addition, the effect of APT depletion and endocytosis inhibitors on cellular uptake was also evaluated quantitatively in LNCaP cells to explore the internalization mechanism of APT-NPs. Finally, blood chemistry, and renal and liver function parameters were measured in the xenograft mouse model of PCa to see whether APT-NPs had any demonstrable toxicity in mice in vivo. The results showed that APT-NPs prolonged the survival duration of the PCa tumor-bearing mice as compared with the unmodified NPs. In addition, they had a potential PCa-targeting effect in vivo. In conclusion, this research provides a prototype for the safe and efficient delivery of miRNA expression vectors to PCa cells, which may prove useful for preclinical and clinical studies on the treatment of PCa.

Aptamer-mediated selective delivery of short RNA therapeutics in cancer cells

RNA interference (RNAi) is an important biological process that ultimately leads to suppression of gene expression. Activators of RNAi are typically small interfering RNAs (siRNA) and microRNAs (miRNA) that offer considerable therapeutic potnetial. However, a major obstacle to take these these molecules to the clinic is the absence of safe and reliable means for their specific delivery to target cells. In this regard, a highly promising class of molecules is represented by nucleic acid aptamers. These are short, structured, single-stranded RNAs or DNAs oligonucleotides that, by binding with high specificity to target molecules, provide high affinity ligands and potential antagonists of disease-associated proteins. Further, because of the high binding specificity, aptamers represent a powerful tool for the selective delivery of therapeutic cargos, including mi/siRNAs, chemotherapeutics, toxins and nanoparticles to cancer cells or tissues, thus potentially increasing the efficacy of a given therapy as well as reducing toxicity. In this review, we will focus on recent advances in the field of aptamer-mediated mi/siRNA delivery, discussing their potential and challenges in cancer therapy.

Cell-type-specific, Aptamer-functionalized Agents for Targeted Disease Therapy

One hundred years ago, Dr. Paul Ehrlich popularized the "magic bullet" concept for cancer therapy in which an ideal therapeutic agent would only kill the specific tumor cells it targeted. Since then, "targeted therapy" that specifically targets the molecular defects responsible for a patient's condition has become a long-standing goal for treating human disease. However, safe and efficient drug delivery during the treatment of cancer and infectious disease remains a major challenge for clinical translation and the development of new therapies. The advent of SELEX technology has inspired many groundbreaking studies that successfully adapted cell-specific aptamers for targeted delivery of active drug substances in both in vitro and in vivo models. By covalently linking or physically functionalizing the cell-specific aptamers with therapeutic agents, such as siRNA, microRNA, chemotherapeutics or toxins, or delivery vehicles, such as organic or inorganic nanocarriers, the targeted cells and tissues can be specifically recognized and the therapeutic compounds internalized, thereby improving the local concentration of the drug and its therapeutic efficacy. Currently, many cell-type-specific aptamers have been developed that can target distinct diseases or tissues in a cell-type-specific manner. In this review, we discuss recent advances in the use of cell-specific aptamers for targeted disease therapy, as well as conjugation strategies and challenges.

Coupling of a bifunctional peptide R13 to OTMCS-PEI copolymer as a gene vector increases transfection efficiency and tumor targeting

BACKGROUND

A degradable polyethylenimine (PEI) derivative coupled to a bifunctional peptide R13 was developed to solve the transfection efficiency versus cytotoxicity and tumor-targeting problems of PEI when used as a gene vector.

METHODS

We crossed-linked low molecular weight PEI with N-octyl-N-quaternary chitosan (OTMCS) to synthesize a degradable PEI derivative (OTMCS-PEI), and then used a bifunctional peptide, RGDC-TAT (49-57) called R13 to modify OTMCS-PEI so as to prepare a new gene vector, OTMCS-PEI-R13. This new gene vector was characterized by various physicochemical methods. Its cytotoxicity and gene transfection efficiency were also determined both in vitro and in vivo.

RESULTS

The vector showed controlled degradation and excellent buffering capacity. The particle size of the OTMCS-PEI-R13/DNA complexes was around 150-250 nm and the zeta potential ranged from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 23.5 U DNase I/μg DNA. Further, the polymer was resistant to dissociation induced by 50% fetal bovine serum and 400 μg/mL sodium heparin. Compared with PEI 25 kDa, the OTMCS-PEI-R13/DNA complexes showed higher transfection efficiency both in vitro and in vivo. Further, compared with OTMCS-PEI, distribution of OTMCS-PEI-R13 at tumor sites was markedly enhanced, indicating the tumor-targeting specificity of R13.

CONCLUSION

OTMCS-PEI-R13 could be a potential candidate as a safe and efficient gene delivery carrier for gene therapy.

Current progress on aptamer-targeted oligonucleotide therapeutics

Exploiting the power of the RNAi pathway through the use of therapeutic siRNA drugs has remarkable potential for treating a vast array of human disease conditions. However, difficulties in delivery of these and similar nucleic acid-based pharmacological agents to appropriate organs or tissues, remains a major impediment to their broad clinical application. Synthetic nucleic acid ligands (aptamers) have emerged as effective delivery vehicles for therapeutic oligonucleotides, including siRNAs. In this review, we summarize recent attractive developments in creatively employing cell-internalizing aptamers to deliver therapeutic oligonucleotides (e.g., siRNAs, miRNAs, anti-miRs and antisense oligos) to target cells. We also discuss advancements in aptamer-siRNA chimera technology, as well as, aptamer-functionalized nanoparticles for siRNA delivery. In addition, the challenges and future prospects of aptamer-targeted oligonucleotide drugs for clinical translation are further highlighted.

Multifunctional aptamer-miRNA conjugates for targeted cancer therapy

While microRNAs (miRNAs) clearly regulate multiple pathways integral to disease development and progression, the lack of safe and reliable means for specific delivery of miRNAs to target tissues represents a major obstacle to their broad therapeutic application. Our objective was to explore the use of nucleic acid aptamers as carriers for cell-targeted delivery of a miRNA with tumor suppressor function, let-7g. Using an aptamer that binds to and antagonizes the oncogenic receptor tyrosine kinase Axl (GL21.T), here we describe the development of aptamer-miRNA conjugates as multifunctional molecules that inhibit the growth of Axl-expressing tumors. We conjugated the let-7g miRNA to GL21.T and demonstrate selective delivery to target cells, processing by the RNA interference machinery, and silencing of let-7g target genes. Importantly, the multifunctional conjugate reduced tumor growth in a xenograft model of lung adenocarcinoma. Therefore, our data establish aptamer-miRNA conjugates as a novel tool for targeted delivery of miRNAs with therapeutic potential.

Dendrimer nanoscaffolds for potential theranostics of prostate cancer with a focus on radiochemistry

Dendrimers are a class of structurally defined macromolecules featured with a central core, a low-density interior formed by repetitive branching units, and a high-density exterior terminated with surface functional groups. In contrast to their polymeric counterparts, dendrimers are nanosized and symmetrically shaped, which can be reproducibly synthesized on a large scale with monodispersity. These unique features have made dendrimers of increasing interest for drug delivery and other biomedical applications as nanoscaffold systems. Intended to address the potential use of dendrimers for the development of theranostic agents, which combines therapeutics and diagnostics in a single entity for personalized medicine, this review focuses on the reported methodologies of using dendrimer nanoscaffolds for targeted imaging and therapy of prostate cancer. Of particular interest, relevant chemistry strategies are discussed due to their important roles in the design and synthesis of diagnostic and therapeutic dendrimer-based nanoconjugates and potential theranostic agents, targeted or nontargeted. Given the developing status of nanoscaffolded theranostics, major challenges and potential hurdles are discussed along with the examples representing current advances.

PET imaging in prostate cancer: focus on prostate-specific membrane antigen

Prostate cancer (PCa) is the second leading cause of cancer-related death in American men. Positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease, detection of metastatic lesions and, ultimately, for predicting the aggressiveness of disease. Prostate-specific membrane antigen (PSMA) is a well-characterized imaging biomarker of PCa. Because PSMA levels are directly related to androgen independence, metastasis and progression, PSMA could prove an important target for the development of new radiopharmaceuticals for PET. Preclinical data for new PSMA-based radiotracers are discussed and include new (89)Zr- and (64)Cu-labeled anti-PSMA antibodies and antibody fragments, (64)Cu-labeled aptamers, and (11)C-, (18)F-, (68)Ga-, (64)Cu-, and (86)Y-labeled low molecular weight inhibitors of PSMA. Several of these agents, namely (68)Ga- HBED-CC conjugate 15, (18)F-DCFBC 8, and BAY1075553 are particularly promising, each having detected sites of PCa in initial clinical studies. These early clinical results suggest that PET/CT using PSMA-targeted agents, especially with compounds of low molecular weight, will make valuable contributions to the management of PCa.

Current progress of RNA aptamer-based therapeutics

Aptamers are single-stranded nucleic acids that specifically recognize and bind tightly to their cognate targets due to their stable three-dimensional structure. Nucleic acid aptamers have been developed for various applications, including diagnostics, molecular imaging, biomarker discovery, target validation, therapeutics, and drug delivery. Due to their high specificity and binding affinity, aptamers directly block or interrupt the functions of target proteins making them promising therapeutic agents for the treatment of human maladies. Additionally, aptamers that bind to cell surface proteins are well suited for the targeted delivery of other therapeutics, such as conjugated small interfering RNAs (siRNA) that induce RNA interference (RNAi). Thus, aptamer-siRNA chimeras may offer dual-functions, in which the aptamer inhibits a receptor function, while the siRNA internalizes into the cell to target a specific mRNA. This review focuses on the current progress and therapeutic potential of RNA aptamers, including the use of cell-internalizing aptamers as cell-type specific delivery vehicles for targeted RNAi. In particular, we discuss emerging aptamer-based therapeutics that provide unique clinical opportunities for the treatment various cancers and neurological diseases.

Degradable copolymer based on amphiphilic N-octyl-N-quatenary chitosan and low-molecular weight polyethylenimine for gene delivery

Background

Chitosan shows particularly high biocompatibility and fairly low cytotoxicity. However, chitosan is insoluble at physiological pH. Moreover, it lacks charge, so shows poor transfection. In order to develop a new type of gene vector with high transfection efficiency and low cytotoxicity, amphiphilic chitosan was synthesized and linked with low-molecular weight polyethylenimine (PEI).

Methods

We first synthesized amphiphilic chitosan – N-octyl-N-quatenary chitosan (OTMCS), then prepared degradable PEI derivates by cross-linking low-molecular weight PEI with amphiphilic chitosan to produce a new polymeric gene vector (OTMCS–PEI). The new gene vector was characterized by various physicochemical methods. We also determined its cytotoxicity and gene transfecton efficiency in vitro and in vivo.

Results

The vector showed controlled degradation. It was very stable and showed excellent buffering capacity. The particle sizes of the OTMCS–PEI/DNA complexes were around 150–200 nm with proper zeta potentials from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 2.25 U DNase I/μg DNA. Furthermore, they were resistant to dissociation induced by 50% fetal bovine serum and 1100 μg/mL sodium heparin. OTMCS–PEI revealed lower cytotoxicity, even at higher doses. Compared with PEI 25 KDa, the OTMCS–PEI/DNA complexes also showed higher transfection efficiency in vitro and in vivo.

Conclusion

OTMCS–PEI was a potential candidate as a safe and efficient gene vector for gene therapy.

Aptamer-mediated delivery of splice-switching oligonucleotides to the nuclei of cancer cells

To reduce the adverse effects of cancer therapies and increase their efficacy, new delivery agents that specifically target cancer cells are needed. We and others have shown that aptamers can selectively deliver therapeutic oligonucleotides to the endosome and cytoplasm of cancer cells that express a particular cell surface receptor. Identifying a single aptamer that can internalize into many different cancer cell-types would increase the utility of aptamer-mediated delivery of therapeutic agents. We investigated the ability of the nucleolin aptamer (AS1411) to internalize into multiple cancer cell types and observed that it internalizes into a wide variety of cancer cells and migrates to the nucleus. To determine if the aptamer could be utilized to deliver therapeutic oligonucleotides to modulate events in the nucleus, we evaluated the ability of the aptamer to deliver splice-switching oligonucleotides. We observed that aptamer-splice-switching oligonucleotide chimeras can alter splicing in the nuclei of treated cells and are effective at lower doses than the splice switching oligonucleotides alone. Our results suggest that aptamers can be utilized to deliver oligonucleotides to the nucleus of a wide variety of cancer cells to modulate nuclear events such as RNA splicing.

Degradable polyethylenimine derivate coupled to a bifunctional peptide R13 as a new gene-delivery vector

Background

To solve the efficiency versus cytotoxicity and tumor-targeting problems of polyethylenimine (PEI) used as a nonviral gene delivery vector, a degradable PEI derivate coupled to a bifunctional peptide R13 was developed.

Methods

First, we synthesized a degradable PEI derivate by crosslinking low-molecular-weight PEI with pluronic P123, then used tumor-targeting peptide arginine-glycine-aspartate-cysteine (RGDC), in conjunction with the cell-penetrating peptide Tat (49–57), to yield a bifunctional peptide RGDC-Tat (49–57) named R13, which can improve cell selection and increase cellular uptake, and, lastly, adopted R13 to modify the PEI derivates so as to prepare a new polymeric gene vector (P123-PEI-R13). The new gene vector was characterized in terms of its chemical structure and biophysical parameters. We also investigated the specificity, cytotoxicity, and gene transfection efficiency of this vector in αvβ3-positive human cervical carcinoma Hela cells and murine melanoma B16 cells in vitro.

Results

The vector showed controlled degradation, strong targeting specificity to αvβ3 receptor, and noncytotoxicity in Hela cells and B16 cells at higher doses, in contrast to PEI 25 KDa. The particle size of P123-PEI-R13/DNA complexes was around 100–250 nm, with proper zeta potential. The nanoparticles can protect plasmid DNA from being digested by DNase I at a concentration of 6 U DNase I/μg DNA. The nanoparticles were resistant to dissociation induced by 50% fetal bovine serum and 600 μg/mL sodium heparin. P123-PEI-R13 also revealed higher transfection efficiency in two cell lines as compared with PEI 25 KDa.

Conclusion

P123-PEI-R13 is a potential candidate as a safe and efficient gene-delivery carrier for gene therapy.

Degradable gene delivery systems based on Pluronics-modified low-molecular-weight polyethylenimine: preparation, characterization, intracellular trafficking, and cellular distribution

Background

Cationic copolymers consisting of polycations linked to nonionic amphiphilic block polymers have been evaluated as nonviral gene delivery systems, and a large number of different polymers and copolymers of linear, branched, and dendrimeric architectures have been tested in terms of their suitability and efficacy for in vitro and in vivo transfection. However, the discovery of new potent materials still largely relies on empiric approaches rather than a rational design. The authors investigated the relationship between the polymers’ structures and their biological performance, including DNA compaction, toxicity, transfection efficiency, and the effect of cellular uptake.

Methods

This article reports the synthesis and characterization of a series of cationic copolymers obtained by grafting polyethyleneimine with nonionic amphiphilic surfactant polyether-Pluronic^® consisting of hydrophilic ethylene oxide and hydrophobic propylene oxide blocks. Transgene expression, cytotoxicity, localization of plasmids, and cellular uptake of these copolymers were evaluated following in vitro transfection of HeLa cell lines with various individual components of the copolymers.

Results

Pluronics can exhibit biological activity including effects on enhancing DNA cellular uptake, nuclear translocation, and gene expression. The Pluronics with a higher hydrophilic-lipophilic balance value lead to homogeneous distribution in the cytoplasm; those with a lower hydrophilic-lipophilic balance value prefer to localize in the nucleus.

Conclusion

This Pluronic-polyethyleneimine system may be worth exploring as components in the cationic copolymers as the DNA or small interfering RNA/microRNA delivery system in the near future.