Efficient pro-survival/angiogenic miRNA delivery by an MRI-detectable nanomaterial

Self-Assembled Fluorinated Nanoparticles as Sensitive and Biocompatible Theranostic Platforms for 19F MRI

Theranostics is a novel paradigm integrating therapy and diagnostics, thereby providing new prospects for overcoming the limitations of traditional treatments. In this context, perfluorocarbons (PFCs) are the most widely used tracers in preclinical fluorine-19 magnetic resonance (19F MR), primarily for their high fluorine content. However, PFCs are extremely hydrophobic, and their solutions often display reduced biocompatibility, relative instability, and subpar 19F MR relaxation times. This study aims to explore the potential of micellar 19F MR imaging (MRI) tracers, synthesized by polymerization-induced self-assembly (PISA), as alternative theranostic agents for simultaneous imaging and release of the non-steroidal antileprotic drug clofazimine. In vitro, under physiological conditions, these micelles demonstrate sustained drug release. In vivo, throughout the drug release process, they provide a highly specific and sensitive 19F MRI signal. Even after extended exposure, these fluoropolymer tracers show biocompatibility, as confirmed by the histological analysis. Moreover, the characteristics of these polymers can be broadly adjusted by design to meet the wide range of criteria for preclinical and clinical settings. Therefore, micellar 19F MRI tracers display physicochemical properties suitable for in vivo imaging, such as relaxation times and non-toxicity, and high performance as drug carriers, highlighting their potential as both diagnostic and therapeutic tools.

A Molecular Troika of Angiogenesis, Coagulopathy and Endothelial Dysfunction in the Pathology of Avascular Necrosis of Femoral Head: A Comprehensive Review

Avascular necrosis of the femoral head (ANFH) is a painful disorder characterized by the cessation of blood supply to the femoral head, leading to its death and subsequent joint collapse. Influenced by several risk factors, including corticosteroid use, excessive alcohol intake, hypercholesterolemia, smoking and some inflammatory disorders, along with cancer, its clinical consequences are thrombus formation due to underlying inflammation and endothelial dysfunction, which collaborates with coagulopathy and impaired angiogenesis. Nonetheless, angiogenesis resolves the obstructed free flow of the blood by providing alternative routes. Clinical manifestations of early stage of ANFH mimic cysts or lesions in subchondral bone, vasculitis and transient osteoporosis of the hip, rendering it difficult to diagnose, complex to understand and complicated to cure. To date, the treatment methods for ANFH are controversial as no foolproof curative strategy is available, and these depend upon different severity levels of the ANFH. From an in-depth understanding of the pathological determinants of ANFH, it is clear that impaired angiogenesis, coagulopathy and endothelial dysfunction contribute significantly. The present review has set two aims, firstly to examine the role and relevance of this molecular triad (impaired angiogenesis, coagulopathy and endothelial dysfunction) in ANFH pathology and secondly to propose some putative therapeutic strategies, delineating the fact that, for the better management of ANFH, a combined strategy to curtail this molecular triangle must be composed rather than focusing on individual contributions.

Advances in miR-132-Based Biomarker and Therapeutic Potential in the Cardiovascular System

Atherosclerotic cardiovascular disease and subsequent heart failure threaten global health and impose a huge economic burden on society. MicroRNA-132 (miR-132), a regulatory RNA ubiquitously expressed in the cardiovascular system, is up-or down-regulated in the plasma under various cardiac conditions and may serve as a potential diagnostic or prognostic biomarker. More importantly, miR-132 in the myocardium has been demonstrated to be a master regulator in many pathological processes of ischemic or nonischemic heart failure in the past decade, such as myocardial hypertrophy, fibrosis, apoptosis, angiogenesis, calcium handling, neuroendocrine activation, and oxidative stress, through downregulating target mRNA expression. Preclinical and clinical phase 1b studies have suggested antisense oligonucleotide targeting miR-132 may be a potential therapeutic approach for ischemic or nonischemic heart failure in the future. This review aims to summarize recent advances in the physiological and pathological functions of miR-132 and its possible diagnostic and therapeutic potential in cardiovascular disease.

Therapeutic Biomaterial Approaches to Alleviate Chronic Limb Threatening Ischemia

Chronic limb threatening ischemia (CLTI) is a severe condition defined by the blockage of arteries in the lower extremities that leads to the degeneration of blood vessels and is characterized by the formation of non-healing ulcers and necrosis. The gold standard therapies such as bypass and endovascular surgery aim at the removal of the blockage. These therapies are not suitable for the so-called "no option patients" which present multiple artery occlusions with a likelihood of significant limb amputation. Therefore, CLTI represents a significant clinical challenge, and the efforts of developing new treatments have been focused on stimulating angiogenesis in the ischemic muscle. The delivery of pro-angiogenic nucleic acid, protein, and stem cell-based interventions have limited efficacy due to their short survival. Engineered biomaterials have emerged as a promising method to improve the effectiveness of these latter strategies. Several synthetic and natural biomaterials are tested in different formulations aiming to incorporate nucleic acid, proteins, stem cells, macrophages, or endothelial cells in supportive matrices. In this review, an overview of the biomaterials used alone and in combination with growth factors, nucleic acid, and cells in preclinical models is provided and their potential to induce revascularization and regeneration for CLTI applications is discussed.

Induced pluripotent stem cell-derived vascular networks to screen nano-bio interactions

The vascular bioactivity/safety of nanomaterials is typically evaluated by animal testing, which is of low throughput and does not account for biological differences between animals and humans such as ageing, metabolism and disease profiles. The development of personalized human in vitro platforms to evaluate the interaction of nanomaterials with the vascular system would be important for both therapeutic and regenerative medicine. A library of 30 nanoparticle (NP) formulations, in use in imaging, antimicrobial and pharmaceutical applications, was evaluated in a reporter zebrafish model of vasculogenesis and then tested in personalized humanized models composed of human-induced pluripotent stem cell (hiPSC)-derived endothelial cells (ECs) with "young" and "aged" phenotypes in 3 vascular network formats: 2D (in polystyrene dish), 3D (in Matrigel) and in a blood vessel on a chip. As a proof of concept, vascular toxicity was used as the main readout. The results show that the toxicity profile of NPs to hiPSC-ECs was dependent on the "age" of the endothelial cells and vascular network format. hiPSC-ECs were less susceptible to the cytotoxicity effect of NPs when cultured in flow than in static conditions, the protective effect being mediated, at least in part, by glycocalyx. Overall, the results presented here highlight the relevance of in vitro hiPSC-derived vascular systems to screen vascular nanomaterial interactions.

microRNAs in oral cancer: Moving from bench to bed as next generation medicine

Oral cancer is the thirteenth most common cancer in the world, with India contributing to 33% of the global burden. Lack of specific non-invasive markers, non-improvement in patient survival and tumor recurrence remain a major clinical challenge in oral cancer. Epigenetic regulation in the form of microRNAs (miRs) that act as tumor suppressor miRs or oncomiRs has gained significant momentum with the advancement in the field, suggesting the potential for clinical application of miRs in oral cancer. The current review of literature identified miR-21, miR-27a(-3p), miR-31, miR-93, miR-134, miR-146, miR-155, miR-196a, miR-196b, miR-211, miR-218, miR-222, miR-372 and miR-373 to be up-regulated and let-7a, let-7b, let-7c, let-7d, let-7e, let-7f, let-7g, let-7i, miR-26a, miR-99a-5p, miR-137, miR-139-5p, miR-143-3p, miR-184 and miR-375 to be down-regulated in oral cancer. Mechanistic studies have uncovered several miRs that are deregulated at varying levels and in different stages of oral cancer progression, thus providing clinical utility in better diagnosis as well as usefulness in prognosis by identifying patients with poor prognosis or stratifying patients based on responsiveness to chemo- and radio-therapy. Lastly, exogenous modulation of miR expression using miRNA-based drugs in combination with first-line agents may be adopted as a new therapeutic modality to treat oral cancer. Knowledge of miRs and their involvement in key molecular processes, clinical association, responsiveness to therapy and clinical advancement may highlight additional avenues in order to improve patient morbidity and mortality. Furthermore, combinatorial approaches with miR-therapy may be efficacious in oral cancer.

Control of Angiogenesis via a VHL/miR-212/132 Axis

A common feature of tumorigenesis is the upregulation of angiogenesis pathways in order to supply nutrients via the blood for the growing tumor. Understanding how cells promote angiogenesis and how to control these processes pharmaceutically are of great clinical interest. Clear cell renal cell carcinoma (ccRCC) is the most common form of sporadic and inherited kidney cancer which is associated with excess neovascularization. ccRCC is highly associated with biallelic mutations in the von Hippel–Lindau (VHL) tumor suppressor gene. Although upregulation of the miR-212/132 family and disturbed VHL signaling have both been linked with angiogenesis, no evidence of a possible connection between the two has yet been made. We show that miRNA-212/132 levels are increased after loss of functional pVHL, the protein product of the VHL gene, in vivo and in vitro. Furthermore, we show that blocking miRNA-212/132 with anti-miRs can significantly alleviate the excessive vascular branching phenotype characteristic of vhl^−/− mutant zebrafish. Moreover, using human umbilical vascular endothelial cells (HUVECs) and an endothelial cell/pericyte coculture system, we observed that VHL knockdown promotes endothelial cells neovascularization capacity in vitro, an effect which can be inhibited by anti-miR-212/132 treatment. Taken together, our results demonstrate an important role for miRNA-212/132 in angiogenesis induced by loss of VHL. Intriguingly, this also presents a possibility for the pharmaceutical manipulation of angiogenesis by modulating levels of MiR212/132.

Is There Preclinical and Clinical Value for 19F MRI in Stem Cell Cardiac Regeneration?

Cardiovascular regeneration aims to renew damaged or necrotic tissue and to enhance cardiac functional performance. Despite the hope arisen from the introduction and use of stem cells (SCs) as a novel cardiac regenerative approach, to-this-date, clinical trial findings are still ambivalent despite preclinical successes. Concurrently, noninvasive magnetic resonance imaging (MRI) advances have been based on nanotechnological breakthroughs that have (a) allowed fluorinated nanoparticles and ultrasmall iron oxide single-cell labeling, (b) explored imaging detection sensitivity limits (for preclinical/low-field clinical settings), and (c) accomplished cellular tracking in vivo. Nevertheless, outcomes have been far from ideal. Herein, the recently developed preclinical and clinical 1H and 19F MRI approaches for direct cardiac SC labeling techniques intended for cellular implantation and their potential for tracking these cells in health and infarcted states are summarized. To this extent, the potential preclinical and clinical values of 19F MRI and tracking of SCs for cardiac regeneration in myocardial infarction are questioned and challenged.

Core-Shell Polymer-Based Nanoparticles Deliver miR-155-5p to Endothelial Cells

Heart failure occurs in over 30% of the worldwide population and most commonly originates from cardiovascular diseases such as myocardial infarction. microRNAs (miRNAs) target and silence specific mRNAs, thereby regulating gene expression. Because the endogenous miR-155-5p has been ascribed to vasculoprotection, loading it onto positively charged, core-shell poly(isobutylcyanoacrylate) (PIBCA)-polysaccharide nanoparticles (NPs) was attempted. NPs showed a decrease (p < 0.0001) in surface electrical charge (ζ potential), with negligible changes in size or shape when loaded with the anionic miR-155-5p. Presence of miR-155-5p in loaded NPs was further quantified. Cytocompatibility up to 100 μg/mL of NPs for 2 days with human coronary artery endothelial cells (hCAECs) was documented. NPs were able to enter hCAECs and were localized in the endoplasmic reticulum (ER). Expression of miR-155-5p was increased within the cells by 75-fold after 4 hours of incubation (p < 0.05) and was still noticeable at day 2. Differences between loaded NP-cultured cells and free miRNA, at days 1 (p < 0.05) and 2 (p < 0.001) suggest the ability of prolonged load release in physiological conditions. Expression of miR-155-5p downstream target BACH1 was decreased in the cells by 4-fold after 1 day of incubation (p < 0.05). This study is a first proof of concept that miR-155-5p can be loaded onto NPs and remain intact and biologically active in endothelial cells (ECs). These nanosystems could potentially increase an endogenous cytoprotective response and decrease damage within infarcted hearts.

Improved cellular uptake of perfluorocarbon nanoparticles for in vivo murine cardiac 19F MRS/MRI and temporal tracking of progenitor cells

Herein, we maximize the labeling efficiency of cardiac progenitor cells (CPCs) using perfluorocarbon nanoparticles (PFCE-NP) and ¹⁹F MRI detectability, determine the temporal dynamics of single-cell label uptake, quantify the temporal viability/fluorescence persistence of labeled CPCs in vitro, and implement in vivo, murine cardiac CPC MRI/tracking that could be translatable to humans. FuGENE^HD-mediated CPC PFCE-NP uptake is confirmed with flow cytometry/confocal microscopy. Epifluorescence imaging assessed temporal viability/fluorescence (up to 7 days [D]). Nonlocalized murine ¹⁹F MRS and cardiac MRI studied label localization in terminal/longitudinal tracking studies at 9.4 T (D1-D8). A 4-8 fold ¹⁹F concentration increase is evidenced in CPCs for FuGENE vs. directly labeled cells. Cardiac ¹⁹F signals post-CPC injections diminished in vivo to ~31% of their values on D1 by D7/D8. Histology confirmed CPC retention, dispersion, and macrophage-induced infiltration. Intra-cardiac injections of PFCE-NP-labeled CPCs with FuGENE can be visualized/tracked in vivo for the first time with ¹⁹F MRI.

Capturing intracellular oncogenic microRNAs with self-assembled DNA nanostructures for microRNA-based cancer therapy

Aberrantly overexpressed oncogenic microRNAs (miRNAs, miRs) are excellent targets for therapeutic interventions.

Aberrantly overexpressed oncogenic microRNAs (miRNAs, miRs) are excellent targets for therapeutic interventions. Nevertheless, thus far, little progress has been made in developing miRNA-based drugs and techniques for clinical applications, especially for overexpressed miRNAs. In this study, we demonstrate that self-assembled DNA nanostructures bearing multiple DNA sequences that are complementary to a target miRNA can effectively capture the overexpressed oncogenic miRNA and subsequently inhibit cancer cell proliferation. Specifically, a DNA nanotube structure that carries functional DNA segments (single-stranded, duplex and hairpin forms) was designed and synthesized to capture two well-known overexpressed miRNAs, miR-21 and miR-155. It was found that all three DNA nanotubes significantly reduced both miRNA levels and inhibited cancer cell growth. Moreover, the capture efficiency was highly concentration dependent and was associated with the structural design of the DNA nanotube. These results demonstrate that through careful design, programmable DNA nanostructures can hijack the natural cellular machinery and can serve as nucleic acid drugs themselves. The concept of using self-assembled DNA nanostructures to disrupt the intracellular machinery for therapeutic purposes opens a new paradigm for exploiting self-assembled DNA nanostructures for miRNA-based anticancer therapy.

Modulation of Angiogenic Activity by Light-Activatable miRNA-Loaded Nanocarriers

The combinatorial delivery of miRNAs holds great promise to modulate cell activity in the context of angiogenesis. Yet, the delivery of multiple miRNAs with spatiotemporal control remains elusive. Here, we report a plasmonic nanocarrier to control the release of two microRNAs. The nanocarrier consists of gold nanorods modified with single-stranded DNA for hybridization with complementary DNA-conjugated microRNAs. DNA strands with distinct melting temperatures enable the independent release of each microRNA with a near-infrared laser using the same wavelength but different powers. Tests in human outgrowth endothelial cells (OECs) indicate that this system can be used to silence different targets sequentially and, by doing so, to modulate cell activity with spatiotemporal resolution. Finally, using an in vivo acute wound healing animal model, it is demonstrated that the order by which each miRNA was released in transplanted OECs significantly impacted the wound healing kinetics.

MicroRNA-124-loaded nanoparticles increase survival and neuronal differentiation of neural stem cells in vitro but do not contribute to stroke outcome in vivo

There is a high quest for novel therapeutic strategies to enhance recovery after stroke. MicroRNA-124 (miR-124) has been described as neuroprotective and anti-inflammatory molecule. Moreover, miR-124 is a well described enhancer of adult neurogenesis that could offer potentially beneficial effects. Herein, we used miR-124-loaded nanoparticles (miR-124 NPs) to evaluate their therapeutic potential in an in vitro and in vivo model of stroke. For that, neuroprotective and neurogenic responses were assessed in an in vitro model of stroke. Here, we found that miR-124 NPs decreased cell death and improved neuronal differentiation of subventricular zone (SVZ) neural stem cell cultures after oxygen and glucose deprivation. In contrast, intravenous injection of miR-124 NPs immediately after permanent focal ischemia induced by photothrombosis (PT) did not provide a better neurological outcome. In addition, treatment did not affect the number of 5-bromo-2'-deoxyuridine (BrdU)- and doublecortin/BrdU- positive cells in the SVZ at the study endpoint of 14 days after PT. Likewise, the ischemic insult did not affect the numbers of neuronal progenitors in the SVZ. However, in PT mice miR-124 NPs were able to specifically augment interleukin-6 levels at day 2 post-stroke. Furthermore, we also showed that NPs reached the brain parenchyma and were internalized by brain resident cells. Although, promising in vitro data could not be verified in vivo as miR-124 NPs treatment did not improve functional outcome nor presented beneficial actions on neurogenesis or post-stroke inflammation, we showed that our NP formulation can be a safe alternative for drug delivery into the brain.

Fast, quantitative, murine cardiac 19F MRI/MRS of PFCE-labeled progenitor stem cells and macrophages at 9.4T

Purpose

To a) achieve cardiac ¹⁹F-Magnetic Resonance Imaging (MRI) of perfluoro-crown-ether (PFCE) labeled cardiac progenitor stem cells (CPCs) and bone-derived bone marrow macrophages, b) determine label concentration and cellular load limits, and c) achieve spectroscopic and image-based quantification.

Methods

Theoretical simulations and experimental comparisons of spoiled-gradient echo (SPGR), rapid acquisition with relaxation enhancement (RARE), and steady state at free precession (SSFP) pulse sequences, and phantom validations, were conducted using ¹⁹F MRI/Magnetic Resonance Spectroscopy (MRS) at 9.4 T. Successful cell labeling was confirmed using flow cytometry and confocal microscopy. For CPC and macrophage concentration quantification, in vitro and post-mortem cardiac validations were pursued with the use of the transfection agent FuGENE. Feasibility of fast imaging is demonstrated in murine cardiac acquisitions in vivo, and in post-mortem murine skeletal and cardiac applications.

Results

SPGR/SSFP proved favorable imaging sequences yielding good signal-to-noise ratio values. Confocal microscopy confirmed heterogeneity of cellular label uptake in CPCs. ¹⁹F MRI indicated lack of additional benefits upon label concentrations above 7.5–10 mg/ml/million cells. The minimum detectable CPC load was ~500k (~10k/voxel) in two-dimensional (2D) acquisitions (3–5 min) using the butterfly coil. Additionally, absolute ¹⁹F based concentration and intensity estimates (trifluoroacetic-acid solutions, macrophages, and labeled CPCs in vitro and post-CPC injections in the post-mortem state) scaled linearly with fluorine concentrations. Fast, quantitative cardiac ¹⁹F-MRI was demonstrated with SPGR/SSFP and MRS acquisitions spanning 3–5 min, using a butterfly coil.

Conclusion

The developed methodologies achieved in vivo cardiac ¹⁹F of exogenously injected labeled CPCs for the first time, accelerating imaging to a total acquisition of a few minutes, providing evidence for their potential for possible translational work.

Gene delivery nanoparticles to modulate angiogenesis

Angiogenesis is naturally balanced by many pro- and anti-angiogenic factors while an imbalance of these factors leads to aberrant angiogenesis, which is closely associated with many diseases. Gene therapy has become a promising strategy for the treatment of such a disordered state through the introduction of exogenous nucleic acids that express or silence the target agents, thereby engineering neovascularization in both directions. Numerous non-viral gene delivery nanoparticles have been investigated towards this goal, but their clinical translation has been hampered by issues associated with safety, delivery efficiency, and therapeutic effect. This review summarizes key factors targeted for therapeutic angiogenesis and anti-angiogenesis gene therapy, non-viral nanoparticle-mediated approaches to gene delivery, and recent gene therapy applications in pre-clinical and clinical trials for ischemia, tissue regeneration, cancer, and wet age-related macular degeneration. Enhanced nanoparticle design strategies are also proposed to further improve the efficacy of gene delivery nanoparticles to modulate angiogenesis.

Temporal accumulation and localization of isoflurane in the C57BL/6 mouse and assessment of its potential contamination in 19 F MRI with perfluoro-crown-ether-labeled cardiac progenitor cells at 9.4 Tesla

Purpose

To assess the uptake, accumulation, temporal stability, and spatial localization of isoflurane (ISO) in the C57BL/6 mouse, and to identify its potential interference with the detection of labeled cardiac progenitor cells using ¹⁹F MRI/MR spectroscopy (MRS).

Materials and Methods

Objectives are demonstrated using (a) in vitro ISO tests, (b) in vivo temporal accumulation/spatial localization C57BL/6 studies (n = 3), and (c) through injections of perfluoro‐crown‐ether (PFCE) labeled cardiac progenitor cells into femoral muscle areas of the murine hindlimb post‐mortem (n = 1) using ¹H/¹⁹F MRI/MRS at 9.4 Tesla. Data were acquired using double‐gated spoiled gradient echo images and pulse‐acquire spectra. For the in vivo study, the temporal stability of ISO resonances was quantified using coefficient of variability (CV) (5 min) estimates.

Results

Two ISO resonances were observed in vivo that correspond to the ‐CF₃ and ‐OCHF₂ moieties. CV values ranged between 3.2 and 6.4% (‐CF₃) and 6.4 and 11.2% (‐OCHF₂). Reductions of the ISO dose (2.0 to 1.7%) at 80 min postinduction had insignificant effects on ISO signals (P = 0.23; P = 0.71). PFCE‐labeled cells exhibited a resonance at −16.25 ppm in vitro that did not overlap with the ISO resonances, a finding that is confirmed with MRS post‐mortem using injected, labeled cells. Based on ¹⁹F MRI, similar in vivo/post‐mortem ISO compartmentalization was also confirmed in peripheral and thoracic skeletal muscles.

Conclusion

Significant ISO accumulation was observed by ¹⁹F MRS in vivo with temporally stable signals over 90 min postinduction. ISO effects on PFCE labels are anticipated to be minimal but may be more prominent for perfluoropolyether or perfluorooctyl bromide labels.

Level of Evidence: 1

Technical Efficacy: Stage 1

J. MAGN. RESON. IMAGING 2017;45:1659–1667

Molecular Imaging of Stem Cell Transplantation for Liver Diseases: Monitoring, Clinical Translation, and Theranostics

Stem cell transplantation has been investigated to rescue experimental liver failure and is promising to offer an alternative therapy to liver transplantation for liver diseases treatment. Several clinical studies in this field have been carried out, but the therapeutic benefit of this treatment is still controversial. A major obstacle to developing stem cell therapies in clinic is being able to visualize the cells in vivo. Imaging modalities allow optimization of delivery, detecting cell survival and functionality by in vivo monitoring these transplanted graft cells. Moreover, theranostic imaging is a brand new field that utilizes nanometer-scale materials to glean diagnostic insight for simultaneous treatment, which is very promising to improve stem cell-based therapy for treatment of liver diseases. The aim of this review was to summarize the various imaging tools that have been explored with advanced molecular imaging probes. We also outline some recent progress of preclinical and clinical studies of liver stem cells transplantation. Finally, we discuss theranostic imaging for stem cells transplantation for liver dysfunction and future opportunities afforded by theranostic imaging.

Traceable microRNA-124 loaded nanoparticles as a new promising therapeutic tool for Parkinson's disease

Parkinson's disease (PD), a neurodegenerative disorder characterized by the selective degeneration of the nigrostriatal dopaminergic pathway, is a major socio-economic burden in modern society. While there is presently no cure for PD, enhancing the number of neural stem cells (NSCs) and/or stimulating their differentiation into new neurons are promising therapeutic strategies. Many proneurogenic factors have been implicated in controlling NSCs activity, including the microRNA (miR)-124. However, current strategies described for the intracellular delivery of miR involve mostly unspecific or inefficient platforms. In Saraiva et al. we developed miR-124 loaded nanoparticles (NPs) able to efficiently deliver miR-124 into neural stem/progenitor cells and boost neuronal differentiation and maturation in vitro. In vivo, the intracerebroventricular injection of miR-124 NPs increased the number of new neurons in the olfactory bulb of healthy and 6-hydroxidopamine (6-OHDA) lesioned mice, a model for PD. Importantly, miR-124 NPs enhanced the migration of new neurons into the 6-OHDA lesioned striatum, culminating in motor function improvement. Given the recent advent of clinical trials for miR-based therapies and the theranostic applications of our NPs, we expect to support the clinical translation of our delivery platform in the context of PD and other neurodegenerative diseases which may benefit from enhancing miR levels.

PGMA-Based Star-Like Polycations with Plentiful Hydroxyl Groups Act as Highly Efficient miRNA Delivery Nanovectors for Effective Applications in Heart Diseases

Poly(glycidyl methacrylate)-based star-like polycations with rich hydrophilic hydroxyl groups can efficiently transfer miRNA into primary cardiac fibroblasts for effective applications in cardiac diseases, such as inhibition of cardiac fibrosis and hypertrophy.

MicroRNA-124 loaded nanoparticles enhance brain repair in Parkinson's disease

Modulation of the subventricular zone (SVZ) neurogenic niche can enhance brain repair in several disorders including Parkinson's disease (PD). Herein, we used biocompatible and traceable polymeric nanoparticles (NPs) containing perfluoro-1,5-crown ether (PFCE) and coated with protamine sulfate to complex microRNA-124 (miR-124), a neuronal fate determinant. The ability of NPs to efficiently deliver miR-124 and prompt SVZ neurogenesis and brain repair in PD was evaluated. In vitro, miR-124 NPs were efficiently internalized by neural stem/progenitors cells and neuroblasts and promoted their neuronal commitment and maturation. The expression of Sox9 and Jagged1, two miR-124 targets and stemness-related genes, were also decreased upon miR-124 NP treatment. In vivo, the intracerebral administration of miR-124 NPs increased the number of migrating neuroblasts that reached the granule cell layer of the olfactory bulb, both in healthy and in a 6-hydroxydopamine (6-OHDA) mouse model for PD. MiR-124 NPs were also able to induce migration of neurons into the lesioned striatum of 6-OHDA-treated mice. Most importantly, miR-124 NPs proved to ameliorate motor symptoms of 6-OHDA mice, monitored by the apomorphine-induced rotation test. Altogether, we provide clear evidences to support the use of miR-124 NPs as a new therapeutic approach to boost endogenous brain repair mechanisms in a setting of neurodegeneration.

Regulation of angiogenesis through the efficient delivery of microRNAs into endothelial cells using polyamine-coated carbon nanotubes

MicroRNAs (miRNAs) directly regulate gene expression at a post-transcriptional level and represent an attractive therapeutic target for a wide range of diseases. Here, we report a novel strategy for delivering miRNAs to endothelial cells (ECs) to regulate angiogenesis, using polymer functionalized carbon nanotubes (CNTs). CNTs were coated with two different polymers, polyethyleneimine (PEI) or polyamidoamine dendrimer (PAMAM), followed by conjugation of miR-503 oligonucleotides as recognized regulators of angiogenesis. We demonstrated a reduced toxicity for both polymer-coated CNTs, compared with pristine CNTs or polymers alone. Moreover, polymer-coated CNT stabilized miR-503 oligonucleotides and allowed their efficient delivery to ECs. The functionality of PAMAM-CNT-miR-503 complexes was further demonstrated in ECs through regulation of target genes, cell proliferation and angiogenic sprouting and in a mouse model of angiogenesis. This comprehensive series of experiments demonstrates that the use of polyamine-functionalized CNTs to deliver miRNAs is a novel and effective means to regulate angiogenesis.

Therapeutic Potentials of Noncoding RNAs: Targeted Delivery of ncRNAs in Cancer Cells

Knowledge of multiple actions of short noncoding RNAs (ncRNAs) has truly allowed for viewing DNA, RNA, and protein in novel ways. The ncRNAs are an attractive new class of therapeutics, especially against undruggable targets for the treatment of cancer and other diseases. Despite the potential of ncRNAs in cancer therapy, many challenges remain, including rapid degradation and clearance, poor cellular uptake, off-target effects, and immunogenicity. Rational design, chemical modifications, and delivery carriers offer significant opportunities to overcome these challenges. In this chapter, the development of ncRNAs as cancer therapeutics from early stages to clinical trials and strategies for ncRNA-targeted delivery to cancer cells will be introduced.

Efficient delivery of therapeutic miRNA nanocapsules for tumor suppression

miRNA nanocapsules are synthesized with enhanced stability for miRNA delivery with high transduction efficiency, offering a novel class of miRNA vectors for cancer therapy.

Nanoscale strategies: treatment for peripheral vascular disease and critical limb ischemia

Peripheral vascular disease (PVD) is one of the most prevalent vascular diseases in the U.S. afflicting an estimated 8 million people. Obstruction of peripheral arteries leads to insufficient nutrients and oxygen supply to extremities, which, if not treated properly, can potentially give rise to a severe condition called critical limb ischemia (CLI). CLI is associated with extremely high morbidities and mortalities. Conventional treatments such as angioplasty, atherectomy, stent implantation and bypass surgery have achieved some success in treating localized macrovascular disease but are limited by their invasiveness. An emerging alternative is the use of growth factor (delivered as genes or proteins) and cell therapy for PVD treatment. By delivering growth factors or cells to the ischemic tissue, one can stimulate the regeneration of functional vasculature network locally, re-perfuse the ischemic tissue, and thus salvage the limb. Here we review recent advance in nanomaterials, and discuss how their application can improve and facilitate growth factor or cell therapies. Specifically, nanoparticles (NPs) can serve as drug carrier and target to ischemic tissues and achieve localized and sustained release of pro-angiogenic proteins. As nonviral vectors, NPs can greatly enhance the transfection of target cells with pro-angiogenic genes with relatively fewer safety concern. Further, NPs may also be used in combination with cell therapy to enhance cell retention, cell survival and secretion of angiogenic factors. Lastly, nano/micro fibrous vascular grafts can be engineered to better mimic the structure and composition of native vessels, and hopefully overcome many complications/limitations associated with conventional synthetic grafts.

Delivery and targeting of miRNAs for treating liver fibrosis

Liver fibrosis is a pathological condition originating from liver damage that leads to excess accumulation of extracellular matrix (ECM) proteins in the liver. Viral infection, chronic injury, local inflammatory responses and oxidative stress are the major factors contributing to the onset and progression of liver fibrosis. Multiple cell types and various growth factors and inflammatory cytokines are involved in the induction and progression of this disease. Various strategies currently being tried to attenuate liver fibrosis include the inhibition of HSC activation or induction of their apoptosis, reduction of collagen production and deposition, decrease in inflammation, and liver transplantation. Liver fibrosis treatment approaches are mainly based on small drug molecules, antibodies, oligonucleotides (ODNs), siRNA and miRNAs. MicroRNAs (miRNA or miR) are endogenous noncoding RNA of ~22 nucleotides that regulate gene expression at post transcription level. There are several miRNAs having aberrant expressions and play a key role in the pathogenesis of liver fibrosis. Single miRNA can target multiple mRNAs, and we can predict its targets based on seed region pairing, thermodynamic stability of pairing and species conservation. For in vivo delivery, we need some additional chemical modification in their structure, and suitable delivery systems like micelles, liposomes and conjugation with targeting or stabilizing the moiety. Here, we discuss the role of miRNAs in fibrogenesis and current approaches of utilizing these miRNAs for treating liver fibrosis.

MicroRNAs as novel biological targets for detection and regulation

MicroRNAs are being considered as a novel type of bio-markers and potential therapeutic targets for various diseases. Diverse chemical tools are being developed for the detection or regulation of microRNAs with bio-medical implications. Chemical probes have been developed for use in combination with in situ signal amplification strategies to realize sensitive detection of microRNAs of low abundance. Regulation of microRNAs aberrantly expressed in tumours represents a new approach to cancer chemotherapy. Synthetic oligonucleotides including antisense oligonucleotides and microRNA mimics have been successfully delivered into cells or tissues to inhibit or enhance the function of specific endogenous microRNAs. Small-molecule modifiers of microRNAs that modify the expression or function of endogenous microRNAs are emerging not only as useful probes to explore microRNA-involved regulatory networks, but also as potential therapeutic reagents. In this tutorial review, we discuss the strategies developed by chemists in recent years for microRNA detection and regulation, with a focus on the potential of these chemical tools in microRNA-related biomedical applications.

Inflammatory modulation of stem cells by Magnetic Resonance Imaging (MRI)-detectable nanoparticles

Novel MRI-detectable PLGA nanoparticles can track hematopoietic stem cells and down-regulate the secretion of pro-inflammatory cytokines by interfering with TLRs.

Sustained delivery of proangiogenic microRNA-132 by nanoparticle transfection improves endothelial cell transplantation

Transplantation of endothelial cells (ECs) for therapeutic vascularization or tissue engineering is a promising method for increasing tissue perfusion. Here, we report on a new approach for enhanced EC transplantation using targeted nanoparticle transfection to deliver proangiogenic microRNA-132 (miR-132) to cultured ECs before their transplantation, thereby sensitizing cells to the effects of endogenous growth factors. We synthesized biodegradable PLGA polymer nanoparticles (NPs) that were loaded with miR-132 and coated with cyclic RGD (cRGD) peptides that target integrin αvβ3 expressed on cultured human umbilical vein ECs (HUVECs), increasing NP uptake through clathrin-coated pits. Unlike previously reported NPs for miR delivery, these NPs slowly release RNA for several weeks. The endocytosed NPs remain in clathrin-coated vesicles from which they mediate intracellular delivery of siRNA or miRNA. Transfection of HUVECs with miR-132 enhances growth factor-induced proliferation and migration in 2D culture, producing a 1.8- and 5-fold increase, respectively. However, while the effects of conventional transfection were short-lived, NP transfection produced protein knockdown and biological effects that were significantly longer in duration (≥ 6 d). Transfection of HUVECs with miR-132 NP resulted in a 2-fold increase in the number of microvessels per square millimeter compared to lipid after transplantation into immunodeficient mice and led to a higher number of mural cell-invested vessels than control transfection. These data suggest that sustained delivery of miR-132 encapsulated in a targeted biodegradable polymer NP is a safe and efficient strategy to improve EC transplantation and vascularization.

Progress in microRNA delivery

MicroRNAs (miRNAs) are non-coding endogenous RNAs that direct post-transcriptional regulation of gene expression by several mechanisms. Activity is primarily through binding to the 3' untranslated regions (UTRs) of messenger RNAs (mRNA) resulting in degradation and translation repression. Unlike other small-RNAs, miRNAs do not require perfect base pairing, and thus, can regulate a network of broad, yet specific, genes. Although we have only just begun to gain insights into the full range of biologic functions of miRNA, their involvement in the onset and progression of disease has generated significant interest for therapeutic development. Mounting evidence suggests that miRNA-based therapies, either restoring or repressing miRNAs expression and activity, hold great promise. However, despite the early promise and exciting potential, critical hurdles often involving delivery of miRNA-targeting agents remain to be overcome before transition to clinical applications. Limitations that may be overcome by delivery include, but are not limited to, poor in vivo stability, inappropriate biodistribution, disruption and saturation of endogenous RNA machinery, and untoward side effects. Both viral vectors and nonviral delivery systems can be developed to circumvent these challenges. Viral vectors are efficient delivery agents but toxicity and immunogenicity limit their clinical usage. Herein, we review the recent advances in the mechanisms and strategies of nonviral miRNA delivery systems and provide a perspective on the future of miRNA-based therapeutics.