Platform For Delivery Of Therapeutics Research Articles

A smart drug delivery system responsive to pH/enzyme stimuli based on hydrophobic modified sodium alginate

A biocompatible dual-stimuli responsive drug delivery for hydrophobic drugs based on self-assembled polymeric micelles was presented. Hydrophobic modified alginate (HMA), used dodecyl glycidyl ether as a hydrophobic group, could form self-assembled micelles in aqueous solution above the critical micelle concentration. Doxorubicin (DOX) was chosen as a model drug and successfully loaded in HMA micelles. The percentage of drug loading efficiency of the HMA was determined as 65.4% by using fluorescence measurement. The pH-triggered and enzyme-triggered release behavior of DOX from DOX-HMA micelles indicated that the release of DOX was accelerated in acidic medium and that the release rate was dramatically enhanced in the presence of Alpha-L-fucosidase. It was found that almost 80% DOX was released from the DOX-HMA micelles in the presence of AFU at pH 5.5. Moreover, in vitro drug release studies exhibited that the DOX-HMA was effectively taken up by the cancer cells, and the blank micelles showed low toxicity toward the cancer cells, while the drug loaded micelles had high toxicity, even than the free drugs. These results demonstrate that HMA may serve as a general platform for therapeutic delivery.

Thermoresponsive, hollow, degradable core-shell nanoparticles for intra-articular delivery of anti-inflammatory peptide

Inflammation following joint trauma contributes to cartilage degradation and progression of post traumatic osteoarthritis (PTOA). Therefore, drug delivery vehicles that deliver effective anti-inflammatory treatments have the potential to prevent PTOA. We have developed solid and hollow, thermoresponsive nanoparticles for the controlled release of our anti-inflammatory MK2-inhibiting (MK2i) peptide for intra-articular injection to halt inflammation that contributes to the advancement of PTOA. This system exploits the thermosensitive characteristic of N-isopropyl acrylamide (NIPAm) to transition phases when passing through its lower critical solution temperature (LCST). The nanoparticles (NPs) swell below the LCST and constrict above it.Non-crosslinked poly(NIPAm) (pNIPAm), held above its LCST, formed hydrophobic cores around which shells composed of NIPAm, degradable crosslinker N, N′-bis (acryloyl) cystamine (BAC), sulfated 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and acrylic acid (AAc) were polymerized. Removal of the non-crosslinked pNIPAm cores via diffusion produced thermosensitive, degradable nanoparticles with low density, or hollow, cores. The data presented here revealed low-density, termed hollow, nanoparticles (hNPs) load and release significantly more MK2i than solid nanoparticles (sNPs). Furthermore, drug loading below the LCST of NIPAm results in roughly 2.5 times more therapeutic encapsulation compared to loading particles in their constricted state. Hollow nanoparticles increase drug loading compared to solid nanoparticles, are taken up into chondrocytes within 24 h, cleared from the cells within 6 days, significantly decrease the secretion of the proinflammatory cytokine IL-6, and, via intra-articular injection, are successfully delivered into the joint space of rats. The peptide loaded nanoparticles provide a reproducible platform for intra-articular delivery of therapeutics.

Tumor- and mitochondria-targeted nanoparticles eradicate drug resistant lung cancer through mitochondrial pathway of apoptosis

Chemotherapeutic drugs frequently encounter multidrug resistance. ATP from mitochondria helps overexpression of drug efflux pumps to induce multidrug resistance, so mitochondrial delivery as a means of “repurposing’’ chemotherapeutic drugs currently used in the clinic appears to be a worthwhile strategy to pursue for the development of new anti-drug-resistant cancer agents. TPP-Pluronic F127-hyaluronic acid (HA) (TPH), with a mitochondria-targeting triphenylphosphine (TPP) head group, was first synthesized through ester bond formation. Paclitaxel (PTX)-loaded TPH (TPH/PTX) nanomicelles exhibited excellent physical properties and significantly inhibited A549/ADR cells. After TPH/PTX nanomicelles entered acidic lysosomes through macropinocytosis, the positively charged TP/PTX nanomicelles that resulted from degradation of HA by hyaluronidase (HAase) in acidic lysosomes were exposed and completed lysosomal escape at 12 h, finally localizing to mitochondria over a period of 24 h in A549/ADR cells. Subsequently, TPH/PTX caused mitochondrial outer membrane permeabilization (MOMP) by inhibiting antiapoptotic Bcl-2, leading to cytochrome C release and activation of caspase-3 and caspase-9. In an A549/ADR xenograft tumor model and a drug-resistant breast cancer-bearing mouse model with lung metastasis, TPH/PTX nanomicelles exhibited obvious tumor targeting and significant antitumor efficacy. This work presents the potential of a single, nontoxic nanoparticle (NP) platform for mitochondria-targeted delivery of therapeutics for diverse drug-resistant cancers.

Exploiting Prophage-Mediated Lysis for Biotherapeutic Release by Lactobacillus reuteri.

Lactobacillus reuteri has the potential to be developed as a microbial therapeutic delivery platform because of an established safety profile, health-promoting properties, and available genome editing tools. Here, we show that L. reuteri VPL1014 exhibits a low mutation rate compared to other Gram-positive bacteria, which we expect will contribute to the stability of genetically modified strains. VPL1014 encodes two biologically active prophages, which are induced during gastrointestinal transit. We hypothesized that intracellularly accumulated recombinant protein can be released following bacteriophage-mediated lysis. To test this, we engineered VPL1014 to accumulate leptin, our model protein, inside the cell. In vitro prophage induction of recombinant VPL1014 released leptin into the extracellular milieu, which corresponded to bacteriophage production. We also employed a plasmid system that does not require antibiotic in the growth medium for plasmid maintenance. Collectively, these data provide new avenues to exploit native prophages to deliver therapeutic molecules.IMPORTANCE Lactic acid bacteria (LAB) have been explored as potential biotherapeutic vehicles for the past 20 years. To secrete a therapeutic in the extracellular milieu, one typically relies on the bacterial secretion pathway, i.e., the Sec pathway. Overexpression of a secreted protein can overload the secretory pathway and impact the organism's fitness, and optimization of the signal peptide is also required to maximize the efficiency of the release of mature protein. Here, we describe a previously unexplored approach to release therapeutics from the probiotic Lactobacillus reuteri We demonstrate that an intracellularly accumulated recombinant protein is released following prophage activation. Since we recently demonstrated that prophages are activated during gastrointestinal transit, we propose that this method will provide a straightforward and efficient approach to deliver therapeutics in vivo.

Graphene Oxide as a Multifunctional Platform for Intracellular Delivery, Imaging, and Cancer Sensing

Graphene oxide (GO), the most common derivative of graphene, is an exceptional nanomaterial that possesses multiple physical properties critical for biomedical applications. GO exhibits pH-dependent fluorescence emission in the visible/near-infrared, providing a possibility of molecular imaging and pH-sensing. It is also water soluble and has a substantial platform for functionalization, allowing for the delivery of multiple therapeutics. GO physical properties are modified to enhance cellular internalization, producing fluorescent nanoflakes with low (<15%) cytotoxicity at the imaging concentrations of 15 μg/mL. As a result, at lower flake sizes GO rapidly internalizes into HeLa cells with the following 70% fluorescence based clearance at 24 h, assessed by its characteristic emission in red/near-IR. pH-dependence of GO emission is utilized to provide the sensing of acidic extracellular environments of cancer cells. The results demonstrate diminishing green/red (550/630 nm) fluorescence intensity ratios for HeLa and MCF-7 cancer cells in comparison to HEK-293 healthy cells suggesting a potential use of GO as a non-invasive optical sensor for cancer microenvironments. The results of this work demonstrate the potential of GO as a novel multifunctional platform for therapeutic delivery, biological imaging and cancer sensing.

Specific delivery of delta-5-desaturase siRNA via RNA nanoparticles supplemented with dihomo-γ-linolenic acid for colon cancer suppression

We have previously demonstrated that DGLA treatment along with Delta-5-Desaturase (D5D) siRNA in various types of cancer cells enhances the formation of 8-HOA from COX-2-catalyzed DGLA peroxidation, which in turn inhibits cancer cell growth and migration. However, delivery of naked siRNA remains a formidable challenge due to its “off-target” effect. In this study, we employed RNA nanotechnology for specific delivery of D5D-siRNA to xenograft colon tumors using 3WJ RNA nanoparticles. When a targeting module, i.e., the EpCAM aptamer, was incorporated, the 3WJ pRNA nanoparticles were able specifically deliver D5D siRNA to human colon cancer HCA-7 cells both in vitro and in vivo, resulting in significant downregulation of D5D expression. Co-treatment with DGLA in combination with 3WJ-EpCAM-siRNA induced a higher DGLA/AA ratio and enhanced formation of 8-HOA at a threshold level, and in HCA-7 tumor-bearing mice, induced significant tumor suppression. We further confirmed that 8-HOA formation, promoted by COX-2-catalyzed DGLA peroxidation, inhibited HDAC and consequently induced apoptosis in tumor cells. Therefore, the 3WJ RNA nanoparticle system holds great promise as a suitable therapeutic delivery platform for colon cancer therapy.

Platelet-Inspired Nanocells for Targeted Heart Repair After Ischemia/Reperfusion Injury.

Cardiovascular disease is the leading cause of mortality worldwide. While reperfusion therapy is vital for patient survival post-heart attack, it also causes further tissue injury, known as myocardial ischemia/reperfusion (I/R) injury in clinical practice. Exploring ways to attenuate I/R injury is of clinical interest for improving post-ischemic recovery. A platelet-inspired nanocell (PINC) that incorporates both prostaglandin E2 (PGE2)-modified platelet membrane and cardiac stromal cell-secreted factors to target the heart after I/R injury is introduced. By taking advantage of the natural infarct-homing ability of platelet membrane and the overexpression of PGE2 receptors (EPs) in the pathological cardiac microenvironment after I/R injury, the PINCs can achieve targeted delivery of therapeutic payload to the injured heart. Furthermore, a synergistic treatment efficacy can be achieved by PINC, which combines the paracrine mechanism of cell therapy with the PGE2/EP receptor signaling that is involved in the repair and regeneration of multiple tissues. In a mouse model of myocardial I/R injury, intravenous injection of PINCs results in augmented cardiac function and mitigated heart remodeling, which is accompanied by the increase in cycling cardiomyocytes, activation of endogenous stem/progenitor cells, and promotion of angiogenesis. This approach represents a promising therapeutic delivery platform for treating I/R injury.

Neurotheranostics as personalized medicines.

The discipline of neurotheranostics was forged to improve diagnostic and therapeutic clinical outcomes for neurological disorders. Research was facilitated, in largest measure, by the creation of pharmacologically effective multimodal pharmaceutical formulations. Deployment of neurotheranostic agents could revolutionize staging and improve nervous system disease therapeutic outcomes. However, obstacles in formulation design, drug loading and payload delivery still remain. These will certainly be aided by multidisciplinary basic research and clinical teams with pharmacology, nanotechnology, neuroscience and pharmaceutic expertise. When successful the end results will provide "optimal" therapeutic delivery platforms. The current report reviews an extensive body of knowledge of the natural history, epidemiology, pathogenesis and therapeutics of neurologic disease with an eye on how, when and under what circumstances neurotheranostics will soon be used as personalized medicines for a broad range of neurodegenerative, neuroinflammatory and neuroinfectious diseases.

BSA-based Cu2Se nanoparticles with multistimuli-responsive drug vehicles for synergistic chemo-photothermal therapy.

Functionalized-nanoparticles have been developed as novel therapeutic delivery platform for simultaneous drug loading and therapy over the past decade. Rationally-designed biocompatible nanosystem simultaneously with multistimuli-responsive property and synergistic therapeutic potential are highly desirable for modern biological applications. Herein, Cu2Se nanoparticles (Cu2SeNPs) with suitable size have been functionalized by bull serum albumin (BSA) through a simply, facile and controllable method. As a result, Cu2SeNPs modified by BSA (BSA-Cu2SeNPs) showed excellent biocompatibility and stability. The strong absorbance of BSA-Cu2SeNPs at near infrared region imparts them with high photothermal efficiency. Then loading doxorubicin (DOX, anticancer drug) on the surface of BSA-Cu2SeNPs, and consequently, a novel multifunctional nanosystem of BSA-Cu2SeNPs-DOX is designed. The BSA-Cu2SeNPs can achieve high DOX loading capacity (approximately 157 μg DOX per mg of Cu2Se). Furthermore, a rational and precise release of DOX from the BSA-Cu2SeNPs-DOX could be easily realized under the stimulates of the pH and temperature, which remarkably improved antitumor efficacy of combined chemotherapy and photothermal therapy triggered by 808 nm NIR laser. Thus, the BSA-Cu2SeNPs-DOX could serve as an ideal nanoplatform for cancer diagnosis and treatment in future. The results of cell experiments show that the BSA-Cu2SeNPs-DOX exhibited favorable selective cellular uptake cells. Under the NIR laser irradiation, BSA-Cu2SeNPs-DOX could induce the excessive expression of ROS, eventually leading to the death of U251 cells. Both in vitro and in vivo experiments indicate that the nanosystem of BSA-Cu2SeNPs-DOX showed excellent synergistic therapeutic effect and multistimuli-responsive drug vehicle, which will exert huge potential for future clinical application.

The future of marginal kidney repair in the context of normothermic machine perfusion.

Normothermic machine perfusion (NMP) is a technique that utilizes extracorporeal membrane oxygenation to recondition and repair kidneys at near body temperature prior to transplantation. The application of this new technology has been fueled by a significant increase in the use of the kidneys that were donated after cardiac death, which are more susceptible to ischemic injury. Preliminary results indicate that NMP itself may be able to repair marginal organs prior to transplantation. In addition, NMP serves as a platform for delivery of therapeutics. The isolated setting of NMP obviates problems of targeting a particular therapy to an intended organ and has the potential to reduce the harmful effects of systemic drug delivery. There are a number of emerging therapies that have shown promise in this platform. Nutrients, therapeutic gases, mesenchymal stromal cells, gene therapies, and nanoparticles, a newly explored modality, have been successfully delivered during NMP. These technologies may be effective at blocking multiple mechanisms of ischemia‐ reperfusion injury (IRI) and improving renal transplant outcomes. This review addresses the mechanisms of renal IRI, examines the potential for NMP as a platform for pretransplant allograft modulation, and discusses the introduction of various therapies in this setting.

Multistimulative Nanogels with Enhanced Thermosensitivity for Intracellular Therapeutic Delivery.

The flexibility and hydrophilicity of nanogels suggest their potential for the creation of nanocarriers with good colloidal stability and stimulative ability. In the present study, biocompatible AGP and AGPA nanogels with triple-stimulative properties (thermosensitivity, pH sensitivity, and redox sensitivity) were prepared by incorporating poly(N-isopropylacrylamide) (PNIPAM) or poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-AA)) into alginate (AG) emulsion nanodrops, followed by fixation with a disulfide-containing molecule (cystamine dihydrochloride (Cys)). Compared to AG/PNIPAM(AGP) nanogels, AG/P(NIPAM-AA) (AGPA) nanogels exhibited more sensitive volumetric expansion by switching the temperature from 40 to 25 °C under physiological medium. This expansion occurs because P(NIPAM-AA) with -COOH groups can be fixed inside the nanogels via chemical bonding with Cys, whereas PNIPAM was encapsulated in the nanogels through simple physical interactions with the AG matrix. AGPA nanogels carrying an anticancer drug tend to easily enter cells upon heating, thereby exerting toxicity through a cold shock and reverse thermally induced release of an anticancer drug. Upon internalization inside cells, the nanogels use the reducible and acidic intracellular environments to effectively release the drug to the nucleus to impart anticancer activity. These results demonstrate that multifunctional nanogels may be used as a general platform for therapeutic delivery.

Formulation of Nonionic Surfactant Vesicles (NISV) Prepared by Microfluidics for Therapeutic Delivery of siRNA into Cancer Cells.

Small interfering RNAs (siRNA) have a broad potential as therapeutic agents to reversibly silence any target gene of interest. The clinical application of siRNA requires the use of safe and effective delivery systems. In this study, we investigated the use of nonionic surfactant vesicles (NISV) for the delivery of siRNA. Different types of NISV formulations were synthesized by microfluidic mixing and then evaluated for their physiochemical properties and cytotoxicity. The ability of the NISV to carry and transfect siRNA targeting green fluorescent protein (GFP) into A549 that stably express GFP (copGFP-A549) was evaluated. Flow cytometry and Western blotting were used to study the GFP expression knockdown, and significant knockdown was observed as a result of siRNA delivery to the cells by NISV. This occurred in particular when using Tween 85, which was able to achieve more than 70% GFP knockdown. NISV were thus demonstrated to provide a promising and effective platform for therapeutic delivery of siRNA.

Plant‐Based Hollow Microcapsules for Oral Delivery Applications: Toward Optimized Loading and Controlled Release

Efficient oral administration of protein‐based therapeutics faces significant challenges due to degradation from the highly acidic conditions present in the stomach and proteases present in the digestive tract. Herein, investigations into spike‐covered sunflower sporopollenin exine capsules (SECs) for oral protein delivery using bovine serum albumin (BSA) as a model drug are reported and provide significant insights into the optimization of SEC extraction, SEC loading, and controlled release. The phosphoric‐acid‐based SEC extraction process is optimized. Compound loading is shown to be driven by the evacuation of air bubbles from SEC cavities through the porous SEC shell wall, and vacuum loading is shown to be the optimal loading method. Three initial BSA‐loading proportions are evaluated, leading to a practical loading efficiency of 22.3 ± 1.5 wt% and the determination that the theoretical maximum loading is 46.4 ± 2.5 wt%. Finally, an oral delivery formulation for targeted intestinal delivery is developed by tableting BSA‐loaded SECs and enteric coating. BSA release is inhibited for 2 h in simulated gastric conditions followed by 100% release within 8 h in simulated intestinal conditions. Collectively, these results indicate that sunflower SECs provide a versatile platform for the oral delivery of therapeutics.

In situ biodegradable crosslinking of cationic oligomer coating on mesoporous silica nanoparticles for drug delivery

Although layer-by-layer assembly using anionic and cationic polymer has been a popular way to develop core-shell nanoparticles, the strong electrostatic interactions may limit shell degradability, thus hampering their application as a platform for controlled therapeutic delivery. In this study, we demonstrate a simple approach to developing mesoporous nanohybrids via a process of pre-drug loading (using doxorubicin (DOX) as a model drug) into mesoporous silica nanoparticles (MSN), followed by surface functionalization with a kind of cationic oligomer (low molecular weight polyethylene imine, LPEI) and in situ crosslinking by degradable N,N′-bis(acryloyl)cystamine (BAC). The presence of LPEI shell affords the nanohybrids with charge-reversal ability, which means that the acidic tumor extracellular microenvironment can transform the negative surface charge at neutral conditions into positive-charged ones. The nanohybrids displayed a pH- and redox-dual sensitivity in DOX release under conditions that mimic intracellular reductive conditions and acidic tumor microenvironments. The nanohybrids can be effectively internalized into A549 cells (a carcinomic human alveolar basal epithelial cell line), resulting in a high DOX intracellular accumulation and an improved anticancer cytotoxicity when compared with free DOX, suggesting their high potential as a new platform for therapeutic delivery.

Abstract No. 419 - CT-guided intra-tumoral injection of gold-coated Clostridium novyi-NT spores for bacteriolytic therapy in solid tumors

Bacteriolytic therapy using anaerobic bacteria is considered as a promising approach for the treatment of solid tumors. To improve therapeutic efficacy while potentially reducing toxicity, we demonstrate an approach to label Clostridium novyi-NT (C. novyi-NT) spores with branched gold nanoparticles (BGNP) thus permitting intra-procedural X-ray CT visualization of spore delivery to solid tumors upon intra-tumoral injection. C. Novyi-NT spores were kindly provided by BioMed Valley Discoveries (Kansas City, MO, USA). BGNP were synthesized in an aqueous solution of sodium cholate and then the BGNP were modified with 4-mercaptobenzoic acid to render negatively charge. BGNP-coated spores were prepared using a simple electrostatic deposition method. In vitro phantom and in vivo (PC-3 human prostate cancer mice model) CT studies were performed using a micro-CT imaging system (NanoPET/CT®, Mediso Ltd-Bioscan Inc., Hungary-US). Successful preparation of BGNP-coated C. Novyi-NT spores was confirmed by various physico-chemical characterization methods. In the PC3 mouse model, BGNP-coated spores were locally injected into the hypoxic center of each tumor guided with CT confirmation of intra-tumoral delivery. The therapeutic efficacy of these CT-guided infused BGNP-coated spores demonstrated in immunohistochemical analyses such as H&E and TUNEL staining. The infused BGNP-coated spores exhibited strong therapeutic efficacy consistent with that observed for native spores suggesting that the innate anti-tumoral function was preserved. Our BGNP-coating on the C. Novyi-NT spores have the potential to not only facilitate CT image-guided bacteriolytic procedures but also to serve as a novel BGNP-mediated combinational therapeutic delivery platform.

Abstract 12592: Targeted Delivery of AntimiR-23a Using Ultrasound and Microbubbles Suppresses Cardiac Hypertrophy and Improves Cardiac Function in vivo

Background: MicroRNAs ( miRs ) are dysregulated in various cardiovascular diseases. An antimiR against miR-23a suppressed hypertension-induced cardiac hypertrophy in preclinical models, but clinical translation is limited by a lack of cardiac-targeted delivery systems. Ultrasound-targeted microbubble (MB) destruction (UTMD) is a novel therapeutic delivery platform that utilizes MBs as nucleic acid carriers and offers a non-invasive image-guided approach to target delivery of molecular therapeutics to the heart. We hypothesized that cardiac delivery of an antimiR against miR-23a using UTMD suppresses cardiac hypertrophy and improves cardiac function in hypertensive mice. Methods: Cationic lipid MBs were loaded with negative control antimiR ( NC ) or antimiR-23a. C57BL/6 mice were implanted with phenylephrine-loaded osmotic minipumps (100 mg/kg/d) and received UTMD treatments (1.3 MHz, MI setting=1.0) with 300 pmol antimiR 0, 3, and 7 days later. A third group (no phenylephrine, No-PE) of age matched mice received no treatments. At 2 weeks, miR-23a levels were measured using RT-PCR. Left ventricular (LV) mass and function were serially assessed with echocardiography. Results: UTMD treatment with antimiR-23a knocked down cardiac miR-23a by 41 ± 8% compared to UTMD treatment with NC (n=8-9/group, p&lt;0.01). As expected, phenylephrine increased LV mass relative to No-PE mice. However, compared to treatment with UTMD + NC, LV mass in mice with UTMD + antimiR-23a was 16 ± 2% lower after 1 week (p &lt; 0.05), and remained lower during the study (p=0.06) (Figure 1). By 2 weeks, fractional shortening had decreased in UTMD + NC but was preserved in UTMD + antimiR-23a (45.2% vs. 37.7%, p &lt; 0.05). Conclusions: To our knowledge, this is the first study to demonstrate suppression of cardiac hypertrophy and preservation of cardiac function with UTMD-targeted delivery of a miRNA inhibitor. Our data suggest that UTMD could be used to deliver other miRNA therapeutics for cardiac therapy.

In Vivo Biological Evaluation of High Molecular Weight Multifunctional Acid-Degradable Polymeric Drug Carriers with Structurally Different Ketals.

Understanding the influence of degradable chemical moieties on in vivo degradation, tissue distribution, and excretion is critical for the design of novel biodegradable drug carriers. Polyketals have recently emerged as a promising therapeutic delivery platform due to their ability to degrade under mild acidic intracellular compartments and generation of nontoxic degradation products. However, the effect of chemical structure of the ketal groups on the in vivo degradation, biodistribution, and pharmacokinetics of water-soluble ketal-containing polymers has not been explored. In the present work, we synthesized high molecular weight, water-soluble biodegradable hyperbranched polyglycerols (BHPGs) through the incorporation of structurally different ketal groups into the main chain of highly biocompatible polyglycerols. BHPGs showed pH and ketal group structure dependent degradation in buffer solutions. When the polymers were intravenously administered in mice, a strong dependence of in vivo degradation, biodistribution, and clearance on the ketal group structure was observed. All the BHPGs demonstrated degradation and clearance in vivo, with minimal tissue accumulation. Interestingly, an unanticipated degradation behavior of BHPGs with structurally different ketal groups was observed in vivo in comparison to their degradation in buffer solutions. BHPGs with cyclohexyl ketal (CHK) and cyclopentyl ketal (CPK) groups degraded much faster and were cleared from circulation much rapidly, while BHPG with glycerol hydroxy butanone ketal (GHBK) group degraded at a much slower rate and exhibited similar plasma half-life as that of nondegradable HPG. BHPG-GHBK also showed significantly lower tissue accumulation than nondegradable HPG after 30 days of administration. The difference in in vivo degradation may be attributed to the difference in hydrophobic characteristics of different ketal containing polymers, which may change their interaction with proteins and cells in vivo. This is the first study that demonstrates the influence of chemical structure of ketal groups on in vivo degradation and circulation profile of polymers, and through proper surface modifications, these polymers would be useful as multifunctional drug carriers.

Formulation, functional evaluation and ex vivo performance of thermoresponsive soluble gels - A platform for therapeutic delivery to mucosal sinus tissue

Mucoadhesive in situ gelling systems (soluble gels) have received considerable attention recently as effective stimuli-transforming vectors for a range of drug delivery applications. Considering this fact, the present work involves systematic formulation development, optimization, functional evaluation and ex vivo performance of thermosensitive soluble gels containing dexamethasone 21-phosphate disodium salt (DXN) as the model therapeutic.A series of in situ gel-forming systems comprising the thermoreversible polymer poloxamer-407 (P407), along with hydroxypropyl methyl cellulose (HPMC) and chitosan were first formulated. The optimized soluble gels were evaluated for their potential to promote greater retention at the mucosal surface, for improved therapeutic efficacy, compared to existing solution/suspension-based steroid formulations used clinically.Optimized soluble gels demonstrated a desirable gelation temperature with Newtonian fluid behaviour observed under storage conditions (4–8°C), and pseudoplastic fluid behaviour recorded at nasal cavity/sinus temperature (≈34°C). The in vitro characterization of formulations including rheological evaluation, textural analysis and mucoadhesion studies of the gel form were investigated. Considerable improvement in mechanical properties and mucoadhesion was observed with incorporation of HPMC and chitosan into the gelling systems. The lead poloxamer-based soluble gels, PGHC4 and PGHC7, which were carried through to ex vivo permeation studies displayed extended drug release profiles in conditions mimicking the human nasal cavity, which indicates their suitability for treating a range of conditions affecting the nasal cavity/sinuses.

Vascular Development and Regeneration in the Mammalian Heart.

Cardiovascular diseases including coronary artery disease are the leading cause of death worldwide. Unraveling the developmental origin of coronary vessels could offer important therapeutic implications for treatment of cardiovascular diseases. The recent identification of the endocardial source of coronary vessels reveals a heterogeneous origin of coronary arteries in the adult heart. In this review, we will highlight recent advances in finding the sources of coronary vessels in the mammalian heart from lineage-tracing models as well as differentiation studies using pluripotent stem cells. Moreover, we will also discuss how we induce neovascularization in the damaged heart through transient yet highly efficient expression of VEGF-modified mRNAs as a potentially therapeutic delivery platform.

Abstract 14662: Targeted Delivery of an Anti-miR to Cardiomyocytes Using Ultrasound and Microbubbles Suppresses Hypertrophy

Introduction: MicroRNAs (miRs) are dysregulated in various cardiovascular diseases and anti-miRs have been developed to therapeutically inhibit the activity of specific miRs. An anti-miR against miR-23a suppressed hypertension-induced cardiac hypertrophy in preclinical models, but clinical translation is limited by a lack of targeted cardiac delivery systems. Ultrasound (US) targeted microbubble (MB) destruction (UTMD) is a novel therapeutic delivery platform that utilizes MBs as nucleic acid carriers. We hypothesized that UTMD-mediated delivery of anti-miR-23a suppresses cardiomyocyte hypertrophy and assessed UTMD-mediated functional delivery of anti-miR-23a to cultured cardiomyocytes (CMs) in vitro to lay the groundwork for future in vivo translational studies. Methods: Neonatal CMs were isolated from hearts of 1 to 2 day old Sprague Dawley rats. MBs were loaded with LNA-modified negative control anti-miR (NC) or anti-miR-23a, added to CM cultures (anti-miR concentration 300 pM) and insonified with a clinical US imaging system (1.3 MHz, MI setting=1.6). CMs were exposed to 100 μM phenylephrine (PE) to induce hypertrophy. Levels of miR-23a and FOXO3a (miR-23a target) were assessed by qRT-PCR 48 hr after UTMD and normalized to that in NC treated CMs. To quantify hypertrophy, CM surface areas pre- and post-PE were measured by a blinded observer. Results: UTMD treatment with anti-miR-23a knocked down CM miR-23a levels by 51 ± 24% compared to UTMD treatment with NC (N=5-6 per group, p &lt; 0.01). Expression of FOXO3a mRNA (miR-23a target) was 47 ± 16% higher following UTMD-mediated anti-miR-23a delivery compared to NC (N=3 per group, p &lt; 0.05). The increase in CM surface area upon PE exposure was 22 ± 13% less with UTMD-mediated anti-miR-23a delivery compared to NC (N=3 per group, p &lt; 0.05). Conclusions: To our knowledge, this is the first study of UTMD-mediated modulation of miR levels in cardiac tissue with an anti-miR. UTMD mediated delivery of anti-miR-23a to CMs caused knockdown of miR-23a levels, restored expression of downstream target mRNA levels, and suppression of CM hypertrophy. These results lay important groundwork for future in vivo studies leading to targeted clinical strategies to therapeutically modulate miRNA activity in the human heart.