Topical Synthetic Platelets Loaded With Gentamicin Decrease Bacteria in Deep Partial-Thickness Burns.

INTRODUCTION: Prolonged inflammation and infection in burns may cause inadequate healing. Platelet granules contain anti-inflammatory mediators that impact wound healing. Synthetic platelets (SPs) avoid portability and storage difficulties of natural platelets and can be loaded with bioactive agents. We evaluated wound healing outcomes in deep partial-thickness (DPT) burns treated topically with SP loaded with antibiotics. MATERIALS AND METHODS: Thirty DPT burns were created on the dorsum of two Red Duroc hybrid pigs. Six wounds were randomized into five groups: SP alone, SP loaded with gentamicin vesicles, SP with gentamicin mixture, vehicle control (saline), or dry gauze. Wounds were assessed from postburn days 3-90. Primary outcome was re-epithelialization percentage at postburn day 28. Secondary outcomes included wound contraction percentage, superficial blood flow relative to normal skin controls, and bacterial load score. RESULTS: Results showed that re-epithelialization with the standard of care (SOC) was 98%, SP alone measured 100%, SP loaded with gentamicin vesicles was 100%, and SP with gentamicin mixture was 100%. Wound contraction was 5.7% in the SOC and was ∼10% in both the SP loaded with gentamicin vesicles and SP with gentamicin mixture groups. Superficial blood flow in the SOC was 102.5%, SP alone was 170%, the SP loaded was 155%, and gentamicin mixture 162.5%. Bacterial load score in the SOC was 2.2/5.0 and was significantly less at 0.8/5.0 in SP loaded with gentamicin vesicles (P > 0.05). SP and gentamicin mixture scored 2.7 and 2.3/5.0. CONCLUSIONS: Topical SP treatment did not significantly improve outcomes. However, SP loaded with gentamicin-infused vesicles decreased bacterial load.

Efficacy of platelet-inspired hemostatic nanoparticles on bleeding in von Willebrand disease murine models.

The lack of innovation in von Willebrand disease (VWD) originates from many factors including the complexity and heterogeneity of the disease but also from a lack of recognition of the impact of the bleeding symptoms experienced by patients with VWD. Recently, a few research initiatives aiming to move past replacement therapies using plasma-derived or recombinant von Willebrand factor (VWF) concentrates have started to emerge. Here, we report an original approach using synthetic platelet (SP) nanoparticles for the treatment of VWD type 2B (VWD-2B) and severe VWD (type 3 VWD). SP are liposomal nanoparticles decorated with peptides enabling them to concomitantly bind to collagen, VWF, and activated platelets. In vitro, using various microfluidic assays, we show the efficacy of SPs to improve thrombus formation in VWF-deficient condition (with human platelets) or using blood from mice with VWD-2B and deficient VWF (VWF-KO, ie, type 3 VWD). In vivo, using a tail-clip assay, SP treatment reduced blood loss by 35% in mice with VWD-2B and 68% in mice with VWF-KO. Additional studies using nanoparticles decorated with various combinations of peptides demonstrated that the collagen-binding peptide, although not sufficient by itself, was crucial for SP efficacy in VWD-2B; whereas all 3 peptides appeared necessary for mice with VWF-KO. Clot imaging by immunofluorescence and scanning electron microscopy revealed that SP treatment of mice with VWF-KO led to a strong clot, similar to those obtained in wild-type mice. Altogether, our results show that SP could represent an attractive therapeutic alternative for VWD, especially considering their long half-life and stability.

Receptor-Mediated Attachment and Uptake of Hyaluronan Conjugates by Breast Cancer Cells.

Chemotherapy, a mainstay modality for cancer, is often hindered by systemic toxicity and side effects. With the emergence of nanomedicine, the development of drug therapy has shifted toward targeted therapy. Hyaluronan (HA) is an ideal molecule as a targeted delivery system because many carcinomas overexpress HA receptors. We have conjugated resveratrol, a natural polyphenol, and 3-(5-methoxy, 2-methyl-1H-indol-3-yl)-1-(4-pyridinyl)-2-propen-1-one (MOMIPP), a chalcone, to HA with the goal of enhancing drug bioavailability and targeting triple negative breast cancers. We demonstrate the ability of HA conjugates to accumulate in the tumor interstitium within 6 h after tail vein injections. In vitro, these conjugates interact with their target receptors, which are overexpressed by triple negative breast cancer cells under static and physiological flow. These interactions result in enhanced uptake and efficacy of the therapeutic, as demonstrated by a reduced IC50 over that of nonconjugated drugs. Thus, HA offers a platform to solubilize, target, and enhance the efficacy of chemotherapeutics.

In vivo gene delivery with L-tyrosine polyphosphate nanoparticles.

The concept of gene therapy is promising; however, the perceived risks and side effects associated with this technology have severely dampened the researchers' enthusiasm. Thus, the development of a nonviral gene vector without immunological effects and with high transfection efficiency is necessary. Currently, most nonviral vectors have failed to achieve the in vivo transfection efficiencies of viral vectors due to their toxicity, rapid clearance, and/or inappropriate release rates. Although our previous studies have successfully demonstrated the controlled-release of plasmid DNA (pDNA) polyplexes encapsulated into nanoparticles formulated with l-tyrosine polyphosphate (LTP-pDNA nanoparticles), the in vivo transfection capabilities and immunogenicity of this delivery system have yet to be examined. Thus, we evaluate LTP-pDNA nanoparticles in an in vivo setting via injection into rodent uterine tissue. Our results demonstrate through X-gal staining and immunohistochemistry of uterine tissue that transfection has successfully occurred after a nine-day incubation. In contrast, the results for the control nanoparticles show results similar to those of shams. Furthermore, reverse transcriptase polymerase chain reaction (RT-PCR) from the injected tissues confirms the transfection in vivo. To examine the immunogenicity, the l-tyrosine polyphosphate (LTP) nanoparticles have been evaluated in a mouse model. No significant differences in the activation of the innate immune system are observed. These data provide the first report for the potential use of controlled-release nanoparticles formulated from an amino acid based polymer as an in vivo nonviral vector for gene therapy.

The Interactions between L-tyrosine based nanoparticles decorated with folic acid and cervical cancer cells under physiological flow.

Many anticancer drugs have been established clinically, but their efficacy can be compromised by nonspecific toxicity and an inability to reach the desired cancerous intracellular spaces. In order to address these issues, researchers have explored the use of folic acid as a targeted moiety to increase specificity of chemotherapeutic drugs. To expand upon such research, we have conjugated folic acid to functionalized poly(ethylene glycol) and subsequently decorated the surface of l-tyrosine polyphosphate (LTP) nanoparticles. These nanoparticles possess the appropriate size (100-500 nm) for internalization as shown by scanning electron microscopy and dynamic light scattering. Under simulated physiological flow, LTP nanoparticles decorated with folic acid (targeted nanoparticles) show a 10-fold greater attachment to HeLa, a cervical cancer cell line, compared to control nanoparticles and to human dermal fibroblasts. The attachment of these targeted nanoparticles progresses at a linear rate, and the strength of this nanoparticle attachment is shown to withstand shear stresses of 3.0 dyn/cm(2). These interactions of the targeted nanoparticles to HeLa are likely a result of a receptor-ligand binding, as a competition study with free folic acid inhibits the nanoparticle attachment. Finally, the targeted nanoparticles encapsulated with a silver based drug show increased efficacy in comparison to nondecorated (plain) nanoparticles and drug alone against HeLa cells. Thus, targeted nanoparticles are a promising delivery platform for developing anticancer therapies that overexpress the folate receptors (FRs).

In vitro antimicrobial studies of silver carbene complexes: activity of free and nanoparticle carbene formulations against clinical isolates of pathogenic bacteria.

OBJECTIVES: Silver carbenes may represent novel, broad-spectrum antimicrobial agents that have low toxicity while providing varying chemistry for targeted applications. Here, the bactericidal activity of four silver carbene complexes (SCCs) with different formulations, including nanoparticles (NPs) and micelles, was tested against a panel of clinical strains of bacteria and fungi that are the causative agents of many skin and soft tissue, respiratory, wound, blood, and nosocomial infections. METHODS: MIC, MBC and multidose experiments were conducted against a broad range of bacteria and fungi. Time-release and cytotoxicity studies of the compounds were also carried out. Free SCCs and SCC NPs were tested against a panel of medically important pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Acinetobacter baumannii (MRAB), Pseudomonas aeruginosa, Burkholderia cepacia and Klebsiella pneumoniae. RESULTS: All four SCCs demonstrated strong efficacy in concentration ranges of 0.5-90 mg/L. Clinical bacterial isolates with high inherent resistance to purified compounds were more effectively treated either with an NP formulation of these compounds or by repeated dosing. Overall, the compounds were active against highly resistant bacterial strains, such as MRSA and MRAB, and were active against the biodefence pathogens Bacillus anthracis and Yersinia pestis. All of the medically important bacterial strains tested play a role in many different infectious diseases. CONCLUSIONS: The four SCCs described here, including their development as NP therapies, show great promise for treating a wide variety of bacterial and fungal pathogens that are not easily killed by routine antimicrobial agents.

Non-viral gene delivery using nanoparticles.

Although the potential benefits of gene therapy for the treatment of acquired and inherited genetic diseases have been demonstrated through preclinical studies, the results of human gene therapy trials have been disappointing. Recombinant viruses are the primary vectors of choice because of their ability to protect genetic materials, cross cellular membranes, escape from endosomes and transport their genetic materials into the nucleus. Unfortunately, viral vectors have been unable to gain widespread clinical application because of their toxicity and immunogenicity. Consequently, the need for safer alternatives has led to the development of liposomes, cationic polyplexes, microparticles and nanoparticles. Although these alternative vectors have shown promise, degradable nanoparticles are the only non-viral vectors that can provide a targeted intracellular delivery with controlled release properties. Furthermore, the potential advantage of degradable nanoparticles over their non-degradable counterparts is the reduced toxicity and the avoidance of accumulation within the target tissue after repeated administration. In this article, current non-viral gene delivery devices are reviewed with a special emphasis on nanoparticle gene delivery systems. Also, the authors highlight their philosophy and efforts on the development of l-tyrosine-based polyphosphate nanoparticle-based non-viral gene delivery systems and assess the potential benefits and shortcomings of their approach.

Nanospheres formulated from L-tyrosine polyphosphate exhibiting sustained release of polyplexes and in vitro controlled transfection properties.

Currently, viruses are utilized as vectors for gene therapy, since they transport across cellular membranes, escape endosomes, and effectively deliver genes to the nucleus. The disadvantage of using viruses for gene therapy is their immune response. Therefore, nanospheres have been formulated as a nonviral gene vector by blending l-tyrosine-polyphosphate (LTP) with polyethylene glycol grafted to chitosan (PEG-g-CHN) and linear polyethylenimine (LPEI) conjugated to plasmid DNA (pDNA). PEG-g-CHN stabilizes the emulsion and prevents nanosphere coalescence. LPEI protects pDNA degradation during nanosphere formation, provides endosomal escape, and enhances gene expression. Previous studies show that LTP degrades within seven days and is appropriate for intracellular gene delivery. These nanospheres prepared by water-oil emulsion by sonication and solvent evaporation show diameters between 100 and 600 nm. Also, dynamic laser light scattering shows that nanospheres completely degrade after seven days. The sustained release of pDNA and pDNA-LPEI polyplexes is confirmed through electrophoresis and PicoGreen assay. A LIVE/DEAD cell viability assay shows that nanosphere viability is comparable to that of buffers. X-Gal staining shows a sustained transfection for 11 days using human fibroblasts. This result is sustained longer than pDNA-LPEI and pDNA-FuGENE 6 complexes. Therefore, LTP-pDNA nanospheres exhibit controlled transfection and can be used as a nonviral gene delivery vector.

The antimicrobial efficacy of sustained release silver-carbene complex-loaded L-tyrosine polyphosphate nanoparticles: characterization, in vitro and in vivo studies.

The pressing need to treat multi-drug resistant bacteria in the chronically infected lungs of cystic fibrosis (CF) patients has given rise to novel nebulized antimicrobials. We have synthesized a silver-carbene complex (SCC10) active against a variety of bacterial strains associated with CF and chronic lung infections. Our studies have demonstrated that SCC10-loaded into L-tyrosine polyphosphate nanoparticles (LTP NPs) exhibits excellent antimicrobial activity in vitro and in vivo against the CF relevant bacteria Pseudomonas aeruginosa. Encapsulation of SCC10 in LTP NPs provides sustained release of the antimicrobial over the course of several days translating into efficacious results in vivo with only two administered doses over a 72 h period.

Nanospheres formulated from L-tyrosine polyphosphate as a potential intracellular delivery device.

Current delivery devices for drugs and genes such as films and microspheres are usually formulated from polymers that degrade over a period of months. In general, these delivery systems are designed to achieve an extracellular release of their encapsulated drugs. For drugs that require interaction with cellular machinery, the efficacies of both macroscopic and microscopic delivery systems are normally low. In contrast, nano-sized drug delivery vehicles could achieve high delivery efficiencies, but they must degrade quickly, and the delivery system itself should be nontoxic to cells. In this aspect, biodegradable nanospheres formulated from l-tyrosine polyphosphate (LTP) have been produced from an emulsion of oil and water for the potential use as an intracellular delivery device. Scanning electron microscopy (SEM) and dynamic laser light scattering (DLS) show that LTP nanospheres possess a diameter range between 100 and 600 nm. SEM reveals nanospheres formulated from LTP are spherical and smooth. Additionally, DLS studies demonstrate that nanospheres degrade hydrolytically in 7 days. Confocal microscopy reveals LTP nanospheres are internalized within human fibroblasts. Finally, the cell viability after exposure to LTP nanospheres and determined with a LIVE/DEAD Cell Viability Assay is comparable to a buffer control. In conclusion, our nanospheres have been shown to be nontoxic to human cells, possess the appropriate size for endocytosis by human cells, and degrade within 7 days. Therefore LTP nanospheres can be used for a sustained intracellular delivery device.

Anticancer Activity of Ag(I) N-Heterocyclic Carbene Complexes Derived from 4,5-Dichloro-1H-Imidazole.

A class of Ag(I) N-heterocyclic carbene silver complexes, 1-3, derived from 4,5-dichloro-1H-imidazole has been evaluated for their anticancer activity against the human cancer cell lines OVCAR-3 (ovarian), MB157 (breast), and Hela (cervical). Silver complexes 1-3 are active against the ovarian and breast cancer cell lines. A preliminary in vivo study shows 1 to be active against ovarian cancer in mice. The results obtained in these studies warrant further investigation of these compounds in vivo.

Low doses of antigen coupled to anti-CR2 mAbs induce rapid and enduring IgG immune responses in mice and in cynomolgus monkeys.

The complement system and B cell complement receptor 2 (CR2), specific for C component C3dg, play important roles in both the innate and adaptive immune response. We used hapten and protein conjugates of anti-CR2 mAbs as models for C3dg-opsonized antigens and immune complexes to examine the handling of and immune response to these reagents in mice and in non-human primates (NHP). Mice immunized and boosted i.v. with only 100 ng of Alexa 488 rat anti-mouse CR1/2 mAb 7G6 had strong IgG immune responses to the Alexa 488 hapten and to rat IgG, compared to very weak immune responses in mice treated with a comparable isotype control; larger doses of Alexa 488 mAb 7G6 did not increase the immune response. A vaccine constructed by cross-linking anthrax protective antigen to mAb 7G6 proved to be effective at low doses in generating sufficiently high titer serum IgG antibodies to neutralize anthrax lethal toxin in vitro and to protect mice from i.v. challenge with anthrax lethal toxin. When biotinylated HB135, a mouse mAb specific for human CR2, was injected i.v. into NHP, the probe manifested the same initial marginal zone B cell binding and subsequent localization to follicular dendritic cells as we have previously reported for comparable experiments in mice. Moreover, i.v. immunization of NHP with 1 microg/kg of Alexa 488 mAb HB135 promoted an IgG immune response to the Alexa 488 hapten and to mouse IgG. Taken together, these results demonstrate the efficacy of using anti-CR2 mAbs as antigen carriers for i.v. immunization with small amounts of antigens without adjuvant.

Analyses of the in vivo trafficking of stoichiometric doses of an anti-complement receptor 1/2 monoclonal antibody infused intravenously in mice.

Complement plays a critical role in the immune response by opsonizing immune complexes (IC) and thymus-independent type 2 Ags with C3 breakdown product C3dg, a CR2-specific ligand. We used a C3dg-opsonized IC model, anti-CR1/2 mAb 7G6, to investigate how such substrates are processed. We used RIA, whole body imaging, flow cytometry, and fluorescence immunohistochemistry to examine the disposition of 0.1- to 2-microg quantities of mAb 7G6 infused i.v. into BALB/c mice. The mAb is rapidly taken up by the spleen and binds preferentially to marginal zone (MZ) B cells; within 24 h, the MZ B cells relocate and transfer mAb 7G6 to follicular dendritic cells (FDC). Transfer occurs coincident with loss of the extracellular portion of MZ B cell CR2, suggesting that the process may be mediated by proteolysis of CR2. Intravenous infusion of an FDC-specific mAb does not induce comparable splenic localization or cellular reorganization, emphasizing the importance of MZ B cells in intrasplenic trafficking of bound substrates. We propose the following mechanism: binding of C3dg-opsonized IC to noncognate MZ B cells promotes migration of these cells to the white pulp, followed by CR2 proteolysis, which allows transfer of the opsonized IC to FDC, thus facilitating presentation of intact Ags to cognate B cells.