Lipid membrane editing with peptide cargo linkers in cells and synthetic nanostructures.

Current strategies for deploying synthetic nanocarriers involve the creation of agents that incorporate targeting ligands, imaging agents, and/or therapeutic drugs into particles as an integral part of the formulation process. Here we report the development of an amphipathic peptide linker that enables postformulation editing of payloads without the need for reformulation to achieve multiplexing capability for lipidic nanocarriers. To exemplify the flexibility of this peptide linker strategy, 3 applications were demonstrated: converting nontargeted nanoparticles into targeting vehicles; adding cargo to preformulated targeted nanoparticles for in vivo site-specific delivery; and labeling living cells for in vivo tracking. This strategy is expected to enhance the clinical application of molecular imaging and/or targeted therapeutic agents by offering extended flexibility for multiplexing targeting ligands and/or drug payloads that can be selected after base nanocarrier formulation.

A Patient Experience Course Syllabus: Integrating Service Sciences Research to Enhance Health-Care Delivery.

We present here a syllabus for teaching patient experience that draws on service sciences to address the current state of patient experience. The syllabus was the result of an ongoing collaboration between educators at the Hotel College and the School of Medicine at the University of Nevada at Las Vegas. The syllabus was developed after a thorough literature review in the field of services marketing, patient experience, hospitality marketing, management and leadership, health-care administration, and health-care communication and after consultation with subject matter experts. We believe that the syllabus provides an action plan for universities and hospitals to introduce and teach the topic of hospitality and patient experience as part of the medical and nursing school curriculum. The syllabus can also be adapted for teaching in executive education programs.

Acoustic activation of targeted liquid perfluorocarbon nanoparticles does not compromise endothelial integrity.

Perfluorocarbon nanoparticles consisting essentially of liquid perfluoro-octyl bromide (PFOB) core surrounded by a lipid monolayer can serve as highly specific site-targeted contrast and therapeutic agents after binding to cellular biomarkers. Based on previous findings that ultrasound applied at 2 MHz and 1.9 mechanical index (MI) for a 5-min duration dramatically enhances the cellular interaction of targeted PFOB nanoparticles with melanoma cells in vitro without inducing apoptosis or other harmful effects to cells that are targeted, we sought to define mechanisms of interaction and the safety profile of ultrasound used in conjunction with liquid perfluorocarbon nanoparticles for targeted drug delivery, as compared with conventional microbubble ultrasound contrast agents under identical insonification conditions. Cell-culture inserts were used to grow a confluent monolayer of human umbilical vein endothelial cells. Definity in conjunction with continuous wave ultrasound (2.25 MHz for 1 and 5 min) increased the permeability of monolayer by four to six times above the normal, decreased transendothelial electrical resistance (a sign of reduced membrane integrity), and decreased cell viability by approximately 50%. Histological evaluation demonstrated extensive disruptions of cell monolayers. Nanoparticles (both nontargeted and targeted) elicited no changes in these different measures under similar insonification conditions and did not disrupt cell monolayers. We hypothesize that ultrasound facilitates drug transport from the perfluorocarbon nanoparticles not by cavitation-induced effects on cell membrane but rather by direct interaction with the nanoparticles that stimulate lipid exchange and drug delivery.

Postformulation peptide drug loading of nanostructures.

Cytolytic peptides have commanded attention for their anticancer potential because the membrane-disrupting function that produces cell death is less likely to be overcome by resistant mutations. Congruently, peptides that are involved in molecular recognition and biological activities become attractive therapeutic candidates because of their high specificity, better affinity, reduced immunogenicity, and reduced off target toxicity. However, problems of inadequate delivery, rapid deactivation in vivo, and poor bioavailability have limited clinical application. Therefore, peptide drug development for clinical use requires an appropriate combination of an effective therapeutic peptide and a robust delivery methodology. In this chapter, we describe methods for the postformulation insertion of peptide drugs into lipidic nanostructures, the physical characterization of peptide-nanostructure complexes, and the evaluation of their therapeutic effectiveness both in vitro and in vivo.

Cytolytic peptide nanoparticles ('NanoBees') for cancer therapy.

Cytolytic peptides are an attractive class of anticancer candidates because of their wide-spectrum lytic properties. However, their therapeutic potential cannot be realized without a proper delivery vehicle, because of their off-target toxicity, nonspecificity, and unfavorable pharmacokinetics. The physical properties of perfluorocarbon (PFC)-core surfactant-coated nanoparticles render them a highly promising delivery vehicle for targeted therapeutic applications of cytolytic peptides. This article provides an overview of the mechanism underlying the anticancer efficacy of cytolytic peptides, the limitations in clinic applications, and the advantages of PFC nanoparticles over traditional FDA-approved nanocarriers such as liposomes. Recent reports of successful anticancer therapeutics delivered by PFC nanoparticles will be discussed, as well as new applications. WIREs Nanomed Nanobiotechnol 2011 3 318-327 DOI: 10.1002/wnan.126 For further resources related to this article, please visit the WIREs website.

Molecularly targeted nanocarriers deliver the cytolytic peptide melittin specifically to tumor cells in mice, reducing tumor growth.

The in vivo application of cytolytic peptides for cancer therapeutics is hampered by toxicity, nonspecificity, and degradation. We previously developed a specific strategy to synthesize a nanoscale delivery vehicle for cytolytic peptides by incorporating the nonspecific amphipathic cytolytic peptide melittin into the outer lipid monolayer of a perfluorocarbon nanoparticle. Here, we have demonstrated that the favorable pharmacokinetics of this nanocarrier allows accumulation of melittin in murine tumors in vivo and a dramatic reduction in tumor growth without any apparent signs of toxicity. Furthermore, direct assays demonstrated that molecularly targeted nanocarriers selectively delivered melittin to multiple tumor targets, including endothelial and cancer cells, through a hemifusion mechanism. In cells, this hemifusion and transfer process did not disrupt the surface membrane but did trigger apoptosis and in animals caused regression of precancerous dysplastic lesions. Collectively, these data suggest that the ability to restrain the wide-spectrum lytic potential of a potent cytolytic peptide in a nanovehicle, combined with the flexibility of passive or active molecular targeting, represents an innovative molecular design for chemotherapy with broad-spectrum cytolytic peptides for the treatment of cancer at multiple stages.

Synthesis and characterization of stable fluorocarbon nanostructures as drug delivery vehicles for cytolytic peptides.

The therapeutic potential of cytolytic peptides is plagued by nonspecificity and enzymatic degradation. We report the first stable incorporation of melittin (a 26 amino acid amphipathic peptide) into an outer lipid monolayer of perfluorocarbon nanoparticles. Melittin binds avidly to the nanoparticles (dissociation constant approximately 3.27 nM) and retains its pore-forming activity after contact-mediated delivery to model bilayer membrane (liposomes) thereby demonstrating the effectiveness of perfluorocarbon nanoparticles as unique nanocarriers for cytolytic peptides.