A fibrin encapsulated liposomes-in-chitosan matrix (FLCM) for delivering water-soluble drugs. Influences of the surface properties of liposomes and the crosslinked fibrin network

Plasma Bead Entrapped Liposomes as a Potential Drug Delivery System to Combat Fungal Infections

Fibrin-based systems offer promises in drug and gene delivery as well as tissue engineering. We established earlier a fibrin-based plasma beads (PB) system as an efficient carrier of drugs and antigens. In the present work, attempts were made to further improve its therapeutic efficacy exploiting innovative ideas, including the use of plasma alginate composite matrices, proteolytic inhibitors, cross linkers, and dual entrapment in various liposomal formulations. In vitro efficacy of the different formulations was examined. Pharmacokinetics of the formulations encapsulating Amphotericin B (AmpB), an antifungal compound, were investigated in Swiss albino mice. While administration of the free AmpB led to its rapid elimination (<72 h), PB/liposome-PB systems were significantly effective in sustaining AmpB release in the circulation (>144 h) and its gradual accumulation in the vital organs, also compared to the liposomal formulations alone. Interestingly, the slow release of AmpB from PB was unusual compared to other small molecules in our earlier findings, suggesting strong interaction with plasma proteins. Molecular interaction studies of bovine serum albumin constituting approximately 60% of plasma with AmpB using isothermal titration calorimetry and in silico docking verify these interactions, explaining the slow release of AmpB entrapped in PB alone. The above findings suggest that PB/liposome-PB could be used as safe and effective delivery systems to combat fungal infections in humans.

Potential Antioxidant and Enzyme Inhibitory Effects of Nanoliposomal Formulation Prepared from Salvia aramiensis Rech. f. Extract

Salvia aramiensis Rech. f. is a species that grows only in Hatay, Turkey and is used as a traditional stomachic tea. Neither the chemical composition nor the potential bioactivity of the plant has been investigated before. Antioxidant activity (1,1-Diphenyl-2-picrylhydrazyl Radical (DPPH^●) and 2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS^+●) radical scavenging and β-carotene/linoleic acid co-oxidation) of 70% methanol, 70% ethanol extracts, and 2% infusion obtained from S. aramiensis aerial parts were determined. The effect of 70% methanol extract on collagenase and elastase enzyme inhibition and its chemical composition via chromatographic methods (LC-MS/MS and HPLC) were analyzed. Nanoliposomes were developed with 70% methanol extract, were characterized, and were evaluated. The key parameters for the most active 70% methanol extract included the following DPPH^•EC₅₀: 28.4 µg/mL, Trolox equivalent antioxidant capacity (TEAC)/ABTS: 1.77 ± 0.09 mmol/L/Trolox. Furthermore 70% methanol extract showed more than 50% inhibition on collagenase and elastase enzymes at all the concentrations. The main component of the extract, rich in phenolic compounds, has been identified as rosmarinic acid; 83.7 µg/mL extract was released from the nanoliposomal formulation. The extract and its formulation are found to be nontoxic on the L929 fibroblast cell line. This study successfully developed a long-term antioxidant and enzyme inhibitory formulation containing S. aramiensis, which has been used safely among the public for years.

Anti-aging formulation of rosmarinic acid-loaded ethosomes and liposomes

The study was aimed to evaluate the effectiveness of rosmarinic acid (RA) loaded ethosomes (ETHs) and liposomes (LPs) when subjected to the transdermal application. RA-loaded ETHs and LPs were prepared, optimised, and characterised. The ex vivo permeation studies of formulations using mouse abdominal skin were performed. Antioxidant activities and the inhibitory effects of formulations on collagenase and elastase enzymes were measured. Optimised ethosomal formulation (F3) was showed nanometric size range (138 ± 1.11 nm) and greatest entrapment (55 ± 1.80%), was selected for further transdermal permeation studies. Skin permeation profile of the nanoformulations analysed by HPLC revealed an enhanced permeation of ETHs. Transdermal flux of ETHs was found to be higher than RA solution and LPs. Enzyme inhibitions of ETHs were the significant difference found between ETHs and LPs (p < 0.05). ETHs were found to be more effective and successful than LPs. Results suggest that ETHs are more effective than LPs for transdermal delivery of RA.

Recent treatment modalities for cardiovascular diseases with a focus on stem cells, aptamers, exosomes and nanomedicine

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Due to the significant impact of CVD on humans, there is a need to develop novel treatment modalities tailored to major classes of cardiac diseases including hypertension, coronary artery disease, cardiomyopathies, arrhythmias, valvular disease and inflammatory diseases. In this article, we discuss recent advancements regarding development of therapeutic strategies based on stem cells, aptamers, exosomes, drug-eluting and dissolvable stents, immunotherapy and nanomedicine for the treatment of CVD. We summarize current research and clinical advances in cardiovascular therapeutics, with a focus on therapies that move beyond current oral- or sublingual-based regimens. This review article provides insight into current research and future treatment strategies that hold a great relevance for future clinical practice in pursuit of improving quality of life of patients suffering from CVD.

Lipogels responsive to near-infrared light for the triggered release of therapeutic agents

Here we report a composite system based on fibrin hydrogels that incorporate in their structure near-infrared (NIR) responsive nanomaterials and thermosensitive liposomes (TSL). Polymerized fibrin networks entrap simultaneously gold-based nanoparticles (NPs) capable of transducing NIR photon energy into heat, and lysolipid-incorporated TSL (LTSL) loaded with doxorubicin hydrochloride (DOX). NIR irradiation of the resulting hydrogels (referred to as "lipogels") with 808nm laser light increased the temperature of the illuminated areas, leading to the release of the liposomal cargo. Levels of DOX that release from the "smart" composites were dependent on the concentration of NIR nanotransducers loaded in the lipogel, the intensity of the electromagnetic energy deposited and the irradiation regime. Released DOX retained its bioactivity, as shown in cultures of epithelial carcinoma cells. Finally, the developed drug delivery platform was refined by using NIR-photoabsorbers based on copper sulfide NPs to generate completely biodegradable composites as well as through the incorporation of cholesterol (Ch) in LTSL formulation, which lessens leakiness of the liposomal cargo at physiological temperature. This remotely controlled system may suit well for those therapies that require precise control over the dose of delivered drug in a defined spatiotemporal framework.

STATEMENT OF SIGNIFICANCE

Hydrogels composed of fibrin embedding nanoparticles responsive to near infrared (NIR) energy and thermosensitive liposomes loaded with doxorubicin hydrochloride (DOX), were prepared by in situ polymerization. NIR-light irradiation of these constructs, referred to as "NIR responsive lipogels", results in the controlled release of DOX to the surrounding medium. This technology may use fully degradable components and can preserve the bioactivity of liposomal cargo after remote triggering to finely regulate the dose and bioavailability of delivered payloads. NIR responsive lipogels technology overcomes the limitations of drug release systems based on the combination of liposomes and degradable polymeric materials, which in many cases lead to insufficient release at therapy onset or to overdose during high degradation period.

Fibrin matrices: The versatile therapeutic delivery systems

Fibrin sealants, that have been employed for over a century by surgeons to stop post surgery bleeding, are finding novel applications in the controlled delivery of antibiotics and several other therapeutics. Fibrinogen can be easily purified from blood plasma and converted by thrombolysis to fibrin that undergoes spontaneous aggregation to form insoluble clot. During the gelling, fibrin can be formulated into films, clots, threads, microbeads, nanoconstructs and nanoparticles. Whole plasma clots in the form of beads and microparticles can also be prepared by activating endogenous thrombin, for possible drug delivery. Fibrin formulations offer remarkable scope for controlling the porosity as well as in vivo degradability and hence the release of the associated therapeutics. Binding/covalent-linking of therapeutics to the fibrin matrix, crosslinking of the matrix with bifunctional reagents and coentrapment of protease inhibitors have been successful in regulating both in vitro and in vivo release of the therapeutics. The release rates can also be remarkably lowered by preentrapment of therapeutics in insoluble particles like liposomes or by anchoring them to the matrix via molecules that bind them as well as fibrin.

Nanoparticle-based bioactive agent release systems for bone and cartilage tissue engineering

The inability to deliver bioactive agents locally in a transient but sustained manner is one of the challenges on the development of bio-functionalized scaffolds for tissue engineering (TE) and regenerative medicine. The mode of release is especially relevant when the bioactive agent is a growth factor (GF), because the dose and the spatiotemporal release of such agents at the site of injury are crucial to achieve a successful outcome. Strategies that combine scaffolds and drug delivery systems have the potential to provide more effective tissue regeneration relative to current therapies. Nanoparticles (NPs) can protect the bioactive agents, control its profile, decrease the occurrence and severity of side effects and deliver the bioactive agent to the target cells maximizing its effect. Scaffolds containing NPs loaded with bioactive agents can be used for their local delivery, enabling site-specific pharmacological effects such as the induction of cell proliferation and differentiation, and, consequently, neo-tissue formation. This review aims to describe the concept of combining NPs with scaffolds, and the current efforts aiming to develop highly multi-functional bioactive agent release systems, with the emphasis on their application in TE of connective tissues.

Liposomes in tissue engineering and regenerative medicine

Liposomes are vesicular structures made of lipids that are formed in aqueous solutions. Structurally, they resemble the lipid membrane of living cells. Therefore, they have been widely investigated, since the 1960s, as models to study the cell membrane, and as carriers for protection and/or delivery of bioactive agents. They have been used in different areas of research including vaccines, imaging, applications in cosmetics and tissue engineering. Tissue engineering is defined as a strategy for promoting the regeneration of tissues for the human body. This strategy may involve the coordinated application of defined cell types with structured biomaterial scaffolds to produce living structures. To create a new tissue, based on this strategy, a controlled stimulation of cultured cells is needed, through a systematic combination of bioactive agents and mechanical signals. In this review, we highlight the potential role of liposomes as a platform for the sustained and local delivery of bioactive agents for tissue engineering and regenerative medicine approaches.

Polysaccharide nanosystems for future progress in cardiovascular pathologies

Natural polysaccharides have received a lot of attention in the biomedical field. Indeed, sources of polysaccharides, extracted or produced from plants, bacteria, fungi or algae, are diverse and renewable. Moreover, recent progresses in polysaccharide chemistry and nanotechnologies allow elaborating new dedicated nanosystems. Polysaccharide-based nanosystems may be designed for interacting in several biological processes. In particular, the atherothrombotic pathology is highly concerned by polysaccharide-mediated recognition. Atherothrombotic diseases, regardless of the anatomical localization, remain the main causes of morbidity and mortality in the industrialized world. This review intends to provide an overview on polysaccharide-based nanosystems as drug delivery systems and targeted contrast agents for molecular imaging with an emphasis on the treatment and imaging of cardiovascular pathologies.

Immobilization of bioactive factor-loaded liposomes on the surface of electrospun nanofibers targeting tissue engineering

Dexamethasone-loaded liposomes immobilized at the surface of electrospun polycaprolactone nanofiber meshes successfully promoted the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells.

The influence of lipid composition and surface charge on biodistribution of intact liposomes releasing from hydrogel-embedded vesicles

Mixed drug delivery systems possess advantages over discrete systems, and can be used as a strategy to design more effective formulations. They are more valuable if the embedded particles perform well, rather than using drugs that have been affected by the surrounding vehicle. In order to address this concept, different liposomes have been incorporated into hydrogel to evaluate the potential effect on the controlled release of liposomes. Radiolabeled liposomes, with respect to different acyl chain lengths (DMPC, DPPC, or DSPC) and charges (neutral, negative [DSPG], or positive [DOTAP]) were integrated into chitosan-glycerophosphate. The results obtained from the biodistribution showed that the DSPC liposomes had the highest area under the curve (AUC) values, both in the blood (206.5%ID/gh(-1)) and peritoneum (622.3%ID/gh(-1)), when compared to the DPPC and DMPC formulations, whether in liposomal hydrogel or dispersion. Interesting results were observed in that the hydrogel could reverse the peritoneal retention of negatively charged liposomes, increasing to 8 times its AUC value, to attain the highest amount among all formulations. The interactions between the liposomes and chitosan-glycerophosphate, confirmed by the Fourier transform infrared (FTIR) spectra as shifted characteristic peaks, were observed in the combined systems. Overall, the hydrogel could control the release of intact liposomes, which could be manipulated by both the liposome type and interactions between the two vehicles.

Hydrogel-embeded vesicles, as a novel approach for prolonged release and delivery of liposome, in vitro and in vivo

A novel delivery concept based on the integration of liposomes in hydrogel for the controlled release of liposomes was developed. As an in situ forming hydrogel, chitosan-glycerophosphate was used and gelation time at different temperatures was studied. Liposomes (DSPC/chol/DOPE) were labelled with (99m)Tc-hexamethylpropyleneamineoxime ((99m)Tc-HMPAO). (99m)Tc-HMPAO solution, hydrogel/(99m)Tc-HMPAO, (99m)Tc-HMPAO liposomes and hydrogel/(99m)Tc-HMPAO liposomes were injected into mouse peritoneum. The percentages of radioactive injected dose per gram of tissue (%ID/g) and %ID of peritoneum lavage were obtained. Results showed that free label left the peritoneal cavity rapidly in both solution and hydrogel forms, such that the activity was 2.5 and 3.8 (%ID) after one hour, respectively. The values for liposomes and liposomal hydrogel were 25.8 and 51.2 (%ID) and decreased to 1.9 and 19.2 after 24 h, respectively. The blood profile of liposomal hydrogel showed a two-phase profile including a descending trend in early hours regarding gel formation followed by an ascending trend due to gel disappearance by time. Free label had high activity in reticuloendothelial system (RES) and the gastrointestinal tract during the early hours and then dropped. In contrast, the accumulation of liposomes increased in RES during 24 h in the range of 1-34.5 and 1.1-35.1 (%ID/g) for plain liposomes and liposomal hydrogel, respectively. Overall, incorporation of liposomes in hydrogel could be a useful strategy to prolong the release of liposomes.

A hybrid hydrogel biomaterial by nanogel engineering: bottom-up design with nanogel and liposome building blocks to develop a multidrug delivery system

New hybrid poly(ethylene glycol) (PEG) hydrogels crosslinked with both nanogels and nanogel-coated liposome complexes are obtained by Michael addition of the acryloyl group of a cholesterol-bearing pullulan (CHP) nanogel to the thiol group of pentaerythritol tetra(mercaptoethyl) polyoxyethylene. The nanogel-coated liposome complex is stably retained after gelation and the complexes are well dispersed in the hybrid gel. Microrheological measurements show that the strength and gelation time of the hybrid hydrogel can be controlled by changing the liposome:nanogel ratio. The hydrogel is gradually degraded by hydrolysis under physiological conditions. In this process, the nanogel is released first, followed by the nanogel-coated liposomes. Hybrid hydrogels that can incorporate various molecules into the nanogel and liposomes, and release them in a two-step controllable manner, represent a new functional scaffold capable of delivering multiple drugs, proteins or DNA.

Vaccine potential of cytosolic proteins loaded fibrin microspheres of Cryptococcus neoformans in BALB/c mice

Cryptococcosis is a leading mycological cause of mortality among immunologically compromised individuals. In order to develop an effective vaccine against Cryptococcus neoformans, the cytosolic proteins (Cp) of the pathogen have been used as an antigen in combination with different formulations. In the present study, we have demonstrated that Cp encapsulated poly-lactide co-glycolide (PLGA) microsphere further co-encapsulated into the biocompatible fibrin cross-linked plasma beads (Fib-PLGA-Cp) mediated cytosolic delivery elicited strong immune response in the BALB/c mice. In contrast, other formulations of Cp failed to impart significant level of protection. The immune response, involved with Fib-PLGA-Cp protection, appear to interact with the target cells by both endocytosis as well as membrane fusion mode, thus helping in the activation of both CD4(+) and CD8(+) T-cells. Analysis of cytokine profiles in immunized animals revealed that the protective response was associated with the Th1/Th2 polarization in favor of type-1 cytokine [interferons (IFN)-γ and interleukin (IL)-2] cells. Furthermore, vaccination with Fib-PLGA-Cp elicited high immunoglobulin (Ig) G(l) and IgG(2a) isotype response; successfully cleared fungal burden in vital organs and also increased the survival rate of immunized animals. Altogether the present study is a clear indicative of the possible use of fibrin microsphere-based targeted delivery of cytosolic proteins to induce protective immune responses against experimental murine cryptococcosis.

A review on composite liposomal technologies for specialized drug delivery

The combination of liposomes with polymeric scaffolds could revolutionize the current state of drug delivery technology. Although liposomes have been extensively studied as a promising drug delivery model for bioactive compounds, there still remain major drawbacks for widespread pharmaceutical application. Two approaches for overcoming the factors related to the suboptimal efficacy of liposomes in drug delivery have been suggested. The first entails modifying the liposome surface with functional moieties, while the second involves integration of pre-encapsulated drug-loaded liposomes within depot polymeric scaffolds. This attempts to provide ingenious solutions to the limitations of conventional liposomes such as short plasma half-lives, toxicity, stability, and poor control of drug release over prolonged periods. This review delineates the key advances in composite technologies that merge the concepts of depot polymeric scaffolds with liposome technology to overcome the limitations of conventional liposomes for pharmaceutical applications.

Fibrin-lipoplex system for controlled topical delivery of multiple genes

Nonviral gene delivery via natural biomacromolecules show great promise as controlled release systems while avoiding the associated drawbacks with viral gene delivery such as immunogenicity and safety issues. Here, a fibrin-lipoplex system for topical delivery of multiple genes is described. In vitro release analysis showed efficient retention of the lipoplexes in the fibrin scaffold. The biomolecular interaction between fibrinogen and liposomes was investigated qualitatively using surface plasmon resonance. The strong binding between the lipoplexes and the fibrinogen component of the scaffold was observed and that could explain the in vitro release profile observed in our studies. Both in vitro and in vivo transfection studies using multiple reporter genes were performed to establish the bioactivity of released lipoplexes. The ability of the lipoplexes to transfect fibroblasts in vitro was shown to be maintained even after extended periods of encapsulation within the scaffold. Furthermore, in a rabbit ear ulcer model, the fibrin-lipoplex system was shown to have significantly higher transfection efficiency for two reporter genes at day 7 when compared to lipoplexes alone, suggesting that this fibrin-lipoplex system is suitable for extended release of lipoplexes for topical gene delivery applications.

Cell-controlled and spatially arrayed gene delivery from fibrin hydrogels

We investigated fibrin-mediated gene transfer by embedding pDNA within the hydrogel during polymerization and using two modes of gene transfection with cells placed either on the surface (2D transfection) or within the hydrogel (3D transfection). Using this model, we found that cell transfection depended strongly on the local cell-pDNA microenvironment as defined by the 2D vs. 3D context, target cell type and density, as well as fibrinogen and pDNA concentrations. When cells were embedded within the fibrin matrix lipofectamine-induced cell death decreased significantly, especially at low target cell density. Addition of fibrinolytic inhibitors decreased gene transfer in a dose-dependent manner, suggesting that fibrin degradation may be necessary for efficient gene transfer. We also provided proof-of-concept that fibrin-mediated gene transfer can be used for spatially localized gene delivery, which is required in cell-transfection microarrays. When lipoplex-containing hydrogels were spotted in an array format gene transfer was strictly confined to pDNA-containing fibrin spots with no cross-contamination between neighboring sites. Collectively, our data suggest that fibrin may be used as a biomaterial to deliver genes in an efficient, cell-controlled and spatially localized manner for potential applications in vitro or in vivo.

Liposomes/chitosan scaffold/human fibrin gel composite systems for delivering hydrophilic drugs--release behaviors of tirofiban in vitro

A new liposomes/chitosan scaffold/human fibrin gel composite system (LCSHFG), as a depot drug delivery system, was developed to deliver low-molecular weight hydrophilic drugs. An antithrombosis drug, Tirofiban, was used as a model drug. Human fibrin gels encapsulated Tirofiban loaded liposomes were formed within chitosan scaffolds to configure the LCSHFG. The in vitro release behaviors of Tirofiban from LCSHFG were studied by characterizing the constituents of LCSHFG. The results show that the release periods of Tirofiban from LCSHFG with 50 microm pores in the chitosan scaffolds are generally 20% or longer more than those with 200 microm pores. The following results were obtained for the system that comprised 50 microm pores. The release periods of Tirofiban from LCSHFG loaded with stearylamine (SA)-liposomes can sustain 20% longer and significantly less burst release (p < 0.01, n = 3) than with liposomes. The release profiles of Tirofiban from LCSHFG change markedly when 0.5 and 2.5% glutaraldehyde is used to cross-link the system. Additionally, for all liposomes, the release periods of Tirofiban from cross-linked LCSHFG with 2.5% glutaraldehyde are 40% or more longer time (e.g., 19 days) with significantly less burst release (p < 0.01, n = 3) than those of noncrosslinked LCSHFG. Notably, the bioactivity of released Tirofiban from LCSHFG that is crosslinked by 2.5% glutaraldehyde effectively inhibits adenosine diphosphate inducing platelet aggregation. The work also suggests that LCSHFG may have potential as a depot drug delivery system for low-molecular-weight hydrophilic drugs.

Accelerating thrombolysis with chitosan-coated plasminogen activators encapsulated in poly-(lactide-co-glycolide) (PLGA) nanoparticles

Accelerating thrombolysis using plasminogen activators (PAs) encapsulated liposomes or PEG microparticles by pressure-driven permeation have been demonstrated in vitro and in vivo in animal models. However, designing and delivering PA-encapsulated nanoparticles (NPs) to enhance thrombolysis by applying electrostatic forces or ligand-receptor interactions between the NPs and blood clots has not been proposed. Therefore, without a pressure-driving factor, tissue-plasminogen activator (t-PA) encapsulated in PLGA NPs with chitosan (CS) and CS-GRGD coating and their thrombolysis capabilities in a blood clot-occluded tube model were evaluated by determining clot lysis times and the masses of the digested clots. The characteristics and release profiles of t-PA-encapsulated PLGA, PLGA/CS and PLGA/CS-GRGD NPs are determined by FT-IR, a laser particle/zeta potential analyzer and HPLC. Additionally, the permeation capacities of the NPs into flat blood clots were examined. For example, the mean particle sizes and encapsulation efficacies of t-PA for the NPs are in the ranges 260-320 nm and 65.5-70.5%, respectively. The results reveal that the NPs for the shortest clot lysis time and the highest weight percentages of digested clot are PLGA/CS (20.7 +/- 0.7 min) and PLGA/CS-GRGD (25.7 +/- 1.3 wt%), respectively. Compared with t-PA solution, the NPs can significantly shorten clot lysis times in the following order: PLGA/CS NPs (38.8 +/- 1.5%) > PLGA/CS-GRGD NPs (16.3 +/- 1.0%) > PLGA NPs (7.7 +/- 1.2%). Compared with t-PA solution, the NPs significantly increase the weight of digested clots in the order, PLGA/CS-GRGD (40.9 +/- 1.5%) > PLGA/CS (27.8 +/- 1.2%) > PLGA (8.6 +/- 0.6%). The highest release rate of t-PA in the fast release phase and the highest permeability into intra-clots of PLGA/CS and PLGA/CS-GRGD NPs, respectively, correspond to the shortest clot lysis time and the largest increase in weight of the digested clots among the NP system. In conclusion, the NPs designed based on new concepts significantly accelerate thrombolysis in vitro in this model, and may be useful in clinical study.