Nano-Co-Delivery of Berberine and Anticancer Drug Using PLGA Nanoparticles: Exploration of Better Anticancer Activity and In Vivo Kinetics.

PURPOSE: Combinatorial approach can be beneficial for cancer treatment with better patient recovery. Co-delivery of natural and synthetic anticancer drug not only valuable to achieve better anticancer effectivity but also to ascertain toxicity. This study was aimed to co-deliver berberine (natural origin) and doxorubicin (synthetic origin) utilizing conjugation/encapsulation strategy through poly (lactic-co-glycolic acid) (PLGA) nanoparticles. METHODS: Doxorubicin was efficiently conjugated to PLGA via carbodiimide chemistry and the PLGA-doxorubicin conjugate (PDC) was used for encapsulation of berberine (PDBNP). RESULTS: Significant anti-proliferative against MDA-MB-231 and T47D breast cancer cell lines were observed with IC50 of 1.94 ± 0.22 and 1.02 ± 0.36 µM, which was significantly better than both the bio-actives (p < 0.05). The ROS study revealed that the PDBNP portrayed the slight increase in the reactive oxygen species (ROS) pattern in MDA-MB-231 cell line in a dose-dependent manner, while in T47D cells, no significant change in ROS was seen. PDBNP exhibits significant alteration (depolarization) in mitochondrial membrane permeability and arrest of cell cycle progression at sub G1 phase while the Annexin V/PI assay followed by confocal microscopy resulted into cell death mode to be because of necrosis against MDA-MB-231 cells. In vivo studies in Sprague Dawley rats revealed almost 14-fold increase in half life and a significant increase in plasma drug concentration. CONCLUSION: The overall approach of PLGA based co-delivery of doxorubicin and berberine witnessed synergetic effect and reduced toxicity as evidenced by preliminary toxicity studies.

Bendamustine-PAMAM Conjugates for Improved Apoptosis, Efficacy, and in Vivo Pharmacokinetics: A Sustainable Delivery Tactic.

Successful delivery of a chemotherapeutic agent like bendamustine still remains a challenge in clinical conditions like chronic lymphatic leukemia (CLL), non-Hodgkin lymphoma (NHL), and multiple myeloma. We have conjugated bendamustine to polyamidoamine (PAMAM) dendrimers after conjugating with N-(hydroxyethyl)maleimide (spacer) via an ester bond. The particle size of PAMAM-bendamustine conjugate was 49.8 ± 2.5 nm. In vitro drug release resulted in sustained release with improved solution stability of drug up to 72 h. In a 24 h cytotoxicity study by MTT assay against human monoblastic leukemia cells (THP-1), the IC50 value for PAMAM-bendamustine was 32.1 ± 4.8 µM compared to 50.42 ± 3.4 µM and 2303 ± 106.5 µM for bendamustine and PAMAM dendrimer, respectively. Significantly higher cell uptake and apoptosis were observed in THP-1 cells by PAMAM-bendamustine conjugate which was confirmed by flow cytometry and confocal laser scanning microscopy. Preliminary in vivo studies undertaken included pharmacokinetics studies, organ distribution studies, and tumor inhibition studies. In healthy Wistar rat model (1CBM IV push model), the pharmacokinetic studies revealed that bioavailability and t1/2 increased significantly, i.e., almost 8.5-fold (193.8 ± 1.116 vs 22.8 ± 0.158 µg mL-1/h) and 5.1-fold (0.75 ± 0.005 vs 3.85 ± 0.015 h), respectively, for PAMAM-bendamustine conjugate compared to pure bendamustine ( p < 0.05), however, clearance and volume of distribution were found to be decreased compared to those of free drug. The study suggests that PAMAM-bendamustine conjugate was not only stable for the longer period but also least toxic and highly taken up by THP-1 cells to exert an anticancer effect at the reduced dose. Tumor inhibition and biodistribution studies in tumor-bearing BALB/c mice revealed that PAMAM-bendamustine conjugate was more effective than the pure drug and showed higher accumulation in the tumor.

Correction to: Radiolabeled PLGA Nanoparticles for Effective Targeting of Bendamustine in Tumor Bearing Mice.

The typesetter did not use the Fig. 6 provided by the author with his proof corrections, and instead duplicated Fig. 7 by the Fig. 6 caption. The original article has been corrected.

Radiolabeled PLGA Nanoparticles for Effective Targeting of Bendamustine in Tumor Bearing Mice.

PURPOSE: Bendamustine is an important drug for the treatment of chronic lymphatic leukaemia (CLL), non-Hodgkin lymphoma (NHL). However, its delivery is challenging due to its instability. Current approach reports the development and characterization of bendamustine encapsulated PLGA nanoparticles for the effective targeting to leukemic cells. METHODS: The prepared, bendamustine loaded PLGA nanoparticles (BLPNP) were developed and characterized for particle size, zeta potential and polydispersity index. The formed nanoparticles were further characterized with the help of electron microscopy for surface morphology. The formed nanoparticles were evaluated for cytotoxicity, cell uptake, ROS and cell apoptosis against THP-1 leukemic cells as a part of in vitro evaluation. In vivo organ bio-distribution and tumor regression studies were performed to track in vivo behaviour of BLPNP. RESULTS: The average particle size was 138.52 ± 3.25 nm, with 0.192 ± 0.036 PDI and - 25.4 ± 1.38 mV zeta potential. TEM images revealed the homogeneous particle size distribution with uniform shape. In vitro release exhibited a sustained drug-release behaviour up to 24 h. Cytotoxicity against THP-1 cells through MTT assay observed IC50 value of 27.8 ± 2.1 µM for BLPNP compared to pure drug, which was 50.42 ± 3.4 µM. Moreover, in vitro studies like cell-uptake and cell apoptosis studies further confirmed the higher accumulation of BLPNP in comparison to the pure drug. Organ distribution and tumor regression studies were performed to track in vivo behaviour of bendamustine loaded nanoparticles. CONCLUSION: The overall study described a promising approach in terms of safety, least erythrocytic toxicity, better IC50 value with enhance tumor targeting and regression.

Smartly Engineered PEGylated Di-Block Nanopolymeric Micelles: Duo Delivery of Isoniazid and Rifampicin Against Mycobacterium tuberculosis.

In an attempt to deliver multiple drugs through a nanoparticulate platform, the present study was designed to deliver isoniazid (INH) and rifampicin (RMP) together through conjugation/encapsulation approaches using PEG-PLA (polyethylene glycol-poly-L-lactic acid) polymeric micelles. The objective of this study is to identify the preparation and evaluation of PEGylated polymeric micelles with dual drug delivery of INH and RMP for the effective treatment of tuberculosis (TB). Synthesized PEG-PLA di-block-copolymer was further conjugated to INH-forming PEG-PLA-INH (PPI) conjugate. Separately, these conjugates were loaded with RMP building the rifampicin-loaded PEG-PLA-INH polymeric micelles (PMC). The critical micelle concentration (CMC) for the PEG-PLA copolymer was found to be 8.9 ± 0.96 mg/L, and the size and zeta potential were observed to be 187.9 ± 2.68 nm and - 8.15 ± 1.24 mV (0.251 ± 0.042 pdi), respectively. Percent drug loading of PMC was 16.66 ± 1.52 and 23.07 ± 1.05 with entrapment efficiency of 72.30 ± 3.49 and 78.60 ± 2.67% for RMP and INH, respectively. RBC hemolysis capacity of PMC was significantly less than pure RMP and INH. Microplate Alamar blue assay (MABA) along with microscopy showed that the nanoconstructed PMC were more effective than the drugs, and approximately 8-fold reduction in overall minimum inhibitory concentration (MIC) was observed. The prepared duo drug-loaded nano-engineered polymeric micelles were highly effective against sensitive Mycobacterium tuberculosis strains and found to be less hemolytic in nature. The micelles could be further explored (in the future) for in vivo anti-TB studies to establish further to achieve better treatment for TB.

Galactose-Anchored Gelatin Nanoparticles for Primaquine Delivery and Improved Pharmacokinetics: A Biodegradable and Safe Approach for Effective Antiplasmodial Activity against P. falciparum 3D7 and in Vivo Hepatocyte Targeting.

Primaquine phosphate (PQ) is mainly used as a radical cure therapy to eradicate relapse of malaria at the liver stage, which is particularly caused by P. falciparum and P. vivax. In the present study, PQ-loaded galactosylated gelatin nanoparticles (Gel-LA-PQ-NPs) were formulated using a one-step desolvation technique. The mean particle size of Gel-LA-PQ-NPs was found to be 93.48 ± 6.36 nm with a zeta potential of 4.80 ± 0.20 mV having 69.90 ± 1.53% encapsulation efficiency. Electron microscopy demonstrated that the NPs were spherical in shape and uniformly distributed without any cluster formation. The in vitro release of PQ from Gel-LA-PQ-NPs has been facilitated in sustained manner, and the release was three times slower than the naïve drug. The prepared nanoparticles (Gel-LA-PQ-NPs) were significantly (p < 0.0001) less hemolytic than the pure drug PQ. The hematological ex vivo study further supported that the developed Gel-LA-PQ-NPs were safer than PQ. The in vitro antiplasmodium assay revealed that the IC50 value against the blood stage of asexual P. falciparum 3D7 strains was significantly (p < 0.01) less (2.862 ± 0.103 µM) for Gel-LA-PQ-NPs than naïve PQ (3.879 ± 0.655 µM). In vivo pharmacokinetic parameters of Gel-LA-PQ-NPs such as half-life and AUC were significantly higher for Gel-LA-PQ-NPs, i.e., with higher bioavailability. Galactosylation of the NPs led to liver targeting of the PQ in animal studies. Approximately eight-fold higher accumulation of PQ was observed in liver compared to pure drug (i.e., PQ). Conclusively, the prepared galactosylated gelatin nanocarrier holds the promising potential and hepatic targetability of an antimalarial, maintaining its safety and biocompatibility.

Conjugated and Entrapped HPMA-PLA Nano-Polymeric Micelles Based Dual Delivery of First Line Anti TB Drugs: Improved and Safe Drug Delivery against Sensitive and Resistant Mycobacterium Tuberculosis.

PURPOSE: First line antiTB drugs have several physical and toxic manifestations which limit their applications. RIF is a hydrophobic drug and has low water solubility and INH is hepatotoxic. The main objective of the study was to synthesize, characterize HPMA-PLA co-polymeric micelles for the effective dual delivery of INH and RIF. METHODS: HPMA-PLA co-polymer and HPMA-PLA-INH (HPI) conjugates were synthesized and characterized by FT-IR and 1H-NMR spectroscopy. Later on RIF loaded HPMA-PLA-INH co-polymeric micelles (PMRI) were formulated and characterized for size, zeta potential and surface morphology (SEM, TEM) as well as critical micellar concentration. The safety was assessed through RBC's interaction study. The prepared PMRI were evaluated through MABA assay against sensitive and resistant strains of M. Tuberculosis. RESULTS: Size, zeta and entrapment efficiency for RIF loaded HPMA-PLA-INH polymeric micelles (PMRI) was 87.64 ± 1.98 nm, -19 ± 1.93 mV and 97.2 ± 1.56%, respectively. In vitro release followed controlled and sustained delivery pattern. Sustained release was also supported by release kinetics. Haemolytic toxicity of HPI and PMRI was 8.57 and 7.05% (p < 0.01, INH Vs PMRI; p < 0.0001, RIF Vs PMRI), respectively. MABA assay (cytotoxicity) based MIC values of PMRI formulation was observed as ≥0.0625 and ≥0.50 µg/mL (for sensitive and resistant strain). The microscopic analysis further confirmed that the delivery approach was effective than pure drugs. CONCLUSIONS: RIF loaded and INH conjugated HPMA-PLA polymeric micelles (PMRI) were more effective against sensitive and resistant M tuberculosis. The developed approach can lead to improved patient compliance and reduced dosing in future, offering improved treatment of tuberculosis.

Polymeric Micelles: Recent Advancements in the Delivery of Anticancer Drugs.

Nanotechnology, in health and medicine, extensively improves the safety and efficacy of different therapeutic agents, particularly the aspects related to drug delivery and targeting. Among various nano-carriers, polymer based macromolecular approaches have resulted in improved drug delivery for the diseases like cancers, diabetes, autoimmune disorders and many more. Polymeric micelles consisting of hydrophilic exterior and hydrophobic core have established a record of anticancer drug delivery from the laboratory to commercial reality. The nanometric size, tailor made functionality, multiple choices of polymeric micelle synthesis and stability are the unique properties, which have attracted scientists and researchers around the world to work upon in this opportunistic drug carrier. The capability of polymeric micelles as nano-carriers are nowhere less significant than nanoparticles, liposomes and other nanocarriers, as per as the commercial feasibility and presence is concerned. In fact polymeric micelles are among the most extensively studied delivery platforms for the effective treatment of different cancers as well as non-cancerous disorders. The present review highlights the sequential and recent developments in the design, synthesis, characterization and evaluation of polymeric micelles to achieve the effective anticancer drug delivery. The future possibilities and clinical outcome have also been discussed, briefly.

Biodegradable nanoparticulate co-delivery of flavonoid and doxorubicin: Mechanistic exploration and evaluation of anticancer effect in vitro and in vivo.

The proposed study involves delivering drug/bioactive using a single nanoplatform based on poly lactic-co-glycolic acid (PLGA) for better efficacy, synergistic effect, and reduced toxicity. PLGA was conjugated to doxorubicin (D1), and this conjugate was used for encapsulation of naringenin (D2) to develop naringenin loaded PLGA-doxorubicin nanoparticles (PDNG). The PDNG NPs were 165.4 ± 4.27 nm in size, having 0.112 ± 0.035 PDI, with -10.1 ± 2.74 zeta potential. The surface morphology was confirmed through transmission electron microscopy (TEM) and atomic force microscopy (AFM). The in vitro studies revealed that PDNG NPs exhibited selective anticancer potential in breast cancer cells, and induced apoptosis with S-phase inhibition via an increase in intrinsic reactive oxygen species (ROS) and altering the mitochondrial potential. The results also signified the efficient uptake of nanoparticles encapsulated drugs by cells besides elevating the caspase level suggesting programmed cell death induction upon treatment. In vivo studies results revealed better half-life (27.35 ± 1.58 and 11.98 ± 1.21 h for doxorubicin and naringenin) with higher plasma drug concentration. In vivo biodistribution study was also in accordance with the in vitro studies and in line with the in vivo pharmacokinetic. In vivo tumor regression assay portrayed that the formulation PDNG halts the tumor growth and lessen the tumor volume with the stable bodyweight of the mice. Conclusively, the dual delivery approach was beneficial and highly effective against tumor-induced mice.

Doxorubicin and Crocin Co-delivery by Polymeric Nanoparticles for Enhanced Anticancer Potential In Vitro and In Vivo.

Development of a biodegradable nanoplatform poly(lactic-co-glycolic acid) (PLGA) for co-delivery of two drugs is hugely imperative and beneficial in anticancer therapeutics. In this study, co-delivery of a natural phytoconstituent, crocin (carotenoid), and a commonly prescribed drug, doxorubicin, was attempted using a nanoparticulate platform in the form of PLGA nanoparticles. Doxorubicin was chemically conjugated, while crocin was encapsulated physically in prepared PLGA nanoparticles (PDCR NPs). Prepared NPs were well-characterized for size, ζ, and surface morphology. PDCR NPs were of 174.2 ± 1.57 nm in size. The transmission electron microscopy (TEM) and atomic force microscopy (AFM) images revealed the spherical shape and smooth surface morphology of the nanoparticles, respectively. The entrapment efficiency and drug loading were found to be 58.95 ± 2.58 and 13.89 ± 1.09%, respectively. The drug release pattern of PDCR NPs showed a sustained and controlled release pattern throughout 48 h in PBS buffer pH 7.4 and acetate buffer pH 6.5. PDCR NPs were significantly less hemolytic than doxorubicin (p < 0.0001). Investigational formulation selectively produced cytotoxic effects on breast cancer cells via decreasing reactive oxygen species (ROS) and altering the mitochondrial potential that led to apoptosis with cell-cycle arrest at the G2/M phase. Prepared NPs were able to upregulate the caspase levels as well as efficient uptake by cells in a time-dependent manner. In vivo plasma drug profile studies in healthy rats revealed prolonged persistence of crocin and doxorubicin in systemic circulation. Additionally, the PDCR NPs portrayed reduced tumor volume as compared to control groups in the tumor-induced animal studies, which were favorable. Conclusively, the co-delivery of natural anticancer bioactive crocin along with doxorubicin in PDCR NPs provides a possible controlled-release nanoplatform for efficient drug delivery in vitro and in vivo.

Polymeric Nanocarriers: A New Horizon for the Effective Management of Breast Cancer.

BACKGROUND: Delivery of chemotherapeutic drugs for the diagnosis and treatment of cancer is becoming advanced day by day. However, the challenge of the effective delivery system still does exist. In various types of cancers, breast cancer is the most commonly diagnosed cancer among women. Breast cancer is a combination of different diseases. It cannot be considered as only one entity because there are many specific patient factors, which are involved in the development of this disease. Nanotechnology has opened a new area in the effective treatment of breast cancer due to the several benefits offered by this technology. METHODS: Polymeric nanocarriers are among one of the effective delivery systems, which has given promising results in the treatment of breast cancers. Nanocarriers does exert their anticancer effect either through active or passive targeting mode. RESULTS: The use of nanocarriers has been resolute about the adverse effects of chemotherapeutic drugs such as poor solubility and less penetrability in tumor cells. CONCLUSION: The present review is focused on recent developments regarding polymeric nanocarriers, such as polymeric micelles, polymeric nanoparticles, dendrimers, liposomes, nanoshells, fullerenes, carbon nanotubes (CNT) and quantum dots, etc. for their recent advancements in breast cancer therapy.

Polypropyleneimine and polyamidoamine dendrimer mediated enhanced solubilization of bortezomib: Comparison and evaluation of mechanistic aspects by thermodynamics and molecular simulations.

Bortezomib (BTZ) is the first proteasome inhibitor approved by the US-FDA is majorly used for the treatment of newly diagnosed and relapsed multiple myeloma including mantle cell lymphoma. BTZ is hydrophobic in nature and is a major cause for its minimal presence as marketed formulations. The present study reports the design, development and characterization of dendrimer based formulation for the improved solubility and effectivity of bortezomib. The study also equally focuses on the mechanistic elucidation of solubilization by two types of dendrimers i.e. fourth generation of poly (amidoamine) dendrimers (G4-PAMAM-NH2) and fifth generation of poly (propylene) imine dendrimers (G5-PPI-NH2). It was observed that aqueous solubility of BTZ was concentration and pH dependent. At 2mM G5-PPI-NH2 concentration, the fold increase in bortezomib solubility was 1152.63 times in water, while approximately 3426.69 folds increase in solubility was observed at pH10.0, respectively (p<0.05). The solubility of the drug was increased to a greater extent with G5-PPI-NH2 dendrimers because it has more hydrophobic interior than G4-PAMAM-NH2 dendrimers. The release of BTZ from G5-PPI-NH2 complex was comparatively slower than G4-PAMAM-NH2. The thermodynamic treatment of data proved that dendrimer drug complexes were stable at all pH with values of ΔG always negative. The experimental findings were also proven by molecular simulation studies and by calculating RMSD and intermolecular hydrogen bonding through Schrodinger software. It was concluded that PPI dendrimers were able to solubilize the drug more effectively than PAMAM dendrimers through electrostatic interactions.

Enhanced apoptotic and anticancer potential of paclitaxel loaded biodegradable nanoparticles based on chitosan.

Taxanes have established and proven effectivity against different types of cancers; in particular breast cancers. However, the high hemolytic toxicity and hydrophobic nature of paclitaxel and docetaxel have always posed challenges to achieve safe and effective delivery. Use of bio-degradable materials with an added advantage of nanotechnology could possibly improve the condition so as to achieve better and safe delivery. In the present study paclitaxel loaded chitosan nanoparticles were formulated and optimized using simple w/o nanoemulsion technique. The observed average size, pdi, zeta potential, entrapment efficiency and drug loading for the optimized paclitaxel loaded chitosan nanoparticle formulation (PTX-CS-NP-10) was 226.7±0.70nm, 0.345±0.039, 37.4±0.77mV, 79.24±2.95% and 11.57±0.81%; respectively. Nanoparticles were characterized further for size by Transmission Electron Microscopy (TEM). In vitro release studies exhibited sustained release pattern and more than 60% release was observed within 24h. Enhanced in vitro anticancer activity was observed as a result of MTT assay against triple negative MDA-MB-231 breast cancer cell lines. The observed IC50 values obtained for PTX-CS-NP-10 was 9.36±1.13µM and was almost 1.6 folds (p<0.05) less than the pure drug. Similarly, PTX-CS-NP-10 were extremely biocompatible and safe as observed for haemolytic toxicity which was almost 4 folds less (p<0.05) than the naïve drug. Anticancer activity was further evaluated using flow cytometry for apoptosis. Cell apoptosis study revealed that PTX-CS-NP-10 treatment resulted into enhanced (almost double) late cell apoptosis than naïve paclitaxel. Hence the developed nanoparticulate formulation not only reduced the overall toxicity but also resulted into improved anticancer efficacy of paclitaxel. It can be concluded that a robust, stable and comparatively safe nanoformulation of paclitaxel was developed, characterized and evaluated.

PLGA Nanoparticles and Their Versatile Role in Anticancer Drug Delivery.

Nanotechnological advancement has become a key standard for the diagnosis and treatment of several complex disorders such as cancer by utilizing the enhanced permeability and retention effect and tumor-specific targeting. Synthesis and designing the formulation of active agents in terms of their efficient delivery is of prime importance for healthcare. The use of nanocarriers has resolved the undesirable characteristics of anticancer drugs such as low solubility and poor permeability in cells. Several types of nanoparticles (NPs) have been designed with the use of various polymers along or devoid of surface engineering for targeting tumor cells. All NPs include polymers in their framework and, of these, polylactide-co-glycolide (PLGA) is biodegradable and Food and Drug Administration approved for human use. PLGA has been used extensively in the development of NPs for anticancer drug delivery. The extensive use of PLGA NPs is promising for cancer therapy, with higher efficiency and less adverse effects. The present review focused on recent developments regarding PLGA NPs, the methods used for their preparation, their characterization, and their utility in the delivery of chemotherapeutic agents.

Biodegradable nano-architectural PEGylated approach for the improved stability and anticancer efficacy of bendamustine.

Bendamustine is a drug of choice for the treatment of several cancers including non- Hodgkin lymphoma (NHL) and Chronic Lymphocytic Leukemia (CLL). The unstable nature of the drug, however, offers a major obstacle in its effective formulation development. The present study was aimed to achieve improved stability and efficacy of bendamustine via co-polymeric PEG-PLGA nanoparticulate approach. PEG-PLGA co-polymeric conjugate was synthesized and characterized by FT-IR and 1H NMR spectroscopy. Bendamustine loaded nanoparticles (PLGA and PEG-PLGA) were prepared, optimized and characterized for size, zeta and electron microscopy (SEM and TEM). The average size, pdi (polydispersity index), zeta potential and entrapment efficiency for bendamustine loaded PEG-PLGA nanoparticles (PPBNP 15) was 297.3±2.055nm, 0.256±0.012, -6.62±0.081mV and 52.30±3.66%, respectively. The in vitro release studies displayed sustained release nature of bendamustine. The Krosmeyer-Peppas model was the best fit model as a result of kinetic modelling for in vitro release. The ex vivo hemolytic toxicity of the PPBNP 15 was significantly less (approx. 11%; 4 folds) compared to pure drug (p<0.05). The cytotoxicity study showed significantly higher anticancer activity against MCF-7, T47D and PC-3 cells (p<0.05) compared to naïve bendamustine. The developed biodegradable nanoparticles improved the stability of bendamustine and were equally stable, less toxic and highly effective against different cancerous cells.

Dendrimers as an Effective Nanocarrier in Cardiovascular Disease.

In the last two decades, dendrimers have proven their capabilities in drug delivery, physical stabilization of the drug, solubility enhancement of the poorly soluble drugs and gene delivery. Several key features of dendrimers such as excellent control over molecular structure, nanoscopic size, availability of multiple functional groups at the periphery and narrow polydispersity index distinguish them as a superior choice over available polymers. The diversity of bio-actives loaded in dendrimers due to covalent and non-covalent interactions, such as hydrogen bonding and hydrophobic interaction contribute to the physical forces for binding of bioactives. The key advantage of drug-loaded dendrimers is the delayed and sustained-release of bioactives because of the encapsulation of the drug in the hydrophobic cavities of the dendrimer that acts as a sink to retain the drug molecules for extended duration. Because of these features researchers are particularly excited about the potential application of dendrimers as a versatile carrier for drug delivery. Collectively, this review focuses on detailed note on the delivery and improved solubility of poorly soluble anti-cardiovascular bioactives, nitric oxide (NO) donor for anti-thrombosis, gene delivery and delivery of receptor agonists for cardio-protective action of the receptors using dendrimers.