Targeted Nanomedicines for Cancer Therapy, From Basics to Clinical Trials.

Traditional systemic chemotherapy involves the wide distribution of drug molecules in the body, causing toxic side effects in the healthy tissues and limiting the therapeutic dose required at the site of drug action. In order to decrease side effects and increase the drug efficacy, recent research on chemotherapy focuses on drug targeting. Targeted therapy can be achieved by several mechanisms including; 1) using an antibody as a drug that is specific to a disease biomarker, 2) using an antibody (or peptide) as a targeting agent conjugated to the drug molecule, 3) delivering the drug molecules to the target tissue in a nano-carrier with or without the targeting agent attached on its surface. The third approach involves the nanomedicines that can be targeted to diseased tissues by both passive (extravasating at diseased sites due to leaky vasculature) and active (specific interaction of the targeting agent with disease biomarker) targeting mechanisms. In this review we will cover the passively targeted nanomedicines prepared using nano drug carriers. Ideally the carrier particle should be in the right size (1-100nm), stable enough to prevent drug leakage during circulation, and safe not to cause any damage to healthy tissues. Competition for all these properties generated many different types of materials to be used as nanodrug delivery systems. After a brief review of most commonly used drug carriers, we discuss the clinical use of the targeted nanomedicines with regard to their pharmacokinetic and pharmacodynamics properties, and how these properties vary from conventional formulations providing free drugs in the circulation after administration.

Expression and localization of VPAC1, the major receptor of vasoactive intestinal peptide along the length of the intestine.

Vasoactive intestinal peptide (VIP) is an endogenous neuropeptide with a broad array of physiological functions in many organs including the intestine. Its actions are mediated via G protein-coupled receptors, and vasoactive intestinal peptide receptor 1 (VPAC1) is the key receptor responsible for majority of VIP's biological activity. The distribution of VPAC1 along the length of the gastrointestinal tract and its subcellular localization in intestinal epithelial cells have not been fully characterized. The current studies were undertaken to determine VPAC1 distribution and localization so that VIP-based therapies can be targeted to specific regions of the intestine. The results indicated that the mRNA levels of VPAC1 showed an abundance pattern of colon > ileum > jejunum in the mouse intestine. In parallel, the VPAC1 protein levels were higher in the mouse colon, followed by the ileum and jejunum. Immunofluorescence studies in mouse colon demonstrated that the receptor was specifically localized to the luminal surface, as was evident by colocalization with the apical marker villin but not with the basolateral marker Na+/K+-ATPase. In the human intestine, VPAC1 mRNA expression exhibited a distribution similar to that in mouse intestine and was highest in the sigmoid colon. Furthermore, in the human colon, VPAC1 also showed predominantly apical localization. The physiological relevance of the expression and apical localization of VPAC1 remains elusive. We speculate that apical VPAC1 in intestinal epithelial cells may have relevance in recognizing secreted peptides in the intestinal lumen and therefore supports the feasibility of potential therapeutic and targeting use of VIP formulations via oral route to treat gastrointestinal diseases.NEW & NOTEWORTHY These studies for the first time present comprehensive data on the relative characterization of vasoactive intestinal peptide (VIP) receptors in the intestinal mucosa. Vasoactive intestinal peptide receptor 1 (VPAC1) was identified as the predominant receptor with higher levels in the colon compared with the small intestine and was mainly localized to the apical membrane. In addition, the findings in the human tissues were consistent with VPAC1 expression in the mouse intestine and open possibilities to target colonic tissues with VIP for treating diseases such as inflammatory bowel disease.

Vasoactive Intestinal Peptide Nanomedicine for the Management of Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is a chronic relapsing disorder of the intestine, with increasing incidence worldwide. At present, the management of IBD is an unmet medical need due to the ineffectiveness of currently available drugs in treating all patients, and there is strong demand for novel therapeutics. In this regard, vasoactive intestinal peptide, a potent anti-inflammatory endogenous hormone, has shown promise in managing multiple immune disorders in animal models. However, when administered in the free form, VIP undergoes rapid degradation in vivo, and with continuous infusion, it causes severe dose limiting side effects. To overcome these barriers, we have developed a superior mode to deliver VIP in its native form, using sterically stabilized micelles (VIP-SSM). Our previous studies demonstrated that, VIP, when administered in SSM, prevented joint damage and inflammation in a mouse model of rheumatoid arthritis at a significantly lower dose than the free peptide, completely abrogating the serious side effect of hypotension associated with VIP. In the current study, we demonstrate the therapeutic benefit of VIP-SSM over free peptide in reversing severe colitis associated with IBD. First, we conducted preliminary studies with dextran sulfate sodium (DSS) induced colitis in mice, to determine the effectiveness of VIP administered on alternate days in reducing disease severity. Thereafter, a single intra peritoneal injection of VIP-SSM or the free peptide was used to determine its therapeutic effect on the reversal of colitis and associated diarrhea. The results demonstrated that when administered on alternate days, both VIP-SSM and VIP were capable of alleviating DSS colitis in mice. However, when administered as a single dose, in a therapeutic setting, VIP-SSM showed superior benefits compared to the free peptide in ameliorating colitis phenotype. Namely, the loss of solid fecal pellets and increased fluid accumulation in colon resulting from DSS insult was abrogated in VIP-SSM treated mice and not with free VIP. Furthermore, reduced protein and mRNA levels of the major chloride bicarbonate exchanger, down regulated in adenoma (DRA), seen with DSS was reversed with VIP-SSM, but not with the free peptide. Similarly, VIP-SSM treatment significantly reduced the elevated mRNA levels of pro-inflammatory cytokines and showed significant histologic recovery when compared to mice treated with free VIP. Therefore, these results demonstrated that as a single dose, the anti-inflammatory and antidiarrheal effects of VIP can be achieved effectively when administered as a nanomedicine. Therefore, we propose VIP-SSM to be developed as a potential therapeutic tool for treating ulcerative colitis, a type of IBD.

GLP-1 nanomedicine alleviates gut inflammation.

The gut hormone, glucagon like peptide-1 (GLP-1) exerts anti-inflammatory effects. However, its clinical use is limited by its short half-life. Previously, we have shown that GLP-1 as a nanomedicine (GLP-1 in sterically stabilized phospholipid micelles, GLP-1-SSM) has increased in vivo stability. The current study was aimed at testing the efficacy of this GLP-1 nanomedicine in alleviating colonic inflammation and associated diarrhea in dextran sodium sulfate (DSS) induced mouse colitis model. Our results show that GLP-1-SSM treatment markedly alleviated the colitis phenotype by reducing the expression of pro-inflammatory cytokine IL-1ß, increasing goblet cells and preserving intestinal epithelial architecture in colitis model. Further, GLP-1-SSM alleviated diarrhea (as assessed by luminal fluid) by increasing protein expression of intestinal chloride transporter DRA (down regulated in adenoma). Our results indicate that GLP-1 nanomedicine may act as a novel therapeutic tool in alleviating gut inflammation and associated diarrhea in inflammatory bowel disease (IBD).

TREM-1-accentuated lung injury via miR-155 is inhibited by LP17 nanomedicine.

Triggering receptors expressed on myeloid cell-1 (TREM-1) is a superimmunoglobulin receptor expressed on myeloid cells. Synergy between TREM-1 and Toll-like receptor amplifies the inflammatory response; however, the mechanisms by which TREM-1 accentuates inflammation are not fully understood. In this study, we investigated the role of TREM-1 in a model of LPS-induced lung injury and neutrophilic inflammation. We show that TREM-1 is induced in lungs of mice with LPS-induced acute neutrophilic inflammation. TREM-1 knockout mice showed an improved survival after lethal doses of LPS with an attenuated inflammatory response in the lungs. Deletion of TREM-1 gene resulted in significantly reduced neutrophils and proinflammatory cytokines and chemokines, particularly IL-1ß, TNF-α, and IL-6. Physiologically deletion of TREM-1 conferred an immunometabolic advantage with low oxygen consumption rate (OCR) sparing the respiratory capacity of macrophages challenged with LPS. Furthermore, we show that TREM-1 deletion results in significant attenuation of expression of miR-155 in macrophages and lungs of mice treated with LPS. Experiments with antagomir-155 confirmed that TREM-1-mediated changes were indeed dependent on miR-155 and are mediated by downregulation of suppressor of cytokine signaling-1 (SOCS-1) a key miR-155 target. These data for the first time show that TREM-1 accentuates inflammatory response by inducing the expression of miR-155 in macrophages and suggest a novel mechanism by which TREM-1 signaling contributes to lung injury. Inhibition of TREM-1 using a nanomicellar approach resulted in ablation of neutrophilic inflammation suggesting that TREM-1 inhibition is a potential therapeutic target for neutrophilic lung inflammation and acute respiratory distress syndrome (ARDS).

A new lipid-based nano formulation of vinorelbine.

Vinorelbine (VLB) is a semi-synthetic Vinca alkaloid which is currently used in treatment of different cancer types mainly advanced breast cancer (ABC) and advanced/metastatic non-small cell lung cancer (NSCLC). However, its marketed formulation has been reported to have serious side effects, such as granulocytopenia, which is the major dose-limiting toxicity. Other unwanted effects include venous discoloration and phlebitis proximal to the site of injection, as well as localized rashes and urticaria, blistering, and skin sloughing. Our long-term aim in synthesizing a novel nanomicellar vinorelbine formulation is to reduce or even eliminate these side effects and increase drug activity by formulating the drug in a lipid-based system as a nanomedicine targeted to the site of action. To this end, the purpose of this study was to prepare, characterize, and determine the in vitro efficacy of vinorelbine-loaded sterically stabilized, biocompatible, and biodegradable phospholipid nanomicelles (SSM; size, ∼15 nm). Our results indicated that vinorelbine incorporate at high quantities and within the interface between the core and palisade sections of the micelles. Incorporation ratio of drug within sterically stabilized micelles increased as the total amount of drug in the system increased, and no drug particles were formed at the highest drug concentrations tested. The nanomicellar formulation of vinorelbine was ∼6.7-fold more potent than vinorelbine dissolved in DMSO on MCF-7 cell line. Collectively, these data indicate that vinorelbine-loaded SSM can be developed as a new, safe, stable, and effective nanomedicine for the treatment of breast and lung cancers.

Novel, biocompatible, and disease modifying VIP nanomedicine for rheumatoid arthritis.

Despite advances in rheumatoid arthritis (RA) treatment, efficacious and safe disease-modifying therapy still represents an unmet medical need. Here, we describe an innovative strategy to treat RA by targeting low doses of vasoactive intestinal peptide (VIP) self-associated with sterically stabilized micelles (SSMs). This spontaneous interaction of VIP with SSM protects the peptide from degradation or inactivation in biological fluids and prolongs circulation half-life. Treatment with targeted low doses of nanosized SSM-VIP but not free VIP in buffer significantly reduced the incidence and severity of arthritis in an experimental model, completely abrogating joint swelling and destruction of cartilage and bone. In addition, SSM associated VIP, unlike free VIP, had no side-effects on the systemic functions due to selective targeting to inflamed joints. Finally, low doses of VIP in SSM successfully downregulated both inflammatory and autoimmune components of RA. Collectively, our data clearly indicate that VIP-SSM should be developed to be used as a novel nanomedicine for the treatment of RA.

Solubilization of therapeutic agents in micellar nanomedicines.

We use atomistic molecular dynamics simulations to reveal the binding mechanisms of therapeutic agents in PEG-ylated micellar nanocarriers (SSM). In our experiments, SSM in buffer solutions can solubilize either ≈11 small bexarotene molecules or ≈6 (2 in low ionic strength buffer) human vasoactive intestinal peptide (VIP) molecules. Free energy calculations reveal that molecules of the poorly water-soluble drug bexarotene can reside at the micellar ionic interface of the PEG corona, with their polar ends pointing out. Alternatively, they can reside in the alkane core center, where several bexarotene molecules can self-stabilize by forming a cluster held together by a network of hydrogen bonds. We also show that highly charged molecules, such as VIP, can be stabilized at the SSM ionic interface by Coulombic coupling between their positively charged residues and the negatively charged phosphate headgroups of the lipids. The obtained results illustrate that atomistic simulations can reveal drug solubilization character in nanocarriers and be used in efficient optimization of novel nanomedicines.

A novel peptide nanomedicine for treatment of pancreatogenic diabetes.

Pancreatogenic diabetes (PD) is a potentially fatal disease that occurs secondary to pancreatic disorders. The current anti-diabetic therapy for PD is fraught with adverse effects that can increase morbidity. Here we investigated the efficacy of novel peptide nanomedicine: pancreatic polypeptide (PP) in sterically stabilized micelles (SSM) for management of PD. PP exhibits significant anti-diabetic efficacy but its short plasma half-life curtails its therapeutic application. To prolong and improve activity of PP in vivo, we evaluated the delivery of PP in SSM. PP-SSM administered to rats with PD, significantly improved glucose tolerance, insulin sensitivity and hepatic glycogen content compared to peptide in buffer. The studies established the importance of micellar nanocarriers in protecting enzyme-labile peptides in vivo and delivering them to target site, thereby enhancing their therapeutic efficacy. In summary, this study demonstrated that PP-SSM is a promising novel anti-diabetic nanomedicine and therefore should be further developed for management of PD. FROM THE CLINICAL EDITOR: Pancreatic peptide was earlier demonstrated to address pancreatogenic diabetes, but its short half-life represented major difficulties in further development for therapeutic use. PP-SSM (pancreatic polypeptide in sterically stabilized micelles) is a promising novel anti-diabetic nanomedicine that enables prolonged half-life and increased bioactivity of PP, as shown in this novel study, paving the way toward clinical studies in the near future.

Human pancreatic polypeptide in a phospholipid-based micellar formulation.

PURPOSE: Pancreatic polypeptide (PP) has important glucoregulatory functions and thereby holds significance in the treatment of diabetes and obesity. However, short plasma half-life and aggregation propensity of PP in aqueous solution, limits its therapeutic application. To address these issues, we prepared and characterized a formulation of PP in sterically stabilized micelles (SSM) that protects and stabilizes PP in its active conformation. METHODS: PP-SSM was prepared by incubating PP with SSM dispersion in buffer. Peptide-micelle association and freeze-drying efficacy of the formulation was characterized in phosphate buffers with or without sodium chloride using dynamic light scattering, fluorescence spectroscopy and circular dichroism. The degradation kinetics of PP-SSM in presence of proteolytic enzyme was determined using HPLC and bioactivity of the formulation was evaluated by in vitro cAMP inhibition study. RESULTS: PP self-associated with SSM and this interaction was influenced by presence/absence of sodium chloride in the buffer. The formulation was effectively lyophilized, demonstrating feasibility for its long-term storage. The stability of peptide against proteolytic degradation was significantly improved and PP in SSM retained its bioactivity in vitro. CONCLUSIONS: Self-association of PP with phospholipid micelles addressed the delivery issues of the peptide. This nanomedicine should be further developed for the treatment of diabetes.

Polymyxin B self-associated with phospholipid nanomicelles.

CONTEXT: Although Polymyxin B (PXB) is an effective antibiotic for Gram-negative bacterial infections, clinical use is hampered by toxicity and protein binding, which may be overcome by delivering PXB using a safe nanocarrier. OBJECTIVE: To determine whether PXB self-associates with long-circulating biocompatible/biodegradable PEGylated phospholipid nanomicelles (SSM) and change the PXB in vitro bioactivity. MATERIALS AND METHODS: PXB and SSM (15 nm) composed of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N [methoxy(polyethylene glycol)-2000] (DSPE-PEG(2000)) were prepared in 10 mM HEPES-buffered saline. Interactions between PXB and SSM were determined by dynamic light scattering and fluorescence spectroscopy. Anti-infective effects of PXB-SSM were tested against Pseudomonas aeruginosa strain PA01 in vitro. RESULTS: Approximately four PXB molecules self-associated with each SSM. However, significant decrease in P. aeruginosa killing was observed with PXB-SSM relative to PXB alone (P < 0.05). Empty SSM had no significant effect on bacterial growth. DISCUSSION: PXB's self-association with SSM resulted in mitigation of the in vitro antibacterial activity. This phenomenon could be attributed, in part, to PEG(2000) hindering electrostatic interactions between cationic PXB and anionic bacterial cell wall. CONCLUSION: PXB association with SSM formed a stable nanomedicine, resulting in decreased bioactivity of the drug in vitro. Effectiveness of this nanomedicine in vivo is yet to be studied.

Structure and dynamics of highly PEG-ylated sterically stabilized micelles in aqueous media.

Molecular assemblies of highly PEG-ylated phospholipids are important in many biomedical applications. We have studied sterically stabilized micelles (SSMs) of self-assembled DSPE­PEG2000 in pure water and isotonic HEPES-buffered saline solution. The observed SSM sizes of 2­15 nm largely depend on the solvent and the lipid concentration used. The critical micelle concentration of DSPE­PEG2000 is 10 times higher in water than in buffer, and the viscosity of the dispersion dramatically increases with the lipid concentration. To explain the experimentally observed results, we performed atomistic molecular dynamics simulations of solvated SSMs. Our modeling revealed that the observed assemblies have very different aggregation numbers (N(agg) ≈ 90 in saline solution and N(agg) < 8 in water) because of very different screening of their charged PO4(­) groups. We also demonstrate that the micelle cores can inflate and their coronas can fluctuate strongly, thus allowing storage and delivery of molecules with different chemistries.

Actively targeted low-dose camptothecin as a safe, long-acting, disease-modifying nanomedicine for rheumatoid arthritis.

PURPOSE: Camptothecin (CPT), a potent topoisomerase I inhibitor, was originally discovered as an anticancer agent to induce programmed cell death of cancer cells. Recent evidence suggests that, similar to cancer, alterations in apoptosis and over-proliferation of key effector cells in the arthritic joint result in rheumatoid arthritis (RA) pathogenesis. Initial in vitro studies have suggested that camptothecin inhibits synoviocyte proliferation, matrix metalloproteinases expression in chrondrocytes and angiogenesis. This study is one of the first to test, in vivo, RA as a new indication for CPT. METHODS: To circumvent insolubility, instability and toxicity of CPT, we used biocompatible, biodegradable and targeted sterically stabilized micelles (SSM) as nanocarriers for CPT (CPT-SSM). We also surface-modified CPT-SSM with vasoactive intestinal peptide (VIP) for active targeting. We then determined whether this nanomedicine abrogated collagen-induced arthritis (CIA) in mice. RESULTS: Based on our findings, this is the first study to report that CPT was found to be efficacious against CIA at concentrations significantly lower than usual anti-cancer dose. Furthermore, a single subcutaneous injection of CPT-SSM-VIP (0.1 mg/kg) administered to CIA mice mitigated joint inflammation for at least 32 days thereafter without systemic toxicity. CPT alone needed at least 10-fold higher dose to achieve the same effect, albeit with some vacuolization in liver histology. CONCLUSION: We propose that CPT-SSM-VIP is a promising targeted nanomedicine and should be further developed as a safe, long-acting, disease-modifying pharmaceutical product for RA.

A novel peptide nanomedicine against acute lung injury: GLP-1 in phospholipid micelles.

PURPOSE: Treatment of acute lung injury (ALI) observed in Gram-negative sepsis represents an unmet medical need due to a high mortality rate and lack of effective treatment. Accordingly, we developed and characterized a novel nanomedicine against ALI. We showed that when human glucagon-like peptide 1(7-36) (GLP-1) self-associated with PEGylated phospholipid micelles (SSM), the resulting GLP1-SSM (hydrodynamic size, ~15 nm) exerted effective anti-inflammatory protection against lipopolysaccharide (LPS)-induced ALI in mice. METHODS: GLP1-SSM was prepared by incubating GLP-1 with SSM dispersion in saline and characterized using fluorescence spectroscopy and circular dichroism. Bioactivity was tested by in vitro cAMP induction, while in vivo anti-inflammatory effects were determined by lung neutrophil cell count, myeloperoxidase activity and pro-inflammatory cytokine levels in LPS-induced ALI mice. RESULTS: Amphipathic GLP-1 interacted spontaneously with SSM as indicated by increased α-helicity and fluorescence emission. This association elicited increased bioactivity as determined by in vitro cAMP production. Correspondingly, subcutaneous GLP1-SSM (5-30 nmol/mouse) manifested dose-dependent decrease in lung neutrophil influx, myeloperoxidase activity and interleukin-6 in ALI mice. By contrast, GLP-1 in saline showed no significant anti-inflammatory effects against LPS-induced lung hyper-inflammatory responses. CONCLUSIONS: GLP1-SSM is a promising novel anti-inflammatory nanomedicine against ALI and should be further developed for its transition to clinics.

Micellar nanomedicine of human neuropeptide Y.

Human neuropeptide Y (NPY) is an important biologics that regulates a multitude of physiological functions and could be amenable to therapeutic manipulations in certain disease states. However, rapid (within minutes) enzymatic degradation and inactivation of NPY precludes its development as a drug. Accordingly, we determined whether self-association of NPY with biocompatible and biodegradable sterically stabilized phospholipid micelles (SSM) improves its stability and bioactivity. We found that in saline NPY spontaneously aggregates; however, in the presence of SSM it self-associates with the micelles as monomers. Three NPY molecules self-associate with 1 SSM at saturation. This process stabilizes the peptide in α-helix conformation, abrogates its degradation by dipeptidyl peptidase-4 and potentiates NPY-induced inhibition of cAMP elaboration in SK-N-MC cells. Collectively, these data indicate that self-association of NPY with SSM stabilizes and protects the peptide in active monomeric conformation, thereby amplifying its bioactivity in vitro. We propose further development of NPY in SSM as a novel, long-acting nanomedicine. FROM THE CLINICAL EDITOR: Human neuropeptide Y (NPY) regulates a multitude of physiological functions and could be amenable to therapeutic manipulations, which is currently limited by its short half life. Self-association of NPY with spherically stabilized micelles (SSM) protects and stabilizes the peptide in active monomeric conformation, thereby amplifying its bioactivity in vitro, enabling future therapeutic considerations.

Targeting breast cancer using pirarubicin-loaded vasoactive intestinal peptide grafted sterically stabilized micelles.

In this study the chemotherapeutic agent Pirarubicin (PRB) which is known for its serious side effects was actively targeted to the breast cancer cells by uploading it to the biocompatible and biodegradable Sterically Stabilized Micelles (SSMs) made of 1,2- Distearoyl- sn- glycero­3- phosphoethanolamine- N- methoxy­ polyethylene glycol 2000 (DSPE-PEG2000) to enhance efficacy and reduce toxicity. Vasoactive intestinal peptide (VIP), the receptors of which are overexpressed on the breast cancer cells, was grafted on the surface of the micelles. To the best of our knowledge this is the first report on active targeting of PRB to tumor site. For this purpose, PRB loaded VIP grafted SSMs (PRB-SSM-VIP) were synthesized and characterized. The in vitro efficiency of PRB-SSM-VIP along with SSM and free PRB was investigated on the MCF-7 breast cancer cells and the in vivo effects were studied on the 4T1 breast cancer bearing nude mice. Solubilizing 300 µg of PRB using 2.81 mg of DSPE-PEG2000 resulted in obtaining monodispersed particles of 12.16 ± 2.7 nm with slow drug release profile. Incorporation of PRB within the hydrophobic DSPE core of SSM was confirmed using differential scanning calorimetry (DSC) and the spherical shape of the synthesized particles was demonstrated using atomic force microscope (AFM). Both in vitro and in vivo studies showed significantly higher activity of PRB-SSM-VIP compared to free PRB. In vivo imaging showed successful accumulation of PRB-SSM-VIP at the tumor site and 98.8% tumor eradication was obtained with no signs of side effects. Current study suggests that SSM-VIP could be used as new drug delivery system for targeting PRB to the breast cancer cells.

Colonic delivery of vasoactive intestinal peptide nanomedicine alleviates colitis and shows promise as an oral capsule.

Aim: To evaluate the efficacy of locally delivered nanomedicine, vasoactive intestinal peptide in sterically stabilized micelles (VIP-SSM) to the colon and conduct in vitro release studies of a potential oral formulation. Materials & methods: Intracolonic instillation of VIP-SSM was tested in a mouse model of dextran sulfate sodium-induced colitis. Based on the effective mouse dose, human equivalent dose containing nanomedicine powder was filled into enteric coated capsules for in vitro release testing. Results: Colonic delivery of VIP-SSM significantly alleviated colitis. VIP-SSM containing capsules completely dissolved at colonic pH allowing micelles to reform with active VIP. Capsule formulations exhibited reproducible release profiles when stored up to 6 weeks demonstrating stability. Conclusion: VIP-SSM is an effective nanomedicine formulation which appears to have potential for oral treatment of colitis in humans. [Formula: see text].

VIP-grafted sterically stabilized phospholipid nanomicellar 17-allylamino-17-demethoxy geldanamycin: a novel targeted nanomedicine for breast cancer.

17-Allylamino-17-demethoxy geldanamycin (17-AAG), an inhibitor of heat shock protein 90 (Hsp90) function, is being developed as antitumor drug in patients with breast cancer. However, water-insolubility and hepatotoxicity limit its use. The purpose of this study was to begin to address these issues by determining whether 17-AAG can be formulated in long-circulating (PEGylated), biocompatible and biodegradable sterically stabilized phospholipid nanomicelles (SSM) to which vasoactive intestinal peptide (VIP) was grafted as an active targeting moiety and, if so, whether these nanomicelles are cytotoxic to MCF-7 human breast cancer cells. We found that particle size of 17-AAG loaded in VIP surface-grafted SSM was 16+/-1 nm and drug content was 97+/-2% (300 microg/ml). Cytotoxicity of 17-AAG loaded in VIP surface-grafted SSM to MCF-7 cells was significantly higher than that of 17-AAG loaded in non-targeted SSM (p<0.05) and similar to that of 17-AAG dissolved in dimethylsulfoxide. Collectively, these data demonstrate that 17-AAG is solubilized at therapeutically relevant concentrations in actively targeted VIP surface-grafted SSM. Cytotoxicity of these nanomicelles to MCF-7 cells is retained implying high affinity VIP receptors overexpressed on these cells mediate, in part, their intracellular uptake thereby amplifying drug potency. We propose that 17-AAG loaded in VIP surface-grafted SSM should be further developed as actively targeted nanomedicine for breast cancer.

Self-associated indisulam in phospholipid-based nanomicelles: a potential nanomedicine for cancer.

This study aimed to begin development of a nanomedicine containing indisulam solubilized in sterically stabilized micelles (SSMs) composed of DSPE-PEG(2000) or sterically stabilized mixed micelles (SSMMs) composed of DSPE-PEG(2000) plus egg phosphatidylcholine. Micelles were prepared by co-precipitation and reconstitution of drug and lipids. Particle size distributions of micellar formulations were determined by quasi-elastic light scattering. Amounts of solubilized drug were determined by reverse-phase high-performance liquid chromatography (RP-HPLC). In vitro cytotoxicity of indisulam in nanocarrier was determined on the MCF-7 cell line by the National Cancer Institute-developed sulforhodamine B assay. Optimal solubilized indisulam concentrations in 5 mM total lipid were 10 microg/mL for SSMMs and 400 microg/mL for SSMs. HPLC results demonstrated that the encapsulation capacity of both micelles was over 95%. In vitro studies showed that indisulam in micellar system was more effective than free indisulam. The optimized formulation was successfully freeze-dried without any addition of lyoprotectants or cryoprotectants. We conclude that SSMs are a promising nanocarrier for indisulam, and indisulam-SSMs should be developed further as a novel targeted nanomedicine.

Preparation of aminoglycoside-loaded chitosan nanoparticles using dextran sulphate as a counterion.

PURPOSE: To prepare aminoglycoside (AG) (streptomycin, gentamicin and tobramycin) loaded chitosan nanoparticles with high drug incorporation efficiency and test the in vivo oral efficacy of streptomycin (SM) loaded chitosan nanoparticles in a Mycobacterium tuberculosis (TB) chronic infection mouse model. METHOD: Dextran sulphate (a polyanion) was used to shield the positive charge of AG and increase the drug incorporation in the chitosan nanoparticle. By varying the concentration of each component, the formulation of SM-loaded chitosan nanoparticle was optimized by monitoring the drug incorporation efficacy and particle size. The mechanism of the nanoparticle formation was suggested and the preparation method was applied to two other aminoglycosides (AG): gentamicin (GM) and tobramycin (TM). The resulting nanoparticles were characterized by particle diameter, drug incorporation efficacy, drug loading efficacy and zeta potential. The in vitro drug release from these nanoparticles was carried out in pH 1.2 and pH 7.4 buffer. Preliminary in vivo oral efficacy studies of SM-loaded chitosan nanoparticles was performed in a Mycobacterium tuberculosis (TB) chronic infection mouse model. RESULTS: The optimal concentration of streptomycin (SM)/dextran sulphate/chitosan/tripolyphosphate (TPP) for SM nanoparticles preparation was 2/1.2/2/0.8 mg mL(-1). Through calculation, the optimal concentrations of dextran sulphate are 2.5 mg mL(-1) and 2.4 mg mL(-1) for 2 mg mL(-1) gentamicin and tobramycin, respectively (Table 1). The resulting AG chitosan nanoparticles had a high drug incorporation efficacy with particle sizes in the nanometre range. The in vitro drug release studies showed that more than 60% drug is retained inside the nanoparticles in pH 1.2 buffer after 6 h. The preliminary in vivo results indicated that oral SM chitosan nanoparticles induced one log 10 reduction (p < 0.01) in growth of the bacilli and were as effective as subcutaneously injected aqueous SM solution at the same concentration (100 mg kg(-1)). CONCLUSION: Dextran sulphate can significantly increase AG incorporation into the chitosan nanoparticles. The concentration of each component was critical in preparing AG-loaded chitosan nanoparticles. The chitosan nanoparticles designed in this study may provide a promising oral drug delivery formulation for AG which usually, in tuberculosis treatment, is administrated as an injectible preparation.