Nanocarrier-based drug delivery systems for bone cancer therapy: a review.

Bone cancer is a malignant tumor that originates in the bone and destroys the healthy bone tissues. Of the various types of bone tumors, osteosarcoma is the most commonly diagnosed primary bone malignancy. The standard treatment for primary malignant bone tumors comprises surgery, chemotherapy and radiotherapy. Owing to the lack of proven treatments, different forms of alternative therapeutic approaches have been examined in recent decades. Among the new therapeutic methodologies, nanotechnology-based anticancer therapy has paved the way for new targeted strategies for bone cancer treatment and bone regeneration. They include approaches such as the co-delivery of multiple drug cargoes, the enhancement of their biodistribution and transport properties, normalizing accumulation and the optimization of drug release profiles to overcome shortcomings of the existing therapy. This review examines the standard treatments for osteosarcoma, their lacunae, and the evolving therapeutic strategies based on nanocarrier-mediated combinational drug delivery systems, and future perspectives for osteosarcoma therapy.

Combinational delivery of anticancer drugs for osteosarcoma treatment using electrosprayed core shell nanocarriers.

In bone cancer treatment, local delivery of chemotherapeutic agents is preferred compared to other routes of administration. Delivery of multiple drugs using biodegradable carriers improves the treatment efficiency and overcomes drug resistance and toxicity. With this approach, we have developed multilayer biodegradable core shell nanoparticles (NPs) using the electro-spraying technique to deliver methotrexate (MTX) and doxorubicin (DOX) for the treatment of osteosarcoma. These core-shell NPs with a mean particle size of 212 ± 41 nm consist of hydroxyapatite (HA) and DOX as core with the outer shell made of chitosan (CH) followed by polycaprolactone (PCL) with MTX. The encapsulation efficiency of MTX was around 85% and DOX was 38%. In vitro drug release studies were performed in phosphate buffered saline (PBS) at pH 5 and pH 7.4 for 8 days. Different release profiles were observed in both acidic and alkaline pH. The sequential release of MTX followed by DOX was observed in both pH in sustained manner. Human osteosarcoma MG 63 (OMG-63) cells lines were used to test the cytotoxicity of drug loaded NPs. Multi-drug encapsulated bioresorbable and biodegradable electro-sprayed core shell NPs will be promising as a bone substitute for the treatment of osteosarcoma.

Charge Coupling Enhanced Photocatalytic Activity of BaTiO3/MoO3 Heterostructures.

In this work, we proposed an efficient heterostructure photocatalyst by integrating the ferroelectric BaTiO3 (BTO) layer with the semiconductor MoO3 layer, availing the ferroelectric polarization of BaTiO3 and high generation of photoinduced charge carriers in the MoO3 layer. The effect of MoO3 layer thickness (tMoO3) on the photocatalytic efficiency of the BTO/MoO3 heterostructures is found to be optimum at tMoO3 = 67 nm as tMoO3 varies from 40 to 800 nm. The BTO/MoO3 heterostructure with tMoO3 = 67 nm exhibits a high efficiency of 86% for the degradation of rhodamine B (RhB) under the exposure of UV-visible light for 60 min. The photocatalysis rate kinetics analysis reveals that the rate constant in the heterostructure is 1.7 times of pure BTO and 3.2 times of pure MoO3 films. The enhanced photocatalytic activity in the heterostructures is attributed to the electric field-driven carrier separation due to the ferroelectric polarization and the heterojunction band bending. The charge coupling effect between BaTiO3 and MoO3 is evident from the current-voltage characteristics. The maximum lattice strain in the heterostructure with tMoO3 = 67 nm as evident from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and photoluminescence (PL) analysis further confirms the charge transfer between the layers. The degradation as well as decolorization efficiency of the BTO/MoO3 heterostructure is higher than that of pure BTO and MoO3 films. Radical trapping experiments reveal that electrons are the major contributors to the photocatalytic activity of the BTO/MoO3 heterostructure. The reusability test shows only a reduction of 5% in the efficiency of the heterostructure after five photocatalysis cycles. The heterostructure can also efficiently decompose the other dyes such as rose bengal and methyl violet. Thus, our findings prove that an efficient and reusable photocatalyst can be designed through the integration of the ferroelectrics with the semiconductor layers.

Conjugating doxorubicin to polymannose: a new strategy for target specific delivery to lung cancer cells.

As mannose receptors are known to be over-expressed in cancer cells, we synthesized polymannose-doxorubicin (PM-DOX) conjugates with the objective of targeting the drug to cancer cells. DOX was conjugated to oxidized PM through Schiff's linkages to obtain PM-DOX conjugates. In order to examine the superior targeting efficacy of PM-DOX conjugate, sodium alginate (SA) was conjugated to DOX by similar chemistry and compared with PM-DOX conjugate. The cytotoxicity of the conjugates was investigated in A549 cell lines using MTT Assay and the cell uptake and retention studies, were performed using flow cytometry and cell imaging. In vitro drug release studies with both PM-DOX and SA-DOX conjugates showed an initial burst release of DOX up to 37-39% at 1 h, followed by a steady release up to 58-62% at 24 h in human plasma while negligible release was observed in phosphate buffered saline. The conjugates exhibited negligible hemolytic potential to human erythrocytes compared to free DOX. The PM-DOX conjugate showed better cytotoxic potential against A549 cells at lower concentration (equivalent to 0.27 µg/mL of DOX) at 72 h compared to free DOX and SA-DOX conjugate. Further, PM-DOX conjugate showed enhanced uptake by the cells in comparison with SA-DOX conjugate thereby confirming the target specificity of PM to the cancer cells.

Polysorbate Surfactants as Drug Carriers: Tween 20-Amphotericin B Conjugates as Anti-Fungal and Anti-Leishmanial Agents.

BACKGROUND: Amphotericin B (AmB), a polyene antibiotic used for the treatment of fungal and leishmanial infections is virtually insoluble in water and exhibits severe toxicity. AmB has been conjugated to various soluble polymers for improving its solubility and reducing its toxicity. Conjugating AmB to a polysorbate surfactant such as polyoxyethylene sorbitan monolaurate (Tween 20), was examined to improve its solubility and reduce its toxicity. METHODS: AmB was coupled to Tween 20 via carbamate linkage at 15 and 30 wt% concentrations in high yield by activating the hydroxyl groups of the surfactant using p- nitrophenyl chloroformate. The conjugates were characterized by using 1H NMR, IR, UV and HPLC analysis and were examined for their toxicity, and anti-fungal and anti-leishmanial activities in vitro. RESULTS: Tween-AmB conjugates were soluble to the extent of 10 mg/mL in water, showed improved critical micelle concentration in comparison with AmB, exhibited negligible hemolytic potential even at a concentration of 1000 µM and were not toxic against human embryonic kidney cell line (HEK293T) at similar concentrations. The conjugates showed potent anti-fungal activity against Candida albicans, Candida parapsilosis and Cryptococcus neoformans and anti-leishmanial activity against intramacrophage amastigotes of Leishmania donovani. CONCLUSIONS: Tween 20 is a surfactant approved by the US FDA as an additive in food and pharmaceutical preparations. Synthesis of drug conjugates with surfactants such as Tween-20 could open up new opportunities to improve the solubility of many drugs, reduce their toxicity and could possibly target the brain as polysorbates known to facilitate nanoparticulate systems to cross the blood-brain barrier.

Synthetic polymannose as a drug carrier: synthesis, toxicity and anti-fungal activity of polymannose-amphotericin B conjugates.

Polymannose (PM) having a weight-average molar mass (Mw) of 30-53 kDa was synthesized by the polycondensation of mannose using phosphorous acid as the catalyst and characterized by various techniques such as NMR, IR, GPC and polarimetry. 2D NMR results confirmed the presence of (1 â†’ 6)-linked α-D-mannose residues as backbone with O-3 and O-2 substituted linear or branched chains in PM. Amphotericin B (AmB) was conjugated to periodate-oxidized PM through Schiff's linkages at 20 wt% concentration. The AmB-PM conjugates were highly soluble in phosphate buffered saline (180-250 mg/mL), exhibited negligible hemolytic potential to human erythrocytes even at a concentration of 200 µg/mL (equivalent to ~40 µg/mL AmB) and were non-toxic to human embryonic kidney (HEK293T) cells even at a concentration of 250 µg/mL (equivalent to ~50 µg/mL AmB). The minimum inhibitory concentration of the AmB-PM conjugates against C. albicans, C. parapsilosis and C. neoformans was in the range of 0.5-1.0 µg/mL. Mannose receptors are widely expressed on myeloid cells such as macrophages, neutrophils, and dendritic cells. Therefore, apart from treating fungal infections, AmB-PM conjugates also may have therapeutic potential for the treatment of macrophage-associated diseases such as leishmaniasis where mannose receptors are overexpressed.

Synthetic Polysaccharides as Drug Carriers: Synthesis of Polyglucose-Amphotericin B Conjugates and In Vitro Evaluation of Their Anti-Fungal and Anti-Leishmanial Activities.

While many naturally occurring polysaccharides have been widely used as drug carriers, there are two main drawbacks in their use: the first is their physical properties such as molecular weight, branching, type of glycosidic linkages and solubility depend on their source and the method of isolation and purification, the second is many of them are contaminated with proteins and protein removal is essential for preventing immune reactions. Synthetic polysaccharides on the other hand can be tailor made from their respective monomers with consistent physical properties and are, free from protein contamination, both being significant advantages in their use. Although, the synthesis of polysaccharides such as polyglucose, polymannose, polygalactose etc., by the polycondensation of their respective monomers have been reported more than half a century ago, their use as drug carriers have not received any attention so far. In this report, we show that polyglucose (PG) having a weight average molar mass of 37,000 g/mol can be synthesized in a single step by the melt polycondensation of glucose in over 70% yield. Oxidation using sodium periodate generated aldehyde functions on the polymer. Amphotericin B, (AmB) a water-insoluble polyene antibiotic was chosen as a model drug to couple onto periodate oxidized PG via imine linkage at ~20 wt% concentration. The drug loading capacity of the conjugates was above 90%. Further reduction using sodium borohydride gave the more stable amine conjugates with any residual aldehyde on the polymer backbone getting reduced to hydroxyl groups. The conjugates were highly soluble in water and stable on storage. At ten times the concentration of AmB, the conjugates produced negligible hemolysis to human blood. The AmB conjugates were then evaluated for their anti-fungal activity against C. albicans and A. fumigatus and anti-leishmanial activity against different strains of L. donovani in culture. The conjugates showed potent anti-fungal and anti-leishmanial activity. The use of synthetic polysaccharides in drug delivery and in other biomedical applications will have many potential advantages.

Amphotericin B-albumin conjugates: Synthesis, toxicity and anti-fungal activity.

Amphotericin B (AmB), a hydrophobic drug with negligible aqueous solubility was conjugated to bovine serum albumin (BSA) via amide bond coupling to give 6 to 8 wt% drug payload. The resulting conjugate was characterized using SDS-PAGE and UV-visible, FTIR and CD spectroscopy. The conjugate was water-soluble to the extent of 150 mg/ml, was non-toxic to HEK 293 T cells at a concentration of 500 µg/ml (equivalent to ~30 µg AmB) and showed hemolysis of <5% at 200 µg/ml (equivalent to ~12 µg AmB) against human erythrocytes in vitro. In vitro release studies at 37 °C demonstrated steady release of AmB up to 20% from the conjugate with little burst effect in phosphate buffered saline whereas thrice the amount was released in human plasma in 72 h. AmBisome® used as a reference showed a very similar release profile in plasma. The conjugate exhibited potential anti-fungal activity against yeast strains such as C. albicans, C. neoformans and C. parapsilosis with the minimum inhibitory concentration (MIC) equivalent to AmB ranging from 0.7 to 1.1 µg/ml while AmBisome® and AmB alone showed the MIC between 0.78 and 1.5 and 0.53-0.78 µg/ml respectively. Although AmB has been conjugated to various natural and synthetic polymers to improve its solubility and reduce its toxicity, the results obtained in this study using the model protein BSA as a carrier point to the possibility of taking this pro-drug approach to human clinical use using human serum albumin (HSA) as the carrier, since HSA has emerged as a versatile drug carrier for treating diabetes and cancer and improving the pharmacokinetic profile of many drugs with US FDA approving HSA as a drug carrier for the anti-cancer drug paclitaxel (Abraxane®) for human use.

Ceramic core with polymer corona hybrid nanocarrier for the treatment of osteosarcoma with co-delivery of protein and anti-cancer drug.

For the treatment of metastatic bone cancer, local delivery of therapeutic agents is preferred compared to systemic administration. Delivery of an anti-cancer drug and a protein that helps in bone regeneration simultaneously is a challenging approach. In this study, a nanoparticulate carrier which delivers a protein and an anti-cancer drug is reported. Bovine serum albumin (BSA) as a model protein was loaded into hydroxyapatite (HA) nanoparticles (NPs) and methotrexate (MTX) conjugated to poly(vinyl alcohol) was coated onto BSA-loaded HA NPs. Coating efficiency was in the range of 10-17 wt%. In vitro drug release showed that there was a steady increase in the release of both BSA and MTX with 76% of BSA and 88% of MTX being released in 13 days. Cytotoxicity studies of the NPs performed using human osteosarcoma (OMG-63) cell line showed the NPs were highly biocompatible and exhibited anti-proliferative activity in a concentration-dependent manner.

Synthesis and evaluation of anti-fungal activities of sodium alginate-amphotericin B conjugates.

Sodium alginate (SA) was oxidized using periodate and amphotericin B (AmB) was conjugated via imine and amine linkages to the oxidized alginate. Oxidization drastically reduced the molecular weight (MW) of the alginate. The conjugates were highly water-soluble to the extent of 1000mg/mL making them useful for therapeutic applications. SA-AmB conjugates derived from 20 and 50% oxidized alginate were non-toxic to HEK 293T and RAW 264.7 cell line at 100µg/mL and was also non-hemolytic to human blood at 100µg/mL. In vitro release of AmB into phosphate buffer from the imine conjugates was negligible with less than 0.2% of the drug released in 48h. Capping of residual aldehyde handles using 2-ethanolamine or glycine resulted in increased release of the drug in vitro. Injectable gels of gelatin crosslinked with oxidized alginate incorporating the SA-AmB conjugates as well as AmB were also fabricated and drug release was examined. In vitro release from the gel discs showed that AmB was released to the extent of 15-20% in 2days. The SA-AmB conjugates showed potent anti-fungal activity against C. albicans, C. neoformans and C. parapsilosis. The injectable gels seem to have potential for prolonged release of AmB when implanted.

Tyrosine-derived novel antimicrobial hydantoin polymers: synthesis and evaluation of anti-bacterial activities.

A new approach for the design and synthesis of cyclic N-halamine polymers having anti-bacterial activity based on a vinyl derivative of tyrosine-derived hydantoin is reported. The synthesis of N-halamine polymers generally involves the chemical modification of 5,5'-disubstituted hydantoin to introduce polymerizable vinyl moieties thereby restricting the halogen capture only on the amide nitrogen. Here we show the possibility of synthesizing vinyl monomers of N-halamine from α-amino acids wherein both the amide and imide nitrogens are available for halogen capture. Thus, a hydantoin monomer was synthesized from L-tyrosine and copolymerized with methyl methacrylate and 2-(hydroxyethyl)methacrylate, to obtain random co-polymers. The monomer and its co-polymers were characterized using NMR, IR, HRMS, GPC, DSC, EDAX and TGA analysis. Films of the co-polymers cast from 10% acetone solutions were exposed to sodium hypochlorite solution to activate the hydantoin moieties. The oxidative chlorine content of the films ranged from 0.6 to 0.9%. The activated films were exposed to both Gram positive (S. aureus) and Gram negative (E. coli) bacteria using standard protocols. Polymers having chlorine content as little as 0.6% exhibited 6 log reduction in the bacterial growth within 30 min of exposure. The method allows the halogenation of both amide and imide nitrogens and could be applied to the preparation of a number of vinyl hydantoins from many amino acids.

Phosphine-mediated reaction of 3-methyl allenoate and isatins: a protocol for the synthesis of spirofuran oxindoles.

A facile synthesis of spirofuran oxindoles via phosphine-mediated reaction of 3-alkyl allenoate with isatins is presented.

Modified gum arabic cross-linked gelatin scaffold for biomedical applications.

The present work deals with development of modified gum arabic cross-linked gelatin scaffold for cell culture. A new biocompatible scaffold was developed by cross-linking gelatin (Gel) with gum arabic, a polysaccharide. Gum arabic was subjected to periodate oxidation to obtain gum arabic aldehyde (GAA). GAA was reacted with gelatin under appropriate pH to prepare the cross-linked hydrogel. Cross-linking occurred due to Schiff's base reaction between aldehyde groups of oxidized gum arabic and amino groups of gelatin. The scaffold prepared from the hydrogel was characterized by swelling properties, degree of cross-linking, in vitro degradation and scanning electron microscopy (SEM). Cytocompatibility evaluation using L-929 and HepG2 cells confirmed non-cytotoxic and non-adherent nature of the scaffold. These properties are essential for generating multicellular spheroids and hence the scaffold is proposed to be a suitable candidate for spheroid cell culture.

Extra-anatomic Bypass from Right Common Iliac Artery for Superior Mesenteric Artery Thrombosis in a Post-thrombectomy Patient: A Case Report.

Superior mesenteric artery occlusion caused by atherosclerosis superimposed with long segment thrombosis in a 54 year old male who previously underwent a resection-anastomosis and thrombectomy procedure was treated by extra anatomic bypass grafting. The abdominal aorta could not be used for inflow due to marked adhesions from previous surgery and severe atherosclerotic changes in the wall. A vein graft was bypassed from the right common iliac artery to the superior mesenteric artery to provide effective reperfusion.

Polyurethane thermoplastic elastomers with inherent radiopacity for biomedical applications.

Synthesis and characterization of three different radiopaque thermoplastic polyurethane elastomers are reported. Radiopacity was introduced to the polyurethanes by incorporating an iodinated chain extender, namely, 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA), into the polymer chain during polyurethane synthesis. Radiopaque polyurethanes (RPUs) were synthesized by reacting 4,4'-methylenebis(phenyl isocyanate) (MDI), IBPA, and three different diols. The polyols used for the synthesis were polypropylene glycol, polycaprolactone diol, and poly(hexamethylene carbonate) diol. RPUs were characterized by infrared spectroscopy, contact angle measurements, thermogravimetry, dynamic mechanical analysis, energy dispersive X-ray analysis, gel permeation chromatography, X-ray fluorescence spectroscopy, and X-radiography. X-ray images showed that all RPUs prepared using IBPA as the chain extender are highly radiopaque compared with an Aluminum wedge of equivalent thickness. Elemental analysis revealed that the polyurethanes contained 18-19% iodine in the polymer matrix. The RPUs developed have radiopacity equivalent to that of a polymer filled with 20 wt % barium sulfate. Results revealed that RPUs of wide range of properties may be produced by incorporating different diols as the soft chain segment. Cell culture cytotoxicity studies conducted using L929 cells by direct contact test and MTT assay proved that these RPUs are noncytotoxic in nature.

Venous aneurysm complicating dialytic arteriovenous fistula.

A case of venous aneurysm complicating arteriovenous fistula created for chronic haemodialysis is presented. The patient underwent successful ligation and excision of the fistula and creation of a fistula on the opposite limb.

Stem cell therapy for cardiovascular disorders - our clinical experience.

BACKGROUND: Autologous Bone Marrow stem Cell transplantation is a viable therapeutic option for patients with end stage heart failure due to cardiomyopathy of varied etiology as there are only limited treatment options other than cardiac transplantation. The rationale behind the application of stem cells in these patients include Stem cells directly replace the affected cells by differentiation into the damaged cell typeStem cells also exert Paracrine effects by secretion of growth factors (VGEF,FGF-1)to stimulate local cell growthIn addition to the above, stem cells release signaling factors which recruit stem cells from elsewhere by modulating the immune system. MATERIALS & METHODS: In this presentation we describe our study on a series of 13 patients who received isolated and expanded CD 34 cells from the bone marrow. Seven had ischemic dysfunction, three had dilated cardiomyopathy and three had primary pulmonary hypertension. Five patients received the stem cells via intracoronary injection, three directly into the myocardium and three intrapulmonary. RESULTS: All patients showed functional improvement of the myocardium recorded by non-invasive investigations and improvement in the quality of life. Follow up period ranged from 6 months to 2 years. CONCLUSION: Our experience with bone marrow derived stem cells in patients with cardiomyopathy has been encouraging. More studies are planned in the future.

Blood compatibility of surface modified poly(ethylene terephthalate) (PET) by plasma polymerized acetobromo-alpha-D-glucose.

Poly (ethylene terephthalate) (PET) was surface modified by plasma polymerization of acetobromo-alpha-D-glucose (ABG) at different radio frequency (RF) powers. Plasma polymerization was carried out by vaporizing ABG in the powder form by heating at 135 degrees C. Surface modification resulted in improved hydrophilicity and smoothness of the surface especially at low RF powers (30-50 W), but at high RF powers, the surface was found to be etched and the hydrophilicity decreased as evidenced by atomic force microscopy (AFM) and contact angle measurements. The plasma polymerized ABG film was found to be extensively cross-linked as evidenced by its insolubility in water. Infra red (IR) and X-ray photoelectron spectroscopy (XPS) were employed to characterize the plasma polymerized ABG films. IR studies revealed that at lower RF powers, polymerization was taking place mainly by breaking up of acetoxy group while retaining the ring structures to a major extent during the polymerization process whereas at high RF powers, the rupture of ring structures was indicated. XPS indicated a reduction in the percentage of oxygen in the polymers going from low to high RF powers suggestive of complete destruction of the acetoxy group at high RF powers. Cross-cut tests showed excellent adhesive properties of the plasma polymerized ABG films onto PET. Static platelet adhesion tests using platelet rich human plasma showed significantly reduced adhesion of platelets onto modified PET surface as evidenced by scanning electron microscopy. Polymerization of glucose and its derivatives using RF plasma has not been reported so far and the preliminary results reported in this study shows that this could be an interesting approach in the surface modification of biomaterials.

Synthesis and characterization of iodinated polyurethane with inherent radiopacity.

The synthesis and characterization of polyurethane (PU) with excellent radiopacity for medical and allied applications are reported. Bisphenol-A (BPA) was iodinated to obtain 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA) which was used as a chain extender for the preparation of a radiopaque PU. The PU was prepared by reacting 4,4'-methylenebis(phenyl isocyanate) (MDI), poly(tetramethylene glycol) (PTMG) and IBPA in 2.2:1.2:1 molecular ratio and is characterized by infrared spectroscopy (IR), thermogravimetry (TGA), dynamic mechanical analysis (DMA), energy dispersive X-ray analysis (EDX), gel permeation chromatography (GPC) and X-radiography. X-ray images showed that the PU prepared using IBPA as the chain extender is highly radiopaque. An in vitro cytotoxicity test using L929 mouse fibroblast cells shows that the PU is non-cytotoxic. The outlined synthesis of a PU with radiocontrast properties opens up the possibility of synthesizing many different kinds of radiopaque PUs with desirable range of physical properties exploiting the versatility in their chemical synthesis.