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1.  Nanoprodrugs of NSAIDs: Preparation and Characterization of Flufenamic Acid Nanoprodrugs 
Journal of Drug Delivery  2011;2011:980720.
We demonstrated that hydrophobic derivatives of the nonsteroidal anti-inflammatory drug (NSAID)flufenamic acid (FA), can be formed into stable nanometer-sized prodrugs (nanoprodrugs) that inhibit the growth of glioma cells, suggesting their potential application as anticancer agent. We synthesized highly hydrophobic monomeric and dimeric prodrugs of FA via esterification and prepared nanoprodrugs using spontaneous emulsification mechanism. The nanoprodrugs were in the size range of 120 to 140 nm and physicochemically stable upon long-term storage as aqueous suspension, which is attributed to the strong hydrophobic interaction between prodrug molecules. Importantly, despite the highly hydrophobic nature and water insolubility, nanoprodrugs could be readily activated into the parent drug by porcine liver esterase, presenting a potential new strategy for novel NSAID prodrug design. The nanoprodrug inhibited the growth of U87-MG glioma cells with IC50 of 20 μM, whereas FA showed IC50 of 100 μM, suggesting that more efficient drug delivery was achieved with nanoprodrugs.
PMCID: PMC3095474  PMID: 21603162
2.  Reactive Oxygen Species-Activated Nanoprodrug of Ibuprofen for Targeting Traumatic Brain Injury in Mice 
PLoS ONE  2013;8(4):e61819.
Traumatic brain injury (TBI) is an enormous public health problem, with 1.7 million new cases of TBI recorded annually by the Centers for Disease Control. However, TBI has proven to be an extremely challenging condition to treat. Here, we apply a nanoprodrug strategy in a mouse model of TBI. The novel nanoprodrug contains a derivative of the nonsteroidal anti-inflammatory drug (NSAID) ibuprofen in an emulsion with the antioxidant α-tocopherol. The ibuprofen derivative, Ibu2TEG, contains a tetra ethylene glycol (TEG) spacer consisting of biodegradable ester bonds. The biodegradable ester bonds ensure that the prodrug molecules break down hydrolytically or enzymatically. The drug is labeled with the fluorescent reporter Cy5.5 using nonbiodegradable bonds to 1-octadecanethiol, allowing us to reliably track its accumulation in the brain after TBI. We delivered a moderate injury using a highly reproducible mouse model of closed-skull controlled cortical impact to the parietal region of the cortex, followed by an injection of the nanoprodrug at a dose of 0.2 mg per mouse. The blood brain barrier is known to exhibit increased permeability at the site of injury. We tested for accumulation of the fluorescent drug particles at the site of injury using confocal and bioluminescence imaging of whole brains and brain slices 36 hours after administration. We demonstrated that the drug does accumulate preferentially in the region of injured tissue, likely due to an enhanced permeability and retention (EPR) phenomenon. The use of a nanoprodrug approach to deliver therapeutics in TBI represents a promising potential therapeutic modality.
PMCID: PMC3634829  PMID: 23637912
3.  Inhibition of laminin-8 in vivo using a novel poly(malic acid)-based carrier reduces glioma angiogenesis 
Angiogenesis  2006;9(4):183-191.
We have previously shown that laminin-8, a vascular basement membrane component, was over-expressed in human glioblastomas multiforme and their adjacent tissues compared to normal brain. Increased laminin-8 correlated with shorter glioblastoma recurrence time and poor patient survival making it a potential marker for glioblastoma diagnostics and prediction of disease outcome. However, laminin-8 therapeutic potential was unknown because the technology of blocking the expression of multi-chain complex proteins was not yet developed. To inhibit the expression of laminin-8 constituents in glioblastoma in vitro and in vivo, we used Polycefin, a bioconjugate drug delivery system based on slime-mold Physarum polycephalum-derived poly(malic acid). It carries an attached transferrin receptor antibody to target tumor cells and to deliver two conjugated morpholino antisense oligonucleotides against laminin-8 α4 and β1 chains. Polycefin efficiently inhibited the expression of both laminin-8 chains by cultured glioblastoma cells. Intracranial Polycefin treatment of human U87MG glioblastoma-bearing nude rats reduced incorporation of both tumor-derived laminin-8 chains into vascular basement membranes. Polycefin was thus able to simultaneously inhibit the expression of two different chains of a complex protein. The treatment also significantly reduced tumor microvessel density (p < 0.001) and area (p < 0.001) and increased animal survival (p < 0.0004). These data suggest that laminin-8 may be important for glioblastoma angiogenesis. Polycefin, a versatile nanoscale drug delivery system, was suitable for in vivo delivery of two antisense oligonucleotides to brain tumor cells causing a reduction of glioblastoma angiogenesis and an increase of animal survival. This system may hold promise for future clinical applications.
PMCID: PMC3487708  PMID: 17109197
Tumor angiogenesis; Glioma; Laminin-8; Multiple drug targeting; Poly(malic acid)
4.  Polycefin, a New Prototype of a Multifunctional Nanoconjugate Based on Poly(β-l-malic acid) for Drug Delivery 
Bioconjugate chemistry  2006;17(2):317-326.
A new prototype of nanoconjugate, Polycefin, was synthesized for targeted delivery of antisense oligonucleotides and monoclonal antibodies to brain tumors. The macromolecular carrier contains: 1. biodegradable, nonimmunogenic, nontoxic β-poly(l-malic acid) of microbial origin; 2. Morpholino antisense oligonucleotides targeting laminin α4 and β1 chains of laminin-8, which is specifically overexpressed in glial brain tumors; 3. monoclonal anti-transferrin receptor antibody for specific tissue targeting; 4. oligonucleotide releasing disulfide units; 5. l-valine containing, pH-sensitive membrane disrupting unit(s), 6. protective poly(ethylene glycol); 7. a fluorescent dye (optional). Highly purified modules were conjugated directly with N-hydroxysuccinimidyl ester-activated β-poly-(l-malic acid) at pendant carboxyl groups or at thiol containing spacers via thioether and disulfide bonds. Products were chemically validated by physical, chemical, and functional tests. In vitro experiments using two human glioma cell lines U87MG and T98G demonstrated that Polycefin was delivered into the tumor cells by a receptor-mediated endocytosis mechanism and was able to inhibit the synthesis of laminin-8 α4 and β1 chains at the same time. Inhibition of laminin-8 expression was in agreement with the designed endosomal membrane disruption and drug releasing activity. In vivo imaging showed the accumulation of intravenously injected Polycefin in brain tumor tissue via the antibody-targeted transferrin receptor-mediated endosomal pathway in addition to a less efficient mechanism known for high molecular mass biopolymers as enhanced permeability and retention effect. Polycefin was nontoxic to normal and tumor astrocytes in a wide range of concentrations, accumulated in brain tumor, and could be used for specific targeting of several biomarkers simultaneously.
PMCID: PMC3487710  PMID: 16536461
5.  CXCR4-Mediated Glioma Tumor Tracking by Bone Marrow-Derived Neural Progenitor/Stem Cells 
Molecular cancer therapeutics  2009;8(9):2746-2753.
Malignant gliomas manifest frequent tumor recurrence after surgical resection and/or other treatment, due to its nature of invasiveness and dissemination. The recognized brain tumor-tracking property of neural progenitor/stem cells (NSCs) opened the possibility of targeting malignant brain tumors using NSCs. We and others have previously demonstrated that fetal NSCs can be utilized to deliver therapeutic molecules to brain tumors. Our recent work has further shown that gene delivery by bone marrow-derived NSCs (BM-NSCs) achieves therapeutic effects in a glioma model. In this study, we isolate and characterize BM-NSCs which also express the chemokine receptor CXCR4. We show that CXCR4 is required for their chemotaxis and extracelluilar matrix invasion against a gradient of glioma soluble factors. Furthermore, LacZ-labeled BM-NSCs implanted in the contralateral side of the brain were shown to track gliomas as early as day 1, and increased through day 3 and day 7. Intracranial glioma tracking by BM-NSCs is significantly inhibited by pre-incubation of BM-NSCs with a blocking anti-CXCR4 antibody, suggesting a CXCR4-dependent tracking mechanism. Glioma tracking BM-NSCs were found to express progenitor/stem cell markers, as well as CXCR4. Although BrdU incorporation assays and proliferating antigen staining indicated that tumor tracking BM-NSCs were mostly non-proliferating, these cells survive in the local tumor environment with little apoptosis. Elucidating the molecular mechanism of brain tumor tracking by adult source stem cells may provide basis for the development of future targeted therapy for malignant brain tumors.
PMCID: PMC2760002  PMID: 19723878
glioma; neural stem cells; bone marrow; CXCR4; gene delivery
6.  Nanoconjugate based on polymalic acid for tumor targeting 
Chemico-biological interactions  2007;171(2):195-203.
A new prototype of polymer-derived drug delivery system, the nanoconjugate Polycefin, was tested for its ability to accumulate in tumors based on enhanced permeability and retention (EPR) effect and receptor mediated endocytosis. Polycefin was synthesized for targeted delivery of Morpholino antisense oligonucleotides into certain tumors. It consists of units that are covalently conjugated with poly(β-L-malic acid) (Mw 50,000, Mw/Mn 1.3) highly purified from cultures of myxomycete Physarum polycephalum. The units are active in endosomal uptake, disruption of endosomal membranes, oligonucleotide release in the cytoplasm, and protection against enzymatic degradation in the vascular system. The polymer is biodegradable, non-immunogenic and non-toxic. Polycefin was also coupled with AlexaFluor 680 C2-maleimide dye for in vivo detection.
Nude mice received subcutaneous injections of MDA-MB 468 human breast cancer cells into the left posterior mid-dorsum or intracranial injections of human glioma cell line U87MG. Polycefin at concentration of 2.5 mg/kg was injected via the tail vein. In vivo fluorescence tumor imaging was performed at different time points, 0–180 min up to 24 h after the drug injection. The custom-made macro-illumination imaging MISTI system was used to examine the in vivo drug accumulation in animals bearing human breast and brain tumors. In breast tumors the fluorescence signal in large blood vessels and in the tumor increased rapidly until 60 min and remained in the tumor at a level 6 times higher than in non-tumor tissue (180 min) (p < 0.003). In brain tumors drug accumulated selectively in 24 h without any detectable signal in non-tumor areas. The results of live imaging were corroborated histologically by fluorescence microscopic examination of various organs. In addition to tumors, only kidney and liver showed some fluorescent signal. © 2007 Elsevier Ireland Ltd. All rights reserved.
PMCID: PMC2329596  PMID: 17376417
Brain glioma; Breast cancer; EPR effect; Fluorescence imaging; Drug delivery system; Poly(malic acid)
7.  Brain tumor tandem targeting using a combination of monoclonal antibodies attached to biopoly(β-L-malic acid) 
Tumor-specific targeting using achievements of nanotechnology is a mainstay of increasing efficacy of anti-tumor drugs. To improve drug targeting we covalently conjugated for the first time two different monoclonal antibodies, an anti-mouse transferrin receptor antibody and a mouse autoimmune anti-nucleosome antibody 2C5, onto the drug delivery nanoplatform, poly(β-L-malic acid). The active anti-tumor drug components attached to the same carrier molecule were antisense oligonucleotides to vascular protein laminin-8. The resulting drug, a new Polycefin variant, was administered intravenously into glioma-bearing xenogeneic animals. The drug delivery system was targeted across mouse endothelial system by the anti-mouse transferring receptor antibody and to the tumor cell surface by the anti-nucleosome antibody 2C5. The targeting efficacies of the Polycefin variants bearing either two antibodies or each single antibody were compared in vitro and in vivo. ELISA confirmed the co-existence of two antibodies on the same nanoplatform molecule and their functional activities. Fluorescence imaging analysis after 24 h of intravenous injection demonstrated significantly higher tumor accumulation of Polycefin variants with the tandem configuration of antibodies than with single antibodies. The results suggest improved efficacy for tandem configuration of antibodies than for single configurations carried by a drug delivery vehicle.
PMCID: PMC2394675  PMID: 17630012
Enhanced tumor targeting; Antibody tandem configuration; Nanobiopolymer; Brain tumor; Poly(β-L-malic acid)

Results 1-7 (7)