Samuel M Cohen

University of Nebraska at Omaha, Omaha, NE, USA

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Publications (4)16.26 Total impact

  • Article: Biodegradable hybrid polymer micelles for combination drug therapy in ovarian cancer.
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    ABSTRACT: The co-delivery of drug combination at a controlled ratio via the same vehicle to the cancer cells is offering the advantages such as spatial-temporal synchronization of drug exposure, synergistic therapeutic effects and increased therapeutic potency. In an attempt to develop such multidrug vehicle this work focuses on functional biodegradable and biocompatible polypeptide-based polymeric micelles. Triblock copolymers containing the blocks of ethylene glycol, glutamic acid and phenylalanine (PEG-PGlu-PPhe) were successfully synthesized via NCA-based ring-opening copolymerization and their composition was confirmed by (1)H NMR. Self-assembly behavior of PEG-PGlu90-PPhe25 was utilized for the synthesis of hybrid micelles with PPhe hydrophobic core, cross-linked ionic PGlu intermediate shell layer, and PEG corona. Cross-linked (cl) micelles were about 90 nm in diameter (ξ-potential = -20 mV), uniform (narrow size distribution), and exhibited nanogels-like behavior. Degradation of cl-micelles was observed in presence of proteolytic enzymes (cathepsin B). The resulting cl-micelles can incorporate the combination of drugs with very different physical properties such as cisplatin (15 w/w% loading) and paclitaxel (9 w/w% loading). Binary drug combination in cl-micelles exhibited synergistic cytotoxicity against human ovarian A2780 cancer cells and exerted superior antitumor activity by comparison to individual drug-loaded micelles or free cisplatin in cancer xenograph model in vivo. Tunable composition and stability of these hybrid biodegradable micelles provide platform for drug combination delivery in a broad range of cancers.
    Journal of Controlled Release 05/2013; · 5.73 Impact Factor
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    Article: Preparation and In Vivo Evaluation of Dichloro(1,2-Diaminocyclohexane)platinum(II)-Loaded Core Cross-Linked Polymer Micelles.
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    ABSTRACT: The therapeutic performance of oxaliplatin can be improved by incorporating the central cis-dichloro(1,2-diaminocyclohexane)platinum(II) (DACHPt) motif into the core cross-linked block copolymer micelles. We describe here the preparation, cellular uptake, and in vivo evaluation of core cross-linked micelles loaded with DACHPt. Stable drug-loaded micelles were prepared at high drug loading (~25 w/w%) and displayed a considerably increased in vitro cytotoxicity compared to free oxaliplatin against A2780 ovarian cancer cells. The DACHPt-loaded micelle formulation was well tolerated in mice and exhibited improved antitumor activity than oxaliplatin alone in an ovarian tumor xenograft model.
    Chemotherapy research and practice. 01/2012; 2012:905796.
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    Article: Cisplatin-loaded core cross-linked micelles: comparative pharmacokinetics, antitumor activity, and toxicity in mice.
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    ABSTRACT: Polymer micelles with cross-linked ionic cores are shown here to improve the therapeutic performance of the platinum-containing anticancer compound cisplatin. Biodistribution, antitumor efficacy, and toxicity of cisplatin-loaded core cross-linked micelles of poly(ethylene glycol)-b-poly(methacrylic acid) were evaluated in a mouse ovarian cancer xenograft model. Cisplatin-loaded micelles demonstrated prolonged blood circulation, increased tumor accumulation, and reduced renal exposure. Improved antitumor response relative to free drug was seen in a mouse model. Toxicity studies with cisplatin-loaded micelles indicate a significantly improved safety profile and lack of renal abnormalities typical of free cisplatin treatment. Overall, the study supports the fundamental possibility of improving the potential of platinum therapy using polymer micelle-based drug delivery.
    International Journal of Nanomedicine 01/2012; 7:2557-71. · 3.13 Impact Factor
  • Article: Folate-decorated nanogels for targeted therapy of ovarian cancer.
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    ABSTRACT: Nanogels are comprised of swollen polymer networks and nearly 95% water and can entrap diverse chemical and biological agents for cancer therapy with very high loading capacities. Here we use diblock copolymer poly(ethylene oxide)-b-poly(methacrylic acid) (PEO-b-PMA) to form nanogels with the desired degree of cross-linking. The nanogels are further conjugated to folic acid (FA) and loaded with different types of drugs (cisplatin, doxorubicin). For the first time we demonstrate a tumor-specific delivery and superior anti-tumor effect in vivo of an anti-cancer drug using these polyelectrolyte nanogels decorated with folate-targeting groups. This reinforces the use of nanogels for the therapy of ovarian and other cancers, where folate receptor (FR) is overexpressed.
    Biomaterials 08/2011; 32(23):5417-26. · 7.40 Impact Factor