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Phospholipid-modified PEI-based nanocarriers for in vivo siRNA therapeutics against multidrug-resistant tumors.

Essex S, Navarro G, Sabhachandani P, Chordia A, Trivedi M, Movassaghian S, Torchilin VP - Gene Ther. (2014)

Bottom Line: First, we studied the biodistribution of DOPE-PEI nanocarriers and the effect of PEG coating in a subcutaneous breast tumor model.Four hours postinjection, PEGylated carriers showed an 8% injected dose (ID) accumulation in solid tumor via the enhanced permeability and retention effect and 22% ID in serum due to a prolonged, PEG-mediated circulation.Second, we established the therapeutic efficacy and safety of DOPE-PEI/siRNA-mediated P-gp downregulation in combination with doxorubicin (Dox) chemotherapy in MCF-7/MDR xenografts.

View Article: PubMed Central - PubMed

Affiliation: Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, MA 02115, USA.

ABSTRACT
Multidrug resistance (MDR) mediated by P-glycoprotein overexpression in solid tumors is a major factor in the failure of many forms of chemotherapy. Here we evaluated phospholipid-modified, low-molecular-weight polyethylenimine (DOPE-PEI) nanocarriers for intravenous delivery of anti-P-pg siRNA to tumors with the final goal of modulating MDR in breast cancer. First, we studied the biodistribution of DOPE-PEI nanocarriers and the effect of PEG coating in a subcutaneous breast tumor model. Four hours postinjection, PEGylated carriers showed an 8% injected dose (ID) accumulation in solid tumor via the enhanced permeability and retention effect and 22% ID in serum due to a prolonged, PEG-mediated circulation. Second, we established the therapeutic efficacy and safety of DOPE-PEI/siRNA-mediated P-gp downregulation in combination with doxorubicin (Dox) chemotherapy in MCF-7/MDR xenografts. Weekly injection of siRNA nanopreparations and Dox for up to 5 weeks sensitized the tumors to otherwise non-effective doses of Dox and decreased the tumor volume by threefold vs controls. This therapeutic improvement in response to Dox was attributed to the significant, sequence-specific P-gp downregulation in excised tumors mediated by the DOPE-PEI formulations.

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Biophysical characterization of DOPE-PEI nanocarriers. (A) Schematic illustration of the nanocarriers’ assembly with the mean diameter and the zeta potential of the formulations. (B) Detailed structure and morphology of free siRNA, DOPE-PEI and PEG-PE components and assembled nanocarriers by AFM and TEM. (C) Stability of nanocarriers indicated by the change in size after incubation with 150mM NaCl for up to 1h at RT.
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Figure 2: Biophysical characterization of DOPE-PEI nanocarriers. (A) Schematic illustration of the nanocarriers’ assembly with the mean diameter and the zeta potential of the formulations. (B) Detailed structure and morphology of free siRNA, DOPE-PEI and PEG-PE components and assembled nanocarriers by AFM and TEM. (C) Stability of nanocarriers indicated by the change in size after incubation with 150mM NaCl for up to 1h at RT.

Mentions: DOPE-PEI/siRNA complexes were prepared as described 22. The complexes were also mixed with the micelle-forming material, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethyleneglycol)-2000] (PEG-PE), to improve stability 26. The biophysical characterizations of DOPE-PEI/siRNA and DOPE-PEI/PEG/siRNA are shown in Fig. 2. The detailed structure and the effect of PEG addition on the morphology of the formulations was studied by dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electronic microscopy (TEM). DLS was used to determine the hydrodynamic diameter of the complexes whereas, AFM and TEM were chosen as methods that allowed sample visualization, measurement of the real size (not the hydrodynamic) of the complexes and additionally gave a three dimensional profile of the sample (in the case of AFM). The formation of the PEG-PE corona around the DOPE-PEI/siRNA core was proposed based on the fact that the zeta potential drastically changed from an average of about + 48 mV for DOPE-PEI/siRNA complexes to about + 13 mV after the addition of PEG-PE, suggesting a cationic charge-shielding effect, whereas the mean size measured by DLS was not affected by the addition of PEG (Fig 2A). The zeta potential for free PEG-PE micelles was - 27 ± 8 mV in accordance with reported values 27. By AFM analysis, the DOPE-PEI/siRNA complexes appeared as well-developed, individualized, rounded particles with a broad size distribution ranging from 50-500 nm. DOPE-PEI/PEG/siRNA particles exhibited an almost spherical shape and a narrower size distribution. TEM analysis of DOPE-PEI/siRNA and DOPE-PEI/PEG/siRNA complexes confirmed the protective and stabilizing effect of the PEG-PE corona. The DOPE-PEI/siRNA complexes appeared like ovoid particles. Some concentric ovoid structures were also visualized with a mean particle size of 110.4 ± 20.4 nm. The DOPE-PEI/PEG/siRNA micelles appeared as almost spherical particles (Fig. 2B). The mean particle size for the DOPE-PEI/PEG/siRNA complex was 95.8 ± 38.7 nm.


Phospholipid-modified PEI-based nanocarriers for in vivo siRNA therapeutics against multidrug-resistant tumors.

Essex S, Navarro G, Sabhachandani P, Chordia A, Trivedi M, Movassaghian S, Torchilin VP - Gene Ther. (2014)

Biophysical characterization of DOPE-PEI nanocarriers. (A) Schematic illustration of the nanocarriers’ assembly with the mean diameter and the zeta potential of the formulations. (B) Detailed structure and morphology of free siRNA, DOPE-PEI and PEG-PE components and assembled nanocarriers by AFM and TEM. (C) Stability of nanocarriers indicated by the change in size after incubation with 150mM NaCl for up to 1h at RT.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4352110&req=5

Figure 2: Biophysical characterization of DOPE-PEI nanocarriers. (A) Schematic illustration of the nanocarriers’ assembly with the mean diameter and the zeta potential of the formulations. (B) Detailed structure and morphology of free siRNA, DOPE-PEI and PEG-PE components and assembled nanocarriers by AFM and TEM. (C) Stability of nanocarriers indicated by the change in size after incubation with 150mM NaCl for up to 1h at RT.
Mentions: DOPE-PEI/siRNA complexes were prepared as described 22. The complexes were also mixed with the micelle-forming material, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethyleneglycol)-2000] (PEG-PE), to improve stability 26. The biophysical characterizations of DOPE-PEI/siRNA and DOPE-PEI/PEG/siRNA are shown in Fig. 2. The detailed structure and the effect of PEG addition on the morphology of the formulations was studied by dynamic light scattering (DLS), atomic force microscopy (AFM), and transmission electronic microscopy (TEM). DLS was used to determine the hydrodynamic diameter of the complexes whereas, AFM and TEM were chosen as methods that allowed sample visualization, measurement of the real size (not the hydrodynamic) of the complexes and additionally gave a three dimensional profile of the sample (in the case of AFM). The formation of the PEG-PE corona around the DOPE-PEI/siRNA core was proposed based on the fact that the zeta potential drastically changed from an average of about + 48 mV for DOPE-PEI/siRNA complexes to about + 13 mV after the addition of PEG-PE, suggesting a cationic charge-shielding effect, whereas the mean size measured by DLS was not affected by the addition of PEG (Fig 2A). The zeta potential for free PEG-PE micelles was - 27 ± 8 mV in accordance with reported values 27. By AFM analysis, the DOPE-PEI/siRNA complexes appeared as well-developed, individualized, rounded particles with a broad size distribution ranging from 50-500 nm. DOPE-PEI/PEG/siRNA particles exhibited an almost spherical shape and a narrower size distribution. TEM analysis of DOPE-PEI/siRNA and DOPE-PEI/PEG/siRNA complexes confirmed the protective and stabilizing effect of the PEG-PE corona. The DOPE-PEI/siRNA complexes appeared like ovoid particles. Some concentric ovoid structures were also visualized with a mean particle size of 110.4 ± 20.4 nm. The DOPE-PEI/PEG/siRNA micelles appeared as almost spherical particles (Fig. 2B). The mean particle size for the DOPE-PEI/PEG/siRNA complex was 95.8 ± 38.7 nm.

Bottom Line: First, we studied the biodistribution of DOPE-PEI nanocarriers and the effect of PEG coating in a subcutaneous breast tumor model.Four hours postinjection, PEGylated carriers showed an 8% injected dose (ID) accumulation in solid tumor via the enhanced permeability and retention effect and 22% ID in serum due to a prolonged, PEG-mediated circulation.Second, we established the therapeutic efficacy and safety of DOPE-PEI/siRNA-mediated P-gp downregulation in combination with doxorubicin (Dox) chemotherapy in MCF-7/MDR xenografts.

View Article: PubMed Central - PubMed

Affiliation: Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, MA 02115, USA.

ABSTRACT
Multidrug resistance (MDR) mediated by P-glycoprotein overexpression in solid tumors is a major factor in the failure of many forms of chemotherapy. Here we evaluated phospholipid-modified, low-molecular-weight polyethylenimine (DOPE-PEI) nanocarriers for intravenous delivery of anti-P-pg siRNA to tumors with the final goal of modulating MDR in breast cancer. First, we studied the biodistribution of DOPE-PEI nanocarriers and the effect of PEG coating in a subcutaneous breast tumor model. Four hours postinjection, PEGylated carriers showed an 8% injected dose (ID) accumulation in solid tumor via the enhanced permeability and retention effect and 22% ID in serum due to a prolonged, PEG-mediated circulation. Second, we established the therapeutic efficacy and safety of DOPE-PEI/siRNA-mediated P-gp downregulation in combination with doxorubicin (Dox) chemotherapy in MCF-7/MDR xenografts. Weekly injection of siRNA nanopreparations and Dox for up to 5 weeks sensitized the tumors to otherwise non-effective doses of Dox and decreased the tumor volume by threefold vs controls. This therapeutic improvement in response to Dox was attributed to the significant, sequence-specific P-gp downregulation in excised tumors mediated by the DOPE-PEI formulations.

Show MeSH
Related in: MedlinePlus