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Published on: April 16, 2019
Efficient delivery of an antisense oligodeoxyribonucleotide formulated in folate receptor-targeted liposomes
Shih-Jiuan Chiu1, Guido Marcucci, Robert J Lee
1Division of Pharmaceutics, College of Pharmacy, The Ohio State University, Columbus, OH 43210, USA.
Background:
Folate receptors (FRs) are cellular surface markers for numerous solid tumors and myeloid leukemias. The aim of this study was to develop an antisense oligodeoxyribonucleotide (ODN) carrier targeting FR-overexpressing cancer cells using folate (FA) as the targeting moiety. G3139, a phosphorothioate antisense ODN against human bcl2 mRNA, was evaluated in this study.
Materials And Methods:
G3139-containing liposomes were prepared using an ethanol dilution method. For the targeted formulation, 0.5 mol% of folate-PEG-DSPE was incorporated as a targeting ligand into cationic liposomes composed of DC-Chol/egg PC/PEG-DSPE at 25:65:10 mol/mol. Particle size and surface charge were measured and cellular uptake was assessed by fluorescence microscopy and flow cytometry. The ODN-containing formulations were evaluated in FR+ KB cells for Bcl2 down-regulation measured by Western blot. The cytotoxicity of the formulations was determined by MTT assay.
Results:
The G3139-containing liposomes had an average diameter of 80-90 nm with high ODN entrapment efficiency (70-80%). Incorporation of the folate ligand did not significantly alter the particle size and entrapment efficiency. The formulation exhibited colloidal stability in a serum-containing environment. In uptake studies, the folate-targeted formulation showed ligand concentration-dependent uptake that was up to 6-fold more efficient than that of the non-targeted formulation (p < 0.05). The uptake could be blocked by an excess amount of free folate, thus indicating an FR-dependent mechanism.
Conclusion:
FR-targeted G3139-containing liposomes showed promising transfection activity in KB cells. FR-targeted formulations were capable of specific targeting to FR-overexpressing cell lines and optimizing the amount of folate ligand in the liposomal formulation can result in more efficient antisense delivery.
Insights
Folate receptor-targeted liposomes efficiently deliver antisense oligodeoxyribonucleotides (ODNs) to cancer cells. This targeted delivery enhances cellular uptake and down-regulates Bcl2, showing promise for cancer therapy.
Area of Science:
- Nanomedicine
- Cancer Biology
- Drug Delivery
Background:
- Folate receptors (FRs) are key biomarkers overexpressed on various solid tumors and myeloid leukemias.
- Antisense oligodeoxyribonucleotides (ODNs) offer therapeutic potential but require effective delivery systems.
- This study focuses on developing a targeted delivery system for G3139, an antisense ODN against bcl2 mRNA.
Purpose of the Study:
- To develop and evaluate folate (FA)-functionalized liposomes as a targeted carrier for G3139.
- To assess the targeting efficiency and cellular uptake of FR-overexpressing cancer cells.
- To determine the therapeutic efficacy of the targeted formulation in down-regulating Bcl2 and reducing cell viability.
Main Methods:
- G3139-loaded cationic liposomes were prepared using an ethanol dilution method.
- Folate-PEG-DSPE was incorporated into liposomes for FR targeting.
- Cellular uptake was quantified using fluorescence microscopy and flow cytometry.
- Bcl2 down-regulation and cytotoxicity were assessed in FR+ KB cells via Western blot and MTT assay.
Main Results:
- Liposomes exhibited optimal size (80-90 nm) and high ODN entrapment (70-80%), with folate incorporation not affecting these properties.
- The folate-targeted liposomes demonstrated a 6-fold increase in cellular uptake compared to non-targeted liposomes (p < 0.05).
- Uptake was confirmed to be FR-dependent, as it was inhibited by free folate.
Conclusions:
- Folate receptor-targeted liposomes show significant potential for delivering G3139 antisense ODN to FR-overexpressing cancer cells.
- The targeted formulation achieved specific delivery and enhanced transfection activity in KB cells.
- Optimizing folate ligand density on liposomes can further improve antisense delivery efficiency.
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