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Zwitterionic poly(carboxybetaine)-based cationic liposomes for effective delivery of small interfering RNA therapeutics without accelerated blood clearance phenomenon.

Li Y, Liu R, Shi Y, Zhang Z, Zhang X - Theranostics (2015)

Bottom Line: For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA.It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes.However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon.

View Article: PubMed Central - PubMed

Affiliation: 1. National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China ; 2. University of Chinese Academy of Sciences, Beijing, 100049, China.

ABSTRACT
For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA. It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes. However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon. Herein, we developed zwitterionic poly(carboxybetaine) (PCB) modified lipoplexes for the delivery of siRNA therapeutics, which could avoid protein adsorption and enhance the stability of lipoplexes as that for PEG. Quite different from the PEGylation, the PCBylated lipoplexes could avoid ABC phenomenon, which extended the blood circulation time and enhanced the tumor accumulation of lipoplexes in vivo. After accumulation in tumor site, the PCBylation could promote the cellular uptake and endosomal/lysosomal escape of lipoplexes due to its unique chemical structure and pH-sensitive ability. With excellent tumor accumulation, cellular uptake and endosomal/lysosomal escape abilities, the PCBylated lipoplexes significantly inhibited tumor growth and induced tumor cell apoptosis.

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Flow cytometric analyses of cellular internalization of cationic liposome/FAM-labeled siRNA lipoplexes in Hela cells after incubation for different times. (A) Comparation of cellular internalization between DSPE-PEG and DSPE-PCB20 lipoplexes with the extension of time. (B) Mechanistic probes of the intracellular kinetics of the DSPE-PEG and DSPE-PCB20 lipoplexes by monitoring the cellular uptake level at 4 ºC or in the presence of various endocytic inhibitors. Data are shown as the mean ± S.D. of three independent experiments.
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Figure 8: Flow cytometric analyses of cellular internalization of cationic liposome/FAM-labeled siRNA lipoplexes in Hela cells after incubation for different times. (A) Comparation of cellular internalization between DSPE-PEG and DSPE-PCB20 lipoplexes with the extension of time. (B) Mechanistic probes of the intracellular kinetics of the DSPE-PEG and DSPE-PCB20 lipoplexes by monitoring the cellular uptake level at 4 ºC or in the presence of various endocytic inhibitors. Data are shown as the mean ± S.D. of three independent experiments.

Mentions: After the lipoplexes accumulated in tumor site, the siRNA molecules must be transported into tumor cells, and more siRNA in the cytoplasm would induce more significant gene silencing effect 42. The cellular uptake of DSPE-PCB20 lipoplexes at N/P ratio of 5/1 was evaluated after incubation with Hela cells by flow cytometric analysis. As shown in Figure 8A, the fluorescence intensity of FAM-labeled siRNA in Hela cells was increased with the extension of culturing time from 0.25 to 2.5 h. In addition, the fluorescence intensity of FAM-labeled siRNA for DSPE-PCB20 lipoplexes was about 2 times of that for DSPE-PEG lipoplexes after 2.5 h incubation, indicating that DSPE-PCB20 lipoplexes had better cellular uptake ability than that of DSPE-PEG lipoplexes. This might be attributed to the unique chemical structure of DSPE-PCB20 that the cationic quaternary amine groups assisted the cationic liposomes in retaining the siRNA and cellular uptake.


Zwitterionic poly(carboxybetaine)-based cationic liposomes for effective delivery of small interfering RNA therapeutics without accelerated blood clearance phenomenon.

Li Y, Liu R, Shi Y, Zhang Z, Zhang X - Theranostics (2015)

Flow cytometric analyses of cellular internalization of cationic liposome/FAM-labeled siRNA lipoplexes in Hela cells after incubation for different times. (A) Comparation of cellular internalization between DSPE-PEG and DSPE-PCB20 lipoplexes with the extension of time. (B) Mechanistic probes of the intracellular kinetics of the DSPE-PEG and DSPE-PCB20 lipoplexes by monitoring the cellular uptake level at 4 ºC or in the presence of various endocytic inhibitors. Data are shown as the mean ± S.D. of three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4377727&req=5

Figure 8: Flow cytometric analyses of cellular internalization of cationic liposome/FAM-labeled siRNA lipoplexes in Hela cells after incubation for different times. (A) Comparation of cellular internalization between DSPE-PEG and DSPE-PCB20 lipoplexes with the extension of time. (B) Mechanistic probes of the intracellular kinetics of the DSPE-PEG and DSPE-PCB20 lipoplexes by monitoring the cellular uptake level at 4 ºC or in the presence of various endocytic inhibitors. Data are shown as the mean ± S.D. of three independent experiments.
Mentions: After the lipoplexes accumulated in tumor site, the siRNA molecules must be transported into tumor cells, and more siRNA in the cytoplasm would induce more significant gene silencing effect 42. The cellular uptake of DSPE-PCB20 lipoplexes at N/P ratio of 5/1 was evaluated after incubation with Hela cells by flow cytometric analysis. As shown in Figure 8A, the fluorescence intensity of FAM-labeled siRNA in Hela cells was increased with the extension of culturing time from 0.25 to 2.5 h. In addition, the fluorescence intensity of FAM-labeled siRNA for DSPE-PCB20 lipoplexes was about 2 times of that for DSPE-PEG lipoplexes after 2.5 h incubation, indicating that DSPE-PCB20 lipoplexes had better cellular uptake ability than that of DSPE-PEG lipoplexes. This might be attributed to the unique chemical structure of DSPE-PCB20 that the cationic quaternary amine groups assisted the cationic liposomes in retaining the siRNA and cellular uptake.

Bottom Line: For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA.It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes.However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon.

View Article: PubMed Central - PubMed

Affiliation: 1. National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China ; 2. University of Chinese Academy of Sciences, Beijing, 100049, China.

ABSTRACT
For efficient delivery of small interfering RNA (siRNA) to the target diseased site in vivo, it is important to design suitable vehicles to control the blood circulation of siRNA. It has been shown that surface modification of cationic liposome/siRNA complexes (lipoplexes) with polyethylene glycol (PEG) could enhance the circulation time of lipoplexes. However, the first injection of PEGylated lipoplexes in vivo induces accelerated blood clearance and enhances hepatic accumulation of the following injected PEGylated lipoplexes, which is known as the accelerated blood clearance (ABC) phenomenon. Herein, we developed zwitterionic poly(carboxybetaine) (PCB) modified lipoplexes for the delivery of siRNA therapeutics, which could avoid protein adsorption and enhance the stability of lipoplexes as that for PEG. Quite different from the PEGylation, the PCBylated lipoplexes could avoid ABC phenomenon, which extended the blood circulation time and enhanced the tumor accumulation of lipoplexes in vivo. After accumulation in tumor site, the PCBylation could promote the cellular uptake and endosomal/lysosomal escape of lipoplexes due to its unique chemical structure and pH-sensitive ability. With excellent tumor accumulation, cellular uptake and endosomal/lysosomal escape abilities, the PCBylated lipoplexes significantly inhibited tumor growth and induced tumor cell apoptosis.

Show MeSH
Related in: MedlinePlus