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Poly(ethylene glycol)-block-poly(ε-caprolactone)-and phospholipid-based stealth nanoparticles with enhanced therapeutic efficacy on murine breast cancer by improved intracellular drug delivery.

He X, Li L, Su H, Zhou D, Song H, Wang L, Jiang X - Int J Nanomedicine (2015)

Bottom Line: Although PEG chains can efficiently preserve liposomes from rapid clearance by the reticuloendothelial system (RES), its application has been hindered by poor cellular uptake and unsatisfactory therapeutic effect.The cellular uptake level was closely related to the PEG chain length of PEG-b-PCL; a shorter PEG chain resulted in higher cellular uptake.Consistent with the results of the in vitro study, in vivo experiments showed that LPPs allowed significantly improved bioavailability and prolonged T1/2β as compared to free PTX injection.

View Article: PubMed Central - PubMed

Affiliation: West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, People's Republic of China.

ABSTRACT

Background: Effective anticancer drug delivery to the tumor site without rapid body clearance is a prerequisite for successful chemotherapy. 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-(methoxy[polyethyleneglycol]-2000) (DSPE-PEG2000) has been widely used in the preparation of stealth liposomes. Although PEG chains can efficiently preserve liposomes from rapid clearance by the reticuloendothelial system (RES), its application has been hindered by poor cellular uptake and unsatisfactory therapeutic effect.

Methods: To address the dilemma, we presented a facile approach to fabricate novel stealth nanoparticles generated by poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL), soybean phosphatidylcholine (SPC), and cholesterol, namely LPPs (L represented lipid and PP represented PEG-b-PCL), for the delivery of anticancer drug paclitaxel (PTX). LPPs were prepared using the thin film hydration method. Two PEG-b-PCL polymers with different molecular weights (MW; PEG2000-b-PCL2000, MW: 4,000 Da and PEG5000-b-PCL5000, MW: 10,000 Da) were used to fabricate stealth nanoparticles. Conventional PEGylated liposome (LDP2000, L represented lipid and DP2000 represented DSPE-PEG2000) composed of SPC, cholesterol, and DSPE-PEG2000 was used as the control. The physical properties, cellular uptake, endocytosis pathway, cytotoxicity, pharmacokinetics, tumor accumulation, and anticancer efficacy of free PTX, PTX-loaded LPPs, and LDP2000 were systemically investigated after injection into 4T1 breast tumor-bearing mice.

Results: LPPs were vesicles around 100 nm in size with negative zeta potential. With enhanced stability, LPPs achieved sustainable release of cancer therapeutics. The cellular uptake level was closely related to the PEG chain length of PEG-b-PCL; a shorter PEG chain resulted in higher cellular uptake. Moreover, the cellular internalization of LPP2000 modified by PEG2000-b-PCL2000 on 4T1 cells was 2.1-fold higher than LDP2000 due to the improved stability of LPP2000. The cytotoxicity of PTX-loaded LPP2000 was also higher than that of LDP2000 and LPP5000 as observed using a WST-8 assay, while blank LPPs showed negligible toxicity. Consistent with the results of the in vitro study, in vivo experiments showed that LPPs allowed significantly improved bioavailability and prolonged T1/2β as compared to free PTX injection. More importantly, LPPs mainly accumulated at the tumor site, probably due to the enhanced permeation and retention effect (EPR effect). As a nanomedicine, LPP2000 (tumor inhibition rate of 75.1%) significantly enhanced the therapeutic effect of PTX in 4T1 breast tumor-bearing mice by inhibiting tumor growth compared to LDP2000 and LPP5000 (tumor inhibition rates of 56.3% and 49.5%, respectively).

Conclusion: Modification of liposomes with PEG2000-b-PCL2000 can simultaneously improve drug accumulation at the target tumor site and tumor cells, showing great promise for utilization as a PEG modification tool in the fabrication of stealth nanoparticles for cancer chemotherapy.

No MeSH data available.


Related in: MedlinePlus

Intravenous administration of PTX formulations inhibited the growth of 4T1 murine breast tumors in vivo and prolonged the survival of treated mice.Notes: (A) Suppression of tumor growth in each treatment group. The arrows indicate the injection of PTX formulations. (B) PTX groups versus the saline or LPP2000 group, with tumor growth inhibition of PTX formulations. (C) Weight of subcutaneously transplanted tumors in each treatment group. (D) Survival curves of mice in each group. * and ** represented P<0.05 and P<0.01, respectively.Abbreviation: PTX, paclitaxel.
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f5-ijn-10-1791: Intravenous administration of PTX formulations inhibited the growth of 4T1 murine breast tumors in vivo and prolonged the survival of treated mice.Notes: (A) Suppression of tumor growth in each treatment group. The arrows indicate the injection of PTX formulations. (B) PTX groups versus the saline or LPP2000 group, with tumor growth inhibition of PTX formulations. (C) Weight of subcutaneously transplanted tumors in each treatment group. (D) Survival curves of mice in each group. * and ** represented P<0.05 and P<0.01, respectively.Abbreviation: PTX, paclitaxel.

Mentions: To evaluate the antitumor efficacy of PTX formulations in vivo, we next established the animal transplant tumor models. BALB/c mice bearing 4T1 cells received intravenous administration of PTX formulations and saline every 3 days for 10 days. As shown in Figures 5A and B, a rapid increase in tumor volume was observed in the saline group, while the PTX-treated groups exhibited inhibition effects to different extents. Treatment with free PTX resulted in a tumor inhibition rate of 32.5%, while the PTX nanoparticles groups (LDP2000, LPP2000, and LPP5000) exhibited more potent anticancer effects (inhibition rates of 56.3%, 75.1%, and 49.5%, respectively). This result again confirms the importance of sufficient accumulation of cargo (in this case, PTX) into tumors via the EPR effect by PEGylated nanoparticles. LPP2000 displayed the most significant tumor growth inhibition among the PEGylated nanoparticles, which was mainly due to its highest cellular uptake efficiency and good stability in serum. Mice body weight and survival were monitored to evaluate nanoparticle toxicity. As shown in Figure 5C, no significant changes in mice body weight were found throughout the whole experiment period (Figure 5C). However, some deaths were observed a few minutes after the injection of free PTX, LDP2000, and LPP5000 containing PTX (Figure 5D). This result reveals that PTX formulations except LPP2000 could cause some acute toxicity and even death in mice after intravenous injection, despite the fact that they caused only negligible or a little changes in mice body weight. Therefore, LPP2000 was safer than other three formulations. In addition, the median survival time was greatly prolonged in mice that received PTX-loaded LPP2000 (mean =48 days) compared with other groups (normal saline: 28 days, LDP2000: 41 days, LPP5000: 32 days, free PTX: 31 days).


Poly(ethylene glycol)-block-poly(ε-caprolactone)-and phospholipid-based stealth nanoparticles with enhanced therapeutic efficacy on murine breast cancer by improved intracellular drug delivery.

He X, Li L, Su H, Zhou D, Song H, Wang L, Jiang X - Int J Nanomedicine (2015)

Intravenous administration of PTX formulations inhibited the growth of 4T1 murine breast tumors in vivo and prolonged the survival of treated mice.Notes: (A) Suppression of tumor growth in each treatment group. The arrows indicate the injection of PTX formulations. (B) PTX groups versus the saline or LPP2000 group, with tumor growth inhibition of PTX formulations. (C) Weight of subcutaneously transplanted tumors in each treatment group. (D) Survival curves of mice in each group. * and ** represented P<0.05 and P<0.01, respectively.Abbreviation: PTX, paclitaxel.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4356685&req=5

f5-ijn-10-1791: Intravenous administration of PTX formulations inhibited the growth of 4T1 murine breast tumors in vivo and prolonged the survival of treated mice.Notes: (A) Suppression of tumor growth in each treatment group. The arrows indicate the injection of PTX formulations. (B) PTX groups versus the saline or LPP2000 group, with tumor growth inhibition of PTX formulations. (C) Weight of subcutaneously transplanted tumors in each treatment group. (D) Survival curves of mice in each group. * and ** represented P<0.05 and P<0.01, respectively.Abbreviation: PTX, paclitaxel.
Mentions: To evaluate the antitumor efficacy of PTX formulations in vivo, we next established the animal transplant tumor models. BALB/c mice bearing 4T1 cells received intravenous administration of PTX formulations and saline every 3 days for 10 days. As shown in Figures 5A and B, a rapid increase in tumor volume was observed in the saline group, while the PTX-treated groups exhibited inhibition effects to different extents. Treatment with free PTX resulted in a tumor inhibition rate of 32.5%, while the PTX nanoparticles groups (LDP2000, LPP2000, and LPP5000) exhibited more potent anticancer effects (inhibition rates of 56.3%, 75.1%, and 49.5%, respectively). This result again confirms the importance of sufficient accumulation of cargo (in this case, PTX) into tumors via the EPR effect by PEGylated nanoparticles. LPP2000 displayed the most significant tumor growth inhibition among the PEGylated nanoparticles, which was mainly due to its highest cellular uptake efficiency and good stability in serum. Mice body weight and survival were monitored to evaluate nanoparticle toxicity. As shown in Figure 5C, no significant changes in mice body weight were found throughout the whole experiment period (Figure 5C). However, some deaths were observed a few minutes after the injection of free PTX, LDP2000, and LPP5000 containing PTX (Figure 5D). This result reveals that PTX formulations except LPP2000 could cause some acute toxicity and even death in mice after intravenous injection, despite the fact that they caused only negligible or a little changes in mice body weight. Therefore, LPP2000 was safer than other three formulations. In addition, the median survival time was greatly prolonged in mice that received PTX-loaded LPP2000 (mean =48 days) compared with other groups (normal saline: 28 days, LDP2000: 41 days, LPP5000: 32 days, free PTX: 31 days).

Bottom Line: Although PEG chains can efficiently preserve liposomes from rapid clearance by the reticuloendothelial system (RES), its application has been hindered by poor cellular uptake and unsatisfactory therapeutic effect.The cellular uptake level was closely related to the PEG chain length of PEG-b-PCL; a shorter PEG chain resulted in higher cellular uptake.Consistent with the results of the in vitro study, in vivo experiments showed that LPPs allowed significantly improved bioavailability and prolonged T1/2β as compared to free PTX injection.

View Article: PubMed Central - PubMed

Affiliation: West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, People's Republic of China.

ABSTRACT

Background: Effective anticancer drug delivery to the tumor site without rapid body clearance is a prerequisite for successful chemotherapy. 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-(methoxy[polyethyleneglycol]-2000) (DSPE-PEG2000) has been widely used in the preparation of stealth liposomes. Although PEG chains can efficiently preserve liposomes from rapid clearance by the reticuloendothelial system (RES), its application has been hindered by poor cellular uptake and unsatisfactory therapeutic effect.

Methods: To address the dilemma, we presented a facile approach to fabricate novel stealth nanoparticles generated by poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL), soybean phosphatidylcholine (SPC), and cholesterol, namely LPPs (L represented lipid and PP represented PEG-b-PCL), for the delivery of anticancer drug paclitaxel (PTX). LPPs were prepared using the thin film hydration method. Two PEG-b-PCL polymers with different molecular weights (MW; PEG2000-b-PCL2000, MW: 4,000 Da and PEG5000-b-PCL5000, MW: 10,000 Da) were used to fabricate stealth nanoparticles. Conventional PEGylated liposome (LDP2000, L represented lipid and DP2000 represented DSPE-PEG2000) composed of SPC, cholesterol, and DSPE-PEG2000 was used as the control. The physical properties, cellular uptake, endocytosis pathway, cytotoxicity, pharmacokinetics, tumor accumulation, and anticancer efficacy of free PTX, PTX-loaded LPPs, and LDP2000 were systemically investigated after injection into 4T1 breast tumor-bearing mice.

Results: LPPs were vesicles around 100 nm in size with negative zeta potential. With enhanced stability, LPPs achieved sustainable release of cancer therapeutics. The cellular uptake level was closely related to the PEG chain length of PEG-b-PCL; a shorter PEG chain resulted in higher cellular uptake. Moreover, the cellular internalization of LPP2000 modified by PEG2000-b-PCL2000 on 4T1 cells was 2.1-fold higher than LDP2000 due to the improved stability of LPP2000. The cytotoxicity of PTX-loaded LPP2000 was also higher than that of LDP2000 and LPP5000 as observed using a WST-8 assay, while blank LPPs showed negligible toxicity. Consistent with the results of the in vitro study, in vivo experiments showed that LPPs allowed significantly improved bioavailability and prolonged T1/2β as compared to free PTX injection. More importantly, LPPs mainly accumulated at the tumor site, probably due to the enhanced permeation and retention effect (EPR effect). As a nanomedicine, LPP2000 (tumor inhibition rate of 75.1%) significantly enhanced the therapeutic effect of PTX in 4T1 breast tumor-bearing mice by inhibiting tumor growth compared to LDP2000 and LPP5000 (tumor inhibition rates of 56.3% and 49.5%, respectively).

Conclusion: Modification of liposomes with PEG2000-b-PCL2000 can simultaneously improve drug accumulation at the target tumor site and tumor cells, showing great promise for utilization as a PEG modification tool in the fabrication of stealth nanoparticles for cancer chemotherapy.

No MeSH data available.


Related in: MedlinePlus