Structural and functional comparisons of pH-sensitive liposomes composed of phosphatidylethanolamine and three different diacylsuccinylglycerols

Collins, D. M.; Litzinger, David C.; Huang, Leaf

doi:10.1016/0005-2736(90)90102-t

Cited by 96 publications

(53 citation statements)

References 28 publications

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“…Inclusion of Chol in DOPE/OA liposome formulations resulted in a significant increase in plasma stability, without decreasing their pH-sensitivity [5]. The use of other amphiphilic stabilizers that were shown to be resistant to the extraction by albumin (such as Chol derivatives-CHEMS, or lipids with double acyl chains-DPSG) resulted in the formation of liposomes exhibiting higher stability in biological fluids, while maintaining their pH-sensitivity [25,46]. In addition to the limitations related to stability and changes in pH-sensitivity, the in vivo efficacy of pHsensitive liposomes depends strongly on the interactions with serum components (opsonins) that influence their pharmacokinetics and biodistribution.…”

Section: Long-circulating Dope-containing Ph-sensitive Liposomesmentioning

confidence: 99%

On the formulation of pH-sensitive liposomes with long circulation times

Simões

Moreira

Fonseca

et al. 2004

Advanced Drug Delivery Reviews

435

244

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Strategies used to enhance liposome-mediated drug delivery in vivo include the enhancement of stability and circulation time in the bloodstream, targeting to specific tissues or cells, and facilitation of intracytoplasmic delivery. pH-sensitive liposomes have been developed to mediate the introduction of highly hydrophilic molecules or macromolecules into the cytoplasm. These liposomes destabilize under acidic conditions found in the endocytotic pathway, and usually contain phosphatidylethanolamine (PE) and titratable stabilizing amphiphiles. Formulations without PE have also been developed. Encapsulated compounds are thought to be transported into the cytoplasm through destabilization of or fusion with the endosome membrane. Incorporation of a low mole percentage of poly(ethylene glycol) (PEG)-conjugated lipids into pHsensitive liposomes confers prolonged circulation times to these liposomes, which are otherwise cleared rapidly. While the incorporation of PEG -lipids reduces the pH-dependent release of encapsulated fluorescent markers in vitro, it does not hinder the cytoplasmic delivery of the markers per cell-associated liposome. This suggests that intracellular delivery is not dictated simply by the destabilization of the liposomes. Antibodies or ligands to cell surface receptors can be coupled to pH-sensitive or sterically stabilized pH-sensitive liposomes for targeting. pH-sensitive liposomes have been used to deliver anticancer drugs, antibiotics, antisense oligonucleotides, ribozymes, plasmids, proteins and peptides to cells in culture or in vivo. D

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Section: Long-circulating Dope-containing Ph-sensitive Liposomesmentioning

confidence: 99%

On the formulation of pH-sensitive liposomes with long circulation times

Simões

Moreira

Fonseca

et al. 2004

Advanced Drug Delivery Reviews

435

244

View full text Add to dashboard Cite

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“…When pH drops to levels suppressing ionization of the amphiphile's carboxyl, the lipid undergoes phase transition with concomitant release of liposomal contents. Such pH-sensitive liposomes are potentially promising as carriers specific to the acidic environment of endosomes and many tumors [15,16,22,23,29,30]. Yet their potential use in vivo is hampered by their fast clearance by RES.…”

Section: Ch3-o'~zo 45~nh2mentioning

confidence: 99%

Liposomes with detachable polymer coating: destabilization and fusion of dioleoylphosphatidylethanolamine vesicles triggered by cleavage of surface‐grafted poly(ethylene glycol)

Kirpotin

Hong

Mullah³

et al. 1996

FEBS Letters

194

112

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Plasma-stable liposomes (100 nm) were prepared from dioleoylphosphatidylethanolamine (DOPE) and 3--6 tool% of a new disulfide-linked poly(ethylene glycol)-phospbolipid conjugate (mPEG-DTP-DSPE). In contrast to similar preparations containing non-cleavable PEG-phospholipid conjugate, thiolytic cleavage of the grafted polymer chains facilitated rapid and complete release of the liposome contents. Furthermore, the detachment of PEG from DOPE liposomes resulted in liposomal fusion. Finally, while formulation of pH-sensitive DOPE/ cholesterol hemisuccinate liposomes with mPEG-DTP-DSPE abolished the pH sensitivity, cleavage of the PEG chains completely restored this property. These are the first examples of new useful properties of liposomes grafted with cleavable polymer.

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“…The efficiency of fusogenic liposomes in introducing their contents into the cells is the same as that of infection with intact Sendai virus (Nakanishi et al, 1995). Huang et al reported that pH-sensitive immunoliposomes can deliver encapsulated DTA into the cytoplasm (Wang and Huang, 1989;Collins et al, 1990;Litzinger and Huang, 1992;Tari et al, 1994). However, these pH-sensitive immunoliposomes showed protein synthesis inhibition of only 50-70% at maximum, and could not kill all the cells (Collins et al, 1990;Tari et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…Huang et al reported that pH-sensitive immunoliposomes can deliver encapsulated DTA into the cytoplasm (Wang and Huang, 1989;Collins et al, 1990;Litzinger and Huang, 1992;Tari et al, 1994). However, these pH-sensitive immunoliposomes showed protein synthesis inhibition of only 50-70% at maximum, and could not kill all the cells (Collins et al, 1990;Tari et al, 1990). Judging from the concentration of DTA required to kill the cells, our system is far more efficient.…”

Section: Discussionmentioning

confidence: 99%