Patent US4789633A successfully refreshed from Google Patents.
US4789633A
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Fused liposome and acid induced method for liposome fusion
Assignee: Biowhittaker Inc A Corp Of Delaware
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Filing: 1984-04-19
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Granted: 1988-12-06
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Expires: 2004-04-19
Abstract
Abstract Liposomes containing phosphatidylethanolamine, palmitoyl homocysteine or oleic acid or palmitic acid, fuse rapidly when the pH of the medium is reduced below 7. Liposome fusion was measured by (a) mixing of the liposomal lipids as shown by resonance energy transfer, (b) gel filtration and (c) electron microscopy. The presence of phosphatidylethanolamine or acid addition esters thereof in the liposomes greatly enhances fusion; whereas the presence of phosphatidylcholine inhibits fusion. During fusion of liposomes containing phosphatidylethanolamine:palmitoyl homocysteine (8:2), almost all of the encapsulate calcein is released. Inclusion of cholesterol (40%) in the liposomes substantially decreases leakage without impairing fusion. Those pH sensitive liposomes are fused to deliver biologically active molecules such as DNA, into living cells.
Inventors
- 👤 Leaf Huang
- 👤 Jerome Connor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:41
CPC Classifications
A; A61; A61K; A61K9/00; A61K9/10; A61K9/127; A61K9/1271; A61K9/1272; C; C12; C12N; C12N15/00; C12N15/09; C12N15/87; C12N15/88; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2984
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
A method of fusing liposomes which comprises: (a) preparing a suspension of liposomes containing at least one lipid which has a tendency to form the inverted hexagonal phase and at least 20 mol percent of palmitoylhomocysteine; and (b) in the absence of externally added divalent cations, proteins or other macromolecules, acidifying the liposome suspension to reduce the pH of the liposomes to below pH 7, such that at least about 20% of said liposomes fuse to one another.
Claim 2
Independent Claim
78 words
A method of fusing liposomes which comprises: (a) preparing a suspension of liposomes containing at least one lipid which has a tendency to form the inverted hexagonal phase and at least 20 mol percent of palmitoylhomocysteine; and (b) in the absence of externally added divalent cations, proteins or other macromolecules, acidifying the liposome suspension to reduce the pH of the liposomes to below pH 7, such that at least about 20% of said liposomes fuse to one another.
Claim 3
Dependent Claim
15 words
The process of claim 1, wherein the inverted hexagonal phase forming lipid is a phosphatidylethanolamine.
Claim 4
Dependent Claim
13 words
The process of claim 1 or 2, wherein the liposomes further comprise cholesterol.
Claim 5
Independent Claim
80 words
A method of inserting foreign material into a living cell which comprises: (a) encapsulating the foreign material in non-leaky, pH sensitive liposomes prepared from cholesterol, at least one lipid which has a tendency to form the inverted hexagonal phase and at least about 20 mol percent of palmitoyl homocysteine; and (b) in the absence of externally added divalent cations, proteins, or macromolecules, containing said living cell, at its physiologicla pH, with said encapsulated, non-leaky, pH sensitive liposomes, whereby insertion occurs.
Claim 6
Independent Claim
80 words
A method of inserting foreign material into a living cell which comprises: (a) encapsulating the foreign material in non-leaky, pH sensitive liposomes prepared from cholesterol, at least one lipid which has a tendency to form the inverted hexagonal phase and at least about 20 mol percent of palmitoyl homocysteine; and (b) in the absence of externally added divalent cations, proteins, or macromolecules, containing said living cell, at its physiologicla pH, with said encapsulated, non-leaky, pH sensitive liposomes, whereby insertion occurs.
Claim 7
Dependent Claim
15 words
The method of claim 4, wherein the inverted hexagonal phase forming lipid is a phosphatidylethanolamine.
Claim 8
Dependent Claim
19 words
The process of claim 4 or 5, wherein the liposomes further comprise at least about 40 mole percent cholesterol.
Claim 9
Dependent Claim
49 words
Liposomes, fused to one another at a pH of less than about 6.5, at a fusion level of at least about 50%, said lipsomes containing at least one lipid which has a tendency to form the inverted hexagonal phase and at least about 20 mol percent of palmitoyl homocysteine.
Claim 10
Dependent Claim
49 words
Liposomes, fused to one another at a pH of less than about 6.5, at a fusion level of at least about 50%, said lipsomes containing at least one lipid which has a tendency to form the inverted hexagonal phase and at least about 20 mol percent of palmitoyl homocysteine.
Claim 11
Dependent Claim
15 words
The liposomes of claim 7, wherein the inverted hexagonal phase forming lipid is a phosphatidylethanolamine.
Claim 12
Dependent Claim
13 words
The liposomes of claim 7 or 8, wherein the liposomes further comprise cholesterol.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-12-06 | 1992-06-06 | 1992-12-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-06 | 1996-06-06 | 1996-12-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-06 | 2000-06-06 | 2000-12-06 | $7700.00 | Window Closed / Lapsed |