Abstract: Reagents for use in preparing a therapeutic liposome composition sensitized to a target cell are described. The reagents include a liposomal composition composed of pre-formed liposomes having an entrapped therapeutic agent and a plurality of targeting conjugates composed of a lipid, a hydrophilic polymer and a targeting ligand. The therapeutic, target-cell sensitized liposome composition is formed by incubating the liposomal composition with a selected conjugate.

Abstract: A compound comprised of a hydrophilic polymer covalently yet reversibly linked to a amine-containing ligand through a dithiobenzyl linkage is described.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: A compound comprised of a hydrophilic polymer covalently yet reversibly linked to a amine-containing ligand through a dithiobenzyl linkage is described.

Abstract: Liposomes containing PEG-substituted neutral lipopolymers provide similar circulation times to liposomes incorporating conventional, negatively charged PEG-substituted phospholipids. Use of the uncharged lipopolymers can also present advantages in terms of interactions with cell surfaces and reduced leakage of charged substances, particularly cationic drugs, from the liposomes. The lipopolymers are of the formula: wherein each of R1 and R2 is an alkyl or alkenyl chain having between about 8 to about 24 carbon atoms, n is about 10 to about 300, Z is selected from the group consisting of hydroxy, alkoxy, benzyloxy, carboxylic ester, sulfonic ester, alkyl or aryl carbonate, amino, and alkylamino, and the linkage L is selected from the group consisting of (i) —X—(C═O)—Y—CH2—, (ii) —X—(C═O)—, and (iii) —X—CH2—, wherein X and Y are independently selected from oxygen, NH, and a direct linkage.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: Conjugates of a hydrophobic moiety, such as a lipid, linked through a cleavable dithiobenzyl linkage to a therapeutic agent are described. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of the therapeutic agent in its original form. The linkage is stable under nonreducing conditions. The conjugate can be incorporated into liposomes for administration in vivo and release of the therapeutic agent in response to endogeneous in vivo reducing conditions or in response to administration of an exogeneous reducing agent.

Abstract: A liposome composition for delivery of a nucleic acid in vivo or ex vivo is described. The liposomes in the composition are comprised of (i) a lipid that is neutral in charge at physiologic pH and positively charged at pH values less than physiologic pH and (ii) a lipid joined to a hydrophilic polymer by a dithiobenzyl linkage. The liposomes are associated with a nucleic acid for delievery to a cell.

Abstract: A liposomal composition and a method of using the same for achieving intracellular delivery of a liposome-entrapped agent is described. The liposomes are composed of a pH sensitive lipid and include a targeting ligand to direct the liposomes to a target cell. The liposomes also include a stabilizing component, such a polymer-derivatized lipid, where the polymer is attached to the lipid by a releasable linkage. Administration of the liposomes results in cellular internalization and destabilization of the liposome for intracellular delivery of the entrapped agent.

Abstract: A fusogenic liposome composition for delivering a liposome-entrapped compound into the cytoplasm of a target cell is described. The liposomes have an outer surface coating of chemically releasable hydrophilic polymer chains which shield hydrophobic polymers on the liposome outer surface. Release of the hydrophilic polymer chains exposes the hydrophobic polymers for interaction with outer cell membranes of the target cells to promote fusion of the liposome with the target cells. Also disclosed is a method for using the composition to deliver a compound to target cells, and a method for selecting suitable hydrophobic polymers for use in the composition.

Abstract: A compound comprised of a hydrophilic polymer covalently yet reversibly linked to a amine-containing ligand through a dithiobenzyl linkage is described.

Abstract: A method of liposome-based therapy for a mammalian subject is disclosed. The method uses liposomes with outer surfaces that contain an affinity moiety effective to bind specifically to a biological surface at which the therapy is aimed, and a hydrophilic polymer coating effective to shield the affinity moiety from interaction with the target surface. The hydrophilic polymer coating is made up of polymer chains covalently linked to surface lipid components in the liposomes through releasable linkages. After a desired liposome biodistribution is achieved, a releasing agent is administered to cause cleaving of a substantial portion of the releasable linkages in the liposomes, to expose the affinity agent to the target surface.

Abstract: Conjugates of a hydrophobic moiety, such as a lipid, linked through a cleavable dithiobenzyl linkage to a therapeutic agent are described. The dithiobenzyl linkage is susceptible to cleavage by mild thiolysis, resulting in release of the therapeutic agent in its original form. The linkage is stable under nonreducing conditions. The conjugate can be incorporated into liposomes for administration in vivo and release of the therapeutic agent in response to endogeneous in vivo reducing conditions or in response to administration of an exogeneous reducing agent.

Abstract: A compound comprised of a hydrophilic polymer covalently yet reversibly linked to a amine-containing ligand through a dithiobenzyl linkage is described.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.

Abstract: Reagents for use in preparing a therapeutic liposome composition sensitized to a target cell are described. The reagents include a liposomal composition composed of pre-formed liposomes having an entrapped therapeutic agent and a plurality of targeting conjugates composed of a lipid, a hydrophilic polymer and a targeting ligand. The therapeutic, target-cell sensitized liposome composition is formed by incubating the liposomal composition with a selected conjugate.

Abstract: Reagents for use in preparing a therapeutic liposome composition sensitized to a target cell are described. The reagents include a liposomal composition composed of pre-formed liposomes having an entrapped therapeutic agent and a plurality of targeting conjugates composed of a lipid, a hydrophilic polymer and a targeting ligand. The therapeutic, target-cell sensitized liposome composition is formed by incubating the liposomal composition with a selected conjugate.

Abstract: A fusogenic liposome composition for delivering a liposome-entrapped compound into the cytoplasm of a target cell is described. The liposomes have an outer surface coating of chemically releasable hydrophilic polymer chains which shield hydrophobic polymers on the liposome outer surface. Release of the hydrophilic polymer chains exposes the hydrophobic polymers for interaction with outer cell membranes of the target cells to promote fusion of the liposome with the target cells. Also disclosed is a polymer-lipid conjugate for use in promoting fusion between target membranes. The conjugate is composed of a first segment composed of a hydrophilic polymer and a second hydrophobic polymer segment. The second segment is joined to the first segment by a bond effective to release the first segment in response to an existing or an induced physiologic condition. Attached to the second segment is a vesicle-forming lipid member.

Abstract: A liposome composition comprising small, surface-bound effector molecules is disclosed. The liposomes have a surface layer of hydrophilic polymer chains, for enhanced circulation time in the bloodstream. The effector molecules are attached to the distal ends of the polymer chains. In one embodiment, the effector is polymyxin B, for treatment of septic shock.