Self-assembling oxygen carrier compositions

Inventors

Pan, Dipanjan • Doctor, Allan • Spinella, Philip C.

Assignees

Kalocyte Inc

Abstract

Synthetic blood substitutes and methods for making them. A lipid-amphiphile blood-substitute precursor compound having a hydrophobic fatty acid/acyl moiety, a hydrophilic head moiety including a phosphate group, and a pH responsive moiety. The lipid-amphiphile precursor is configured to self-assemble from a solution mixture of phospholipid and cholesterol in the presence of hemoglobin and an allosteric effector into a hybrid-vesicle resulting from the combined self-assembly of both the amphiphilic lipid-oligomer and the lipids into an advanced vesicular structure containing a hemoglobin/allosteric effector payload.

Core Innovation

The invention relates to synthetic blood substitutes and methods for making them, specifically involving a lipid-amphiphile blood-substitute precursor compound. This compound includes a hydrophobic fatty acid/acyl moiety, a hydrophilic head moiety with a phosphate group, and a pH responsive moiety. The lipid-amphiphile precursor is designed to self-assemble from a solution mixture of phospholipid and cholesterol in the presence of hemoglobin and an allosteric effector into a hybrid-vesicle. This hybrid-vesicle results from the combined self-assembly of the amphiphilic lipid-oligomer and the lipids into an advanced vesicular structure containing a payload of hemoglobin and allosteric effector.

The synthetic blood substitute has a hybrid vesicle structure with a diameter of about 80 to 300 nm, comprising an outer bilayer of amphiphilic precursor, cholesterol, and PEG-phosphatidylethanolamine (PEG-PE). The payload includes hemoglobin, an allosteric effector, and optionally a reducing agent such as leucomethylene blue. This novel synthetic blood substitute provides a net negative zeta potential, excellent payload retention, and differential gas permeability. Unlike phospholipid bilayers in liposomal-based hemoglobin-based oxygen carriers (HBOCs), the invention allows a tunable membrane utilizing different oligomeric amine moieties in the precursor to vary membrane thickness, offering greater integrity due to counter-ionic hemoglobin-precursor interactions and pH responsiveness.

The pH responsive moiety of the lipid-amphiphile precursor is preferably a tertiary amine that can be finely tuned in pKa through hydrophobic modification of the amines, with increased hydrophobicity of alkyl substituents resulting in a linear decrease of pKa. This high abundance of positive charges in the self-assembled vesicular structure creates a unique charge density that drives the pH shuttle associated with hemoglobin’s oxygen uptake at higher pH and oxygen release at lower pH. The invention further specifies preferred compositions and ratios for phospholipid, cholesterol, allosteric effector, and hemoglobin components, and methods for synthesis, self-assembly, purification, lyophilization, and reconstitution.

Claims Coverage

The patent contains one independent claim defining a composition, which is supported by dependent claims detailing specific components and characteristics of the composition.

The claim coverage defines a composition comprising specific phospholipid, cholesterol, hemoglobin, lipid-amphiphile precursor with defined structural formula, and allosteric effectors, capable of self-assembling into a functional synthetic blood substitute vesicle with defined structural and functional properties including possible inclusion of reducing agents.

Stated Advantages

Documented Applications