The present invention relates to a biodegradable polymeric nanocapsule composition, adaptable for encapsulation of an agent of therapeutic interest for enhancing the in vivo circulation time of thereof and uses thereof.

Description of the Invention

SUMMARY OF THE INVENTION

The present invention provides a multi-purpose biodegradable nanocapsule having an improved in vivo circulation time. The biodegradable nanocapsules of the present invention are adaptable for encapsulating an agent of therapeutic interest and subsequently delivering the same in vivo. The biodegradable nanocapsules of the present invention may be employed to encapsulate a plurality of agents of therapeutic interest, including, without limitation, macromolecules, such as hemoglobin, enzymes, polypeptides, genes, and polymerized proteins and enzymes such as polyhemoglobin etc.

Preferably, the biodegradable nanocapsules of the present invention are adaptable for the controlled release of a variety of encapsulated therapeutic agents, including macromolecules, into in vivo circulation of a recipient upon administration thereto. The nanocapsule compositions of the present invention are further adapted to encapsulate therapeutically effective concentrations of an agent of therapeutic interest and deliver the same into in vivo circulation of a recipient.

In addition, the nanocapsules of the present invention are adaptable to provide controlled release of an encapsulated agent of therapeutic interest in vivo.

According to one embodiment of the present invention a method for preparing a biodegradable nanocapsule having a circulation half-time of at least 35 hours in vivo is provided. This nanocapsule has been shown to effectively deliver an exemplary macromolecule of interest into in vivo circulation with a controlled release rate providing a circulation half-time of the macromolecule of at least 14 hours.

A number of novel approaches were employed in accordance with the present invention to adapt the nanocapsule compositions to release encapsulated macromolecules at controlled rates in vivo. For example, a nanocapsule composition of the present invention was adapted to alter the release rate of encapsulated proteins from a half time of 2 hours in step-wise fashion to a release rate of a half time of at least 24 hours. Accordingly, the present invention provides a nanocapsule composition having an improved circulation time that can maintain an encapsulated agent of therapeutic interest in in vivo circulation for a prolonged period of time. As such, the nanocapsule of the present invention provides a versatile carrier for in vivo delivery and controlled release of a plurality of agents of therapeutic interest encapsulated therein.

One aim of the present invention is to provide a multi-purpose biodegradable nanocapsule having an improved in vivo circulation time.

Another aim of the present invention is to provide a biodegradable nanocapsule membrane having an effective circulation half-time of at least 35 hours.

Another aim of the present invention is to provide a biodegradable nanocapsule composition having an effective circulation half-time of at least 6 hours.

Another aim of the present invention is to provide a biodegradable nanocapsule composition having an effective circulation half-time of at least 14 hours.

Yet another aim of the present invention is to provide a biodegradable nanocapsule composition having an effective circulation half-time of at least 24 hours.

Another aim of the present invention is to provide a multi-purpose biodegradable nanocapsule that is selectively permeable to biological agents of therapeutic interest.

Another aim of the present invention is to provide a multi-purpose biodegradable nanocapsule composition adaptable for the controlled release or delivery of a variety of therapeutic agents of interest in vivo.

A further aim of the present invention is to provide a method for preparing a nanocapsule composition having an improved circulation time in vivo.

Yet a further aim of the present invention is to provide a method for delivering an agent of therapeutic interest in vivo.

In accordance with the present invention there is provided a biodegradable polymeric nanocapsule membrane composition adaptable for encapsulating an agent of therapeutic interest and enhancing in vivo circulation time thereof, said nanocapsule membrane composition comprising a copolymer of polylactic acid polymer and polyethylene glycol wherein said copolymer is soluble in acetone and insoluble in water.

In accordance with another aspect of the present invention there is provided a hemoglobin nanocapsule composition, said composition comprising a biodegradable polymeric nanocapsule membrane encapsulating a therapeutically effective concentration of a hemoglobin preparation; said nanocapsule membrane comprising a copolymer of polylactic acid polymer and polyethylene glycol; said copolymer being soluble in acetone and insoluble in water; wherein said nanocapsule composition is adaptable for enhancing the in vivo circulation time of said hemoglobin preparation.

The hemoglobin nanocapsule composition of the present invention may include other biological agents known to inhibit the production of methemoglobin. Furthermore, the hemoglobin nanocapsule composition of the present invention may be adapted to be selectively permeable to molecules present in in vivo circulation, that prevent the hemoglobin in the nanocapsules from becoming methemoglobin.

In accordance with another aspect of the present invention there is further provided a method for preparing a nanocapsule composition having an enhanced circulation time in vivo, said method comprising: (a) preparing a copolymer mixture of a polylactic acid polymer and polyethylene glycol (PLA-PEG); (b) heating said copolymer mixture; (c) adding an aqueous solution comprising an agent of therapeutic interest to said copolymer mixture; (d) precipitating said copolymer mixture from said aqueous solution; and (e) extracting the nanocapsule composition therefrom; wherein said composition comprises a biodegradable, polymeric nanocapsule membrane encapsulating said agent of therapeutic interest.

The method of the present invention for preparing a nanocapsule composition having enhanced circulation time in vivo, may further include incubating the agent of therapeutic interest with a cross-linker component prior to mixing the agent together with the PLA-PEG preparation. Alternatively, or in addition, the method for preparing a nanocapsule composition of the present invention may further include cross-linking at least some of the encapsulated agent of therapeutic interest to an internal surface of the nanocapsule, wherein a cross-linker component is added subsequent to the mixing of the PLA-PEG mixture with the agent of therapeutic interest.

A cross-linker component of the present invention may be glutaraldehyde. However, it is fully contemplated that alternatives to this cross-linker component, as known in the art, may be employed.

In accordance with still a further aspect of the present invention there is further still provided a delivery system for enhancing the circulation time of an agent of therapeutic interest in vivo, said system comprising: a biodegradable polymeric nanocapsule composition comprising of a copolymer membrane encapsulating said agent of therapeutic interest; wherein said copolymer membrane includes a copolymer of polylactic acid and polyethylene glycol and is soluble in acetone and insoluble in water; said copolymer membrane being adaptable to deliver the encapsulated agent of therapeutic interest into in vivo circulation at a controlled rate of release.

In accordance with the present invention there is still further provided a delivery system for providing the step-wise release of an agent of therapeutic interest in vivo, said system comprising: a plurality of biodegradable polymeric nanocapsule compositions each adapted to release an encapsulated agent of therapeutic interest at a different predetermined rate of release in vivo; wherein each of said plurality of biodegradable polymeric nanocapsules includes a copolymer membrane comprising a copolymer of polylactic acid and polyethylene glycol, said copolymer being soluble in acetone and insoluble in water.

Furthermore, the drug delivery system of the present invention may be further adapted to be selectively permeable to biological components present in in vivo circulation of the recipient. According to this embodiment of the present invention, the quality and integrity of the encapsulated agent of therapeutic interest may be maintained.

Alternatively, or in addition to, the drug delivery system of the present invention may also be adapted to encapsulate other biological components together with the agent of therapeutic interest. According to an alternative embodiment of the present invention, a drug delivery system having improved in vivo stability is provided whereby at least a portion of the encapsulated drug or agent of therapeutic interest is cross-linked to the internal surface of the nanocapsule.

In accordance with the present invention there is also provided a nanocapsule composition comprising a biodegradable polymeric nanocapsule membrane encapsulating a therapeutically effective concentration of a macromolecule; said nanocapsule membrane comprising a copolymer of polylactic acid polymer and polyethylene glycol; said copolymer being soluble in acetone and insoluble in water; wherein said nanocapsule composition is adaptable for enhancing the in vivo circulation time of said macromolecule.

For the purpose of the present invention the following terms are defined below.

The term "therapeutic agent" is intended to mean any agent having a therapeutic potential when administered in vivo, including, without limitation, macromolecules such as hemoglobin, proteins, enzymes, RNA, DNA, and genes.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, improved biodegradable nanocapsules having an increased in vivo circulation time are provided. Preferably, the biodegradable nanocapsules of the present invention are polymeric nanocapsules. The biodegradable nanocapsules of the present invention are adaptable to encapsulate agents of therapeutic interest and deliver the same into in vivo circulation upon administration to a recipient. Furthermore, the nanocapsule compositions of the present invention are adaptable for prolonging the in vivo circulation time of the encapsulated agent contained therein. For practical therapeutic applications, such as blood substitutes, a nanocapsule composition having an in vivo circulation half-time of at least 14 hours, is preferred. As a result, extensive research and development was carried out in connection with the present invention to devise a nanocapsule composition having an increased circulation time in vivo. A novel approach is herein demonstrated, without limitation, in connection with hemoglobin to provide a hemoglobin nanocapsule composition having an improved circulation time and/or controlled rate of release, in vivo.

The present invention provides a novel nanocapsule composition adaptable to encapsulate and effectively deliver agents of therapeutic interest. For example, together with hemoglobin, the nanocapsule composition may be employed to provide a blood substitute. By increasing the in vivo circulation time of an encapsulated agent, a nanocapsule composition of the present invention can significantly increase the duration of functioning of the encapsulated agent in vivo, thereby enhancing the therapeutic effect of the composition. In addition, the nanocapsule composition of the present invention can effectively deliver a given dosage of a therapeutic agent in a controlled manner, thus improving the effectiveness of the dosage while reducing the overall administration required.

According to a preferred aspect of the present invention, a therapeutically effective amount of hemoglobin is encapsulated in a nanocapsule composition and adapted for delivery into the in vivo circulation of a recipient, administered therewith. The encapsulated hemoglobin carries out its function as a blood substitute in transporting oxygen in vivo. Furthermore, when the encapsulated hemoglobin is released from the nanocapsule membrane, it continues to function in the transport of oxygen, thus serving to enhance the total length of function of ht encapsulated hemoglobin in vivo.

The present invention further provides a novel delivery system for the controlled release of a therapeutic agent into in vivo circulation. The ability to modify or adapt the nanocapsule compositions of the present invention to provide a controlled rate of release of the encapsulated agent serves to further provide a novel therapeutic delivery system. Furthermore, a variety of nanocapsule compositions of the present invention may be employed together to provide an effective step-wise therapeutic delivery system. According to this aspect of the present invention, each nanocapsule composition is adapted to deliver an encapsulated agent of therapeutic interest at a predetermined rate of release. When a plurality of these nanocapsule compositions, each having a predetermined rate of release, are administered simultaneously, the encapsulated agent of therapeutic interest is released in vivo in a step-wise fashion.

According to one embodiment of the present invention biodegradable polymeric nanocapsules are provided having an in vivo circulation half time of at least 35 hours, as discussed below. The nanocapsule compositions of the presents invention are adapted to encapsulate a variety of different therapeutic agents, including macromolecules such as hemoglobin, enzymes, RNA, DNA, and other proteins including very large polymerized hemoglobin and enzymes and deliver the same in vivo at a controlled rate of release thereby improving the in vivo circulation time of the encapsulated agent. The nanocapsules compositions of the present invention are further adapted to serve as carriers for therapeutically effective concentrations of an agent of therapeutic interest, providing the controlled in vivo release thereof. According to the present invention, an agent of therapeutic interest may be, without limitation, a macromolecule.

According to one embodiment of the present invention, while the nanocapsules maintain their circulation half-time of 35 hours, we were able to vary the release rate of the enclosed proteins from a release rate of a half time of 2 hours in step-wise fashion to a release rate of a half-time of at least 24 hours in rats. As discussed further hereinbelow, it is expected that the in vivo circulation half-time of the nanocapsule compositions of the present invention would be even greater in humans. Thus, according to the present invention a versatile delivery system for the controlled in vivo release of a variety of therapeutic agents is provided.

An agent of therapeutic interest, for example, may be encapsulated by a nanocapsule composition of the present invention and introduced into in vivo circulation of a recipient by any one of a variety of methods of nanocapsule delivery. For example, a nanocapsule composition of the present invention may be administered by, without limitation, intravenous, intramuscular, intraperitoneal, or subcutaneous delivery, orally or by topical administration. The nanocapsule composition can be modified to provide a controlled rate of release of the encapsulated agent from the nanocapsule carrier. As a result, the agent of interest may be introduced into in vivo circulation at a controlled rate of release for achieving a desired therapeutic effect. The rate of release of a nanocapsule composition of the present invention can be adapted to achieve a desired rate of release of an encapsulated agent of therapeutic interest in a variety of ways, as exemplified herein below.

As exemplified in accordance with the present invention, it is possible to encapsulate hemoglobin within a nanocapsule carrier to obtain a therapeutically effective circulation time thereof, in vivo. Thus, it is fully contemplated that the nanocapsule composition of the present invention is adaptable to encapsulate virtually any agent of therapeutic interest including macromolecules, in a therapeutically effective concentration, for the purpose of providing a controlled drug delivery system.

In accordance with the present invention, a method for the preparation of an nanocapsule composition may include, without limitation, altering the permeability of a nanocapsule membrane; decreasing the rate of degradability of the nanocapsule membrane; or increasing the molecular size of the enclosed agent of therapeutic interest to adapted the nanocapsule composition to maintain a desired circulation half-time and/or controlled rate of release of the encapsulated agent of therapeutic interest is provided.
 

Claim 1 of 64 Claims

1. A biodegradable polymeric nanocapsule composition adaptable for use as an artificial red blood cell, said nanocapsule encapsulating an agent of therapeutic interest; wherein said agent of therapeutic interest is cross-linked to the interior surface of the nanocapsule and enhancing in vivo circulation time thereof, said nanocapsule having a bilayer membrane defining an interior surface and an exterior surface and comprising a diblock copolymer consisting of a polylactic acid polymer block and a polyethylene glycol polymer block, wherein said nanocapsule membrane further comprises a lipid component, wherein said diblock copolymer is soluble in acetone and insoluble in water and wherein said polyethylene glycol is present on both the interior surface and the exterior surface of the membrane thereby defining a hydrophilic interior wherein said cross-linked agent of therapeutic interest is present or is entrapped.

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