WO2009053937A2

WO2009053937A2 - Nano-lipid-based carriers for targeted delivery of viral vectors and process for its production

Info

Publication number: WO2009053937A2
Application number: PCT/IB2008/054399
Authority: WO
Inventors: Mauro Giacca; Ana Cristina Da Silva Filipe; Sérgio Paulo DE MAGALHÃES SIMÕES; Maria da Conceição MONTEIRO PEDROSO DE LIMA
Original assignee: Universidade De Coimbra
Priority date: 2007-10-25
Filing date: 2008-10-24
Publication date: 2009-04-30
Also published as: PT103865A; WO2009053937A3

Abstract

The present invention is related with lipidic nanovesicles which carry genetic material, particularly in the form of recombinant viruses (viral vectors), composed by neutral lipids and/or neutral and negative lipids, a viral vector, and a ligand responsible for the targeting of the nanoparticles to the target cells that will be transduced by the carried viral vectors, in order to guarantee the specific delivery of genes to target cells, as well as their process of production. The process of production of the nanoparticles includes essentially three main stages: 1) association of the viral vectors to the lipidic nanonvesicles; 2) conjugation of a hydrophilic polymer to the surface of the nanovesicles; 3) conjugation of a ligand to the distal end of the hydrophilic polymer. Following this method of preparation, the invention presents adequate characteristics for the delivery of genes to a specific group of cells after administration, namely intravenous administration, independently of the normal tropism of the vector associated to the nanovesicles. This approach allows the treatment of pathologies involving cells not accessible by a local application, and thus minimize the secondary effects that may emerge as a consequence of the unspecific interaction of the viral vectors with other cells, as well as the innate immune response triggered against these vectors. Accordingly, the invention is to be used in the pharmaceutical field, namely for the treatment of neoplastic, inflammatory, cardiovascular and neurodegenerative disease, among others, namely involging gene delivery mediated by viral vectors.

Description

DESCRIPTION

^ΛNano-lipid-based carriers for targeted delivery of viral vectors and process for its production"

Technical Field of the invention

The present invention is related to the pharmaceutical biotechnology, namely within the gene therapy field. The invention relates to methods of preparation of nanoparticles, which are lipid-based carriers of genetic material, with application for the specific and selective delivery of genes to target cells, involved in pathologies. More specifically, it consists of lipid-composed nanoparticles, carrying adenoviral vectors, directed to the target cells and aiming the treatment of pathologies. These nanocarriers are used in a pharmaceutical composition characterised for containing a pharmaceutically acceptable vehicle and can include other compounds, as lisosomotropic agents, preservatives, colloidal stabilizer, peptides with fusogenic properties and nuclear localization signals.

Background of the invention

Gene therapy is a promising therapeutic strategy for the treatment of a variety of pathologies, including hereditary disabilities, as cystic fibrosis, or acquired disabilities, such as cancer or neurodegenerative and cardiovascular diseases. The great number of clinical trials going on, involving gene therapy protocols, emphasises their interest. In this context the effective and specific delivery of genes to target cells are considered critical aspects for the success of the therapeutic approaches mentioned. In this way, the selection of an adequate carrying system, for a safe and effective transfer of the gene, is extremely important.

The evoked interest by the gene therapy area led to the development of several strategies for the delivery of genes. Generally, the vectors used for that purpose may be classified as viral or non-viral vectors. Within the second group, the systems composed of cationic liposomes and plasmid DNA (lipoplexes) are the most representative. Although relatively safe, the transfection effectiveness that characterises these systems is low or inexistent in several cellular types, with toxicity being observed for high doses of cationic liposomes. In addition to the mentioned problems, lipoplexes present inadequate characteristics for intravenous use. The positive charge of the cationic lipids promotes not only the non-specific interaction with negative charge macromolecules existing in the blood system (e.g. Proteins), leading to the destabilisation of the mentioned lipoplexes, but also nonspecific interactions with the blood cells¹ and/or vascular endothelium. This characteristic results not only in nonproductive transduction, but also in secondary effects caused by the transgene expression in other cells that are not the target cells. These characteristics represent restrictions to the success of its applications and for that reason these systems are still far from constituting viable alternatives in gene therapy. The document US6133243 reveals the use of plasmid DNA associated to cationic liposomes for treatment of diseases and is related to cancer treatment methods by administration of an adenoviral DNA/liposome complex to animals carrying tumours. In opposition, the nanoparticles referred in this invention do not present in their composition cationic lipids, usually used to facilitate the interaction with the cells, and besides are associated to viral vectors and not directly to the virus DNA, as written in the document US6133243. In addition, the nanoparticles described within this patent present a targeting system (composed of a hydrophilic polymer and a ligand) , which allows the interaction with the cells in a specific way, instead of the non-specific interaction mediated by the cationic liposomes.

The document WO1999025320 reveals the use of viral DNA complexed with cationic liposomes for treatment of diseases, where the developed system facilitates the transfer of the genes. In the described system the DNA is not preferably contained in a viral particle. The main innovative technical aspects of the patent in evaluation are similar to those mentioned for the document US6133243.

The documents "Crystal et al., 1994"², "Bellon et al., 1991"³ _f "Gahery-Segard et al., 1991'"", "Tursz et al., 1996"⁵ , "Welsh et al., 1994"^6', "Zuckerman et al., 1999"⁷, "Channon et al., 1996"⁸ , "Whitlock et al., 2004"⁹ and "Lamfers et al., 2001"¹⁰ reveal the use of adenoviral vectors for the transfer of genes and consequent transduction in a great variety of cells. For this fact, the use of these vectors has shown to be of great interest. In the mentioned documents, adenoviral vectors are used without any type of modification, while the nanoparticles we presented are based on the association of the mentioned vectors with lipid nanovesicles and posterior targeting.

Other advantages associated to the adenoviral vectors include the possibility of being produced with very high titles, of allowing the cloning of elevated size DNA fragments, as well as the possibility to regulate their expression¹¹.

Nowadays, there are two main limitations associated to these vectors, when their intravenous administration is considered, aiming the delivery of targeted genes to a certain cellular type. One of those limitations is the tropism for other cells, which is in part due to the dispersion of the expression of cellular receptors used by these vectors, for recognition and entry in the cells. This characteristic results not only in non-productive transduction, but also in secondary effects caused by the transgene expression in other cells that are not the target cells. In effect, after administration in a rat model, more than 90% of the vectors are located in the liver. Kupffer cells, the liver predominant macrophages, recognise and internalise adenoviral vectors, which leads to their rapid elimination. This aspect is related to the other limitation of the adenoviral vectors: the immunogenicity ("Brody et al., 1994"¹², "Jooss et al., 1998"^13', "Kaplan et al., 1996"¹⁴, "Schagen et al., 200V¹⁵, "Christ et al., 1991"¹⁶ and "Bessis et al., 2004"¹⁷). Thus, the administration of high doses of these vectors induces toxicity as consequence of the innate immune response activation, which involves the induction of cytokines such as IL6 and IL8, as result of the direct exposure of the viral capsid protein to monocytes and macrophage, or by exposure of viral antigens expressed at the infected cells surface.

On the other hand, the adaptive immune ^■ response is responsible for the vector' s neutralisation, before it reaches the target cells ("Gahery-Segard et al. , 1997"¹⁸, "Yang et al., 1995"¹⁹, "Wohlfart, 1988"²⁰ and "Toogood et al., 1992"²¹) . Even if the antibodies are absent in the first administration ("Bessis et al., 2004"¹⁷), they can quickly develop after viral vectors exposure, preventing subsequent administrations. In this context, it is important to mention that almost all the human population had contact with adenoviruses and therefore possess humoral immunity against these vectors²².

One of the strategies developed by other researchers to circumvent some of the mentioned problems is based on the elimination of the previous mentioned interactions, by association of the viral vectors to cationic liposomes.

The documents "Steel JC et al., 2005"²², "Mizuno M, Yoshida Jj., 1998"²³, "Yotnda P et al., 2002"²⁴, "Mizuno M et al., 2002"²⁵, "Steel JC et al., 2007"²⁶, "Steel JC et al . , 2004"²⁷ and "Lee et al., 2000"²⁸ reveal the association of adenoviral vectors to cationic liposomes, showing that the cationic liposomes have the ability to promote adenoviral vectors mediated transduction and to protect them from preexisting antibodies. The nanoparticles described in this application do not present in their composition cationic lipids, usually used to facilitate the electrostatic interaction with the cells (although in a non specific way) . In addition, the nanoparticles described within this patent present a targeting system (composed of a hydrophilic polymer and a ligand) , which allows the interaction with the cells in a specific way, instead of the non-specific interaction mediated by the cationic liposomes. Moreover, the process of preparation of the nanoparticles includes a step of separation of viral vectors not associated to liposomes, unlike the presented systems.

The document US6110490 reveals the use of multi or bi-layer membranes, containing at least one lipopoliamine, and adenovirus particles.

The main differences regarding the patent US6110490 and the nanoparticles we developed are similar to the ones mentioned in the previous paragraph, except the targeting. However, in the target example mentioned by the authors of that patent, the ligand is directly associated to the liposome membrane, while in the patent in evaluation we present a targeting system that includes a hydrophilic polymer, and where the ligand is covalently attached to the polymer, allowing the distance from the nano-vesicle surface, with unquestionable advantages in terms of interaction specificity with the target cells, while increasing circulation times of the nanoparticles.

However, despite the mentioned advantages, in what concerns the use of mixtures of cationic liposomes and viruses, the previously mentioned disadvantages associated to cationic systems limit the intravenous administration of the mentioned formulations.

The present invention, being undertaken with neutral and/or neutral and negative liposomes, and containing a system to increase the circulation time as well as active targeting for target cells, allows overcoming the existing problems in the state of the art.

Thus, in this invention the liposome composition is different from the previous ones, since, in what concerns lipid composition, liposomes were prepared using neutral and/or neutral and negative lipids, unlike the usual formulations that contain in their composition cationic lipids and cholesterol.

In addition, the preparation methods of the compositions of this invention also differ from the ones revealed in the state of the technique, since the lipid film was prepared with non-cationic lipids and was directly hydrated with the solution containing the adenoviral vectors, unlike the majority of the presented systems, where the liposomes are prepared previously to their complexion with the viral particles or with the viral DNA. The process of extrusion of nanovesicles containing adenoviral vectors, used for reduction and homogenisation of particle size is opposed to currently used processes, where the extrusion, when performed, is made before the association of the adenoviral vectors with liposomes. In the previously mentioned systems, viral vectors not associated to the liposomes were not removed from the formulation. According to our knowledge, the purification process consisting of an ultracentrifugation in caesium chloride gradient is presented for the first time for removal of free viral vectors from liposomes associated to viral vectors. In any of the previously mentioned system it is described the preparation of the targeted nanoparticles through the covalent combination of ligands, or are described the coupling conditions of the polymer and of the ligand to the nanoparticles surface. Within this invention, the coupling conditions were optimised accordingly to the biologic activity and viability of the viral vector.

In addition, the fact that the method of preparations of the compositions includes a step that allows separating (purifying) liposomes from free virus not associated with them, enables lowering the non-specific expression and the inflammatory response that would be mediated by these free vectors .

General description of the invention

The present invention is related to compositions for gene delivery to target cells, as well as their obtaining process.

1. Characteristics of the nanocarriers compositions

The nanocarriers include an association of adenoviral vectors and lipid nanovesicles, which include in their composition neutral lipids, or neutral and negative lipids. The selection of this type of lipids aims at minimising the non-specific interactions of the nano-carriers with the blood components (proteins and cells) and/or vascular endothelial cells or with other organs' cells.

The choice of the lipids DOPE and CHOL as adjuvant lipids is due to the fusogenic properties recognized to DOPE, and to the lipid vesicle stabilisation promoted by CHOL, in the presence of serum. The use of EPC also contributes for the lipid nanovesicles stabilisation and allows lowering the partial amount of the previously mentioned lipids, which may present a tendency to interact with complement molecules, in vivo. The PI molecule was used whenever it was necessary to confer negative charge to the liposomes.

The underlying reasons not to use cationic lipids are related with the aim of decreasing interactions between these and the blood proteins or with the cells' negative surface, therefore enabling the interaction and accumulation in target cells, lowering the risk of secondary effects after intravenous administration.

The nanocarriers compositions, besides containing the carrier nanoparticles, also contain a pharmaceutically acceptable vehicle and can also contain other compounds that facilitate their therapeutic and/or carrier function. For instance, they can contain compounds with fusogenic ability included in the membranes or in the aqueous compartment of the nanoparticles, or other membrane destabilisers (e.g. proteins or peptides), that promote or facilitate the release of the pharmaceutical vehicle from the endosome and its delivery into the intracellular space. It can also contain nuclear location signals that facilitate entry of DNA in the cell nucleus, as well as compounds that inhibit the viral vectors degradation by the proteosome. It can also contain protein compounds, or corresponding genes, that inhibit the exposure of portions of viral proteins or of the transgene at the cellular surface, responsible for the elimination of those cells by the immune system.

The adenoviral vectors enclosed in this invention can be normally used and prepared with current genetic engineer techniques, including the different serotypes, different molecular construction possibilities and different morphologic and structural variants. For instance, the adenoviral vector with deletion of the El gene is produced in cells and then purified in HEPES/sucrose buffer pH 8.0 according to the conventional method of the caesium chloride double gradient. The produced vectors correspond to the serotypes 2 and 5, but can correspond to the other serotypes, and include the therapeutic protein genes under the control of adequate promoters, for instance the cytomegalovirus (CMV) promoter. The adenoviral vector can also be genetically manipulated, in order to lower its immunogenicity and to module its in vivo replication ability.

The nanovesicles surface is modified through the insertion of hydrophilic polymer molecules, such as (poly (ethylene glycol) (PEG) . The advantages of the inclusion of the hydrophilic polymer into the surface of the nano-particle include: (i) increase of the nanoparticles stability; (ii) higher blood circulation times after intravenous administration (pharmacokinetic properties) ; and (iii) to serve as anchor to the covalent coupling of ligands. The hydrophilic polymer used (PEG) allows the coupling of the ligand by covalent conjugation, playing thus acting as bridge between the liposome and the ligand. The fact that the mentioned bond is covalent allows minimising the destabilisation risk associated to the more commonly used liposomes, where the association of ligands to liposomes occurs by electrostatic interactions. In addition, the space between the ligand and the liposome surface, resulting from the PEG molecule, allows preventing the steric hindrance of the liposome surface, facilitating the interaction between the ligand and respective receptor.

The ligands can be a peptide, a protein, a monoclonal antibody (or any other variant such as an antibody fragment) , an aptamer, or any other molecule or construction that results in a specific interaction with an existing receptor at the target cells surface. The selected ligands must be characterised by binding to existing molecules in the target cells in a selective way and with high affinity, and the binding must be followed by internalisation, so that the delivery of the pharmaceutical vehicle to the target cells is maximised. For example, the ligand transferrin is a natural ligand and as such does not stimulate the immune system. The antibody against E- selectin presents a high affinity and selectivity, allowing the efficient DNA delivery to target cells. As selectivity it must be understood the ability to recognise the target cells in the presence of other cells and other compounds, namely proteins, and as affinity it must be understood the strength of the interaction established between the ligands coupled to the nanoparticle and the respective molecule expressed at the surface of the target cell.

The invention presented here also allows to mask the adenoviral vectors, minimising the acute immune response triggered by this type of biologic agents, allowing also the protection against the neutralisation mediated by pre- existent antibodies. As a whole, these characteristics make the nanoparticles, and the compositions, adequate for intravenous administration.

Simultaneously, the possibility of modulating the size and the surface charge of the liposomes allows controlling their physical stability, as well as their pharmacokinetics, allowing the preparation of more adequate compositions for intravenous administration.

On the other hand, the sub-micrometric size of the produced particles allows the blood circulation without the risk of obstruction of small size capillary and for longer periods of time.

Additionally, size changes allow modulating the cellular internalization pathway²⁹'³⁰. For that reason, there was a concern in producing low size particles. The cellular association results obtained by confocal microscopy reveal that the fluorescence of the cells incubated targeted liposomes with 400 nm diameter is mainly concentrated at the cellular membrane, without significant cellular internalization of the nanoparticles.

Since this association profile may compromise the effectiveness of gene delivery to the target cells, it was decided to use liposomes prepared by extrusion through membranes with 200 nm pore diameter. The respective images of confocal microscopy show that the fluorescence detected in this case is due not only to the binding of the immunoliposomes to the cytoplasmic membrane, but also to the internalization by the endothelial cells, as opposite to what was observed with the iramunoliposomes of 400 ran.

The results obtained by the PCS technique indicate that the size of the immunoliposomes extruded through membranes with 200 nm pore diameter is of 185.2 nm (V- 9.4). These liposomes present the mentioned average size one month after their preparation, which is an indicator of the physical stability of the nanoparticles .

Overall, the use of neutral or of negatively charged liposomes allows preventing the non-specific interactions with serum negative proteins and cellular membranes, which associated to the sub-micrometric size and to the presence of a hydrophilic polymer at the surface of the particles confers biologic stability and long circulation times. In addition, the conjugation of the ligand allows the targeted delivery of the recombinant adenovirus to the target cells.

2. Process for obtaining the nanocarriers compositions

2.1 - Association of viral vectors to neutral and negative liposomes

For obtaining the mentioned compositions, according to this invention, viral origin material was prepared and encapsulated in lipid nanovesicles, through a process that involves the hydration of a lipid film.

During the lipid film hydration process, not all the adenoviral vectors get associated to the liposomes. In this sense, it is important that these viruses are removed to prevent the non-specific transduction mediated by these agents .

Thus, after hydration of the lipid film and extrusion of the resulting liposomes, the rAd (recombinant adenovirus) not associated to the liposomes were removed by ultracentrifugation in caesium chloride gradient.

2.1.1 - Characterisation

The caesium chloride method, originally developed to purify the adenovirus from cell debris used in their production, was adapted for purification of the liposomes associated to the rAd.

The ultracentrifugation of a saline solution containing free rAd (not associated to liposomes) originated 3.2% (V- 4.1) of infectious units in the HBS phase (phase from where liposomes are collected after ultracentrifugation) , while 94.5 % (V- 0.8) of the total number of infectious units existent in the gradient are in the interface between the caesium chloride solutions with densities of 1.41 and 1.27. This result shows that the mentioned method is adequate for removing non-encapsulated adenoviral vectors from a mixture containing free and liposome-encapsulated vectors.

The efficiency of encapsulation was determined by quantitative PCR in liposomes containing type 2 adenovirus, encoding the β-galactosidase enzyme, under the control of the cytomegalovirus promoter (Ad₂PCMVLaCZ) . Additionally it is possible to recover the viral particles not associated to the liposomes, by dialysis, and reuse them in the preparation of new nanoparticles .

2.2 - Insertion of a hydrophilic polymer at the surface of the nanovesicles

On the surface of the liposomes there is a mono or bi- functional PEG molecule. The use of bi-functional PEG molecules implies the presence of primary amines or other reactive groups in the composition of liposomes, In this case the coupling of the PEG molecule was performed to the amine group of the DOPE lipid.

The coupling of the bi-functional PEG molecules was performed in the presence of HEPES buffer at pH 7.4 , in the presence of EDTA, since these conditions facilitate the coupling' s reaction, allowing protecting the other reactive group.

The excess of PEG, not coupled to the liposomes, was, in this case, removed by molecular exclusion chromatography, using HEPES buffer at pH 7.2, in the presence of EDTA, since these conditions favour, a posteriori, the conjugation of the ligand to the respective reactive group.

2.3 - Coupling of a ligand to the distal end of the hydrophilic polymer

The ligand is conjugated to the distal end of the PEG molecule, corresponding to the reactive terminal, both in the case of the bi-functional PEG molecules and of the mono-functional ones. Whenever necessary, the ligand is previously activated in order to acquire reactive groups, which react with the reactive terminal of the PEG molecule.

Ligand activation, whenever necessary, may be performed with several compounds, namely with 2-iminothiolane . In these conditions it is necessary to determine the ideal ratio of 2-iminothiolane/ligand, to obtain the ideal quantity of thiol groups (SH) associated to the ligand. Too many thiol groups in the ligand can promote the conjugation of the same molecule to different PEG molecule reactive groups, limiting the interaction with the target cells. The insufficient amount of thol groups in the ligand can compromise their conjugation.

After coupling the ligand, the reactive groups still available are deactivated with the adequate reagents, and the excess of free ligand is then removed by molecular exclusion chromatography.

3 - Demonstration of the effectiveness of the nanocarriers obtained through the described process

The developed nanoparticles can efficiently target cells and have the ability to deliver the adenoviral vectors to the intracellular space, inducing transgene expression only in the target cells, while exhibiting favourable properties for intravenous administration.

The profile of cellular association, obtained by flow cytometry, with 200 nm liposomes containing adenoviral vectors, demonstrates that when the targeted liposomes are incubated with activated endothelial cells, 78% of the cells present a higher fluorescence than the negative controls. These controls correspond to the incubation of non-targeted liposomes (that is, liposomes that were not coupled to the ligand) with activated and resting cells (that is, cells that do not express the surface molecule for which the liposomes were targeted to) , as well as the incubation of targeted liposomes with resting cells. The specificity of the cellular interaction was confirmed by confocal microscopy.

Activated cells refers to cells that were incubated with an inflammatory mediator, for instance TNF-α, expressing and presenting now new molecules on the cellular surface, which are not detected in resting cells (not activated) . This activation process mimics what happens in certain pathologies, where local accumulation of inflammatory mediators, leads to the expression or over-expression of certain molecules such as E-selectin. These molecules thus constitute excellent targets to targeted nanoparticles .

After demonstrating the efficiency of liposome-cell association association, the efficacy of the targeted liposomes to mediate transduction was demonstrated by a dose/response curve, as assessed by flow cytometry. The developed liposomes specifically transduce activated endothelial cells. The incubation of cells in the resting state with targeted liposomes resulted in negligible levels of transduction. The same is valid for non-targeted liposomes incubated both with resting and activated endothelial cells. Increasing the concentration of targeted liposomes incubated with the activated cells results in an increase of the number of transduced cells, until reaching a plateau of 34.25% of transduced cells, for a lipid concentration of 32 μM.

These results are consistent with the cellular association levels previously described and allow concluding that the transduction levels observed in activated endothelial cells, after treatment with targeted liposomes, are dependent on the initial dose of liposomes. The observation of endothelial cells by confocal microscopy confirmed the specificity of the gene delivery and consequent transduction of activated endothelial cells.

It must be highlighted that the transduction studies were performed by incubating the immunoliposomes with the cells for a period of 12 hours, in the presence of non- deactivated fetal bovine serum. The specificity of transduction observed constitutes an indication of the stability of the nanoparticles under experimental conditions that resemble the physiological ones.

In an attempt to gain insights into the mechanisms underlying the delivery of genes mediated by the developed nanoparticles, the activated endothelial cells were incubated with immunoliposomes for 1 hour, at 37 or at 4°C. The results clearly show that at 4°C targeted liposomes are localized at the surface of the cells without undergoing internalisation, as opposed to what is observed when the incubation is made at 37°C. In these conditions it is possible to observe liposomes bound to the cellular surface, but also a significant amount of cytoplasmatic fluorescence, a clear indication of the internalization of the nanoparticles by the cells. These results show that the internalisation of the targeted liposomes is energy dependent, suggesting the involvement of the endocytic pathway.

In addition, using similar conditions, activated endothelial cells were incubated with excess of free ligand (20 μg/ml) . The obtained results show that the excess of ligand was sufficient to abolish the transduction mediated by the immunoliposomes, clearly indicating that the biding and consequent internalisation of the targeted liposomes containing adenoviral vectors is mediated by the ligand coupled to the distal end of the PEG molecule. Overall, these results translate the advantage of the strategy developed in this work: the targeting of adenoviral vectors specifically to activated endothelial cells, through an internalisation pathway which is independent of the natural receptors normally used by these viral vectors.

The developed nanoparticles demonstrated to be effective in the recognition and delivery of recombinant adenovirus to activated endothelial cells, with consequent expression of the carried transgene, while presenting adequate characteristics for systemic administration. These facts illustrate the high potential of the developed nannoparticles for application in gene therapy of pathologies involving endothelial cells.

In addition, their preparation is flexible in several aspects. They can be prepared with neutral lipids, or neutral and negative lipids of diverse nature. The developed nanoparticles also exhibit flexibility regarding the type of viral vector than can be incorporated, including also the inclusion of viral chimeras, resulting from the conjugation of advantageous characteristics from two or more viral vectors in only one viral vector.

4- Advantages over other analogous products and processes and applications

The compositions, according to the present invention, allow allying the advantages of the viral vectors to the targeted liposomes, that is, conjugating the high effectiveness of the transduction characteristic of the adenoviral vectors with the ability of the targeted liposomes to confer protection, mitigate immunogenicity and specifically bind to target cells, while simultaneously exhibit pharmacokinetic properties adequate to an intravenous administration.

The subject of this invention is based on a novel gene delivery system in which the characteristics of the nanovesicles are used in order to overcome the disadvantages associated to the adenoviral vectors. In this regard, it is possible not only to mask the viral vectors, preventing severe immune responses induced by the viral capsid proteins, as well as to prevent the neutralizing effect of preexistent antibodies, that potentially exist in the patients to be treated. The system is versatile towards the introduced viral vector. The developed lipid vesicles exhibit characteristics that minimize the extent of interaction with serum proteins and with non-target cells, while simultaneously, present high circulation times. These properties result from the presence of hydrophilic polymers at the surface of nanovesicles, and from the manipulation of their size and charge. Altogether, the mentioned aspects make the nanoparticles, and all the compositions based on their use, adequate for intravenous administration. Additionally, the conferred targeting properties enable the recognition of the target cells (for example tumor cells or activated endothelial cells, thus leading to cell specific gene delivery and expression. At the same time, the efficiency of expression of the transgene, mediated by the vesicles, is largely improved by the use of the adenoviral vectors, recognized by their efficient transduction of several cellular types.

Therefore, specific gene delivery can be achieved whenever there is an over expression or de novo expression of a cell surface receptor in target cells. Thus, by coupling a ligand to the surface of the liposomes it is possible to promote specific binding of the nanoparticles to the surface of the target cells, the consequent internalization and delivery of the carried genetic material into the cytoplasm.

In addition, the current invention allows the concomitant delivery of genes to activated endothelial cells of the tumor vasculature as well as to tumor cells, depending on the size of the liposomes and on the tropism of the ligand attached to the surface of the nanovesicles, using ligands with affinity for the E-selectine, or for the transferrin receptor, respectively, or the two ligands simultaneously, enabling a wider and efficient therapeutical approach against the tumor.

Accordingly, this invention encompasses important advantages for the treatment of ischemia by promoting angiogenesis, using specific ligands to E-selectine or other surface receptors expressed specifically in activated endothelial cells.

Additionally, it can mediate intravenous delivery of genes to activated endothelial cells in inflammatory situations, such as rheumatoid arthritis, therefore leading to inhibition of the inflammatory process.

Figure Description:

Figure 1: Schematic representation of the targeted nanoparticles containing recombinant Adenovirus (rAd) - rAd (1) encapsulated in liposomes (2), which surface is modified by a hydrophilic polymer (poly (ethylene glycol) or PEG) (4) to which distal end a ligand is attached (3) .

Figure 2: Schematic representation of the interaction between the liposomes that contain adenoviral vectors with the target cells. The nanoparticle presented in Figure 1 interacts with the target cell (5) , which is recognized due to the affinity between the ligand present in the liposomes and the molecules expressed at the cell surface (represented by red circles)

Figure 3: Schematic representation of the cellular internalization of the targeted liposomes. Following recognition and binding of the nanoparticle to specific cell surface receptors, they are internalized through an endocytotic process and delivered into the cytoplasm (6) . After its entrance into the nucleus (7), the viruses undergo decapsidation in order to release the viral DNA, allowing their processing.

Detailed description of the invention

1. Preparation of the nanoparticles

The lipid film, made of Phosphatidylinositol (Liver, Bovine-Sodium Salt) (PI)/ Phosphatidylcholine (Egg, Chicken) (EPC); dioleoylphosphatidylethanolamine (DOPE)/ cholesterol (CHOL) in the molar ratio of 3/2/3/2, or by EPC/DOPE/CHOL in the molar ratio of 5/3/2, was prepared by evaporation of the chlorophorm, using a nitrogen flow. Then, the lipid film was hydrated with an aqueous solution containing the adenoviral vectors, in order to get a total lipid concentration of 4.5 mM and a concentration of adenoviral vectors of 3.5 xlO¹¹ infectious units/ml.

The multilamellar vesicles obtained were extruded through polycarbonate filters with diameters of 200 nm, using a Liposofast device (Avestin, Toronto, Canada) . Non-encapsulated recombinant adenovirus were removed by a caesium chloride gradient.

The caesium chloride gradient was prepared with two solutions with different densities (1.47 and 1.27) . First, 1.5 ml of the solution with density of 1.47 was pipeted, followed by 2.5 ml of the solution with density 1.27, and on top, 0.5 ml of liposomes.

The caesium chloride gradient was ultracentrifugated at 155 000 g during 2 hours, at 18° C.

In the particular case of the evaluation of the efficiency of this gradient to remove non- encapsulated vectors, the last layer consisted of a solution of HBS containing recombinant adenovirus (5 x 10⁷ infection units of Ad₅pCMVGFP) . The determination of the number of infectious units was made in HUVEC cells after dialysis of the different layers using a proper membrane.

After removal of non-encapsulated recombinant adenovirus, the total lipid was determined, based on the concentration of cholesterol, determined by the infinity cholesterol reagent .

The heterofunctional PEG molecule was incubated with liposomes in a ratio of 5 mg per mg of cholesterol, for 2 hours at 4°C, under mild mixing and nitrogen atmosphere, in order for the N-hydroxysuccinimide ester (NHS) to react with the primary amines of the DOPE molecules.

Non-coupled NHS-PEG-MaI molecules were removed by size exclusion chromatography. The elution was performed with HBS pH 7.2 containing 2 mM of EDTA using a sepharose CL-4b column (the elution profile of a NHS-PEG-MaI solution throughout a sepharose CL-4b column was previously determined by a observance measure at 240 nm.

The antibody was previously activated for 1 hour with 2- iminothiolane, in a molar ratio of 1/10. The incubation was performed in HBS pH 8.0 containing 2 mM of EDTA, at room temperature. Then the 2-iminothiolane was removed through a sephadex G-25 column . The activated antibody was incubated with liposomes in a ratio of 0,375 mg/μmol of total lipid, during 2 or 12 hours, at 4° C or at room temperature, under a smooth agitation and in a nitrogen atmosphere.

After this period the maleamide groups still active were inactivated with β- mercaptoethanol (1/5 molar ratio) . Non- coupled antibody and excess of beta mercaptoethanol were removed through a sepharose CL-4b with HBS 7.4.

2. Liposome characterization

2.1. Measurement of the final sizes

The size of the immunoliposomes was measured by photon correlation spectroscopy in submicron particle size analyser from Beckman Coulter. The measurements were performed in HBS pH 7.4, at 25°C, with an equilibration time of 5 minutes, running time of 200 seconds, with the angle of 90°.

2.2. Efficiency determination of the encapsulation

The encapsulation efficiency was measured by determining the concentration of viral genomes by quantitative PCR, and the concentration of cholesterol by de infinity cholesterol reagent. The aim of representing such a parameter corrected for the lipid concentration comes from the need to eliminate the effect of dilutions and of lipid losses in the final value of the encapsulation efficiency.

Quantitative PCR was performed with primers and probe (FAM) designed for pCMV acquired from Applied Biosystems and JumpStart Taq ReadyMix containing the nucleotides and the polymerase purchased from Sigma Genosys. The amplification was performed in an ABI Prism 7000 instrument from Applied Biosystems .

The quantification of the genomes in the samples was performed immediately after the hydration of the lipid film (i) and after removal of the non- encapsulated adenoviral vectors by centrifugation in a cesium chloride gradient (f) . Quantification of cholesterol was performed with the infinity cholesterol reagent accordingly to the manufacture protocol, immediately after hydration of the lipid film (i) , and after removal of non-encapsulated adenoviral vectors (f) .

The encapsulation efficiency was determined as a ratio (EER): (concentration of genomes (f)/ concentration of cholesterol (f))/ (concentration of genomes (i)/ concentration of cholesterol (i) ) .

2.3. Cell culture

Human umbilical vein endothelial cells (HUVEC) were obtained from the Endothelial Cell Facility RuG/AZG (Groningen, the Netherlands) . Isolated cells were cultured on 1% gelatine coated cell culture flasks from Corning^® Costar^® at 37⁰C under 5% C02 and 95% humidity. The culture medium consisted of RPMI 1640 (Gibco) supplemented with 20% fetal calf serum (FCS), 2 mM L-glutamine, 18 U/ml heparin (Sigma) , 100 U/ml penicillin, 100 Dg/ml streptomycin, and . D~. Dg/ml of endothelial cell growth factor from Roche Applied Science.

2.4. Evaluation of the extent of nanoparticle-cell association

The cell association studies were performed by flow cytometry and by confocal microscopy.

For the flow cytometry experiments, HUVEC were plated in 24 well tissue culture plates (Costar) previously coated with 1 % gelatine at a cell density of 10,000 cells per wel,l 24 hours before the incubation with the liposomes. The immunoliposomes and the non-targeted liposomes containing

(LP- Ad-H18/7 or LP- Ad-PEG) or not (LP-H18/7 or LP- PEG) recombinant adenovirus, were incubated with HUVEC in a concentration of 80 μM for 4 hr at 37⁰C in the presence or absence of TNF-α (100 ng/ml) , which was added to the cells 1 hour before addition of the liposomes.

For the confocal microscopy analyses the cells were plated in 8 well chamber slides previously coated with 1% gelatine at a cell density of 10 000 cells/ well. For the cell association experiments of empty liposomes, LP- H18/7 or LP- PEG were incubated with HUVEC in a concentration of 80 μM for 4 hr at 37⁰C in the presence or absence of TNF-α

(100 ng/ml), which was pre-incubated with the cells for 1 hour. For the cell association experiments with liposomes containing Ad, liposomes (LP-Ad- H18/7 or LP- Ad- PEG) were incubated with HUVEC in a concentration of 40 μM. Cells were previously activated upon incubation with 100 ng/ml TNF-α for 4 hours. Cells were then washed and incubated with the formulations only for 1 hour. In parallel, cell association studies were performed at the experiments at 4°C.

2.5. Evaluation of transfection efficiency

The transfection efficiency was evaluated both by flow cytometry and confocal microscopy.

For the flow cytometry experiments HUVEC were plated in 24 well tissue culture plates (Costar) previously coated with 1 % gelatine at a cell density of 10,000 cells per well 24 hours before the transduction experiment. For the transduction experiments LP- Ad-H18/7 or LP- Ad-PEG were incubated with HUVEC in a concentration of 40 μM (unless another concentration is referred) for 12 hr at 37⁰C in the presence or absence of 100 ng/ml TNF-α (pre- incubated with the cells one hour adding the liposomes) In the inhibitory studies, the cells were pre-incubated for 30 min with H18/7, after 4 hours of incubation with TNF- α. The liposomes were then incubated with the cells for 1 hour still in the presence of H18/7 and then the medium was replaced by fresh culture medium, and cells were further incubated for 48 hours before performing the flow cytometry assay.

For the confocal studies the procedure was similar with the exception cells were seeded in 8 well chamber slides, as described in the previous section.

All the experiences were performed in the presence 20%. non- inactivated fetal bovine serum.

2.6. Assessment of the cellular association and transgene expression

For flow cytometry analyses, HUVEC were washed three times with PBS and incubated with trypsin/EDTA to facilitate cells to be detached. Cells were immediately diluted with PBS containing 20% FCS and centrifuged, ressuspended in PBS and analysed by flow cytometry for GFP expression. For the analyses of the levels of transduction liposomes were labelled with Rho- PE in order not to interfere with GFP detection, whereas for the analyses of cell association liposomes were labelled with Fluor- PE.

For confocal microscopy analyses cells were washed with PBS and fixed with 4 %, p- formaldehyde (PFA) at 4°C. PFA was inactivated by incubation with 0.1 M glycin and further washed. Cells were mounted with mounting medium (Vectashield) containing DAPI and analysed by confocal microscopy. Liposomes labelled with Rho- PE were used for the assessment of transduction, whereas liposomes labelled either with Rho- PE or with Fluor- PE were used ofr the evaluation of the extent of cell association. All the experiments were performed in the presence of 20% serum.

Examples Example 1

The incubation of negatively charged liposomes coupled to the ligand transferrin with cells that express trasnferrin receptors lead to an increase on the extent of liposome- cell association, as compared to the condition where those cells are incubated with liposomes without transferrin. Liposomes labeled with 2.5% of Rh-PE were incubated for 4 hours with HEK-293 cells (concentration of 300 μM) . After this period, the cells previously seeded in 8-well plates were washed with PBS, fixed with 4% PFA for 15 minutes and incubated with a 0. IM glycine solution. The plates were washed, mounted with mounting medium Vectashield containing DAPI, and finally analysed by confocal microscopy. The obtained results clearly demonstrate that the extent of liposome-cell association is higher for the liposomes bearing the ligand transferrin coupled to their surface, indicating that the liposomes can be targeted to cells expressing transferrin receptors.

Example 2

Negatively charged liposomes coupled to an anti-E-selectin antibody present a strong interaction with cells that express E-selectin. Empty liposomes, labelled with Fluor- PE, prepared by extrusion throughout membranes with 200 nm pore diameter, were incubated with hetero-functional PEG for 2 hours. After removal of the non-coupled PEG molecules and incubation with the ligand, the targeted liposomes were incubated for 4 hours with activated HUVEC cells (final concentration of 80 μM of lipid) . TNF-α (100 ng/ml) was added to the cells one hour before treatment with liposomes and maintained for the remaining 4 hours incubation period. The TNF-induced ativation process induces the expression of the E-selectin receptor at the cell surface. After this period, the cells were washed and the number of positive cells for the association of lipid determined by flow cytometry.

Example 3

Negatively charged liposomes containing rAd, coupled to an anti-E-selectin antibody exhibit a strong with cells expressng E-selectin at their surface. The immunoliposomes marked with Rh-PE and carrying Ad₅pCMVGFP (LP-H18/7) were incubated for 1 hour with either activated or quiescent HUVEC (total lipid concentration of 40 μM) . The control liposomes (LP-PEG) were incubated with activated or quiescent cells in similar conditions. Activation of HUVEC cells was achieved by incubation of the cells for 4 hours with 100 ng/ml TNF-α, before the incubation with the liposomes. After the incubation with liposomes, cells were washed, fixed and prepared with mounting medium for the analysis by confocal microscopy, using a Pan- Neofluar 40x/0.75 lens.

Example 4

The interaction between endothelial cells and the negatively charged liposomes coupled to an anti-E-selectin antibody, containing rAd, results in the specific transduction of the activated endothelial cells, while no transduction is observed quiescent cells. The immunoliposomes were labelled with Rh-PE and prepared from an initial concentration of 3.75 xlO¹¹ iu/ml Ad₅pCMVGFP and then incubated with activated or quiescent cells (final concentration of 40 μM total lipid) . The same protocol was followed was applied to non-targeted liposomes. After 12 hours of incubation, cell culture medium was replaced by fresh medium and cells incubated for additional 36 hours. Cells were then washed, fixed and prepared with mounting medium to be analysed by confocal microscopy, using a Pan- Neofluar 40x/0.75 lens. The obtained results indicate that the previously reported liposome-cell specific association results lead to specific transduction of target cells expressing E-selectin, this effect not being observed for cells non expressing e-selectin. In addition, it should be emphasized that, under the same experimental conditions, non-targeted nanoparticles (absence of coupled antibody) do not exhibit the same ability to transduct target cells.

Example 5

The interaction between endothelial cells and the negatively charged liposomes coupled to an anti-E-selectin antibody, containing rAd, results in transduction specificity of these cells, this effect being dependent on the initial lipid concentration used. The immunoliposomes were labelled with Rh-PE and prepared from an initial concentration of 3.75 xlO¹¹ iu/ml Ad₅pCMVGFP and then incubated with activated (LP Ad-H18/7 A) or quiescent cells

(LP Ad-H18/7 R) at various final total lipid concentrations .

Similar experimental protocols were applied for non- targeted liposomes, both for activated and quiescent cells

(LP Ad- PEG A and LP Ad- PEG R, respectively) . After 12 hours of incubation, cell culture medium was replaced by fresh medium and the cells incubated for additional 36 hours. Cells were thn washed, detached and analysed by flow cytometry. Results were evaluated considering the levels of fluorescence observed for cells incubated with HBS as the basal fluorescence.

Example 6

Cellular internalization of the negatively charged liposomes coupled to a targeting ligand and containing rAd, is inhibited at 4°C. The immunoliposomes were labelled with Rh-PE and prepared from an initial concentration of 3.75 xlO¹¹ iu/ml Ad₅pCMVGFP and then incubated with activated or quiescent cells (final lipid concentration of 40 μM) for 1 hour at 37°C or at 4°C. Activation of HUVEC cells was achieved by incubation of the cells for 4 hours with 100 ng/ml TNF-α, before the incubation with the liposomes. After the incubation with liposomes, cells were washed, fixed and prepared with mounting medium for the analysis by confocal microscopy, using a Plan- Neofluar lOOx/1.3 oil lens.

The pattern of cell association observed under the various experimental conditions tested for liposomes containing recombinant viruses showed that this process is inhibited at 4°C, which clearly indicate that internalization of the liposomes by the cells is mediated an energy dependent process .

Example 7

The transduction mediated by negatively charged liposomes coupled to a targeting ligand and containing rAd, is inhibited by an excess of free ligand in the cell culture medium.

The immunoliposomes were labelled with Rh-PE and prepared from an initial concentration of 3.75 xlO¹¹ iu/ml Ad₅pCMVGFP and then incubated with activated (LP Ad-H18/7 A) or quiescent cells (LP Ad-H18/7 R) (final lipid concentration of 40 μM) for 1 hour at 37°C.

(LP Ad- PEG A and LP Ad- PEG R, respectively) . The free ligand was added to the activated HUVEC or quiescent cells

(final concentration of 20 μg/ml) 30 minutes before starting the incubation of the cells with the liposomes and maintained for the remaining incubation period. Activation of HUVEC cells was achieved by incubation of the cells for 4 hours with 100 ng/ml TNF-α, before the incubation with the liposomes. After 48 hours, the cells were washed, detached and analyzed by flow cytometry. Results were evaluated considering the levels of fluorescence observed for cells incubated with HBS as the basal fluorescence.

The inhibitory effect of pre-treating the cells with an excess of ligand on the transduction efficiency clearly indicate that levels of transduction is dependent on the extent of liposome-cell binding.

References

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Claims

1. Lipidic-based nano-carriers for targeted delivery of viral vectors characterized by a composition that includes a lipidic component, the lipid vesicles, prepared by neutral and/or neutral and negative lipids, a viral vector containing the genetic material to be transferred to the target cells, a targeting moiety, and also by exhibiting a mean particle size between 100 and 400 nm.

2. Lipidic-based nano-carriers, accordingly to the previous claim, characterized by lipid vesicles containing in their composition neutral lipids and/or neutral and negative lipids, as for non limitative example, DOPE, EPC, PI and CHOL, but not including cationic lipids in their composition

3. Lipidic-based nano-carriers, accordingly to claim 1, characterized by a targeting device that can be composed by a hydrophilic polymer conjugated to the surface of the lipidic vesicles, which in turn enables the conjugation of a ligand.

4. Lipidic-based nano-carriers, accordingly to the previous claim, characterized by a hydrophilic polymer containing one or two reactive groups.

5. Lipidic-based nano-carriers, accordingly to the previous claim, characterized by a hydrophilic polymer that is preferentially a PEG molecule with a molecular weight between 1000 e 5000 Da, and exhibiting mono or bi-functional properties.

6. Lipidic-based nano-carriers, accordingly to the previous claim, characterized by a ligand which is conjugated to the reactive distal end of the hydrophilic polymer molecules.

7. Lipidic-based nano-carriers, accordingly to claim 1, characterized by a targeting moiety composed by only one ligand.

8. Lipidic-based nano-carriers, accordingly to claim 1, characterized by a targeting moiety that can be composed by more than one ligand aiming at targeting different cell populations.

9. Lipidic-based nano-carriers, accordingly to claims 7 and 8, characterized by ligands which are directly coupled to the surface of the nanovesicles

10. Pharmaceutical compositions, characterized by containing particles of Lipidic-based nano-carriers, accordingly to the previous claims.

11. Pharmaceutical compositions, accordingly to the previous claim, characterized by containing a pharmacologically acceptable vehicle, being able to include other compounds, as for non- limitative examples, lisosomotropic agents, preservatives, colloidal stabilizers, peptides with fusogenic properties and nuclear localization signals.

12. Process of production of the Lipidic-based nano- carriers, accordingly to the claims 1 to 8, characterized by the following stages of production:

1) preparation of the lipidic vesicles by hydration of the lipid film with a suspension containing the recombinant viruses, as for non-limitative example, adenoviral vectors, followed by purification;

2) conjugation of a hydrophilic polymer, as for non- limitative example, PEG, followed by purification;

3) conjugation of ligand(s) to the distal end of the hydrophilic polymer, or to the surface of the lipidic vesicles, followed by purification.

13. Process of production of the nano-carriers, accordingly to the previous claim, characterized by extrusion of the liposomic suspension obtained at step 1, so that homogeneous particle size is achieved.

14. Process of production of the nano-carriers, accordingly to the previous claim, characterized by purification process of the liposomic suspension obtained at step 1 to remove non encapsulated viruses, as for non- limitative example, by ultra-centrifugation in cesium chloride .

15. Process of production of the nano-carriers, accordingly to claim 12, in which step 2 is characterized by a hydrophilic polymer with a reactive group, which can be inserted in the lipid mixture before the hydration of the lipid film, or after the formation of the liposomes .

16. Process of production of the nano-carriers, accordingly to claim 12, in which step 2 is characterized by a hydrophilic polymer with two reactive groups, which can be conjugated after the formation of the liposomes.

17. Process of production of the nano-carriers, accordingly to claim 15 and 16, characterized by the formulation being submitted to a process of purification to remove molecules of polymer non-conjugated to the surface of the nano-carriers, as for non-limitative example, size exclusion chromatography.

18. Process of production of the nano-carriers, accordingly to claim 12, in which step 3 is characterized by the ligand, as for non-limitative example, a protein, a peptide, an antibody, a fragment of an antibody, an aptamer or a molecule that exhibits affinity and specificity to a cell receptor, being conjugated to the distal end of a hydrophilic polymer, previously conjugated to the surface of the lipidic based nano- carriers .

19. Process of production of the nano-carriers, accordingly to the previous claim, characterized by the ligand being conjugated covalently to the distal end of a hydrophilic polymer, previously to its insertion at the surface of the lipidic based nano-carrires .

20. Process of production of the nano-carriers, accordingly to the claims 18 and 19, characterized by the formulation being submitted to a process of purification to remove non conjugated ligand molecules, as for non-limitative example, size exclusion chromatography .

21. Use of the nano-carriers described under claims 1 to 8, characterized to be applied for specific delivery of genes to target cells, namely for gene therapy purposes.

22. Use of the nano-carriers, accordingly to the previous claim, characterized for its application for the treatment, as for non-limitative example, of cancer, vascular, neurodegenerative diseases, inflammatory diseases and others associated to processes enrolling activated endothelial cells.

23. Use of the nano-carriers described under claims 1 to 8, characterized for being applied to the production of a pharmaceutical composition for the specific delivery of genetic material to the target cells, preferentially for the application in gene therapy, as for non- limitative example, for the treatment of cancer, vascular, neurodegenerative diseases, as well as for the treatment of pathologies associated with processes enrolling activated endothelial cells.

24. Use, accordingly to the previous claim, characterized by the pharmaceutical composition being preferentially a composition for intravenous administration.

25. Use of the process of production of the nano-carriers, accordingly with the claims 12 to 20, characterized by its application to the production of lipidic-based nano-carriers, containing the genetic material and a targeting moiety of high specificity, responsible for the identification of the target cells that the viral vector will transduce, aiming at gene therapy.