EP1143982A2 - Method for preparing membrane vesicles - Google Patents

Abstract

The invention concerns a method for preparing membrane vesicles from a biological sample, characterised in that it comprises at least a step which consists in treating the sample by anion-exchange chromatography and/or gel permeation. The invention is used for preparing original vesicles or of different types, in particular from cells presenting antigens or tumour cells. The invention also concerns the resulting vesicles and their uses.

Description

 PROCESS FOR THE PREPARATION OF MEMBRANE VESICLES

The present invention relates to a new process for the preparation (in particular the isolation and / or purification) of membrane vesicles. The invention also relates to the membrane vesicles thus prepared, as well as their biological and medical uses, for example.

The membrane vesicles are vesicles, with a diameter generally less than 100 nm, composed of a lipid bilayer containing a cytosolic fraction. Specific membrane vesicles are more specifically derived from intracellular compartments, by fusion with the plasma membrane of a cell, leading to their release into biological fluids or into the supernatant of cells in culture. Such vesicles are generally designated by the term exosome. Exosomes generally have a diameter of between approximately 50 and 90 nm, more particularly between approximately 60 and 80 nm, and advantageously carry membrane proteins (in particular proteins of the major histocompatibility complex) which are in the same orientation as in the membrane. the cells from which they are derived. Furthermore, depending on their origin, the exosomes contain membrane proteins such as CD40, CD80, HSP70 and are devoid of endoplasmic reticulum and golgi apparatus.

The release of exosomes has been demonstrated from different cell types, in various physiological contexts. Thus, it has been shown that B lymphocytes release exosomes carrying molecules of the major histocompatibility class II complex, which play a role in antigen presentation (Raposo et al., J. Exp. Med. 183 (1996) 1161). Likewise, it has been shown that dendritic cells produce exosomes (also called dexosomes), having particular structural and functional characteristics, and playing a role in mediating the immune response, in particular in stimulating cytotoxic T lymphocytes. (Zitvogel et al., Nature Medicine 4 (1998) 594). He has It has also been shown that tumor cells secrete, in a regulated manner, specific exosomes (also designated texosomes), carriers of tumor antigens and capable of presenting these antigens or of transmitting them to the antigen-presenting cells (patent application No. WO99 / 03499). It is also known that mast cell cells accumulate molecules in the intracellular vesicular compartments, which can be secreted under the effect of signals (Smith and Weis, Immunology Today 17 (1996) 60). In general, therefore, it seems that cells emit signals and communicate with each other via membrane vesicles which they release, which can carry antigenic motifs, MHC molecules, or any other signal ( cytokine, growth factor, etc.), which have specific structural and functional characteristics, and are produced in different physiological situations. These vesicles, and in particular exosomes, therefore represent a particularly interesting product for diagnostic, vaccine, therapeutic applications or for transporting molecules of interest. It would therefore be particularly advantageous to have an efficient and usable method on an industrial scale, for preparing membrane vesicles compatible with biological use, in particular pharmacological use.

Conventional methods for preparing membrane vesicles (eg, exosomes) use a series of differential centrifugation steps to separate the vesicles from cells or cell debris present in the culture medium. Thus, the documents cited above essentially describe the preparation of vesicles by a series of centrifugations at 300g, 10,000g and 70,000 or 100,000g, the pellet obtained being then taken up in a saline solution, to constitute a concentrated solution of exosomes . This preparation can be analyzed by conventional biochemical techniques to assess the protein composition of exosomes. A preferred biochemical technique consists of electrophoresis in a denaturing medium associated with protein staining total or detection of specific proteins using antibodies using the western blot technique. The detection of exosomes in the final preparation can be carried out directly by electron microscopy after fixing the preparation with a 4% glutaraldehyde solution.

According to this process, the purity levels of the exosomes are satisfactory insofar as such preparations have made it possible to demonstrate the biological activity and the anti-tumor properties in animal models. However, these previous methods of preparation by centrifugation do not allow fine separation of the membrane vesicles (e.g., exosomes) from cellular proteins or certain macromolecular components (DNA, RNA) or macromolecular complexes. These methods therefore do not exclude the presence of unidentified contaminating biological agents which are incompatible with therapeutic use in humans. In addition, these stages are difficult to extrapolate on an industrial scale, in particular when large volumes have to be treated, or for autologous ex vivo applications (i.e., patient by patient), where the process must generally be implemented in a confined system.

The present invention now provides a solution to this problem. The invention indeed describes new methods allowing the preparation (that is to say the isolation and / or purification) of membrane vesicles under conditions compatible with industrial use and pharmacological applications. Thus, the methods of the invention can be applied both for individualized preparations of autologous exosomes, and for preparations of exosomes obtained from established cell lines, for experimental, biological uses or for the purposes of Prophylactic or therapeutic vaccinations, for example. The present invention is based more particularly on the use of separation methods by chromatography for the preparation of membrane vesicles, and in particular for separating the membrane vesicles from possible contaminating biological entities.

More particularly, a first object of the invention resides in a process for the preparation of membrane vesicles from a biological sample characterized in that it comprises at least one step of treatment of the sample by anion exchange chromatography .

Indeed, the applicant has now shown that the membrane vesicles, in particular the exosomes, can be purified by anion exchange chromatography. Thus, unexpectedly, it is shown in the present application that the exosomes are resolved into a homogeneous peak after anion exchange chromatography. This result is completely unexpected insofar as the exosomes are complex supramolecular objects composed inter alia of a membrane surrounding an internal volume comprising inter alia soluble proteins. In addition, exosomes contain membrane proteins.

A more particular object of the invention therefore relates to a process for the preparation, in particular for the purification of membrane vesicles from a biological sample, comprising at least one step of anion exchange chromatography.

For the implementation of the present invention, it may be a strong or weak anion exchange, preferably a strong one. Furthermore, in a particular embodiment, the chromatography is carried out under pressure. It can thus be more particularly a high performance liquid chromatography (HPLC). Different types of supports can be used for carrying out anion exchange chromatography. Mention may more preferably be made of cellulose, poly (styrene-divinylbenzene), agarose, dextran, acrylamide, silica, the ethylene glycol-methacrylate copolymer, or mixtures, for example agarose-dextran mixtures. In this regard, we can mention by way of illustration various chromatography materials composed of supports as stated above, and in particular the gels Source, Poros, Sepharose, sephadex, Trisacryl, TSK-gel SW or PW, Superdex, Toyopearl HW and sephacryl, for example, which are suitable for carrying out the present invention.

In a particular embodiment, the invention therefore relates to a process for the preparation of membrane vesicles from a biological sample, comprising at least one step during which the biological sample is treated by exchange chromatography. anions on a support chosen from cellulose, poly (styrene-divinylbenzene), silica, acrylamide, agarose, dextran, ethylene glycol-methacrylate copolymer, alone or in mixtures, optionally functionalized.

Furthermore, to improve the chromatographic resolution, it is preferable in the context of the invention to use supports in the form of beads. Ideally, these are beads having a homogeneous and calibrated diameter, and having a sufficiently high porosity to allow the penetration of the objects to be chromatographed (Le., Exosomes). Thus, given the diameter of the exosomes (generally between 50 and 100 nm) it is preferable for the implementation of the invention to use gels of high porosity, in particular between approximately 10 nm and 5 μm, more preferably between approximately 20 nm and approximately 2 μm, even more preferably between approximately 100 nm and approximately 1 μm.

For anion exchange chromatography, the support used must be functionalized by means of a group capable of interacting with an anionic molecule. Generally, this group consists of an amine which can be ternary or quaternary which respectively defines a weak or strong anion exchanger.

In the context of the present invention, it is particularly advantageous to use a strong anion exchanger. Thus preferably used according to the invention a chromatography support as indicated above, functionalized with quaternary amines. According to a more particular embodiment of the invention, the anion exchange chromatography is therefore carried out on a support functionalized with a quaternary amine. Even more preferably, it is a support chosen from poly (styrene-divinylbenzene), acrylamide, agarose, dextran and silica, alone or in mixtures, functionalized with a quaternary amine.

Among the supports functionalized with a quaternary amine, examples include Source Q, Mono Q, Q Sepharose, Poros HQ and Poros QE gels, Fractogel TMAE type gels, and Toyopearl Super Q gels.

A particularly preferred support for carrying out anion exchange chromatography comprises poly (styrene-divinylbenzene). An example of this type of gel which can be used in the context of the invention is the Source Q gel, in particular Source 15 Q (Pharmacia). This support has the advantage of very large internal pores, thus offering little resistance to the circulation of liquid through the gel, while allowing rapid diffusion of the exosomes towards the functional groups, parameters which are particularly important in the case of the exosomes given their cut.

The elution of the biological compounds retained on the column can be done in different ways, and in particular by means of the passage of an increasing concentration gradient of a saline solution, for example from 0 to 2 M. It is possible in particular to use a sodium chloride solution, in concentrations ranging from 0 to 2M, for example. Detection of different fractions as well purified is done by measuring their optical density (OD) at the column outlet by means of a continuous spectrophotometric reading. As an indication, under the conditions used in the examples, the fractions comprising the membrane vesicles were eluted at an ionic strength of between 350 and 700 mM approximately, depending on the types of vesicles.

Different types of columns can be used to carry out this chromatographic step, depending on the needs and the volumes to be treated. For example, depending on the preparations, it is possible to use a column of approximately 100 μl up to 10 ml or more. Thus, the supports available have a capacity which can reach, for example, 25 mg of proteins / ml. As a result, a 100 μl column has a capacity of the order of 2.5 mg of proteins which, taking into account the samples considered, can make it possible to treat culture supernatants of approximately 2 1 (which, after concentration of (a factor 10 to 20 for example, represent volumes of 100 to 200 ml per preparation). It is understood that higher volumes can also be treated, by increasing the volume of the column for example.

Furthermore, for the implementation of the present invention, it is also possible to combine the step of anion exchange chromatography with a step of gel permeation chromatography. Thus, according to a particular embodiment of the invention, a gel permeation chromatography step is added to the anion exchange step, either before or after the exchange chromatography step of 'anions. Preferably, in this embodiment, the permeation chromatography step takes place after the anion exchange step. In addition, in a particular embodiment, the anion exchange chromatography step is replaced by the gel permeation chromatography step. The present application indeed shows that the membrane vesicles can also be purified using liquid chromatography by gel permeation, in particular when this step is combined with exchange chromatography. anions or other step (s) of processing the biological sample, as will be described in detail later.

To carry out the gel permeation chromatographic step, a support preferably chosen from silica, acrylamide, agarose, dextran, ethylene glycol-methacrylate copolymer, or mixtures, for example mixtures, is preferably used. agarose-dextran. By way of illustration, for gel permeation chromatography, a support such as Superdex 200HR (Pharmacia), TSK G6000 (TosoHaas) or even Sephacryl S (Pharmacia) is advantageously used.

The method of the invention can be implemented from different biological samples. In particular, it may be a biological fluid originating from a subject (bone marrow, peripheral blood, etc.), a culture supernatant, a cell lysate, a prepurified solution, or any other composition comprising membrane vesicles.

In this regard, in a particular embodiment of the invention, the biological sample is a culture supernatant of cells producing membrane vesicles.

Furthermore, according to a preferred embodiment of the invention, the biological sample is treated, prior to the chromatographic step, to be enriched in membrane vesicles (enrichment step). Thus, in a particular embodiment, the present invention relates to a process for the preparation of membrane vesicles from a biological sample characterized in that it comprises at least: b) a step of enriching the sample with vesicles membranes, and, c) a step of processing the sample by anion exchange chromatography and / or by gel permeation chromatography.

According to a preferred embodiment, the biological sample is a culture supernatant treated so as to be enriched in membrane vesicles. In in particular, the biological sample can consist of a prepurified solution obtained from a culture supernatant from a population of cells producing membrane vesicles or from a biological fluid by treatments such as centrifugation, clarification, ultrafiltration, nanofiltration and / or affinity chromatography, in particular by clarification and / or ultrafiltration and / or affinity chromatography.

A preferred process for the preparation of membrane vesicles within the meaning of the present invention therefore more particularly comprises the following steps: a) culturing a population of cells producing membrane vesicles (eg of exosomes) under conditions allowing the release of the vesicles , b) a step of enriching the sample with membrane vesicles, and, c) a step of treating the sample by anion exchange chromatography and / or by gel permeation chromatography.

As indicated above, the step for enriching the sample (eg, the supernatant) may comprise one or more steps of centrifugation, clarification, ultrafiltration, nanofiltration and / or affinity chromatography of the supernatant. In a first particular embodiment, the enrichment step comprises (i) a step of eliminating cells and / or cellular debris (clarification step), optionally followed by (ii) a concentration step and / or affinity chromatography. In another particular embodiment, the enrichment step comprises a step of affinity chromatography, optionally preceded by a step of elimination of cells and / or cellular debris (clarification step). A preferred enrichment phase according to the invention comprises (i) a step of eliminating cells and / or cellular debris, (ii) a concentration and (iii) an affinity chromatography. The removal of cells and / or cellular debris can be carried out for example by centrifuging the sample at a low speed, preferably less than 1000 g, for example between 100 and 700 g. Preferred centrifugation conditions during this step are approximately 300g or 600g, for a period of between 1 and 15 minutes for example.

The elimination of cells and / or cellular debris can also be carried out by filtration of the sample, possibly in combination with the centrifugation described above. Filtration can be carried out in particular by successive filtrations by means of filters having a decreasing porosity. In this regard, filters with a porosity greater than 0.2 μm are preferably used, for example between 0.2 and 10 μm. It is possible in particular to use a succession of filters having a porosity of 10 μm, 1 μm, 0.5 μm then 0.22 μm.

A concentration step can also be carried out, so as to reduce the volumes of sample to be treated during the chromatographic steps. Thus, the concentration can be obtained by centrifugation of the sample at high speeds, for example between 10,000 and 100,000 g, so as to pellet the membrane vesicles. In this regard, it can be a series of differential centrifugations, with the last centrifugation carried out around 70,000 g approximately. The membrane vesicles thus pelletized can then be taken up in a smaller volume and in an appropriate buffer for the subsequent stages of the process.

The concentration step can also be carried out by ultrafiltration. This ultrafiltration makes it possible both to concentrate the supernatant and to carry out a first purification of the vesicles. According to a preferred embodiment, the biological sample (for example the supernatant) is subjected to an ultrafiltration, preferably a tangential ultrafiltration. Tangential ultrafiltration consists of concentrating and dividing a solution between two compartments (filtrate and retentate), separated by membranes of determined cutoff thresholds. The separation is carried out by application of a flow in the retentate compartment and of a transmembrane pressure between this compartment and the filtrate compartment. Different systems can be used to perform ultrafiltration, such as, for example, spiral membranes (Millipore, Amicon), flat membranes or hollow fibers (Amicon, Millipore, Sartorius, Pall, GF, Sepracor). Advantageously, in the context of the invention, membranes with a cutoff threshold of less than 1000 kDa, preferably between 300 kDa and 1000 kDa, even more preferably between 300 kDa and 500 kDa, are used.

The affinity chromatography step can be carried out in different ways, on different chromatographic materials and supports. It is advantageously a non-specific affinity chromatography, intended to retain certain contaminants present in the solution, without retaining the objects of interest (ie, the exosomes). It is therefore a negative selection. It is preferably a dye chromatography, making it possible to remove (ie, retain) contaminants such as proteins and enzymes, for example albumin, kinases, dehydrogenases, coagulation factors, interferons or lipoproteins , or co-factors, etc. Preferably, the support used for this chromatography is a support as used for the ion exchange chromatography, functionalized with a dye. As a specific example, the dye can be chosen from Blue Sepharose (Pharmacia), Yellow 86, Green 5 and Brown 10 (Sigma). The support is more preferably agarose. It is understood that any other support and / or dye or reactive group making it possible to retain certain contaminants of the biological sample treated can be used within the framework of the present invention. In a particular embodiment of the invention, the biological sample is obtained by treatment of a culture supernatant of cells producing membrane vesicles, by at least one filtration step.

In another particular embodiment of the invention, the biological sample is obtained by treatment of a culture supernatant of cells producing membrane vesicles, by at least one centrifugation step. In a preferred embodiment of the invention, the biological sample is obtained by treatment of a culture supernatant of cells producing membrane vesicles, by at least one ultrafiltration step. In another preferred embodiment of the invention, the biological sample is obtained by treatment of a culture supernatant of cells producing membrane vesicles, by at least one affinity chromatography step.

A preferred method of more specific preparation of membrane vesicles within the meaning of the present invention comprises the following steps: a) culturing a population of cells producing membrane vesicles (eg of exosomes) under conditions allowing the release of the vesicles, b) the treatment of the culture supernatant to produce a biological sample enriched in membrane vesicles (eg in exosomes) by at least one step of ultrafiltration or affinity chromatography, and c) a step of processing the biological sample by anion exchange chromatography and / or gel permeation. In a preferred embodiment, step b) above comprises filtration of the culture supernatant, followed by ultrafiltration, preferably tangential. In another preferred embodiment, step b) above comprises a clarification followed by affinity chromatography on dye, in particular on Blue Sepharose.

Furthermore, after step c), the harvested material can, if necessary, be subjected to one or more additional steps d) of treatment and / or filtration, in particular for the purpose of sterilization. For this filtration treatment step, filters preferably having a diameter less than or equal to 0.3 μm, even more preferably less than or equal to 0.25 μm, are preferably used. Such filters are for example filters with a diameter of 0.22 μm.

After step d), the material obtained is for example distributed in suitable devices such as vials, tubes, bags, syringes, etc., in an appropriate storage medium. The purified vesicles thus obtained can be stored in the cold, frozen, or used extemporaneously.

A particular preparation process within the meaning of the invention therefore comprises at least the following steps: c) a step of treatment of the biological sample by anion exchange chromatography and / or gel permeation and, d) a filtration step, in particular sterilizing filtration, of the material harvested after step c).

In a first embodiment, the method of the invention comprises: c) a step of processing the biological sample by anion exchange chromatography, and, d) a step of filtration, in particular sterilizing filtration, of the material harvested after step c). In another alternative embodiment, the method of the invention comprises: c) a step of processing the biological sample by gel permeation chromatography, and, d) a step of filtration, in particular of sterilizing filtration, of the collected material after step c).

According to a third alternative embodiment, the method of the invention comprises: c) a step of processing the biological sample by anion exchange chromatography followed or preceded by gel permeation chromatography, and, d) a filtration step, in particular sterilizing filtration, of the material harvested after step c).

The results presented in the examples show that the injection of an exosome preparation into the chromatography column makes it possible to obtain symmetrical absorption peaks, which are perfectly resolved (Fig. N ° 1). The different fractions thus isolated can be analyzed by conventional techniques of electrophoresis of proteins in denaturing gel followed by techniques of coloration with Coumassie blue or techniques of detection of specific proteins using antibodies. It is thus possible to show, for texosomes, that the peak eluted in anion exchange chromatography with a 400 mM saline solution has a protein profile identical to that of an exosome preparation conventionally prepared (Fig. N ° 2). This makes it possible de facto to characterize the peaks elected at lower or higher saline concentrations as relating to distinct, contaminating biological entities. In another experiment, the membrane vesicles produced from dendritic cells (dexosomes) or certain texosomes are eluted at an ionic strength of between 500 and 700 mM approximately, and the vesicles of mast cells around 350 mM. In addition, the results presented in the examples also show that the method of the invention makes it possible to detect any contamination of the preparation with proteins predominant in the culture medium such as bovine serum albumin. Indeed, the chromatography of a standard bovine serum albumin solution under the preceding conditions shows that this gives rise to an eluted peak at a saline concentration distinct from that of the exosomes (FIG. N ° 3).

The method of the invention therefore makes it possible (i) to purify membrane vesicles under conditions of quality and quantity compatible with pharmacological use, and (ii) to reveal the existence of distinct and contaminating biological entities within the biological sample processed.

The process of the invention can be applied to the preparation of membrane vesicles of various origins. Thus, it may in particular be exosomes produced by cells presenting antigens, or by tumor cells, in particular. In addition, they may be primary cells, for example in culture, or also established lines, for example immortalized lines of cells producing membrane vesicles. They may be cells of mammalian origin, in particular of murine or human origin.

In a particular embodiment of the invention, the membrane vesicles are vesicles produced by cells presenting antigens, in particular dendritic cells, B lymphocytes, macrophages and mast cells, optionally after sensitization of these to one or more selected antigens. A particularly preferred application of the present invention lies in the preparation of membrane vesicles produced by dendritic cells. In this regard, it may be human or animal dendritic cells, in particular human or murine. These cells can be primary cells, harvested from starting from a biological fluids of a subject or produced ex vivo from precursor cells, or also cells of established lines, for example immortalized with an oncogene (EP 701 604).

A particular object of the present invention resides in a process for the preparation of membrane vesicles (dexosomes), characterized in that it comprises the following stages: a) obtaining a population of dendritic cells, b) culturing the cells dendritics under conditions allowing the production of membrane vesicles (dexosomes) and, c) purification of the membrane vesicles (dexosomes) by a process comprising at least one step of anion exchange chromatography, under the conditions defined above.

A more preferred embodiment resides in a process for the preparation of dexosomes, characterized in that it comprises the following steps a) obtaining a population of dendritic cells, b) culturing the dendritic cells under conditions allowing the production of dexosomes, c) treatment of the culture supernatant to produce a biological sample enriched in dexosomes, in particular by at least an ultrafiltration or affinity chromatography step, and, d) purification of the dexosomes by a process comprising at least at least one step of anion exchange chromatography and / or gel permeation, under the conditions defined above.

More particularly, for the implementation of this variant of the invention, the dendritic cells are preferably obtained from a biological sample originating from a subject, for example from bone marrow or peripheral blood. In this regard, the techniques for producing dendritic cells have been described in the prior art and can be implemented by a person skilled in the art (see in particular the techniques described in application WO99 / 03499, incorporated herein by reference ). Dendritic cells can thus be prepared from stem cells of the immune system, from monocyte precursors or even isolated directly in differentiated form (Review by Hart, Blood 90 (1997) 3245).

A preferred methodology in the context of the present invention is based on the production of dendritic cells from monocyte or bone marrow precursors. More particularly, it is preferred to use in the context of the present invention dendritic cells obtained by treatment of monocyte precursors (contained in blood or marrow) in the presence of a combination GM-CSF + IL4 or GM-CSF + IL-13 .

Furthermore, for the implementation of the present invention, it is very particularly advantageous to use a population of dendritic cells comprising immature dendritic cells. Advantageously, a population of dendritic cells is used which is composed mainly (i.e., at least 60%, preferably 70%) of immature dendritic cells.

The step of obtaining dendritic cells can therefore advantageously comprise the preparation of a population of dendritic cells comprising immature dendritic cells, in particular of human origin, in particular from monocyte precursors, more particularly by treatment with a combination of cytokines such as GM-CSF + IL-4 or GM-CSF + IL-13.

Furthermore, it is also possible in the context of the present invention to use immortalized dendritic cell populations. They can be immortalized dendritic cell lines (Dl line for example, or any other line produced for example by introduction of the myc oncogene into dendritic cells). It can also be dendritic cells prepared and then immortalized in vitro. The interest of immortalized dendritic cells lies in the constitution of banks of cells sensitized to groups of given antigens, which can be used industrially to prepare dexosomes capable of being administered to entire families of patients.

To produce the membrane vesicles (dexosomes), the dendritic cells can be simply cultured under conventional conditions known to those skilled in the art. Advantageously, however, these cells are cultured under conditions which stimulate the production of dexosomes, in particular in the presence of factors capable of stimulating the production of dexosomes, in particular of a cytokine such as gamma interferon, interleukin-10 or l 'interleukin-12 (see for example application WO99 / 03499). In a preferred embodiment of the method of the invention, the dendritic cells are therefore cultured, during step b) above, under conditions stimulating the production of membrane vesicles.

On the other hand, in a particular variant embodiment, the dendritic cells are sensitized to an antigen, prior to the production of the membrane vesicles. This embodiment thus makes it possible to charge the dendritic cells with particular antigen (s), so as to produce dexosomes having a given immunogenic character. Sensitization can be carried out by various techniques known per se, including, for example, bringing cells into contact with antigenic peptides, antigens, protein complexes, cells or membranes of cells expressing antigens, apoptotic bodies, membrane vesicles. , liposomes, tumor RNAs or any nucleic acid encoding one or more antigens, antigenic determinants or epitopes (possibly carried by a viral or non-viral vector), etc. (see for example application WO99 / 03499). In a preferred mode, sensitization is carried out by incubation with peptides, antigens, RNA or nucleic acids. It is understood that the present application is not limited to techniques for sensitizing or producing dendritic cells.

Another particularly advantageous application of the present invention lies in the preparation of membrane vesicles produced by tumor cells, in particular human cells. It can in particular be any cell originating from a solid or liquid tumor as well as cells transformed or immortalized in vitro. Mention may more preferably be made of solid, hematopoietic or ascites tumors.

A particular application of the present invention also lies in the preparation of membrane vesicles comprising one or more heterologous molecules, in particular recombinant molecules. Thus, it is indeed possible, for example, to genetically modify cells producing membrane vesicles (for example mast cell lines) in order to express, in or on the surface of the vesicles that they produce, molecules of interest ( PCT / FR99 / 02691). The present invention can also make it possible to purify such modified vesicles.

More generally, the invention can be applied to the preparation of membrane vesicles produced by any cell type, in particular exosome type vesicles, preferably having a diameter of less than about 100 nm. They may in particular be cells of macrophages, mast cells, reticulocytes, etc. In the experimental section, we used exosome preparations from (i) cell lines such as tumor cell lines (TS / A), murine dendritic cell lines (Dl), mast cell line (RBL) and (ii) human dendritic cells derived from monocytes. The results obtained can be directly transposed to other primary cultures such as tumor cells, human dendritic cells, B lymphocytes, etc., cultivable under industrially acceptable conditions. The method of the invention can thus be implemented as a step of purifying exosomes in the context of their use in human therapy.

The membrane vesicles thus obtained constitute, depending on their origin, tools for studying cancers or for regulating the immune system, for transferring molecules, for producing antibodies, for labeling, for diagnosis, for building up banks, principles vaccine or medication, etc.

In addition, the process of the invention can also be used as a method for quality control on the possible presence of contaminants (in particular of contaminating proteins) in the culture medium or in preparations of membrane vesicles.

In this regard, the present invention can therefore be implemented both in a preparative method of membrane vesicles and in an analytical system making it possible to control the quality of a preparation of membrane vesicles, whatever their method of preparation.

The present invention therefore also relates to a process for controlling the presence of contaminants, in particular of protein or nucleic origin, in a preparation of membrane vesicles, in particular of exosomes, comprising the treatment of a fraction of said preparation by a step at less anion exchange chromatography, and the detection of the presence of contaminants.

The invention also relates, in general, to the use of anion exchange chromatography, in particular of the high performance liquid type, for the preparation or the purification of membrane vesicles. She relates to the use of affinity chromatography for the preparation or purification of membrane vesicles.

A subject of the invention is also the membrane vesicles prepared by the process of the invention, as well as any composition comprising such vesicles.

The present invention will be more fully described with the aid of the following examples which should be considered as illustrative and not limiting.

Legend of figures

Figure 1: Elution profile after anion exchange chromatography of a sample of exosomes prepared by differential centrifugation.

Figure 2: Analysis of the protein profile of the different elution fractions of an exosome preparation by electrophoresis in SDS PAGE then staining with Coomassie blue.

Figure 3: Elution profile after anion exchange chromatography of a standard bovine serum albumin solution.

Figure 4: Diagram of treatment of a biological sample comprising membrane vesicles by tangential ultrafiltration. Figure 5: General profile of the Blue sepharose 6 fast flow step after centrifugation at 600 and 10,000 g of a dexosome supernatant.

Figure n ° 6: Western blot directed against the MHC II molecules of the exosomes, in the non-adsorbed fraction and in the eluate, from the Blue sepharose 6 fast flow step. Figure n ° 7: General profile of the 15Q source stage after a Blue sepharose fast flow stage.

Figure 8: Details of the elution gradient on the 15Q source after a Blue sepharose 6 fast flow step (enlargement of the rectangular area at the bottom right in Figure 7). Figure 9: Example of a purification profile of exosomes produced from the RBL DR + line (equivalent to 53 μg of proteins) by a Source 15Q column after treatment with DNase and RNase.

Figure n ° 10: Separation of exosomes by a discontinuous NaCl gradient on a Source 15Q support.

Figure 1: Western blot directed against the molecules of the human MHC II of each peak separated by HPLC and ultracentrifuged. Positive control: Human dendritic cells expressing MHC II molecules. Negative control: ultracentrifuged medium and representing background noise. MW = molecular weight; NA = fraction not adsorbed.

General cell culture and molecular biology techniques

1) Cell cultures

The TS / A cell line is a murine cell line established from a spontaneous mammary carcinoma. This line is cultivated at 37 ° C. in the presence of 5% of CO 2 in RPMI medium in the presence of 10% of fetal calf serum (Dominique Dutcher).

The dendritic cell lines are maintained in an IMDM medium containing 10% of inactivated fetal bovine serum, 2 mM of L-glutamine, 50 μM of 2- βME, 100 IU / ml of penicillin, and 100 μg / ml of streptomycin.

2) Protein analysis by SDS PAGE

20μl of sample is diluted in Laemmli buffer (Nature 227 (1970) p680-685) then subjected to thermal denaturation at 95 ° C for 10 min then loaded on 10% acrylamide gels> (Novex 1 mm × 0 0 well). After migration, the gels are stained with Coomassie blue.

Examples

1) Anion exchange chromatography of an exosome preparation produced by tumor cells (TS / A line): analysis by SDS PAGE of the protein profile of the various eluted fractions.

This example illustrates how an anion exchange chromatography step can be used to separate impurities from an exosome preparation.

1. 1) Protocol

In this experiment, the starting material consists of a concentrate of exosomes prepared by differential centrifugation from a culture supernatant of TS / A cells making it possible to separate the exosomes from the cells or cellular debris present in the culture medium. . The first centrifugation is carried out at low speed (300 g for 5 min) in order to pellet the cells in suspension present in the culture supernatant. Two other centrifugations (1200g for 20 minutes then 10,000g for 30 minutes) allow the cellular debris to be pelleted. The supernatant thus clarified is then subjected to a high speed ultracentrifugation of 70,000 g for 1 hour making it possible to pellet the exosomes. This preparation is then washed in a large volume of saline solution to be recentrifuged under the previous conditions. The pellet is then taken up in a volume of approximately 100 μl of saline solution and constitutes a concentrated solution of exosomes. The amount of protein is measured by the Bradford technique (Biorad, Ivry, France). This concentrate has a total protein content of between 500 and 1000 μg / ml. 40 μg of this preparation of exosomes diluted in 500 μl of Tris / HCL 50 mM pH buffer are injected into a column containing Source Q 15 gel (Pharmacia) balanced in a Tris / HCL solution 50 mM pH 8. After rinsing, the adsorbed species are eluted on 30 column volumes with a linear NaCl gradient from 0 to 500 mM, then with a 2M NaCl solution. The elution fractions are analyzed by spectrophotometry at 260 and 280 nm. The elution fractions are grouped into five major fractions (from FI to F5) in order to be able to analyze their respective protein profile. The proteins of each fraction are precipitated by 1/10 by volume of a 100% trichloroacetic acid solution and then rinsed with an acetone solution. The protein pellets are taken up in 20 μl of Laemmli solution, and are deposited on an SDS PAGE acrylamide gel which is then colored with Coomassie blue.

1.2) Results

The elution profiles at 260 and 280 nm are shown in FIG. 1. The profiles show the presence of 3 distinct symmetrical peaks, eluted at the respective saline concentrations of 105 mM, 400 mM and 2 M NaCl.

Analysis of the protein profile of the fractions corresponding to the different peaks shows that the peak eluted at 400 mM NaCl has a protein profile identical to that of an exosome preparation conventionally prepared by centrifugation

(Figure N ° 2). The ratio between the absorptions at 260 and 280 nm measured at a value of 0.8 is compatible with that described in the case of proteins.

The peak eluted (fraction F2) at 105 mM NaCl, on the other hand, presents a different protein profile showing only two distinct bands. The absorbance measurements at 260 and 280 nm give a ratio of 1.6 suggesting the presence of a combination of nucleic acids and proteins.

The fraction F5 eluted at 2 molar of NaCl corresponds to the biological compounds strongly associated with the column. It is therefore possible to separate the exosomes from impurities by an anion exchange step.

2) Anion exchange chromatography of a standard bovine serum albumin solution:

This anion exchange chromatography technique also makes it possible to evaluate the degree of contamination of an exosome preparation by the proteins present in the culture medium. Thus, we show by chromatographing 10 μg of a bovine serum albumin solution, corresponding to the majority protein of the culture medium, that this is eluted at 205 mM NaCl in the form of a narrow peak distinguishable from the peaks previously described. in the case of exosomes.

3) Treatment of a culture supernatant containing exosomes by ultrafiltration.

This example shows that it is possible to concentrate the exosomes by ultrafiltration. In addition, the exosomal preparation is depleted in contaminating proteins such as BSA.

3.1) Protocol: (Figure N ° 4)

150 ml of a cell culture supernatant obtained after centrifugation at 300 g of TSA cells, are subjected to filtration on a filter with a porosity of 0.22 μm (Millipore). The filtrate is diluted by half in PBS. The resulting 300 ml are filtered tangentially with a filtration cassette (10 cm ² of membrane) with a cutoff threshold of 300,000 D (Sartorius).

3.2) Results 7 ml of retentate are obtained after 1 hour of filtration. The retentate was subjected to ultracentrifugation (79,000) to pellet and analyze the exosomes. Analysis by SDS-PAGE followed by staining with Coomassie blue revealed that the sample contained significantly less BSA than the solution which was ultrafiltered. In addition, protein bands specific to exosomes produced from TSA are observed.

Ultrafiltration can therefore be used in a process for purifying exosomes in order to separate them from contaminating proteins.

4) Purification by HPLC of human exosomes produced by human dendritic cells derived from monocytes (MDDC).

4.1) Materials and Methods

. Buffers and stock solutions.

We work with 0.22 μm filtered stock solutions with the exception of water and sodium hydroxide solution. The first buffer is a 100 mM Bis-Tris-Propane (BTP) solution (Sigma, 99%> purity), buffered at pH 6, this buffer is connected to channel A of the chromatograph (BioCad Sprint, Perkin-Elmer) . The second buffer is a 100 mM Bis-Tris-Propane solution, buffered to pH 9, this buffer is connected to channel B of the chromatograph. Water is produced on resin by a Milli-Q system with a resistance of 18 MΩcm. the water is connected to channel C. A solution of sodium chloride (NaCl, Prolabo, 99.5%) purity) is connected to channel C. 3 M. Soda solution is connected to channel F NaOH, Prolabo, 98% minimum purity) 0.1 M. Lane E is used to load the culture supernatants on the columns. All buffers are made from water produced by the Milli-Q system, the buffers are not degassed.

. Columns

Blue Sepharose 6 fast flow (pharmacia):

The first step is carried out with a column of Blue Sepharose 6 fast flow

(Pharmacia). The matrix is agarose coupled with Blue sepharose 6 fast flow

Blue 3 G (7%>). The particle size is between 45 and 165 μm. The maximum linear flow is 750 cm / hr. The gel is stable at pH between 4 and 12, at extreme pH 2 and 14, the gel can be damaged, which leads to a decrease in the fixing capacity (decoupling of Blue sepharose 6 fast flow) and an increase in pressure. (formation of fines).

Blue Sepharose 6 fast flow is specific for components like albumin, kinases, dehydrogenases and other enzymes containing cofactors like NAD ⁺ , coagulation factors, interferons and lipoproteins.

The theoretical fixing capacity of Blue sepharose 6 fast flow is around 15 to

20 mg of serum albumin per ml of gel.

The column volume used is approximately 5.5 ml of gel (Cl 0/10, Pharmacia), ie a theoretical capacity of 80 to 110 mg of albumin serum. The flow rate used is 2 ml / min (150 cm / hr) on the BioCad Sprint and 3.5 ml / min (260 cm / hr) with a Pharmacia detection system. The pressure does not exceed 2.5 bars and is mainly due to the DO measurement cells

Source 15Q:

The second step is carried out with a Source 15Q column (pharmacia), a strong anion exchanger. The matrix is polystyrene crosslinked with divinylbenzene. The size of the beads is 15 μm and is homogeneous. The beads are traversed by a network of pores with a size varying from 20 to 1000 nm. These gels are very resistant to pressure and accept high linear flow rates (1800 cm / hr and more) while keeping a satisfactory resolution and capacity. This is made possible thanks to the homogeneity of the beads and their porosity which increase the molecules' access to the functional groups. The gel is stable at pH between 2 and 12 beyond the gel may suffer significant damage which reduces its capacity.

The theoretical binding capacity of this exchanger is approximately 25 mg of proteins per ml of gel. A 0.8 ml column is used (PEEK column 4.6 mm ID / 50 mm L, Perkin-Elmer), ie a maximum capacity of 20 mg of proteins. The actual capacity, which allows good resolution to be maintained, is around 10%) of this maximum capacity, ie 2 mg of protein. The flow rate used is 5 ml / min (1880 cm hr) and allows rapid separations. The column is packaged with the Poros selfPack system at 15ml / min at 150 bars.

. Chromatograph (BioCad Sprint)

The BioCad is an HPLC system (High Performance Liquid Chromatography) which allows to work at high pressures (maximum 204 bars) and at flow rates ranging from 0.2 to 60 ml / min. You can connect up to 6 buffers (the 6 channels are currently used), and the system can be treated with 0.1 M sodium hydroxide (pH 12) for the depyrogenization of the tubing and the column.

The separations can be carried out at ambient temperature or at 4 ° C. The samples are loaded either by one of the accessible routes or by injection loops for small volumes (from 100 μl to 5 ml). The detection system uses a double-channel UV cell: from 190 to 450 nm for UV and from 366 to 700 nm for the visible. Conventionally, detection at 254 nm is used for nucleic acids and detection at 280 nm for proteins (those are amino acids with a benzene ring such as tyrosines, tryptophanes and phenylalanines which absorb). The system is fully computer controlled (software developed by Perspective biosystem). For each separation, all the parameters (pressure, flow, conductivity, optical density, pH, etc.) can be checked. Finally, the separate sample is either recovered in a 50 ml Falcon tube or collected in silicone eppendorf tubes (Advantec SF-2120 collector) to minimize non-specific interactions.

. Production of exosomes from dendritic cells.

First, dendritic cells are obtained from monocytic precursors of peripheral blood. The isolated monocytes are cultured in the presence of a combination of GM-CSF and IL-13 or IL-4 (see the techniques described in application WO99 / 03499). For the production of exosomes it is preferable to use a population of immature dendritic cells.

4.2) Stage of Blue Sepharose 6 fast flow.

The culture supernatants are centrifuged twice at 600 g and once at 10,000 g before being loaded onto the column of Blue Sepharose 6 fast flow. A 5.5 ml column is used, the flow rate is 2 ml / min (linear flow rate of 150 cm / h, contact time of 2.7 min), the pressure is around 2.5 bars ( fig 5). The column is equilibrated in 12 mM BTP buffer, 150 mM NaCl and pH 7. After equilibration, the supernatant is loaded onto the column and then this is washed with the same equilibration buffer until the DO goes down again Elution fixed proteins are produced in 12 mM BTP, 1.5 M NaCl and pH 7 (in 3 to 4 column volumes). The column is regenerated by passing water (2 to 3 column volumes), then 2 volumes of 0.1 M sodium hydroxide (pH 12) are passed, finally, the column is rebalanced in 12 mM BTP, 150 mM NaCl and pH 7. Quantitative and qualitative aspect of the Blue sepharose 6 fast flow stage:

As described before, the Blue sepharose 6 fast flow step is specific for proteins such as albumin, which is a major contaminant of the culture supernatant. The protein concentration of each fraction of the Blue sepharose 6 fast flow step is measured by a Biorad technique (measurement of an OD at 600 nm). The results are collated in Table 1.

Table 1. Protein concentrations in each fraction of the Blue sepharose 6 fast flow step.

Most of the protein is found either in the eluate (72%) or in the regeneration (32%). The non-adsorbed fraction represents only 7 to 10% of the total proteins loaded on the column of Blue Sepharose 6 fast flow. The step is specific for major contaminants of the supernatant. To verify this specificity of Blue Sepharose 6 fast flow, each fraction is deposited on an SDS-PAGE gel in a reducing condition and stained with silver nitrate. The overload of the column (50 ml of supernatant loaded on a column of Blue sepharose 6 fast flow of 5.5 ml) made it possible to calculate the maximum amount of proteins, of culture supernatant, which it is possible to load on the column by ml of gel (Table 2). In this case the percentage of the non-adsorbed fraction increases from 7 to more than 30% of the amount of protein loaded. This value is between 16 and 18 mg of protein per ml of Blue Sepharose 6 fast flow gel. In conclusion, 1 ml of Blue Sepharose 6 fast flow gel makes it possible to purify approximately 5 to 6 ml of culture supernatant (AIMV 2.5%> of HSA). This value becomes important for the study of scale up since it determines the size of the column to be used and therefore the cost of this step.

Table 2. Study of the overloading of the Blue sepharose 6 fast flow support in the first step.

As expected, the major contaminant of the culture supernatants, after centrifugation at 600 and 10,000 g, is albumin. This contaminant is found, after fixing on the Blue Sepharose 6 fast flow, in the eluate and regeneration fractions. In addition to this contaminant, there are many other low and high molecular weight contaminants.

The Blue sepharose 6 fast flow stage allows the elimination of approximately 90 to 95%> of the contaminants from the culture supernatant. The exosomes are in the non-adsorbed fraction of Blue sepharose 6 fast flow (fig. 6).

4.3) Anion exchanger stage: source 15Q (Pharmacia). Using a 0.8 ml 15Q source column with a flow rate of 5 ml / min (linear flow rate of 1880 cm / h, contact time 0.1 min) with a pressure of the order of 50 bars. The non-adsorbed fraction of Blue Sepharose 6 fast flow is directly loaded on the 15Q source (fig. 7) without changes in the saline concentration (NaCl) or the pH.

After the fixing step, the column is washed in 12 mM BTP buffer, 280 mM NaCl at pH 7 (35 column volumes) until the DO drops to values close to 0. A second washing step is carried out. at a saline concentration of 150 mM NaCl (10 column volumes) to reinforce the interactions of the exosomes with the support.

A first gradient of 150 to 420 mM NaCl is produced in 7 column volumes (FIG. 8) then the gradient is stopped for 9 column volumes. The second gradient starts from 420 mM NaCl to 1 M NaCl in 25 column volumes. The exosomes are eluted in this second gradient in two peaks at 550 and 700 mM NaCl (fig. 8). The column is regenerated by passing 10 volumes of water column then by 10 volumes of 0.1 M sodium hydroxide column (pH 12) and finally by passing 10 column volumes of 3M NaCl. The column is then equilibrated in 12 mM BTP buffer, 150 mM NaCl, pH 7.

Quantitative and qualitative aspects of the source step 15Q.

As can be seen in FIG. 6, the major part of the proteins, of the non-adsorbed fraction of Blue Sepharose 6 fast flow, are not retained by the column. The protein concentrations were measured by a Biorad test (absorption of the OD at 600 nm) and are summarized in Table 3. Table 3. Quantitative aspects of the Source 15Q stage after a Blue sepharose 6 fast flow stage.

95%) of the proteins loaded on the Source 15Q column are not retained. The fractions pooled 4 to 6 and the fractions pooled 19 to 23 represent approximately 1.5%. Regeneration was not dosed. The yield is very close to 100%>: all of the proteins and charged vesicles are eluted from the column. In terms of protein load in the column, Source 15Q is capable of fixing approximately 25 mg of protein (manufacturer's data), i.e. for the 0.8 ml, 20 mg of protein. It is clear that we are very far from the maximum of the column and from 5 to 10% in agreement with good resolution, since these values are between 1 and 2 mg of proteins. Under these conditions, it is possible to purify, with a column of 0.8 ml of Source 15Q, between 200 and 400 ml of culture supernatant. Each elution peak is ultracentrifuged (100,000 g for 1 hour) and pooled to be observed by electron microscopy. The first peak (eluted between 150 and 420 mM NaCl) essentially contains proteins, cellular debris and a few vesicles marked with an anti-MHC IL antibody. The second peak (eluted at 550 mM NaCl), treated in the same way, shows a lower background noise, a much larger number of vesicles marked with an anti MHC II antibody, there is also heterogeneity in the size of the vesicles. . The third peak (eluted at 700 mM NaCl) no longer exhibits background noise, the vesicles are practically all marked with an anti-MHC II antibody and are much more homogeneous in size.

These two fractions (peak 2 and 3) are to be compared with what is obtained by the conventional method of purification by ultracentrifugation. In this case, there is a significant background noise and a large heterogeneity of the vesicles compared to the two chromatography peaks. In addition, it seems that there is a separation between the debris and the exosomes purified by HPLC which is not the case with ultracentrifugation.

4.4) Conclusions

In two chromatography steps, the first using a negative selection (Blue Sepharose 6 fast flow step) of the exosomes the second using a positive selection and a selective elution of the exosomes (Source step 15Q), we remove approximately between 99 and 99.5%> of the proteins of the culture supernatant while keeping the exosomes. The process maintains the integrity of the exosomes by electron microscopy. This process is therefore specific for the purification of exosomes.

By way of example, other columns retaining the proteins of the serum can be used. Furthermore, cationic macroporous columns can be used in place of the Source 15Q.

5) Purification by HPLC of exosomes produced from the RBL (Rat Basophilic Leukemia) line. The exosomes are produced from a RBL line (Rat Basophilic Leukemia) transfected in a stable manner to express, on the exosome membrane, molecules of the human MHC II (PCT / FR99 / 02691). After induction, by an ionophore (iomicyne), the cells degranulate and release exosomes in a protein-free medium (RPMI). After removal of cells by centrifugation at

600 g 10 min the supernatants are collected and treated with a DNase (Sigma) and a R ase (Sigma).

The treated supernatants are then centrifuged at 10,000 g at 37 ° C, 30 min, then at

100,000 g for 1 hour. The ultracentrifugation pellet is loaded onto an ion exchange column, Source

15Q, Pharmacia (fig. 9). A 0.8 ml column is used with a flow rate of 5 ml / min

(linear flow 1880 cm / h, contact time 0.1 min).

The column is equilibrated in 12 mM Bis-Tris-Propane (BTP) buffer, 150 mM NaCl and pH 7. After loading the sample, the column is washed with 15 to 20 column volumes of the same equilibration buffer. Elution is carried out with 25 column volume by varying the salt concentration from 150 mM to 1 M NaCl, the pH is kept constant (FIG. 9). The medium is very little contaminated with proteins since the cells are washed in PBS and the induction as well as the release of the exosomes is done in RPMI alone. This is confirmed by the low absorption observed (280 and 254 nm) in the non-adsorbed fraction of Source 15Q. The presence of the exosomes is confirmed by a western blot directed against the MHC II molecules (fig 11) after separation of the peaks by steps in NaCl (fig. 10) and ultracentrifugation of each of the peaks. 3 peaks are observed, plus a non-adsorbed fraction: a first peak eluted at 350 mM NaCl, a second peak eluted at 700 mM NaCl and finally a third peak eluted at 1.5 M NaCl. The peak at 700 mM is in the majority. In western blot directed against human MHC II molecules, a signal is found in peaks 1 (350 mM NaCl) and in peak 2 (700 mM NaCl). It should be noted that peak 1 which has a signal intensity, in proteins, 7 to 8 times less than peak 2 has a western blot signal equivalent to that of peak 2. This may reflect a higher purity of peak 1 To confirm this fact, the peaks were ultracentrifuged and observed by electron microscopy. Peak 1 is very rich in exosomes labeled with an anti-human MHC II antibody, there is little or no background noise. The exosomes are heterogeneous in size, there does not seem to be any separation of the exosomes not by their size but by a specific mechanism of competition between the eluent (NaCl) and the exosomes. The fractions between the two peaks were analyzed by electron microscopy. There are few exosomes there with a higher background noise than in peak 1.

Peak 2 is very similar to the fractions between the two peaks, there are few exosomes and greater background noise.

Conclusions

Source 15Q is capable of retaining exosomes and separating them from possible contaminants (fig. 9). The vast majority of exosomes are eluted in the same peak at 350 mM NaCl. In electron microscopy the exosomes appear "normal" with specific labeling of the molecules of human MHC II. The heterogeneity of the size of the exosomes (pic 1) seems to indicate that the separation is based on ionic exchanges and not on sieving. Source 15Q can therefore be used as a purification step for RBL exosomes.

Claims

1. Process for the preparation of membrane vesicles from a biological sample, characterized in that it comprises at least one step of treatment of the sample by anion exchange chromatography.

2. Method according to claim 1, characterized in that it comprises at least one step of strong anion exchange chromatography.

3. Method according to one of claims 1 and 2, characterized in that it comprises at least one step of anion exchange chromatography and gel permeation.

4. Method according to one of the preceding claims, characterized in that the biological sample is a biological fluid, a culture supernatant, a cell lysate or a prepurified solution.

5. Method for preparing membrane vesicles from a biological sample, characterized in that it comprises at least: b) a step of enriching the sample with membrane vesicles, and, c) a step of treating the sample by anion exchange chromatography and / or by gel permeation chromatography.

6. Method according to claim 5, characterized in that it comprises a) the culture of a population of cells producing membrane vesicles (eg of exosomes) under conditions allowing the release of the vesicles, b) a step of enrichment of the sample with membrane vesicles, and, c) a step of processing the sample by anion exchange chromatography and / or by gel permeation chromatography.

7. Method according to claims 5 or 6, characterized in that the enrichment step comprises a clarification step, optionally followed by a concentration step.

8. Method according to one of claims 5 to 7, characterized in that the enrichment step comprises a step of affinity chromatography, preferably on dye.

9. Method according to claim 7 or 8, characterized in that the enrichment step comprises a low speed centrifugation step and / or filtration.

10. Method according to one of claims 7 to 9, characterized in that the enrichment step comprises at least one ultrafiltration step, in particular tangential.

11. Process for the preparation of membrane vesicles, characterized in that it comprises the following stages: a) the culture of a population of cells producing membrane vesicles (eg of exosomes) under conditions allowing the release of the vesicles, b ) the treatment of the culture supernatant to produce a biological sample enriched in membrane vesicles (eg in exosomes) by at least one step of ultrafiltration or affinity chromatography, and c) a step of processing the biological sample by chromatography anion exchange and / or gel permeation.

12. The method of claim 11, characterized in that it further comprises a step d) of filtration of the harvested material.

13. Method according to any one of the preceding claims, characterized in that the membrane vesicles have a diameter between approximately 60 and 90 nm.

14. Method according to any one of the preceding claims, characterized in that the membrane vesicles are vesicles produced by cells presenting antigens, in particular dendritic cells, B lymphocytes, macrophages or mast cells.

15. The method of claim 14, characterized in that the membrane vesicles are vesicles produced by dendritic cells, in particular human.

16. Method according to one of claims 1 to 13, characterized in that the membrane vesicles are vesicles produced by tumor cells, in particular human.

17. A method of preparing membrane vesicles, characterized in that it comprises the following steps: a) obtaining a population of dendritic cells, b) culturing the dendritic cells under conditions allowing the production of membrane vesicles and, c) purification of the membrane vesicles by a process comprising at least one step of anion exchange chromatography.

18. A method of preparing membrane vesicles, characterized in that it comprises a) obtaining a population of dendritic cells, b) culturing dendritic cells under conditions allowing the production of membrane vesicles, c) treatment culture supernatant to produce a biological sample enriched in membrane vesicles, in particular by at least one ultrafiltration or affinity chromatography step, and, d) purification of the membrane vesicles by a process comprising at least one chromatography step d exchange of anions and / or gel permeation.

19. The method of claim 17 or 18, characterized in that the dendritic cells are obtained from a biological sample from a subject, for example bone marrow or peripheral blood.

20. Method according to claims 17 to 19, characterized in that the dendritic cells are immature.

21. Method according to one of claims 17 to 20, characterized in that the dendritic cells are sensitized to an antigen, prior to the production of the membrane vesicles.

22. Method according to one of claims 17 to 21, characterized in that, during step b), the dendritic cells are cultured under conditions stimulating the production of membrane vesicles.

23. Use of anion exchange chromatography for the preparation or purification of membrane vesicles.

24. Use of affinity chromatography for the preparation or purification of membrane vesicles.

25. Composition comprising membrane vesicles prepared by the method according to one of claims 1 to 22.