Patent Description:
Elastin is an extracellular matrix protein that is primarily found in skin, blood vessels, lung and other tissues and organs that require a degree of elasticity for function. It is classically formed when lysine residues on tropoelastin molecules become cross-linked with lysine residues on other tropoelastin molecules to form a mass that is more or less insoluble in an aqueous solution.

Elastin, tropoelastin and related proteins are expected to be useful in medical applications including tissue repair and restoration and there is a particular need for compositions having a high solids content of such proteins that can be administered to tissue by injection. While microparticles formed from biomaterials are mentioned in <CIT> and <CIT>, compositions with a less particulate structure having a high solids content of such proteins and properties of flow sufficient to enable tissue delivery by injection are not known. One problem has been that at high solids content, tropoelastin forms a mass that cannot be delivered through needles of varying gauges that are used in clinical and cosmetic applications.

There remains a need for compositions having a high solids content of tropoelastin or other elastic material and properties of flow that enable the composition to be delivered to tissue by injection.

Reference to any prior art in the specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in Australia or any other jurisdiction or that this prior art could reasonably be expected to be ascertained, understood and regarded as relevant by a person skilled in the art.

In certain embodiments there is provided a process for producing microparticles formed from tropoelastin as defined by the claims, including the step of coacervating or polymerising tropoelastin in a liquid phase having a coalescence-controlling agent dissolved therein.

As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

The inventors have found that when tropoelastin is coacervated and cross linked to form elastin, and/or subjected to alkali polymerisation to form an elastic material (as in <CIT>) at high solids content of tropoelastin, a mass is formed that cannot be passed through a surgical needle. The inventors have found that the non-injectable mass is formed because at high solids content the tropoelastin monomers aggregate or coalesce into microparticles or globules which further aggregate or coalesce to form a non-injectable mass. The inventors have further found that formation of the non-injectable mass at high solids content of tropoelastin may be reduced, if not avoided, by coacervating or polymerising tropoelastin in the presence of a coalescence-controlling agent, resulting in formation of a composition having high solids content and properties of flow required in an injectable composition. Further, it has been found that by adjusting the relative amounts of tropoelastin and coalescence-controlling agent it is possible to control the extent of aggregation of globules, hence producing a tropoelastin containing substance in the form of aggregated globules of predetermined size or structure with the desired properties of flow for injectable applications. It is also possible to produce a tropoelastin containing substance in the form of a mass that is also injectable but is substantially devoid of microparticular or globular structure. In this instance, the injectable material may be better described as a deformable mass than as discrete particles or globules. This is remarkable because normally masses formed from cross linked or alkali polymerised tropoelastin are not readily injectable. These embodiments are particularly advantageous in circumstances where a clinical or cosmetic application requires an implant which may be injected into the site of application.

It will be understood that "tropoelastin" refers to a protein that contains at least part of a hydrophobic domain derived from a protein molecule that may be cross linked, usually at lysine residues by lysyl oxidase, to form elastin. A number of isoforms of tropoelastin are known (see for example <CIT>). Tropoelastin cannot normally be found in any significant amount in tissue as it tends to be cross linked to form elastin more or less immediately after synthesis. Tropoelastin may have a sequence that is the same as the entry shown in GenBank entry AAC98394. Other tropoelastin sequences are known in the art, including, but not limited to, CAA33627 (Homo sapiens), P15502 (Homo sapiens), AAA42271 (Rattus norvegicus), AAA42272 (Rattus norvegicus), AAA42268 (Rattus norvegicus), AAA42269 (Rattus norvegicus), AAA80155 (Mus musculus), AAA49082 (Gallus gallus), P04985 (Bos taurus), ABF82224 (Danio rerio), ABF82222 (Xenopus tropicalis), P11547 (Ovis aries). Tropoelastin may also be a fragment of these sequences. An example is amino acids <NUM> to <NUM> of AAC98394. Another example of tropoelastin is described by UniProtKB/Swiss Prot entry P15502. The term tropoelastin is also intended to refer to an elastin like peptide or "ELP". Tropoelastin may be natural or recombinant. For example, tropoelastin may been obtained from a recombinant expression system, examples of which are discussed in <CIT> and <CIT>, and <CIT>, or from peptide synthesis such as solid phase peptide synthesis.

A "tropoelastin homolog" refers to a protein having a sequence that is not the same as, but that is similar to, a tropoelastin reference sequence. It also has the same function as the reference sequence.

"Elastin" refers to an extracellular matrix protein that is normally found in skin, blood vessels, lung and other tissues and organs that require elasticity for formation. It is formed when lysine residues on tropoelastin molecules are covalently cross linked to form a mass that is more or less insoluble in an aqueous solution. Cross linking of tropoelastin molecules in vivo classically occurs via one or more lysyl oxidases. Cross linking of tropoelastin molecules may be mediated in vitro by chemical cross linking agents such as glutaraldehyde or hexamethylenediisocyanate or other cross linking agents capable of reacting with proteins. Examples of amine-reactive cross linkers include disuccinimidyl glutarate (DSG), bis(sulfosuccinimidyl) suberate (BS3), ethylene glycol diglycidyl ether (EGDE) under neutral conditions (pH <NUM>), tris-succinimidyl aminotriacetate (TSAT), disuccinimidyl suberate (DSS) and □-[tris(hydroxymethyl)phosphino]propionic acid (THPP). Examples of carboxyl reactive cross linkers include <NUM>-ethyl-<NUM>-[<NUM>-dimethylaminopropyl]carbodiimide hydrochloride (EDC), and ethylene glycol diglycidyl ether (EGDE) under acidic conditions (pH<<NUM>). As tropoelastin may be provided in a variety of forms, elastin itself may be composed of a variety of structures, influencing the elastic properties of elastin. The degree of cross linking does not need to be complete, where all of the potential reactive sites in the tropoelastin molecules have been cross linked. Instead, the tropoelastin may be only partially cross linked.

"Coacervation" and "coacervating" refers to a process by which tropoelastin - which is generally soluble in aqueous solution at low temperatures - tends to aggregate to form a dense viscoelastic phase as temperature is raised to physiological range. The process is mainly due to interactions between the hydrophobic domains of tropoelastin. Coacervation is generally understood to be an essential precursor to covalent cross linking in the formation of elastin from tropoelastin.

An "elastic material" refers to a material formed from tropoelastin by an alkali polymerisation process involving the hydrophilic domains of tropoelastin as described in <CIT>, an irreversible process that forms a solid that has elastic properties in being stretchable, tensile, resilient and capable of recoil. The elastic material may be only partially polymerised; in certain embodiments the polymerisation reaction is not complete. Elastic material possesses elastic properties whether cross linked or not; the alkali polymerisation process to form elastic material may therefore optionally also include a chemical cross-linking step.

"Globules formed from tropoelastin" or "microparticles formed from tropoelastin" refer to particles that contain or consist of either or both of "elastin" and "elastic material". These particles tend to coalesce or aggregate further into a non-injectable mass in the absence of a coalesence-controlling agent.

An "injectable composition substantially devoid of particulate structure" is a composition formed from tropoelastin, in which the globules formed from tropoelastin have coalesced or aggregated to the point that the globular or particulate structure of the composition is no longer apparent. Despite this, the composition remains injectable.

"Coalescence-controlling agent" refers to a compound or extract that reduces, inhibits or otherwise controls aggregation, clumping or coalescence of particles or globules formed from tropoelastin, so as to permit the composition produced by a process of the invention as defined by the claims to be transmitted, generally by positive pressure through a needle or cannula having a bore or calibre generally used in clinical or cosmetic applications. The coalescence-controlling agent generally increases the viscosity of the liquid phase in which coacervation or polymerisation of tropoelastin to form elastin or an elastic material occurs. In certain embodiments, the coalescence-controlling agent limits the globules formed from tropoelastin from further coalescing with each other. In certain embodiments, the coalescence-controlling agent prevents or inhibits a tropoelastin-containing material that is substantially devoid of particulate structure from forming a non-injectable solid.

The phrase "an amount effective for reducing coalescence" refers to an amount of coalescence-controlling agent that is sufficient to inhibit, slow, retard or substantially prevent coalescence of globules formed from tropoelastin. It is not necessary that all globules are prevented from aggregating or coalescing with other globules. In certain embodiments it is preferable that further coalescence of globules may occur, provided that this does not substantially prevent the composition from being injected. In particular, in certain embodiments the amount effective for preventing coalescence provides for an injectable composition that is substantially devoid of particulate or globular structure.

An "injectable composition" refers to a composition that has properties that enable it to flow through a needle or cannula. Typically, the needle or cannula will have a bore or calibre generally used in clinical or cosmetic applications. In certain embodiments, the composition will pass without significant encumbrance through a needle or cannula with an internal diameter of about <NUM>, corresponding to a <NUM> gauge (G) needle. More preferably, the composition will readily pass through a <NUM> needle. More preferably still, the composition will readily pass through a <NUM> needle.

The term "tissue defect" refers to an abnormality, malformation or imperfection that culminates in abnormal tissue structure and/or function. A tissue defect may stem from, or be generally associated with a congential condition, a surgical procedure, trauma, disease or other injury. Alternatively, a tissue defect may be associated with aging. Examples include loss of tissue elasticity, loss of tissue volume, tissue wrinkling and sagging. "Tissue defect" may also refer to tissue that falls within the anatomically and physiologically normal range of structure and function that a patient considers is inadequate and wishes to augment.

"Correcting a tissue defect" refers to at least partially restoring and/or augmenting tissue structure and/or function, including supporting, enhancing, bulking, or elasticising tissue, or facilitating tissue growth into a tissue defect.

The term "therapeutically effective amount" means the quantity of injectable composition required to alter or correct the tissue defect. The effective amount may vary depending upon the patient's ability to absorb or break down the components of the injectable composition, the nature of the condition being treated, the site of the treatment, the composition of the injectable composition, the concentration and properties of the globules formed from tropoelastin, or alternatively the amount and nature of the tropoelastin-containing mass that substantially lacks particulate structure.

There is provided a process for producing a tropoelastin composition as defined by the claims. The produced tropoelastin composition can be an injectable composition for correcting a tissue defect, the composition including a liquid phase containing a plurality of particles or globules formed from tropoelastin, the liquid phase having a coalescence-controlling agent dissolved therein in an amount effective for reducing coalescence of the globules.

Typically, the average size of the globules formed from tropoelastin will range from <NUM> micrometers to <NUM> micrometers. The globules may be provided in the form of a sphere or microsphere. The preferred microsphere diameter range is generally from about <NUM> to <NUM>, preferably <NUM> to <NUM>. In certain embodiments the globules are substantially coalesced providing the composition with a non particulate appearance.

The tropoelastin is included in the composition in an amount from about <NUM>/mL to about <NUM>/mL. Preferably the tropoelastin is included in an amount from about <NUM>/mL to about <NUM>/mL. More preferably, tropoelastin is included in an amount of about <NUM>/mL to about <NUM>/mL.

As discussed herein, each globule is formed from tropoelastin meaning that the globule itself may include elastin, an elastic material or both. Accordingly the globules may be formed of covalently cross linked or non cross linked tropoelastin or both.

The produced injectable composition will typically possess a more particulate appearance, where the composition possesses discrete or, more typically, partially aggregated or coalesced globules when the concentration of tropoelastin is about <NUM>/mL and below. Without wishing to be bound by theory, it is believed that a particulate appearance results from a reduced level of globule coalescence or aggregation at lower concentrations of tropoelastin.

In other embodiments, there is provided an process for producing a tropoelastin composition as defined by the claims. The produced tropoelastin composition can be an injectable composition for correcting a tissue defect, the composition including aggregated globules formed from tropoelastin and a coalescence-controlling agent in an amount effective for reducing coalescence of the globules.

The produced injectable composition will typically possess a less particulate appearance when the concentration of tropoelastin is about <NUM>/mL and above. Again, without wishing to be bound by theory it is believed that increasing the concentration of tropoelastin results in increased globule coalescence or aggregation, resulting in an injectable composition with a reduced particulate or globular structure.

The composition produced according to the process of the invention includes a coalescence-controlling agent, especially an agent for providing the tropoelastin-containing substance with properties of flow.

Coalescence-controlling agents are generally biocompatible, for example, they may display low toxicity and be non-immunogenic. Coalescence-controlling agents may be synthetic, semi-synthetic or naturally derived molecules.

In one embodiment, the coalescence-controlling agent possesses a net negative charge when dissolved in the liquid phase. In another embodiment, the coalescence-controlling agent includes functional groups that possess a net negative charge when dissolved in the liquid phase.

In one embodiment, the coalescence-controlling agent includes strongly acidic functional groups, for example carboxylates, sulfates, phosphates etc. In another embodiment, the coalescence-controlling agent includes hydroxyl functional groups. The coalescence-controlling agent may be a polyol, possessing multiple hydroxyl functional groups.

In certain embodiments, the coalescence-controlling agent is a polysaccharide. Polysaccharides are polymeric carbohydrate structures, formed of repeating units (typically mono- or di-saccharides) joined together by glycosidic bonds. These structures are often linear, but may contain various degrees of branching. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure, these macromolecules can have distinct properties from their oligosaccharide building blocks.

Preferably, the polysaccharide contains negatively charged functional groups. In another preferred embodiment, coalescence-controlling agent is a polysaccharide that contains iduronic acid, glucuronic acid or N-acetylglucosamine residues. Suitable polysaccharides include, for example, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, hyaluronic acid, xanthan gum, guar gum, β-glucan, alginates, carboxymethyl dextran and their pharmaceutically acceptable salts. Alternatively, the polysaccharide may be a pectin or a derivative thereof, including linear and branched polysaccharides.

In another embodiment, the coalescence-controlling agent is a mono- or oligosaccharide, for example <NUM>'-N-acetylneuraminyl-N-acetyllactosamine, <NUM>'-sialyl-N-acetyllactosamine, <NUM>'-N-acetylneuraminyl-<NUM>-fucosyllactose, <NUM>'-sialyl-N-acetyllactosamine, N-acetylglucosamine, glucose, lactose, maltotritol, sucrose, LS-Tetrasaccharide b and their pharmaceutically acceptable salts and their pharmaceutically acceptable salts. Other coalescence-controlling agents include dextrins, such as succinyl-β-cyclodextrin, carboxymethyl-β-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, and their pharmaceutically acceptable salts.

A polysaccharide derivative may include but is not limited to a cross-linked or uncross-linked polysaccharide typically having a substitution or additional side chain comprising one or more groups consisting of hydrogen; alkyl; aryl; alkylaryl; arylalkyl; substituted alkylaryl containing an atom or atoms of oxygen, nitrogen, sulfur, or phosphorous; substituted arylalkyl containing an atom or atoms of oxygen, nitrogen, sulfur phosphorous, halogen, or metal ion; substituted heterocycle containing an atom or atoms of oxygen, nitrogen, sulfur; phosphorous, halogen or metal ion; and, where said substituted groups may be bound directly to each other or separated by a member selected from the group consisting of ether, keto, amino, oxycarbonyl, sulfate, sulfoxide, carboxamide, alkyne and alkene; including, where said substitutions or additional side chains terminate with groups including but not limited to hydrogen, peptide, aldehyde, amine, arylazide, hydrazide, maleimide, sulfhydryl, active ester, ester, carboxylate, imidoester, halogen or hydroxyl. In certain embodiments a polysaccharide derivative includes a polysaccharide which has been cross-linked using a chemical cross-linker including but not limited to divinyl sulfone (DVS), <NUM>,<NUM>-butanediol diglycidyl ether (BDDE), <NUM>,<NUM>,<NUM>,<NUM>-diepoxyoctane (DEO) or other crosslinkers generally known to those skilled in the art.

The coalescence-controlling agent may be a glycoprotein such as mucin.

In another embodiment, the coalescence-controlling agent is an amino acid. Preferably, the amino acid bears an acidic side chain. Suitable amino acids include aspartic acid, glutamic acid and their pharmaceutically acceptable salts.

In another embodiment, the coalescence-controlling agent is a lipid or fatty acid ester. Suitable fatty acid esters include, for example, phospholipids, dipalmitoyl phosphatidylcholide and glyceryl monooleate. The fatty acid esters may be used in conjunction with or more other agents. For example, propylene glycol and phospholipids may be used in conjunction with one another.

In another embodiment, the coalescence-controlling agent is a synthetic polymer. Such polymers include, for example, polymethacrylates, polyethylene glycols and (block) copolymers with polyethylene glycol subunits. For instance, the copolymers Poloxamer <NUM> and Poloxamer <NUM> may be suitable for use as coalescence-controlling agents.

In another embodiment, the coalescence-controlling agent is a surfactant. Examples of suitable surfactants include sodium lauryl sulfate and polysorbates.

Preferred coalescence-controlling agents include pantothenol, polyethylene glycols, xanthan gum, guar gum, polysorbate <NUM>, N-acetylglucosamine and their pharmaceutically acceptable salts. Particularly preferred coalescence-controlling agents are carboxymethylcellulose, hyaluronic acid, xanthan gum, hydroxypropylmethylcellulose and hydroxypropylcellulose and their pharmaceutically acceptable salts. Typically, when the coalescence-controlling agent is a polysaccharide, the agent is provided in the composition in an amount of from about <NUM> to about <NUM> percent (w/v). Preferably, when the coalescence-controlling agent is a polysaccharide, the agent is provided in an amount of from about <NUM> to about <NUM> percent (w/v).

When the coalescence-controlling agent is carboxymethylcellulose or xanthan gum, the agent may be provided in an amount of from about <NUM> to <NUM> percent (w/v). In a preferred embodiment, when the coalescence-controlling agent is carboxymethylcellulose or xanthan gum, the agent is provided in an amount of from <NUM> to <NUM> percent (w/v).

When the coalescence-controlling agent is hyaluronic acid, the agent may be provided in an amount of from about <NUM> to <NUM> percent (w/v). In a preferred embodiment, when the coalescence-controlling agent is hyaluronic acid, the agent is provided in an amount of from <NUM> to <NUM> percent (w/v).

When the coalescence-controlling agent is a PEG, the agent may be provided in an amount of from about <NUM> to about <NUM> percent (w/v).

It will be understood that the effective amount of coalescence-controlling agent provided is dependent upon a number of factors, for example, the properties of the coalescence-controlling agent, the nature of the other components of the composition, and the method used to form the composition. In particular, the effective amount of coalescence-controlling agent will be dependent upon the concentration of tropoelastin in the composition. Without wishing to be bound by theory, it is believed that the amount of coalescence-controlling agent required to prevent coalescence increases as the concentration of tropoelastin in the composition also increases. Moreover, the nature of the coalescence-controlling agent will affect its ability to control coalescence.

Accordingly, the invention provides for a process for producing a composition including tropoelastin and a polysaccharide coalescence-controlling agent as defined by the claims, wherein the mass ratio of tropoelastin to polysaccharide is from about <NUM>:<NUM> to <NUM>:<NUM>. Preferably, the ratio of tropoelastin to polysaccharide is from about <NUM>:<NUM> to about <NUM>:<NUM>. More preferably, the ratio of tropoelastin to polysaccharide is from about <NUM>:<NUM> to about <NUM>:<NUM>.

In embodiments, the invention provides for a process for producing a composition including tropoelastin and carboxymethylcellulose, wherein the mass ratio of tropoelastin to carboxymethylcellulose is <NUM>:<NUM> to about <NUM>:<NUM>. In certain embodiments, the mass ratio of tropoelastin to carboxymethylcellulose is about <NUM>:<NUM> to about <NUM>:<NUM>.

In further embodiments, the invention provides for a process for producing a composition including tropoelastin and xanthan gum, wherein the mass ratio of tropoelastin to xanthan gum is <NUM>:<NUM> to about <NUM>:<NUM>. In certain embodiments, the mass ratio of tropoelastin to xanthan gum is about <NUM>:<NUM> to about <NUM>:<NUM>. In further embodiments, the invention provides for a process for producing a composition including tropoelastin and hyaluronic acid, wherein the mass ratio of tropoelastin to hyaluronic acid is <NUM>:<NUM> to about <NUM>:<NUM>. In certain embodiments, the mass ratio of tropoelastin to hyaluronic acid is about <NUM>:<NUM> to about <NUM>:<NUM>.

In one embodiment the agent for providing a tropoelastin-containing substance with properties of flow excludes, or is not PEG or DMSO.

In other embodiments, the composition produced according to a process of the current invention as defined by the claims may also include a liquid phase. It will be understood that "liquid phase" generally refers to a biologically acceptable liquid vehicle that is suitable for injection. Typically, the solvent of the liquid phase will be water. Preferred liquid phases include aqueous solutions such as phosphate buffered saline (PBS). The liquid phase may include buffers such as phosphate, citrate, and other organic acids. In another embodiment, the liquid phase includes at least one agent intended to alter the ionic strength of the liquid phase.

The composition produced according to a process of the present invention as defined by the claims may include one or more additional agents active principles or ingredients. The additional agents may provide a therapeutic effect, such as the stimulation of tissue repair. Alternatively, the additional agents may prevent or limit an adverse tissue response. Still further, the additional agents may assist in the stability or viability of the injectable composition. In certain embodiments other compounds are provided as diluents, carriers, excipients or like compounds.

The additional agents may be present (either dissolved or suspended) in the liquid phase of the composition. Alternatively, the additional agents may be present in the globules of the composition.

In one embodiment, pharmaceutical agents, including antibiotics, growth promoters, anti-infectives, antiseptics, angiogenic compounds, anti-cancer agents, anti-inflammatory agents, protease inhibitors and the like, may be included in the composition.

In another embodiment, biological factors such as tissue factors, cytokines, growth factors and the like, may be included in the composition. Particularly preferred are those factors involved in wound healing, fibrosis and granulation.

In another embodiment cells, in particular, cells that are involved in wound healing, may be included in the composition. Examples include epithelial cells, fibrocytes, fibroblasts, keratinocyte precursors, keratinocytes, myofibroblasts, phagocytes and the like.

The composition may be packaged in a variety of ways including a container having deposited therein the composition in an appropriate form. Suitable containers are well-known to those skilled in the art and include materials such as bottles (plastic and glass), syringes, sachets, ampoules, plastic bags, metal cylinders, and the like. The container may also include a tamper-proof assemblage to prevent indiscreet access to the contents of the package. In addition, the container may have deposited thereon a label that describes the contents of the container. The label may also include appropriate warnings.

The invention provides a process for producing a composition formed from tropoelastin including the step of coacervating or polymerising tropoelastin in a liquid phase having a coalescence-controlling agent dissolved therein.

An important advantage of the process is that the composition produced by it may be injected without further manipulation or processing steps. This is a distinguishing aspect of the invention, as many of the compositions of injectable biomaterials currently known in the art require further processing steps (for example, washing to remove cross linking agents) before they can be injected.

Another important advantage of the process is that the composition produced from the process contains a high tropoelastin solids content whilst still maintaining the injectable property of the composition. This is also a distinguishing aspect of the invention compared with other biomaterial-containing compositions known in the art.

Generally a solution of tropoelastin having a concentration greater than about <NUM>/mL is capable of forming an injectable composition of desirable integrity although lesser concentrations are also useful. In most applications the solution concentration is less than about <NUM>/mL. Therefore, a solution of tropoelastin having a concentration from about <NUM>/mL to about <NUM>/mL is preferable. More preferably, a solution of tropoelastin having a concentration between about <NUM>/mL to about <NUM>/mL is used. Most preferably, a solution of tropoelastin having a concentration of between about <NUM>/mL to about <NUM>/mL is used.

The salt concentration of the liquid phase may be controlled by adding salt, including any ionic compound, or low molecular weight species capable of affecting the osmolality of the solution. For instance, NaCl, KCI, MgSO<NUM>, Na<NUM>CO<NUM> or glucose may be used. A preferred salt is NaCl.

Where the intention is to form a composition formed from tropoelastin that consists of elastin (or cross linked tropoelastin), the solution temperature may be raised to physiological ranges of about <NUM>, so that a viscoelastic phase is formed. A cross linking agent such as glutaraldehyde may be added prior to this coacervation step or it may be added after.

Where the intention is to form a composition formed from tropoelastin including elastic material, a pH of about pH <NUM> or more is sufficient to cause an elastic material to form from the tropoelastin in the solution. The pH is generally kept from exceeding about pH <NUM> as above this the elastic material is less well formed. More preferably a pH of between about pH <NUM> and pH <NUM> is desirable. However, most preferably a pH of between about pH <NUM> and pH <NUM> is used. Other pH measures that could be used include <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. A cross linking agent such as glutaraldehyde may be added prior to the change in pH, or it may be added after.

Alkalinity can be adjusted by a number of approaches including <NUM>) directly adding a pH increasing substance to a solution of tropoelastin, <NUM>) by mixing a solution containing sufficient amounts of a pH increasing substance to cause it to be alkaline with a solution of tropoelastin. The pH increasing substance could be a base, buffer, proton adsorbent material. Examples including Tris base, NH<NUM>OH and NaOH have been found to be useful as pH increasing or controlling substances.

Where the pH is alkaline and less than about <NUM>, salt may be required to form the elastic material. Where salt is used, the concentration is generally more than <NUM> and may be up to <NUM>. Preferably, the salt concentration is between about <NUM> and <NUM>. More preferably, the salt concentration is about <NUM>. As pH decreases (and yet remains alkaline) below pH <NUM>, salt is required to cause formation of the elastic material and the amount of salt required increases as pH decreases. So for example, at about pH <NUM> to <NUM>, salt is required, for example a salt concentration equivalent to about <NUM> should be provided to the solution. In some embodiments, the solution is to have an osmolarity equivalent to that of mammalian isotonic saline (<NUM>) or less. In other embodiments, the solution is to have an osmolarity greater than <NUM>. The salt concentration may also be <NUM>.

The salt concentration of the solution may be controlled by adding salt, including any ionic compound, monovalent or divalent ions, or low molecular weight species capable of affecting the osmolality of the solution. For instance, NaCl, KCl, MgSO<NUM>, Na<NUM>CO<NUM> or glucose may be used. A preferred salt is NaCl.

Optionally, the liquid phase may be agitated during coacervation. The liquid phase may be agitated by mechanical means, for example through use of magnetic stirrer apparatus, manual mixing, or placement on an orbital shake.

The process according to the current invention may be carried out in sterile conditions to ensure that the compositions produced by the process are suitable for use in vivo.

In another embodiment, the pH of the composition may be adjusted to a value to within a physiologically acceptable range. In another embodiment, the ionic strength of the composition is adjusted to within a physiologically acceptable range.

In certain embodiments the tropoelastin composition produced by a process of the invention as defined by the claims may be provided in the form of a device, disposable or reusable, including a receptacle for holding the composition. In one embodiment, the device is a syringe. The device may hold <NUM> to <NUM> of the composition. More preferably the device may hold <NUM> to <NUM> of the composition. The composition may be provided in the device in a state that is ready for use for example in a cross linked form, or in a state requiring mixing or addition of further components, such as a cross linker (if cross linking is required).

In other embodiments there is provided a kit for use in one of the above described embodiments, the kit including:.

In certain embodiments the kit may contain one or more active principles or ingredients further to the globules. These active ingredients are described above.

The kit may comprise a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, blister pack, etc. The containers may be formed from a variety of materials such as glass or plastic. The container holds the composition or formulation thereof and may have a sterile access port (for example the container may be an intravenous solution bag or a vial having a stopper pierceable by a hypodermic injection needle). The label or package insert indicates that the composition is used for treating the condition of choice, such as tissue bulking. In one embodiment, the label or package insert includes instructions for use and indicates that the composition can be used to treat a disorder or a complication arising from a tissue defect.

The kit may comprise (a) a first container with the composition produced by the process of the invention; and (b) a second container with an active principle or ingredient contained therein. The kit in this embodiment may further comprise a package insert indicating that the composition and other active principle can be used to treat a disorder. Alternatively, or additionally, the kit may further comprise a second (or third) container comprising a pharmaceutically-acceptable buffer, such as bacteriostatic water for injection (BWFI), phosphate-buffered saline, Ringer's solution and dextrose solution. It may further include other materials desirable from a commercial and user standpoint, including other buffers, diluents, filters, needles, and syringes.

In certain embodiments there is provided a use of the composition produced by a process according to the invention as defined by the claims in the manufacture of a formulation or prosthesis for correcting a tissue defect, especially a defect requiring soft tissue or dermal augmentation.

In other embodiments there is provided a method of soft tissue of dermal augmentation, the method including administering an effective amount of a composition produced by a process according to the invention as defined by the claims to an individual in need of such treatment.

An individual suitable for treatment with this method may display minor symptoms of the aging process, for example, minor wrinkles around the eyes and mouth, minor wrinkles of the lips and a minor decrease in lip volume. Alternatively, the signs of aging may be more pronounced. For example, an individual may show more pronounced signs of aging, with deep set wrinkles and a deepening of the nasolabial fold. Additionally, there may be atrophy or sagging facial structures, such as the malar fat pads. Still further, an individual may wish to augment their appearance in the absence of any signs of aging, for example the individual may wish to augment their lip volume. In certain embodiments the composition may be injected intradermally, intracutaneously and/or subcutaneously. Injection of the composition provides a bulking or filling effect, reducing the appearance of wrinkles or folds, or alternatively providing an aesthetically pleasing effect.

Other tissue defects to which the composition produced by the process of the invention as defined by the claims may be applied include dermal scars arising from, for example, skin diseases (such as acne, mumps, chicken pox or measles), scars from trauma (injury or burns) or from surgical procedures.

Still other tissue defects to which the composition may be applied include gross tissue loss or atrophy, such as lipoatrophy in the facial region of HIV patients as a side effect of retroviral therapies.

In one embodiment there is provided a use of the composition produced according to a process of the invention as defined by the claims for the treatment of a condition associated with an incompetent sphincter. An individual suitable for this treatment may suffer from a condition or a disease such as, for example, intrinsic sphincter deficiency, urinary incontinence, gastrointestinal reflux disease or vesicoureteral reflux. Moreover, an individual suitable for this form of treatment may suffer from faecal incontinence.

Typically, the composition is administered to the site of the tissue defect by injection although other routes of administration may be appropriate depending on the nature of the tissue defect. When the composition is to be administered by injection, a range of needle gauges may be used. The gauge used depends upon, among other things, the nature of the tropoelastin-containing material (for example, its viscosity) and the nature of the defect (for example, the depth of the injection site). For example, when the composition is intended for use in tissue augmentation the needle gauge will generally be in the range of between about <NUM> and <NUM>. Typically, for dermal fillers the needle gauge will be in the range of between about <NUM> and <NUM>. Superficial dermis injections for fine wrinkles may use, for example, needles with a gauge in the range of <NUM>-<NUM> whilst a larger gauge needle such as a <NUM> or a <NUM> needle may be necessary for deep injections beneath the dermis. For incontinence applications, the needle gauge will generally be between about <NUM> to about <NUM>.

The composition may be administered over a number of treatments to correct the tissue defect and/or to achieve or to maintain the desired result.

The examples that follow are intended to illustrate but in no way limit the present invention.

<NUM> tropoelastin was dissolved in <NUM> Phosphate Buffered Saline (PBS) at <NUM> overnight (estimated <NUM> hrs) to provide a final tropoelastin concentration of <NUM>/ml. Keeping the solution on ice throughout, the starting pH of the solution was measured (pH <NUM>) and <NUM>µL <NUM> NaOH was added to take the pH of the solution to a value of <NUM>. The resulting solution was then incubated at <NUM> for <NUM> in a <NUM> tube before being removed from incubator and placed at room temperature.

The microparticles produced tend to coat the side of the tube. An SEM image of a sample of the solution (<FIG>) shows the presence of microparticles with an estimated diameter of <NUM>. The spheres tend to aggregate together due to the 'sticky' nature of the elastin material.

<NUM> tropoelastin was dissolved in <NUM> PBS at <NUM> overnight (estimated <NUM> hrs). Keeping the solution on ice throughout, the starting pH of the solution was measured (pH <NUM>) and <NUM>µL <NUM> NaOH was added to take the pH of the solution to a value of <NUM>. An additional <NUM>µL of PBS was added to make a tropoelastin solution with a final concentration <NUM>/mL. The solution was then incubated at <NUM> overnight (<NUM> hrs) in a <NUM> flat bottomed tube before being removed from the incubator and placed at room temperature.

As can be seen in <FIG> the material produced was a solid elastic material that retained the shape of the tube it was prepared in. More than <NUM> of fluid separated from the resultant solid, suggesting the majority of the <NUM> Tropoelastin (><NUM>) was present in approximately <NUM> of liquid in the construct produced. In other words, the tropoelastin is significantly more concentrated in the solid compared to the starting material (<NUM>/mL) due to the dense aggregation of tropoelastin at this concentration in the absence of a coalescence-controlling agent.

A stock solution <NUM>/mL Tropoelastin was produced by dissolving <NUM> Tropoelastin in <NUM> PBS overnight at <NUM>. A stock solution of <NUM>% (w/v) high viscosity carboxy methylcellulose (CMC; Sigma Cat No.C5013) was produced by dissolving <NUM> CMC in <NUM> PBS with stirring overnight at room temperature. Keeping the solutions on ice throughout, <NUM>µL of the stock Tropoelastin solution was mixed with <NUM>µL PBS and <NUM>µL of the <NUM>% (w/v) CMC. A fresh vial of <NUM>% (v/v) Glutaraldehyde (GA) solution was opened on ice and <NUM>µL <NUM>% (v/v) GA was mixed with <NUM>µL PBS before being added immediately to the Tropoelastin solution. The resultant mixture of <NUM>/mL tropoelastin, <NUM>% (w/v) CMC, <NUM>% (v/v) GA was stirred using a cooled pipette tip (pipette tips were pre-cooled by placing at -<NUM> overnight) prior to being incubated at <NUM> for <NUM> hours in a <NUM> flat-bottomed tube.

The material produced appeared pink and viscous after <NUM> hours incubation and remained the same following the remainder of the <NUM> hour incubation period. The material could be passed through a <NUM> needle and then a <NUM> needle and appeared to become less viscous after needle passage. An SEM image of a sample of the material shows a homogeneous mix of globules with a range of diameters from approximately <NUM> to <NUM> (<FIG>). A low level of coalescence between the globules is evident in this formulation.

H<NUM>O (<NUM>) + PBS (<NUM>) was added to <NUM> freeze-dried tropoelastin and kept at <NUM> - <NUM> to dissolve - resultant concentration, as determined by measuring the UV absorbance at <NUM> of a <NUM>/<NUM> dilution in H<NUM>O, was <NUM>/ml. The concentration was determined using an extinction coefficient of <NUM>/mg.

A <NUM>% solution of HA was prepared in PBS by adding autoclaved PBS to <NUM> of HA (final volume of <NUM>) and stirring with a magnetic stirrer. The sample was stored at <NUM> - <NUM>.

A <NUM>% solution of glutaraldehyde was prepared by adding <NUM>µL of <NUM>% GA to <NUM>µL of PBS and mixing in an Eppendorf tube. All tips were chilled at < <NUM> prior to use.

All components were kept on ice until needed. The required amount of HA, PBS and tropoelastin stock solutions were combined in a <NUM> tube on ice using a pipette. The resultant composition was mixed using a magnetic stirrer at <NUM> - <NUM> for <NUM> minutes and spun briefly in a centrifuge to remove any air bubbles. Glutaraldehyde was added and the resultant composition was mixed using a magnetic stirrer at <NUM> - <NUM> for a further <NUM> minutes. The stirring bar was removed; the sample spun briefly in a centrifuge to remove any air bubbles and then incubated at <NUM> for <NUM> hours. Final composition: <NUM>/ml tropoelastin, <NUM>% HA, <NUM>% glutaraldehyde.

The material produced appeared as a pink viscous gel. The material could be passed directly through a <NUM> needle and did not change appearance after passage through the needle. An SEM image of a sample of the material (<FIG>) shows a homogeneous mix of globules with an approximate diameter of <NUM>. Clear connectivity between the globules is evident. SEM analysis of the material after extrusion through a <NUM> needle and following a wash in excess water or PBS revealed no changes to the structure of the material.

A stock solution <NUM>/mL Tropoelastin was produced by dissolving <NUM> Tropoelastin in <NUM> PBS overnight at <NUM>. A stock solution of <NUM>% (w/v) hyaluronic acid (HA sodium salt from human umbilical cord; Sigma Cat No.H1876) was produced by dissolving <NUM> HA in <NUM> PBS overnight at <NUM>.

In order to produce a titration of Tropoelastin concentration against that of the HA the following samples were prepared by mixing the appropriate solutions on ice:.

All samples were then incubated at <NUM> overnight (<NUM> hrs) in a <NUM> flat-bottomed tube.

The material produced was a homogeneous white liquid that could be passed through a <NUM> needle after sequential extrusions through an <NUM>, <NUM>, <NUM> and <NUM> needle. An SEM image (<FIG>) of the resultant solution reveals a relatively homogeneous mix of coalescing globules formed from tropoelastin with a range of diameters from approximately <NUM> to <NUM>.

The material produced was a thick white paste formed at the bottom of the tube and covered by a white liquid. The paste could be mixed into the rest of the solution; however, the solution remained fairly heterogeneous and clogged up a <NUM> needle - it is likely that the material could be extruded through a broader gauge needle such as <NUM> [N. extrusion was attempted directly into a fixed <NUM> needle only - no sequential extrusion approach was tried here]. An SEM image (<FIG>) of the resultant solution after mixing demonstrates the presence of coalesced globules with a range of diameters from approximately <NUM> to <NUM>.

The material produced was a thick white paste/solid formed at the bottom of the tube. This paste could be partially mixed into the above liquid however this gave rise to a heterogeneous suspension that contained chunks of solid material. It could not be passed through a <NUM> needle although it is likely that the material could be extruded through a broader gauge needle such as <NUM> [N. extrusion was attempted directly into a fixed <NUM> needle only - no sequential extrusion approach was tried here]. An SEM image (<FIG>) of the resultant solution after mixing demonstrates the presence of coalesced globules with a range of diameters from approximately <NUM>-<NUM>.

The material produced was a thick white paste/solid formed at the bottom of the tube. This paste could be partially mixed into the above liquid however this gave rise to a heterogeneous suspension that contained chunks of solid material. It could not be passed through a <NUM> needle, although it is likely that the material could be extruded through a broader gauge needle such as <NUM> [N. extrusion was attempted directly into a fixed <NUM> needle only - no sequential extrusion approach was tried here]. An SEM image (<FIG>) of the resultant solution after mixing demonstrates the presence of coalesced globules with a range of diameters from approximately <NUM>-<NUM>.

Using the above SEM images the size distribution of the globule diameters is shown in <FIG>. As the Tropoelastin concentration increases the globule size and level of coalescence increases.

A <NUM>/mL Tropoelastin solution was produced by dissolving <NUM> Tropoelastin in <NUM>µL PBS overnight at <NUM>. A stock solution of <NUM>% (w/v) high viscosity carboxy methylcellulose (CMC; Sigma Cat No.C5013) was produced by dissolving <NUM> CMC in <NUM> PBS overnight with stirring at room temperature. Keeping the solutions on ice throughout, <NUM>µL Tropoelastin solution was mixed with <NUM>µL of the <NUM>% (w/v) CMC. A fresh vial of <NUM>% (v/v) Glutaraldehyde solution was opened on ice and <NUM>µL <NUM>% (v/v) GA was mixed with <NUM>µL PBS before being added immediately to the Tropoelastin solution. The resultant mixture of <NUM>/mL Tropoelastin, <NUM>% (w/v) CMC, <NUM>% (v/v) GA was stirred using a cooled pipette tip (pipette tips were pre-cooled by placing at -<NUM> overnight). The mixture was placed in an incubator at <NUM> and stirred using a magnetic stirrer for <NUM> hours. The solution was then refrigerated overnight (<NUM> hrs) without stirring.

The material produced was pink, opaque and viscous after the initial <NUM> hr incubation at <NUM>. Following refrigeration the material became slightly translucent (although remaining pink & viscous); however, on warming to room temperature it quickly became opaque once more. The material could be passed through a <NUM> needle. After passage through a needle the solution remained unchanged.

When viewed under the SEM the sample (<FIG>) showed coalesced globules of varying sizes.

<NUM>µl tropoelastin (<NUM>/ml) was added to <NUM>µl <NUM>% CMC on ice. After thorough mixing the pH of the solution was adjusted from <NUM> to <NUM> with <NUM>µl <NUM> NaOH and <NUM>µl PBS was then added while the sample remained on ice. The sample was then incubated at <NUM> for <NUM> with stirring and then stored at <NUM>. For a neutral sample the pH was then adjusted at room temperature from <NUM> to <NUM> with <NUM>µl of <NUM> HCl. The resulting solutions contained <NUM>/mL tropoelastin, <NUM>% (w/v) CMC.

The material produced was a homogeneous white liquid that could be passed through a <NUM> - <NUM> needle. An SEM image of the alkaline solution (<FIG>) and the neutralised alkaline solution (<FIG>) reveals material comprising of coalesced globules. Both materials are a translucent light brown viscous liquid at <NUM> becoming an opaque white/brown viscous liquid with warming.

Samples produced according to Example 4A and Example <NUM> were stored at <NUM> for greater than <NUM> days. After greater than <NUM> days the material was still amenable to injection and its appearance had not changed as judged by SEM.

<NUM>µl tropoelastin (<NUM>/ml) was added to <NUM>µl <NUM>% XG on ice and mixed thoroughly. A fresh vial of <NUM>% (v/v) Glutaraldehyde solution was opened on ice and <NUM>µL <NUM>% (v/v) GA was mixed with <NUM>µL PBS before being added immediately to the Tropoelastin solution. The sample was then incubated at <NUM> for <NUM> with stirring and then stored at <NUM>. The resulting mixture contained <NUM>/mL Tropoelastin, <NUM>% (w/v) XG, <NUM>% (v/v) GA.

The material produced was a translucent pink viscous gel at <NUM> becoming an opaque pink gel with warming. SEM imaging (<FIG>) shows the material is composed of accretions. The material could be passed through a <NUM> needle. After passage through a needle the solution remained unchanged.

<NUM>µl tropoelastin (<NUM>/mL) was added to <NUM>µl <NUM>% hydroxypropylcellulose (HPC) on ice and mixed thoroughly. A fresh vial of <NUM>% (v/v) Glutaraldehyde solution was opened on ice and <NUM>µL <NUM>% (v/v) GA was mixed with <NUM>µL PBS before being added immediately to the Tropoelastin solution. The sample was then incubated at <NUM> for <NUM> with stirring and then stored at <NUM>. The resulting mixture contained <NUM>/mL Tropoelastin, <NUM>% (w/v) HPC, <NUM>% (v/v) GA.

A pink-tinged, soft, bulky material was produced (<FIG>). SEM imaging (<FIG>) shows the material is fibrous with some evidence of accretions. The material could be passed through a <NUM> bore using a syringe.

Optimisation studies were performed to ascertain the possible limits of the mass ratio of tropoelastin: coalescence-controlling agent for a formulation of tropoelastin which is amenable to injection through needle gauges in the range of <NUM> - <NUM>. Samples in bold in the table below could not pass through a <NUM>/<NUM> needle.

The composition is a gel produced from a synthetic human tropoelastin generated by the Escherichia Coli species of bacteria, chemically crosslinked with glutaraldehyde in the presence of a <NUM>% solution of a cellulose derivative at pH = <NUM> and with a final tropoelastin concentration of <NUM>/mL.

The composition is indicated for mid-to-deep dermal implantation for the correction of moderate to severe facial wrinkles and folds, such as nasolabial folds.

The composition is supplied in a disposable syringe with a <NUM> x <NUM>/<NUM>" needle.

Claim 1:
A process for producing a tropoelastin composition comprising
providing tropoelastin, and
coacervating the tropoelastin in a liquid phase with a coalescence-controlling agent, wherein
(a) the concentration of tropoelastin in the tropoelastin composition is <NUM>/mL to <NUM>/mL; and
(b) the concentration of coalescence-controlling agent in the tropoelastin composition is <NUM>% (w/v) to <NUM>% (w/v).