Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
  • A61L27/3683—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix subjected to a specific treatment prior to implantation, e.g. decellularising, demineralising, grinding, cellular disruption/non-collagenous protein removal, anti-calcification, crosslinking, supercritical fluid extraction, enzyme treatment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/225—Fibrin; Fibrinogen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/227—Other specific proteins or polypeptides not covered by A61L27/222, A61L27/225 or A61L27/24
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/24—Collagen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/50—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
  • A61L27/52—Hydrogels or hydrocolloids
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
  • C12N5/0062—General methods for three-dimensional culture
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2430/00—Materials or treatment for tissue regeneration
  • A61L2430/40—Preparation and treatment of biological tissue for implantation, e.g. decellularisation, cross-linking
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N2513/00—3D culture
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N2533/00—Supports or coatings for cell culture, characterised by material
  • C12N2533/50—Proteins
  • C12N2533/54—Collagen; Gelatin
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N2533/00—Supports or coatings for cell culture, characterised by material
  • C12N2533/50—Proteins
  • C12N2533/56—Fibrin; Thrombin
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N2537/00—Supports and/or coatings for cell culture characterised by physical or chemical treatment
  • C12N2537/10—Cross-linking

Definitions

• This invention concerns tissue scaffolds, such as elastin-based tissue scaffolds and methods for forming such scaffolds.
• Elastin is an extracellular structural protein found in connective tissues such as skin, adipose, lung, tendon, ligament, arteries, or cartilage. Its primary function is to retain the shape of tissues after stretching or contraction and has load bearing properties (Banga, 1966; Gray, 1973). In vivo, elastin forms by the process of elastogenesis, through the assembly and cross-linking of the protein tropoelastin (encoded by the ELN gene).
• Tropoelastin typically consists of hydrophobic domains with many Gly, Val, Ala and Pro residues which often occur in repeats of several amino acids, such as Gly-Val-Gly-Val-Pro, Gly-Val-Pro-Gly-Val and Gly-Val-Gly-Val-Ala-Pro; and hydrophobic domains with many Lys and Ala residues which are important in cross-linking. Cross-linking of tropoelastin to form elastin is facilitated by lysyl oxidase.
• Elastin is one of the most stable and abiding proteins in humans with a half-life of 74 years. Its excellent structural and biological properties has attracted attention for tissue
• elastin provides elasticity to tissues and organs, and is abundant where elasticity is of primary importance, such as blood vessels, ligaments, in lung and in skin.
• elastin is a highly insoluble protein therefore, it remains a challenge to use it as a biomaterial (Leach et a/., 2005).
• This invention concerns the formation of a scaffold by cross-linking a composition comprising eiastin, such as solubilised eiastin.
• the invention also concerns a tissue scaffold comprising cross-linked eiastin.
• a method for forming a tissue scaffold comprising cross-linking a composition comprising solubilised eiastin.
• a method comprising cross-linking a composition, wherein the composition comprises eiastin that has been contacted by a solubiiising agent that can solubilise the eiastin.
• a method comprising: a) contacting eiastin with a solubiiising agent that is able to solubilise the eiastin; and b) cross-linking the eiastin composition formed in step a).
• a tissue scaffold comprising cross-linked, solubilised eiastin.
• the eiastin may be extracted or derived from a natural source.
• the eiastin may be derived from a mammalian source.
• the mammalian source may be a bovine source, such as bovine neck ligament, or a human source.
• the eiastin may be recombinant eiastin.
• Eiastin is a highly insoluble protein due to inter-chain cross-links. However, it can be solubilised (Daamen (2007)). Solubilised eiastin is also referred to as hydrolysed eiastin or eiastin peptides.
• solubiiising eiastin include treating it with 0.25 M oxalic acid at 100°C, or treating it with 1 M KOH in 80% ethanol.
• proteolytic enzymes capable of degrading elastic fibres including serine-type elastases from polymorphonuclear leukocytes and several metallo-elastases of monocyte/macrophage origin, also result in solubilised eiastin. Examples of hydrolysed forms of eiastin are show in the table below.
• Oxalic acid solubilisation Heterogeneous mixture average 60 kDa t ⁇ -;; ⁇ ] Oxalic acid solubilisation Heterogeneous mixture, average 3-10 kDa
• Elastin peptides obtained after oxalic acid hydrolysis can be coacervated after suspension in 10 mM sodium acetate with 10 mM NaCI set to pH 5.5 with acetic acid, followed by heating and centrifugation at 37°C. As a result of this, two fractions are formed, a-elastin (a viscous coacervate) and ⁇ -elastin (in the supernatant).
• the prior art has focussed mainly on using insoluble elastin in combination with other components, such as collagen, or has focussed on the ⁇ -elastin soluble component obtained following hydrolysis with oxalic acid and separation from ⁇ -elastin.
• solubilising elastin, and cross-linking the product of that solubilisation step can form a promising and cost-effective tissue scaffold. So, there is no requirement to separate or isolate fractions of elastin, such as separating or isolating a- e!astin and ⁇ -elastin.
• the solubilised elastin that is cross-linked may thus be considered crude or unfractionated.
• the invention may avoid the time, inconvenience and expense associated with isolating the ⁇ -elastin fraction.
• the invention may also improve total yield, as a step to separate ⁇ -elastin and ⁇ -elastin can be avoided.
• a method for forming a tissue scaffold comprising cross-linking a composition comprising unfractionated solubilised elastin
• a method comprising cross-linking a composition comprising elastin, wherein the elastin is unfractionated and the elastin comprises solubilised elastin.
• the method may involve contacting elastin with a solubilising agent that is able to solubilise at least some of the elastin and then cross-linking the resulting composition.
• the unfractionated elastin may thus be crude elastin in which there has been no purification, isolation, separation or refinement of one or more elastin fractions, or one or more different forms of elastin which result from the contact of elastin with a solubilising agent. For instance, there may not have been isolation of one or more soluble elastin fractions, or separation of an insoluble elastin fraction from a soluble elastin fraction.
• the composition may comprise different soluble forms of elastin.
• the composition may comprise elastin that has not been solubilised.
• the composition may thus comprise both soluble and insoluble forms of elastin.
• the elastin following contact with the solubilising agent, the elastin may not be subjected to centrifugation. There may be no fractionation, purification, isolation, separation or refinement of the elastin following contact with the solubilising agent.
• an effective elastin-based tissue scaffold can be formed without requiring fractionation of elastin, in which one or more fractions of elastin are isolated and the isolated fraction(s) are subsequently used to form a scaffold.
• the invention may not require isolation and utilisation of an a-elastin fraction.
• the present invention may not require conventional steps to fractionate the elastin, such as centrifugation and/or coacervation.
• compositions comprising both soluble and insoluble elastin may be used. This may provide a significant benefit over known methods.
• US2004/0136977 requires isolation of water- soluble elastin, involving centrifugation.
• JP2014183886 requires sequential rounds of acid fractionation of insoluble elastin, involving centrifugation.
• the invention does not encompass methods comprising cross-linking of tropoelastin by, for example, the cross-linking of tropoelastin by lysyl oxidase, or the products of such methods.
• Methods of the invention may comprise the step of solubilising the elastin. This may involve contacting the elastin with a solubilising agent that is able to solubilise at least some of the elastin. So, the invention may provide a method comprising: a) solubilising elastin to form a composition comprising unfractionated, solubilised elastin; b) cross-linking the product obtained from step a).
• a method comprising: a) solubilising elastin to form a composition comprising solubilised elastin; b) cross-linking the composition obtained from step a).
• a method comprising: a) contacting elastin with a solubiiising agent to form a composition comprising solubilised elastin; and b) cross- linking the composition obtained from step a),
• a method comprising cross-linking elastin that has been contacted with a solubiiising agent, wherein the elastin has not been fractionated.
• a method comprising cross-linking a composition, the composition comprising elastin, wherein the elastin is unfractionated and comprises solubilised elastin.
• tissue scaffold comprising cross-linked unfractionated solubilised elastin.
• tissue scaffold comprising cross-linked elastin, wherein the composition comprising cross-liked elastin has been formed by cross- linking a formulation comprising elastin that comprises solubilised elastin and wherein the elastin has not been fractionated.
• tissue scaffold comprising cross-linked eiastin, wherein the elastin has been contacted with a solubiiising agent and has not been fractionated.
• the scaffold may be prepared from a solution comprising 1 to 20% (w/v) elastin, for example 5 to 15% (w/v) elastin, such as around 10% (w/v) elastin.
• the elastin is, or has been, solubilised by contacting with acid, most preferably oxalic acid.
• a method of solubiiising elastin comprising contacting elastin with a solubiiising agent that is able to solubilise at least some of the elastin.
• the solubiiising agent is preferably an acid, more preferably oxalic acid.
• a method of solubiiising elastin comprising contacting elastin with an acid, preferably oxalic acid.
• the elastin is solubilised at a temperature less than 100°C, preferably at a temperature of less than or equal to 50°C, more preferably at a temperature of 15 to 30°C, such as room temperature.
• the acid, preferably oxalic acid may be at less than 1 M, preferably less than 0.75M, more preferably at 0.5 , or less than 0.5M.
• the acid may be at least 0.25M.
• the acid may be at 0.2M to 1M, for example 0.25 to 0.75M.
• the method of solubilising elastin, as described herein, is contrary to the established method of solubilising elastin using oxalic acid.
• the conventional method of solubilising elastin using oxalic acid is carried out at 100°C (see, for example, Daamen et al. (2007)).
• effective solubilisation for the purposes of forming a scaffold of the invention, may occur at temperatures less than 100°C.
• the treatment with oxalic acid at temperatures less than 100°C may lead to formation of a mixture comprising a- and ⁇ -elastin. If this is the case, methods of the invention may comprise cross-linking a- and ⁇ - elastin, and scaffolds of the invention may comprise cross-linked a- and ⁇ -elastin.
• compositions comprising solubilised elastin such as unfractionated solubilised elastin, may comprise some elastin that has not been solubilised.
• the composition may thus comprise a mixture of insoluble elastin and soluble elastin.
• the invention may thus provide a method comprising cross-linking a composition comprising soluble elastin and insoluble elastin.
• the invention may thus provide a tissue scaffold comprising cross-linked elastin, wherein the elastin comprises soluble elastin and insoluble elastin.
• the inventors have appreciated that complete solubilisation of the elastin to be cross-linked, may not be required to obtain an effective tissue scaffold.
• a method comprising cross-linking a composition comprising insoluble elastin.
• a tissue scaffold comprising cross-linked, insoluble elastin.
• Solubilisation, or contact with acid preferably takes place for at least 30 seconds, more preferably at least one minute.
• the solubilisation or contact with acid may take place for about 1 to 3 minutes.
• the solubilisation, or contact with acid may take place for up to 5 minutes.
• a method comprising contacting elastin with acid, preferably oxalic acid.
• contact with the acid takes place at a temperature less than 100°C, most preferably at a temperature of less than or equal to 50°C, more preferably at a temperature of 15 to 30°C, such as room temperature or ambient temperature.
• the method may further comprise cross-linking the resulting product.
• a method of forming a tissue scaffold comprising cross-linking a composition comprising a-elastin and ⁇ -elastin.
• tissue scaffold comprising a cross- linked composition comprising a-elastin and ⁇ -elastin.
• Cross-linking may occur using any one of a number of cross-linking agents or cross-linking techniques commonly known to those skilled in the art, such as chemical, radiation and dehydrothermal methods. References herein to "cross-linking" concern covalent cross-linking. Preferably, cross- linking is achieved non-enzymatically, using a chemical cross-linking agent.
• Cross-linking may occur in the presence of the solubilising agent (e.g. acid such as oxalic acid).
• the invention may provide, or make use of, a composition comprising elastin, a solubilising agent and a cross-linking agent.
• Suitable chemical cross-linking agents include: carbodiimide coupling agents such as N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) ; N- hydroxysuccinimide (NHS) , azide coupling agents; diisocyanate cross-linking agents such as hexam ethylene diisocyanate; epoxide cross-linking agents such as epi- chlorhydrin, glycidylethers and glycidylamines; and aldehyde cross-linking agents such as formaldehyde, glutaraldehyde and glyoxal.
• carbodiimide coupling agents such as N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide (EDC) ; N- hydroxysuccinimide (NHS) , azide coupling agents
• diisocyanate cross-linking agents such as hexam
• the chemical cross linking agent may comprises N- (3- dimethylaminopropyl)-N'- ethylcarbodiimide (EDC) and/or N-hydroxysuccinimide (NHS) .
• the chemical cross linking agent may comprise aldehyde cross-linking agents such as formaldehyde, glutaraldehyde and glyoxal.
• Aldehyde cross-linking agents may have the advantage of providing extracellular matrix compositions with improved biocompatibility.
• the aldehyde cross-linking agent is glutaraldehyde.
• glutaraldehyde as a cross-linking agent may provide an advantage of yielding an optimal cross-link density more rapidly than other aldehydes and is also capable of achieving a relatively high density of cross-linking.
• the chemical cross-linking agent is glutaraldehyde.
• the cross-linking agent may be present in an amount of about 0.2 to 5% (v/v), such as 0.5 to 3% (v/v), preferably 0.5 to 1.5% (v/v), e.g. 1% (v/v).
• the method according to the invention may additionally comprise the addition of a toxicity reducing agent (e.g. lysine or sodium borohydride).
• a toxicity reducing agent e.g. lysine or sodium borohydride
• the step of cross-linking the composition comprising solubilised elastin may be carried out at a temperature of 20°C to 50°C, preferably about 37°C.
• Contact or incubation with the cross-linking agent may typically be performed between 1 minute and 24 hours (e.g. 4 hours).
• the cross-linking may take place for about an hour, or at least one hour.
• the cross-linking may take place in the presence of CO2, for example at least 2% CO2 (by volume), for example 2 to 10% CO2 (by volume), or at about 5% CO2 (by volume).
• solubilising agent for solubilising elastin for solubilising elastin, and a cross-linking agent.
• Methods of the invention may comprise casting the composition comprising solubilised elastin.
• Casting may comprise applying the composition comprising solubilised elastin to a mould of a predetermined shape. The casting may occur prior to or during cross-linking. It is preferred that methods of the invention comprise lyophilisation following cross-linking.
• the composition may be frozen at -80°C, preferably overnight, and then lyophiiised for about 48 hours. Preferably, lyophilisation occurs for at least 24 hours.
• composition comprising cross-linked elastin.
• a method comprising lyophilising a composition comprising solubilised and cross-linked elastin.
• a method comprising lyophilising a composition, the composition comprising cross-linked unfractionated solubilised elastin.
• a method of forming a tissue scaffold comprising lyophilising a composition comprising cross-linked elastin, wherein the composition comprising cross-liked elastin has been formed by cross-linking a formulation comprising elastin that is unfractionated and that comprises solubilised elastin.
• step b) solubilising elastin; b) cross-linking solubilised elastin obtained from step a); and c) lyophilising the product from step b).
• a method comprising: a) contacting elastin with a solubilising agent that is able to solubilise the elastin to form a composition comprising solubilised elastin; b) cross-linking the composition produced in step a); and c) lyophilising the product of step b).
• a tissue scaffold comprising lyophiiised, cross- linked elastin.
• tissue scaffold comprising lyophiiised, cross- linked, solubilised elastin.
• tissue scaffold comprising lyophilised, cross- linked unfractionated solubilised elastin.
• a method comprising lyophilising a composition comprising cross-linked a-elastin and ⁇ -elastin.
• tissue scaffold comprising lyophilised, cross-linked a-elastin and ⁇ -elastin.
• tissue scaffold comprising lyophilised, cross-linked elastin, wherein the cross-linked elastin has been formed by cross-linking a composition comprising soluble elastin and insoluble elastin.
• Methods of the invention may comprise washing or cleaning to remove agents involved in solubilising and/or cross-linking. Washing preferably takes place following solubilisation. This may include contacting or washing with a reducing agent, particularly if the cross- linking agent comprises an aldehyde cross-linking agent. Washing may comprise ultrasonic cleaning. For example, the scaffold may be washed using water in an ultrasonic cleaner. The presence of the reducing agent may stabilise the cross-linking process and result in a scaffold with enhanced biological efficacy. Furthermore, the presence of the reducing agent is likely to reduce the cytotoxic effects caused by the leaching of un-reduced cross-linking agent from the composition.
• a suitable reducing agent examples include sodium borohydride or agents with similar carbonyl group reactivity.
• the reducing agent may typically be added in an amount of 0.1% w/v to 10% w/v (e.g. about 1% w/v) .
• the step of washing to remove agents involved in solubilising and/or cross-linking may be carried out for at least 5 hours, preferably at least 8 hours.
• the scaffold may be washed with a reducing agent (such as sodium borohydride) for approximately 8 hours.
• a reducing agent such as sodium borohydride
• the scaffold is agitated or shaken whilst in contact with the reducing agent.
• there may be a further washing step, which may involve washing with water e.g. distilled water, and/or ethanol. This may help to remove any remaining unbound cross-linking agent or oxalic acid.
• a method comprising:
• a method comprising: a) contacting elastin with a solubilising agent that is able to solubilise the elastin; b) cross-linking the
• composition obtained from step a c) lyophilising the product obtained from step b); and d) washing the product of step c).
• the scaffold may be sterilised.
• sterilisation involves washing the scaffold with ethanol and PBS.
• a method comprising: a) solubilising elastin; b) cross-linking the composition obtained from step a); c) lyophilising the product from step b); d) washing the product from step c); and e) sterilising the product from step d).
• a method comprising: a) solubilising elastin; b) cross-linking a composition comprising unfractionated, solubilised elastin obtained from step a); c) lyophilising the product from step b); d) washing the product from step c); and e) sterilising the product from step d).
• a method comprising: a) contacting elastin with a solubilising agent; b) cross-linking the composition produced by a); c) lyophilising the product of step b); d) washing the product of step c); and e) sterilising the product of step d)
• Scaffolds of the invention are preferably sterile.
• a tissue scaffold obtained or obtainable by a method according to the invention.
• scaffolds of the invention are not hydrogels.
• ELPs are biopolymers based on key, repeating elastin sequences.
• ELPs may have repeating peptides, such as pentapeptides or hexapeptides comprising Val, Gly and/or Pro.
• ELPs may possess the elastic properties of elastin using the pentapeptide repeat VPGXG where X is any amino acid besides proline (such as Val or lie) (Zhang et al (2015), Daamen (2007)).
• a method comprising cross-linking elastin derivatives or fragments.
• tissue scaffold comprising cross-linked elastin derivatives or fragments.
• method comprising lyophilising cross- linked elastin derivatives or fragments.
• tissue scaffold comprising lyophilised cross-linked elastin derivatives or fragments.
• Scaffolds of the invention may comprise other extracellular matrix components.
• Scaffolds of the invention may comprise collagen. Consequently, according to the invention, there is provided a scaffold comprising efastin and collagen.
• Scaffolds of the invention may comprise fibrin. Consequently, according to the invention, there is provided a scaffold comprising elastin and fibrin.
• Scaffolds of the invention may comprise collagen and elastin. Consequently, according to the invention, there is provided a scaffold comprising elastin, collagen and fibrin.
• the elastin has been solubilised.
• the elastin is unfractionated, solubilised elastin.
• the elastin may be unfractionated.
• the elastin may comprise solubilised elastin.
• the elastin may comprise insoluble elastin.
• Scaffolds of the invention may be formed by mixing a composition comprising elastin with a) a composition comprising collagen; and/or b) a composition comprising fibrin.
• the composition containing collagen may comprise a collagen hydrogel.
• a collagen hydrogel may be formed by standard procedures.
• the collagen hydrogel may be prepared using 80% rat tail collagen type I and 10X Minimal Essential Medium, neutralised using 5M and 1 M sodium hydroxide and added 10X DMEM (Dulbecco's Modified Eagle Medium).
• the composition containing fibrin may contain a fibrin gel.
• the fibrin gel may be formed by standard procedures.
• the fibrin gel may be prepared with 2% fibrinogen dissolved in 1 ml of PBS, then adding 1 % thrombin with 0.1 M CaCI 2 .
• a method comprising mixing a composition comprising elastin (preferably a composition comprising unfractionated, solubilised elastin) with a composition comprising collagen (preferably a collagen hydrogel), and/or a composition comprising fibrin (preferably a fibrin gel).
• elastin preferably a composition comprising unfractionated, solubilised elastin
• collagen preferably a collagen hydrogel
• fibrin preferably a fibrin gel
• composition comprising elastin (preferably unfractionated, solubilised elastin), collagen and/or fibrin.
• the composition may comprise a cross-linking agent.
• composition comprising elastin is preferably mixed with the composition comprising collagen and/or the composition comprising fibrin, prior to a cross-linking step.
• the resulting scaffold may comprise cross-linked elastin, cross-linked collagen and/or cross-linked fibrin.
• composition comprising elastin; a solubtlising agent for solubilising elastin; a cross-linking agent; and fibrin and/or collagen.
• the cross-linking may proceed as already described herein.
• the cross-linking agent may comprise glutaraldehyde and may be carried out in the presence of C0 2 .
• the cross-linking agent may be added to the composition comprising the elastin, collagen and/or fibrinogen.
• the cross-linking agent may be added to the composition comprising elastin, the composition comprising collagen and/or the composition comprising fibrinogen, prior to mixing the compositions.
• the composition comprising elastin may comprise the cross-linking agent.
• the concentration of the cross-linking agent in the composition comprising elastin may be at a level (e.g.
• the concentration is at a desirable level for cross- linking to take place (e.g. about 1 % v/v).
• the composition Prior to cross-linking, the composition may be cast, as described herein.
• the scaffold may be lyophilised and/or washed, as described herein.
• the relative amounts of elastin, collagen and/or fibrinogen may be adjusted to impart different architectural, mechanical and biodegradation properties to the resulting scaffold. For example, scaffolds containing higher proportions of elastin may result in denser structural networks, greater elasticity and delayed degradation compared to scaffolds with lower proportions of elastin.
• Increasing the amount of fibrin may increase the mechanical strength and accelerate the biodegradation rate.
• Increasing the amount of collagen may also accelerate the biodegradation rate.
• Using particular combinations of elastin, collagen and/or fibrinogen may also allow enhancement of angiogenic properties of the scaffold.
• tissue scaffold according to the invention for use as a medicament.
• a method of promoting tissue healing, regeneration or repair comprising applying a tissue scaffold according to the invention, to a patient.
• the scaffold may be used in wound healing or tissue grafts (such as skin grafts).
• the scaffolds of the invention may be particularly applicable to soft tissue regeneration or repair, such as skin regeneration or vascular tissue regeneration.
• scaffolds may be used in adipose, skin, vascular grafts, heart valves or lung tissue engineering.
• a tissue scaffold according to the invention for use in promoting tissue healing, regeneration or repair.
• use of a tissue scaffold according to the invention in the manufacture of a medicament for promoting tissue healing, regeneration or repair
• the invention may provide a method substantially as described herein with reference to the figures.
• the invention may provide a tissue scaffold substantially as described herein with reference to the figures.
• a scaffold as described herein, seeded with cells may be in vitro or ex vivo.
• the cells may be stem cells, such as human adipose-derived stem cells (hADSCs).
• a method comprising seeding a scaffold of the invention with cells.
• a cell or tissue culture comprising a scaffold as defined herein.
• Scaffolds of the invention may have a mean pore size less than 120 pm. Scaffolds of the invention may have a mean pore size less than 100 pm. Scaffolds of the invention may have a mean pore size of 10 pm or greater. Scaffolds of the invention may have a mean pore size of 20 pm or greater. For instance, scaffolds of the invention may have a mean pore size of 10 to 120 pm. Scaffolds of the invention may have a mean pore size of 20 to 100 pm.
• the pore size distribution may be altered by including collagen and/or fibrin with elastin, or by changing the relative amounts of each component (see, for example, Figures 14 and
• Scaffolds of the invention may have a modal pore size of 80 pm or less.
• the modal pore size may be 60 pm or less.
• the modal pore size may be 1 pm or greater, for example 10 pm or greater, or 20 pm or greater.
• the modal pore size may be in the range of 1 to 80 pm, for example 1 to 60 pm, 20 to 60 pm, or 1 to 60 pm.
• the modal pore size may be in the range of 1-20 pm.
• the modal pore size may be in the range of 20 to 40 pm.
• the modal pore size may be in the range 40 to 60 pm.
• Characteristics of scaffolds such as pore size and porosity may be calculated using appropriate readily-available software.
• ND Nearest Distance
• DiameterJ is another example of an ImageJ plugin that can be used to measure pore parameters.
• Microscopic images of the scaffold e.g. SEM images may be used as input.
• the total porosity of scaffolds of the invention may be at least 25%.
• the total porosity may be at least 40%.
• Figure 1 shows elastin scaffold fabrication process from insoluble elastin (A), mixed with 0.5M oxalic acid (B), Crosslin ked with 1 % GTA and incubated at 37°C for 1 hour (C), frozen at -80°C overnight (D), and lyophilised for 48 hours (E);
• Figure 1 shows scaffolds fabricated without crosslinking agent (A), or with cross-linking agent (B);
• Figure 2 shows a scaffold stabilisation study without crosslinking agent (A), and with crosslinking agent (B) after 28 days in PBS;
• Figure 3 shows a live/dead assay at 1(A), 3 (B) and 7 (C) days for adipose derived stem cells (ADSC) growing on the scaffolds, with green points indicating alive cells;
• Figure 4 shows a cell proliferation assay using alamar blue at 1 , 3 and 7 days;
• Figure 6 shows scanning electron microscopy (SEM) images of elastin scaffolds
• Figure 1 1 shows water contact angle measurements per second for elastin-based scaffolds
• Figure 12 shows an accelerated degradation profile of an elastin scaffold over a period of time
• Figure 13 shows accelerated degradation profiles of elastin-based composite scaffolds
• Figure 14 shows SEM images of elastin scaffolds (50x and 10OOx) and pore % from 0-120+ pm;
• Figure 15 shows pore size pattern for elastin-based composite scaffolds
• Figure 16 shows mechanical testing of anelastin scaffold: p re-test scaffold (A), post-test scaffold (B), stress distribution on the scaffold (C) and break strength of the elastin scaffold (D) (*** denotes the statistical significance of p ⁇ 0.0001 );
• Figure 17 shows mechanical properties for elastin-based composite scaffolds
• Figure 18 shows developing chorio-allantoic membrane (CAM) on an elastin scaffold on embryonic day (ED) 12 (A), total vascular area (B), the processed image for CAM analysis(C) and a number of bifurcation points (D);
• CAM chorio-allantoic membrane
• Figure 19 shows Vascular area (%) for elastin-based composite scaffolds
• Figure 20 shows a gene expression profile of an elastin scaffold
• Figure 21 shows gene expression profiles for elastin-based composite scaffolds
• Figure 22 shows the difference in swelling ratio between Elastin/Collagen and Elastin/Fibrin scaffolds
• Figure 23 shows the difference in degradation profiles between Elastin/Collagen and Elastin/Fibrin scaffolds
• Figure 24 shows the microstructure of Elastin/Collagen and Elastin/Fibrin scaffolds using SEM
• Figure 25 shows the pore size of distribution of Elastin/Collagen and Elastin/Fibrin scaffolds
• Figure 26 shows the results of a live/dead assay for Elastin/Collagen and Elastin/Fibrin scaffolds
• Figure 27 shows the vascular area for Elastin/Collagen and Elastin/Fibrin scaffolds at day
• Insoluble elastin powder was obtained from Sigma (the source of elastin was derived from bovine neck ligament) (Fig. 1A). 100mg of insoluble elastin powder was mixed with 1ml of 0.5M oxalic acid (C2H2O4) (freshly prepared) at room temperature (Fig. IB).
• a homobifunctional cross-linking agent 1% glutaraldehyde (GTA) (v/v), was added to the solution (Fig.l C).
• GTA glutaraldehyde
• the solution was cast in a well of a 24 well plate and incubated at 37°C with 5% C0 2 for one hour (Fig.1 C).
• the mixture was frozen at -80°C overnight (Fig.l D) and lyophilised for 48 hours to form a scaffold (Fig.1 E).
• NaBH 4 sodium boro-hydride
• scaffolds were washed with distilled warm water (60° C) for 15 minutes and two washes of distilled water for 30 minutes each to remove remaining unbound glutaraldehyde from the scaffold.
• scaffolds were washed with 70% ethanol for 15 minutes and then with PBS.
• the fabricated crosslinked elastin scaffold was intact (Fig. 2B). However, the non- crosslinked scaffold was dismantled/disintegrated (Fig. 2A).
• An in vitro scaffold stabilisation study was carried out by comparing scaffolds with and without cross-linking for 28 days in PBS at 37°C and 5% C0 2 . It was found that non- crosslinked scaffolds (Fig. 3A) were dismantled/disintegrated after 28 days in PBS and in contrast crosslinked scaffolds were intact (Fig. 3B). This indicates that this method of fabrication effectively produced an integral scaffold.
• ADSCs adipose-derived stem cells
• Elastin scaffolds were washed with distilled water in an ultra-sonic cleaner for 3 minutes to remove salts and dried for 24 hours in a lyophiliser. Scaffolds were mounted on stubs and sputter- coated with carbon under vacuum. All images were obtained using a secondary electron detector in a Philips XL 30 Field Emission SEM, operated at 5 kV and average working distance was 10 mm.
• Figures 6A and 6B show that elastin scaffolds have an homogeneous structure and are porous in nature.
• Figure 6A is at 50x magnification and Figure 2 is at 250x magnification.
• This cell morphology can maintain ADSCs phenotype and multipotent characteristics without undergoing any differentiation (Zhang and Kilian, 2013).
• An increase in the alamar blue absorbance is an indication of constant cell proliferation.
• Tube 1 Elastin powder (9.7% w/v) + 0.5M oxalic acid + 3% glutaraldehyde (w/v).
• Tube 2 Collagen hydrogel - prepared using 80% rat tail collagen type I (v/v) (First Link, Birmingham, UK) and 10% of 10X Minimal Essential Medium (Invitrogen, Paisley, UK), neutralised using 5M and 1 M sodium hydroxide (Sigma-Aldrich, Dorset, UK) and added 10X DMEM.
• Tube 3 Fibrin gel - prepared with 2% fibrinogen (w/v) dissolved in 1 ml of PBS and for fibrillogenesis, 1% thrombin (w/v) was added along with 0.1 M CaCI2 Tubes 1 to 3 were mixed in varying ratios, cast and then incubated at 37°C with 5% CC1 ⁇ 2 for 1 hour. The final volume after mixing the 3 tubes was always 1ml, which was then cast.
• scaffold 3A For scaffolds that were 2:1 :1 (collagen/elastin/fibrin), 500 ⁇ of Tube 2 were mixed with 250 ⁇ of Tube 1 and 250 ⁇ of Tube 3 (Also referred to herein as scaffold 3A).
• scaffold 3B For scaffolds that were 2:1 :1 (elastin/collagen/fibrin), 500 ⁇ of Tube 1 was mixed with 250 ⁇ of Tube 2 and 250 ⁇ of Tube 3 (Also referred to herein as scaffold 3B).
• scaffold 3C For scaffolds that were 2:1 :1 (fibrin/elastin/collagen), 500 ⁇ of Tube 3 were mixed with 250 ⁇ of Tube 1 and 250 ⁇ of Tube 2 (Also referred to herein as scaffold 3C).
• scaffold 3D referred to herein as scaffold 3D
• the mixture was freeze-dried for 48 hours.
• ADSC adipose derived stem cells
• results for the three-component scaffolds show that ADSC were alive and adhered to the scaffold (Figure 7) and were proliferating until day 7 ( Figure 8).
• the same results were observed in two-component scaffolds (i.e. scaffolds comprising elastin and collagen, or elastin and fibrin).
• the wettability of the elastin scaffold was investigated by developing an experimental setup and a 30 ⁇ _ distilled water droplet was dispensed onto each scaffold and several images were taken over the time interval between 0 to 5 seconds.
• the time at 0 seconds was considered the initial time of contact with a liquid medium (water).
• the WCA was calculated using Young's equation and the angle was measured from the water-scaffold interface to the line tangent and perimeter of the water droplet (Fu et al (2014)).
• the calculated WCA is a demonstration of water-material interaction.
• the calculated WCA for elastin at 0 seconds was 102 ⁇ 7.75° and it was reduced to 73.88 ⁇ 5.90° at 4 seconds. Over the time WCA continued to decrease over time and at reached 0° at 9 seconds which indicated complete wettability of the elastin scaffold ( Figure 10).
• the degradation profile for the elastin-based co-polymers was identical for 3A.3C and 3D. By day 7 almost 40% scaffolds were degraded this pattern was continued until day 42 where almost 70% of scaffolds were degraded. However, 3B, which has 50% of elastin, was the most stable scaffold with 55% degradation until day 42 ( Figure 13). This shows that different degradation pattern of elastin-based scaffolds can be used for various tissue engineering application depending upon regenerative properties of each tissue type.
• the system includes 2 high-performance actuators with temperature-controlled media bath to avoid scaffold drying while testing cell-seeded scaffolds.
• a time synchronised high-resolution CCD camera was used.
• Pathogen-free fertilised eggs were obtained from a commercial supplier and incubated for 3 days at 38°C with 40-45% humidity.
• ED embryonic day
• 3 (ED 3) ex ovo glass bow! set-up was constructed to grow the embryonic culture and maintained at 37.5°C with 3% C0 2 and an average humidity in the range of 80-85% (3).
• elastin scaffold were placed on the developing chorio-allantoic membrane (CAM) to allow infiltration of blood vessels and at ED 12 embryos were euthanised as per home office guideline, and scaffolds were excised and fixed in 4% glutaraldehyde and analysed.
• CAM developing chorio-allantoic membrane
• a total calculated vascular area for ED 10 was 4.78 ⁇ 2.12% and this vascular area increased to 6.01 ⁇ 3.34% at ED 1 1 although this increment was not statistically significant but developed two large vessels with a number of capillary plexus. This trend continues to follow on ED 12 with the calculated vascular area was 8.34 ⁇ 2.67% (Figure 18).
• RNA was isolated by using TRIzol (Invitrogen, Paisley, UK) method on day 1,7 14 and total RNA yield was quantified by using spectrophotometer (Spectronic Camspec Ltd, Garforth, UK).
• cDNA synthesis was carried out using Precision nanoscript 2 reverse transcription kit (Primer Design, Southampton, UK) and quantitative PGR was performed with custom designed and synthesised primers (Table 1 ) (Primer Design, Southampton, UK).
• Oct-4 shows significant downregulation on day 7 and 14 (0.028, p ⁇ 0.0001 ) from day 1 ( 0.031 ).
• Rex-1 downregulated significantly on day 7 (0.026, p ⁇ 0.0001 )and 14 (0.029, p ⁇ 0.0001 ) in comparison to day 1 (0.031 ).
• expression on day 14 was significantly higher than day 7 (p ⁇ 0.0001 ), whereas MyoD-1 was constant at 0.032.
• CEBP showed a marginal upregulation on day 7 ( p ⁇ 0.05) and significantly downregulated to 0.025 on day 14 (p ⁇ 0.0001 ).
• Oct-4, RUX-2 and CEBP showed significant downregulation on day 7 and 14 (p ⁇ 0.0001 ) in comparison and there was no significant difference between expression on day 7 and 14 .
• Oct-4 showed a steady and significant downregulation from 0.030 on day to 0.029 on day 14 (p ⁇ 0.001 ).
• Rex-1 and RUNX-2 downregulated significantly (p ⁇ 0.0001 ) from 0.032 on day 1 to 0.030 and 0.029 respectively on day 7.
• Oct-4, CEBP, PPAR-gamma and MyoD-1 showed identical trend of significant downregulation by 0.04-0.06 units on day 7 and 14 in comparison to day 1 (pO.0001 )
• Figure 22 shows the difference in swelling ratio between Elastin/Collagen and Elastin/Fibrin scaffolds.
• Swelling ratio is an indication of the interaction between a solvent and a polymer. It shows exchange of the affinity and enthalpy between two phases. The higher the crosslinking density inside a polymer then the lower the swelling property, and vice-versa.
• the swelling ratio (SR)of the elastin and its composites was measured from dry mass and wet mass with the following equation
• M. where Md is the dry weight of the scaffold and M w is the wet weight of the scaffold.
• a wet mass of the scaffold was measured by immersing into 2ml of distilled water. Dry and wet mass measured with the digital scale (XS205 Mettler Toledo®) and the SR was calculated using equation (1 )
• Figure 23 shows the difference in degradation profiles between Elastin/Collagen and Elastin/Fibrin scaffolds.
• the experimental protocol was the same as described in Example
• Figure 24 shows the microstructure of Elastin/Collagen (A) and Elastin/Fibrin (B) scaffolds using SEM.
• Figure 25 shows the pore size of distribution of Elastin/Collagen and Elastin/Fibrin scaffolds. ⁇ Biological activity
• Figure 26 shows the results of a live/dead assay for Elastin/Collagen and Elastin/Fibrin scaffolds.
• the experimental protocol was the same as described in Example 1.
• Figure 27 shows the vascular area for Elastin/Collagen and Elastin/Fibrin scaffolds at day 12.
• the experimental protocol was the same as described in Example 7.
• DIJKSTRA P., VERMES, I. & FEIJEN, J. 2006. Electrospinning of collagen and elastin for tissue engineering applications. Biomaterials, 27, 724-734.
• alpha-elastin biomaterials towards a processable elastin mimetic scaffold. Acta Biomater, 1 , 155-64.

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