FIELD OF THE INVENTION

The present invention relates to the field of hemostatic sponges, a method of producing said sponges and their various uses.

BACKGROUND OF THE INVENTION

Biological glues based on coagulation factors of human or animal origin have long been known. A method for producing tissue adhesives based on fibrinogen and factor XIII has been described in U.S. Pat. Nos. 4,362,567, 4,298,598 and 4,377,572. The tissue adhesives are usually applied together with a separate component containing thrombin, which is enzymatically acting on fibrinogen to form fibrin, and on factor XIII to form the active factor XIIIa, which cross-links the fibrin to obtain a stable fibrin clot.

Collagen pads have been used for many years to improve wound healing or to stop bleeding. Their mechanism of action in hemostasis is based on platelets aggregation and activation, the formation of thrombin on the surface of activated platelets and the formation of a hemostatic fibrin clot by the catalytic action of thrombin on fibrinogen. To improve the hemostatic action of collagen pads or sheets it has been suggested to include factors of hemostasis within such pads.

In U.S. Pat. No. 4,600,574 a tissue adhesive based on collagen combined with fibrinogen and factor XIII is described. This material is provided in the lyophilized form, ready for use. The fibrinogen and factor XIII are combined with the collagen by impregnating the collagenous flat material with a solution comprising fibrinogen and factor XIII, and lyophilizing said material.

WO 97/37694 discloses a hemostatic sponge based on collagen and an activator or proactivator of blood coagulation homogeneously distributed therein. This sponge is provided in a dry form, which could be air-dried or lyophilized. However, it still contains a water content of at least 2%.

U.S. Pat. No. 5,614,587 discusses bioadhesive compositions comprising cross-linked collagen using a multifunctionally activated synthetic hydrophilic polymer, as well as methods of using such compositions to effect adhesion between a first surface and a second surface, wherein at least one of the first and second surfaces can be a native tissue surface.

WO2004028404 describes a tissue sealant composed of a synthetic collagen or gelatin and a electrophilic cross-linking agent which are provided in a dry state. Upon wetting of this composition at an appropriate pH a reaction between the 2 components takes place and a gel with sealing properties is formed. Such a sealant works in essential analogously to other known two component sealants (composed of a reagent with multiple electrophilic- and a reagent with multiple nucleophilic groups) which are known in the state of the art or which are available on the market, e.g. Coseal™. In a special embodiment of the invention the two components of the sealant (the electrophilic cross-linker and the synthetic collagen/gelatin) are coated onto a biomaterial.

Collagen-containing compositions which have been mechanically disrupted to alter their physical properties are described in U.S. Pat. Nos. 5,428,024, 5,352,715, and 5,204,382. These patents generally relate to fibrillar and insoluble collagens. An injectable collagen composition is described in U.S. Pat. No. 4,803,075. An injectable bone/cartilage composition is described in U.S. Pat. No. 5,516,532. A collagen-based delivery matrix comprising dry particles in the size range from 5 μm to 850 μm which may be suspended in water and which has a particular surface charge density is described in WO 96/39159. A collagen preparation having a particle size from 1 μm to 50 μm useful as an aerosol spray to form a wound dressing is described in U.S. Pat. No. 5,196,185. Other patents describing collagen compositions include U.S. Pat. Nos. 5,672,336 and 5,356,614.

SUMMARY OF THE INVENTION

The subject of the invention is a hemostatic porous composite sponge comprising

i) a matrix of a biomaterial and

ii) one hydrophilic polymeric component comprising reactive groups wherein i) and ii) are associated with each other so that the reactivity of the polymeric component is retained, wherein associated means that

said polymeric component is coated onto a surface of said matrix of a biomaterial, orsaid matrix is impregnated with said polymeric material, orboth.

It has been found that previous pads of fibrous biomaterials, in particular collagen pads, for wound healing failed to induce hemostasis at conditions with impaired hemostasis (e.g. after heparinization). The sponge according to the present invention improves hemostasis. Furthermore, the sponge according to the present invention shows a strong adherence to the tissue when applied to a wound. The sponge of the present invention further shows improved swelling behavior, i.e. low swelling, after application to a wound.

A further aspect relates to a method of treating an injury comprising administering a hemostatic porous composite sponge to the site of injury.

Also provided is a kit for preparing a wound coverage, comprising a sponge as herein disclosed and a buffer solution. This kit and its components are in particular for the manufacture of a medical sponge for the treatment of an injury.

In one aspect, embodiments of the present invention encompass a hemostatic porous composite sponge. Exemplary sponges may include a matrix of a biomaterial and one hydrophilic polymeric component having reactive groups. The biomaterial and polymeric component can be associated with each other so that the reactivity of the polymeric component is retained. The biomaterial and polymeric component can be associated so that the polymeric component is coated onto a surface of said matrix of a biomaterial, or so that the matrix is impregnated with the polymeric material, or both. The biomaterial can include collagen, gelatin, fibrin, a polysaccharide, e.g. chitosan, a synthetic biodegradable biomaterial, e.g. polylactic acid or polyglycolic acid, and derivatives thereof. The hydrophilic polymer can be a polyalkylene oxide polymer, esp. preferred a PEG comprising polymer, e.g. a multi-electrophilic polyalkylene oxide polymer, e.g. a multi-electrophilic PEG, such as pentaerythritolpoly(ethyleneglycol)ether tetrasuccinimidyl glutarate. In some cases, the biomaterial can be collagen and the polymeric component can be pentaerythritolpoly(ethyleneglycol)ether tetrasuccinimidyl glutarate. The polymeric form can be coated onto the collagen. In some cases, the biomaterial is collagen and the polymeric component is pentaerythritolpoly(ethyleneglycol)ether tetrasuccinimidyl glutarate, and the polymeric form is impregnated into the collagen.

In another aspect, embodiments of the present invention encompass the use of a sponge as described herein for the treatment of an injury such as a wound, a hemorrhage, damaged tissue and/or bleeding tissue. Embodiments also encompass methods of treating an injury such as a wound, a hemorrhage, damaged tissue and/or bleeding tissue. Exemplary methods of treating an injury may include administering a hemostatic sponge as described herein to the site of injury. In some instances, the sponge is applied to the injury together with a buffer solution, e.g. a bicarbonate solution, e.g. on a gauze.

In a further aspect, embodiments of the present invention include kits. For example, a kit may include one or more sponges as described herein, and a buffer solution, e.g. an alkaline buffer solution, such as a bicarbonate, together with instructions for its use.

In still another aspect, embodiments of the present invention encompass methods of manufacturing a hemostatic sponge. Exemplary methods may include, for example, providing a sponge having a matrix of a biomaterial in dried form, providing at least one reactive polymeric material in the form of dry powder, contacting the sponge or biomaterial and the polymeric material so that the polymeric material is present on at least one surface of the sponge, and fixing the polymeric material on the sponge. In some cases, the process of fixing can be achieved by melting at temperatures between 30° C. to 80° C., preferably between 60° C. to 65° C., for a time period sufficient for fixing, preferably between 1 minute to 10 minutes, especially about 4 minutes. In yet another aspect, embodiments of the present invention encompass methods for manufacturing a hemostatic sponge which may include providing a sponge having a matrix of a biomaterial in dried form, providing a reactive polymeric material in the form of a solution, contacting the sponge or biomaterial and the polymeric material so that the sponge or biomaterial is impregnated with the polymeric material, and drying the impregnated biomaterial. Exemplary embodiments further encompass sponges obtainable by the manufacturing methods described herein.

In another aspect, embodiments of the present invention encompass a hemostatic composite having a haemostatic material and a hydrophilic polymeric crosslinker with reactive groups. The composite can have pores which allow external fluids, especially human blood, to access into the composite. In some hemostatic composite embodiments, the haemostatic material is a non-woven or woven fabric of a haemostatic fiber or a porous haemostatic sponge. In some cases, the haemostatic material is a collagen sponge, a fabric of oxidized cellulose, a fibrin sponge, or a gelatin sponge. Embodiments of the present invention further encompass hemostatic composites where the hydrophilic polymeric crosslinker with reactive groups is a polyethylene glycol (PEG), preferably a PEG comprising two or more reactive from succinimidylesters (—CON(COCH2)2), aldehydes (—CHO) and isocyanates (—N═C═O), especially preferred succinimidylesters.

All patent filings, scientific journals, books, treatises, and other publications and materials discussed in this application are hereby incorporated by reference for all purposes. While the exemplary embodiments have been described in some detail, by way of example and for clarity of understanding, those of skill in the art will recognize that a variety of modification, adaptations, and changes may be employed. Therefore, the scope of the present invention is limited solely by the claims.

Those skilled in the art will readily understand that all preferred embodiments disclosed in the following are examples of specific embodiments, but are not necessarily limiting the general inventive concept. Furthermore, all special embodiments can be read on all inventive aspects and embodiments in any combination, if not mutually exclusive. All equivalents or obvious alterations or modifications as recognized by those skilled in the art are included by the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The object of the invention is a hemostatic porous composite sponge comprising a hemostatic porous composite sponge comprising

i) a matrix of a biomaterial and

ii) one hydrophilic polymeric component comprising reactive groups wherein i) and ii) are associated with each other so that the reactivity of the polymeric component is retained, wherein associated means that

said polymeric component is coated onto a surface of said matrix of a biomaterial, e.g. as a continuous or discontinuous layer on at least one surface of said sponge, orsaid matrix is impregnated with said polymeric material orboth.

The term impregnated as meant herein includes the term absorption of polymeric material in a matrix of a biomaterial.

The terms sponge, pad and fleece are used interchangeably in the description of the present invention.

Preferably the biomaterial is collagen, a protein, a biopolymer, or a polysaccharide. Especially preferred is a biomaterial selected from the group consisting of collagen, gelatin (especially cross-linked gelatin), fibrin, a polysaccharide (especially chitosan, oxidized cellulose, aldehyde activated dextrans, starch based polyaldehydes (obtainable by periodate oxidation)), a synthetic biodegradable biomaterial (especially polylactic acid or polyglycolic acid, and derivatives thereof, more preferred collagen.

According to the present invention a porous composite material comprising a water insoluble matrix of a biomaterial with hemostatic properties and a hydrophilic polymeric cross-linking agent in association therewith is provided.

Upon contact with bleeding tissue, a cross-linking reaction of the hydrophilic polymeric cross-linker with the blood proteins leads to formation of a gel with sealing and hemostatic properties. Cross-linking also occurs to the tissue surface proteins and, depending on the nature of the water insoluble matrix biomaterial, may also occur to the matrix biomaterial. The latter reaction contributes to an improved adhesion of the composite material to the wounded tissue surface. Furthermore, it is important for the hemostatic efficacy of the composite according to the present invention that the matrix of the biomaterial has soaking capabilities, i.e. is able to soak/absorb liquids such as blood, serum, plasma. Such soaking capabilities are especially dependent on the hydrophilic nature of the polymer the matrix is made of, and a three-dimensional structure of open interconnected pores, or of a three-dimensional meshwork of hydrophilic fibers. The pore size and the elasticity of the matrix are also important for the soaking capacity. Elasticity means that the matrix can be compressed in aqueous solution and returns to its initial volume after the force causing compression is relieved.

The sponge is a porous network of a biomaterial able to absorb body fluids when applied to the site of an injury. This allows the blood of a wound (including all the blood components, such as blood cells or coagulation proteins) to enter into the sponge. The porous sponge according to the present invention has therefore an inside volume which is accessible for external fluids, such as blood, when applied to a patient. For example, a porous collagen sponge can be made by lyophilization of a collagen gel, suspension or solution by freeze-drying (whereas normal air-drying leads to a collagen film). It follows that in the case of collagen, the resulting porous sponge according to the present invention has typically from 5 to 100 mg collagen/cm3, whereas collagen films have from 650 to 800 mg collagen/cm3. If external fluids, such as blood get in contact with the sponge according to the present invention, the hydrophilic polymeric component comprising reactive groups can react with the blood components and/or with the surface of the matrix of the biomaterial so as to crosslink the components which bind to the (at least two) reactive groups. Furthermore, the sponge is usually flexible and suitable to be applied on diverse tissues and locations with various shapes.

The collagen used for the present invention can be from any collagen material including liquid, pasty, fibrous or powdery materials that can be processed to a porous, especially a porous and fibrous matrix. The preparation of a collagen gel for the production of a sponge is e.g. described in the EP 0891193 (incorporated herein by reference) and may include acidification until gel formation occurs and subsequent pH neutralization. To improve gel forming capabilities or solubility the collagen may be (partially) hydrolyzed or modified, as long as the property to form a stable sponge when dried is not diminished.

The collagen or gelatin of the sponge matrix is preferably of animal origin, preferably bovine or equine. However, also human collagen might be used in case of a hypersensitivity of the patient towards xenogenic proteins. Also synthetic or recombinant collagen may be used. The further components of the sponge are preferably of human origin, which makes the sponge suitable especially for the application to a human.

In a preferred embodiment the porous collagen sponge contains about 5 to about 50, e.g. about 10 to about 30, preferably about 25 mg collagen/cm3of dry sponge.

The biomaterial may be non-crosslinked or crosslinked, preferably the biomaterial has been crosslinked.

The hydrophilic polymeric component of the sponge according to the present invention is a hydrophilic crosslinker which is able to react with its reactive groups once the sponge is applied to a patient (e.g. to a wound of a patient or another place where the patient is in need of a hemostatic activity). Therefore it is important for the present invention that the reactive groups of the polymeric component are reactive when applied to the patient. It is therefore necessary to manufacture the sponge according to the present invention so that the reactive groups of the polymeric component which should react once they are applied to a wound are retained during the manufacturing process.

This can be done in various ways. For example, usual hydrophilic polymeric components have reactive groups which are susceptible to hydrolysis after contact with water. Accordingly, premature contact with water or aqueous liquids has to be prevented before administration of the sponge to the patient, especially during manufacture. However, processing of the hydrophilic polymeric component during manufacturing may be possible also in an aqueous medium at conditions where the reactions of the reactive groups are inhibited (e.g. at a low pH). If the hydrophilic polymeric components can be melted, the melted hydrophilic polymeric components can be sprayed or printed onto the matrix of the biopolymer. It is also possible to sprinkle a dry form (e.g. a powder) of the hydrophilic polymeric component onto the matrix. If necessary, then an increase of the temperature can be applied to melt the sprinkled hydrophilic polymeric component to the matrix to achieve a permanent coating of the sponge. Alternatively, these hydrophilic polymeric components can be taken up into inert organic solvents (inert vis-à-vis the reactive groups of the hydrophilic polymeric components) and brought onto the matrix of the biomaterial. Examples of such organic solvents are dry ethanol, dry acetone or dry dichloromethane (which are e.g. inert for hydrophilic polymeric components, such as NHS-ester substituted PEGs).

In a preferred embodiment the hydrophilic polymer component is a single hydrophilic polymer component and is a polyalkylene oxide polymer, esp. preferred a PEG comprising polymer, in the following called “the material”. The reactive groups of said material are preferably electrophilic groups.

The material may be a multi-electrophilic polyalkylene oxide polymer, e.g. a multi-electrophilic PEG. The material can include two or more electrophilic groups such as —CON(COCH2)2, —CHO, —N═C═O, and/or —N(COCH2)2, e.g. a component as disclosed in the WO2008/016983 (incorporated herein by reference in its entirety) and one of the components of the commercially available ones under the trademark CoSeal®.

Preferred electrophilic groups of the hydrophilic polymeric crosslinker according to the present invention are groups reactive to the amino-, carboxy-, thiol- and hydroxy-groups of proteins, or mixtures thereof.

Preferred amino group-specific reactive groups are NHS-ester groups, imidoester groups, aldehyde-groups, carboxy-groups in the presence of carbodiimdes, isocyanates, or THPP (beta-[Tris(hydroxymethyl)phosphino] propionic acid), especially preferred is Pentaerythritolpoly(ethyleneglycol)ether tetrasuccinimidyl glutarate (=Pentaerythritol tetrakis[1-1′-oxo-5′-succinimidylpentanoate-2-poly-oxoethyleneglycolej ether (=an NHS-PEG with MW 10,000).

Preferred carboxy-group specific reactive groups are amino-groups in the presence of carbodiimides.

Preferred thiol group-specific reactive groups are maleimides or haloacetyls.

Preferred hydroxy group-specific reactive group is the isocyanate group.

The reactive groups on the hydrophilic cross-linker may be identical (homo-functional) or different (hetero-functional). The hydrophilic polymeric component can have two reactive groups (homo-bifunctional or heterobifunctional) or more (homo/hetero-trifunctional or more).

In special embodiments the material is a synthetic polymer, preferably comprising PEG. The polymer can be a derivative of PEG comprising active side groups suitable for cross-linking and adherence to a tissue.

By the reactive groups the hydrophilic polymer has the ability to cross-link blood proteins and also tissue surface proteins. Cross-linking to the biomaterial is also possible.

The multi-electrophilic polyalkylene oxide may include two or more succinimidyl groups. The multi-electrophilic polyalkylene oxide may include two or more maleimidyl groups.

Preferably, the multi-electrophilic polyalkylene oxide is a polyethylene glycol or a derivative thereof.

In a most preferred embodiment the polymeric component is pentaerythritolpoly(ethyleneglycol)ether tetrasuccinimidyl glutarate (═COH102, also pentaerythritol tetrakis[1-1′-oxo-5′-succinimidylpentanoate-2-poly-oxoethyleneglycole]ether).

In one preferred embodiment the sponge of the present invention comprises collagen as the biomaterial and the polymeric component, e.g. COH102, is coated onto the surface of the collagen (=coated form).

Especially preferred the coating is a discontinuous coating, e.g. such as shown inFIG. 6.

In another preferred embodiment the coating is a thin continuous coating, as obtained e.g. by spraying the polymeric component from the melt onto the matrix of biomaterial. Such a coating is comparable to a film-like or glass-like structure, e.g. such as shown inFIG. 7.

In another preferred embodiment the sponge of the present invention comprises collagen as the biomaterial and the polymeric component, e.g. COH102, is impregnated into the collagen (=impregnated form).

The molecular weight of the polymeric component is preferably in a range of 500 to 50000, most preferred about 10000.

The amount of coating of polymeric component on the sponge of said biomaterial is preferably from about 1 mg/cm2to about 20 mg/cm2, more preferred about 2 mg/cm2to about 14 mg/cm2for the coated sponge. The concentration of polymeric component is preferably from about 5 mg/cm3to about 100 mg/cm3, more preferred from about 100 mg/cm3to about 70 mg/cm3for an impregnated sponge.

In another preferred embodiment the sponge of the present invention comprises a combination of impregnated and coated forms. Further, the sponge according to the present invention preserves reactivity of the reactive groups of the hydrophilic polymeric component comprising reactive groups by being dry, e.g. having an overall water content of below 10%, especially below 2%, and especially below 1% in case the polymeric component has hydrolysable reactive groups, e.g. NHS-PEG. Higher water contents (e.g. higher than 10%) would also result in a functional sponge but storage stability would be worsened. Accordingly, water contents of below 2% (w/w) are preferred; below 1% is even more preferred; below 0.5% is specifically preferred.

In another preferred embodiment a further layer of a further biomaterial is present. The further layer can be from the same biomaterial as the matrix or it can be a different biomaterial, e.g. matrix of biomaterial is collagen and the further layer is oxidized cellulose. All combinations of biomaterials as mentioned above may be included.

The sponge as a whole can be biodegradable, being suitable for biological decomposition in vivo, or bioresorbable, i.e. able to be resorbed in vivo, e.g. via degradation by proteases which are present in vivo and groups which are hydrolyseable in vivo. Full resorption means that no significant extracellular fragments remain. A biodegradable material differs from a non-biodegradable material in that a biodegradable material can be biologically decomposed into units which may either be removed from the biological system and/or chemically incorporated into the biological system. In a preferred embodiment the particular material, the matrix material or sponge as a whole can be degraded by a subject, in particular a human subject, in less than 6 month, less than 3 month, less than 1 month, less than 2 weeks.

The sponge may further comprise an activator or proactivator of blood coagulation, including fibrinogen, thrombin or a thrombin precursor, as e.g. disclosed in U.S. Pat. No. 5,714,370 (incorporated herein by reference). Thrombin or the precursor of thrombin is understood as a protein that has thrombin activity and that induces thrombin activity when it is contacted with blood or after application to the patient, respectively. Its activity is expressed as thrombin activity (NIH-Unit) or thrombin equivalent activity developing the corresponding NIH-Unit. The activity in the sponge can be 100-10,000, preferably 500-5,000. In the following thrombin activity is understood to comprise both, the activity of thrombin or any equivalent activity. A protein with thrombin activity might be selected from the group consisting of alpha-thrombin, meizothrombin, a thrombin derivative or a recombinant thrombin. A suitable precursor is possibly selected from the group consisting of: prothrombin, factor Xa optionally together with phospholipids, factor IXa, activated prothrombin complex, FEIBA, any activator or a proactivator of the intrinsic or extrinsic coagulation, or mixtures thereof.

The hemostatic sponge according to the invention might be used together with further physiologic substances. For example, the sponge preferably further comprises pharmacologically active substances, among them antifibrinolytics, such as a plasminogenactivator-inhibitor or a plasmin inhibitor or an inactivator of fibrinolytics. A preferred antifibrinolytic is selected from the group consisting of aprotinin or an aprotinin derivative, alpha2-macroglobulin, an inhibitor or inactivator of protein C or activated protein C, a substrate mimic binding to plasmin that acts competitively with natural substrates, and an antibody inhibiting fibrinolytic activity.

As a further pharmacologically active substance an antibiotic, such as an antibacterial or antimycotic might be used together with the sponge according to the invention, preferably as a component homogeneously distributed in the sponge. Further bioactive substances such as growth factors and/or pain killers may be also present in the inventive sponge. Such a sponge might be useful in e.g. wound healing.

Further combinations are preferred with specific enzymes or enzyme inhibitors, which may regulate, i.e. accelerate or inhibit, the resorption of the sponge. Among those are collagenase, its enhancers or inhibitors. Also, a suitable preservative may be used together with the sponge or may be contained in the sponge.

Although a preferred embodiment relates to the use of the hemostatic sponge which contains the activator or proactivator of blood coagulation as the only active component, further substances that influence the velocity of blood coagulation, hemostasis and quality of the sealing, such as tensile strength, inner (adhesive) strength and durability might be comprised.

Procoagulants that enhance or improve the intrinsic or extrinsic coagulation, such as factors or cofactors of blood coagulation, factor XIII, tissue factor, prothrombin complex, activated prothrombin complex, or parts of the complexes, a prothrombinase complex, phospholipids and calcium ions, protamin, might be used. In case of a surgical procedure where a precise sealing is needed, it might be preferable to prolong the working period after the hemostatic sponge is applied to the patient and before clotting is affected. The prolongation of the clotting reaction will be ensured, if the sponge according to the invention further comprises inhibitors of blood coagulation in appropriate amounts. Inhibitors, such as antithrombin III optionally together with heparin, or any other serine protease inhibitor, are preferred.

It is also preferred to have such additives, in particular the thrombin or a precursor of thrombin evenly distributed in the material in order to prevent local instability or hypercoagulability of the material. Even with a certain water content the thrombin activity is surprisingly stable, probably because of the intimate contact of thrombin and collagen in the homogeneous mixture. Nevertheless, thrombin stabilizers preferably selected from the group consisting of a polyol, a polysaccharide, a polyalkylene glycol, amino acids or mixtures thereof might be used according to the invention. The exemplary use of sorbitol, glycerol, polyethylene glycol, polypropylene glycol, mono- or disaccharides such as glucose or saccharose or any sugar or sulfonated amino acid capable of stabilizing thrombin activity is preferred.

Other examples of additives which can be used according to the present invention include substances such as vasoconstrictors, antibiotics or fucoidans.

A sponge of the present invention may further contains a dye, e.g. riboflavin, or other dye known from the prior art to be biocompatible. The dye may be included e.g. as a further layer (coating) and may especially help the surgeon to identify which one of the surfaces of a coated sponge of the present invention is the active or inactive surface, respectively.

The sponge of the present invention preferably has an overall thickness of less than 3 cm, preferably about 1 mm to about 3 cm, more preferably about 1 mm to about 2 cm, most preferred about 1 mm to about 2 mm.

In a sponge of the present invention the thickness of the coating is preferably from about 0.01 mm to about 1 mm.

The sponge of the present invention is preferably used in minimal invasive surgery, e.g. for laparoscopic application.

The sponge may be dried and after drying, the sponge may have a water content of at least 0.5 (percentages given in w/w here). In certain embodiments the sponge can be freeze-dried or air-dried.

The present invention also provides a wound coverage comprising a sponge according to the invention. The sponge and all additional layers can be provided in a ready to use wound coverage in suitable dimensions. The sponge and/or the coverage can be a pad or a sheet, preferably having a thickness of at least 1 mm or at least 2 mm a or at least 5 mm and/or up to 20 mm, depending on the indication. When the relatively thick flexible sponge is applied to a wound it is important that blood and fibrinogen can be absorbed throughout the sponge before fibrin is formed that might act as a barrier for the absorption of further wound secret.

Another aspect of the invention relates to a method of manufacturing a hemostatic sponge (=process I) comprising

a) providing a sponge comprising a matrix of a biomaterial in dried form,

b) providing one reactive polymeric material in the form of dry powder,

c) contacting a) and b) so that the material of b) is present on at least one surface of said sponge, and

d) fixing the material of b) on the sponge of a).

Fixing may be achieved by melting the polymeric component onto the sponge in a pre-heated oven, e.g. at temperatures between 30° C. to 80° C., preferably between 60° C. to 65° C., for a time period sufficient for fixing, e.g. between 1 minute to 10 minutes, preferably about 4 minutes. Alternatively fixing can be achieved by an infrared heater or any other heat source. The distance between the pad and the heater, the intensity of the heater and the time of exposure to infrared irradiation are adjusted to achieve melting of the coating at a minimum of heat exposure.

Another aspect of the invention relates to a method of manufacturing a hemostatic sponge (=process II) comprising

a) providing a sponge comprising a matrix of a biomaterial in dried form,

b) providing one reactive polymeric material in the form of a solution, e.g. an aqueous solution with a pH of lower than 5, preferably about 3 or a water free organic solvent based solution, e.g. based on ethanol, acetone, methylenechloride and the like,

c) contacting a) and b) so that the material of a) is impregnated with b), and

d) drying the material obtained in step c).

Contacting for achieving impregnation may be done by placing the polymeric solution on top of the sponge and let the solution be soaked into said sponge for a time period sufficient for said absorption, e.g. from about 2 minutes to about 2 hours, preferably 30 minutes.

Drying may include freeze drying or air drying and comprises removing volatile components of the fluid.

In another aspect the present invention provides a hemostatic sponge obtainable by a method of manufacturing according to process (I) or (II).

Another aspect of the invention relates to the use of a sponge of the present invention for the treatment of an injury selected from the group consisting of a wound, a hemorrhage, damaged tissue and/or bleeding tissue. Preferably a sponge of the present invention is used for the sealing of tissues, e.g. lung, spleen, liver; and for hemostasis.

The composite of the present invention can also be used as a ready to use tissue sealant, wherever the concentration of body fluids in proteins is high enough to allow the formation of a sealing gel as described above.

The sponge of the present invention is especially indicated in open and endoscopic/laparoscopic/thoracoscopic/MIS (minimal invasive surgery) surgical procedures as an adjunct to hemostasis, to address surgical bleeding, from oozing to active, when control of bleeding by ligature or conventional procedures is ineffective or impractical.

In a preferred embodiment the sponge of the present invention is applied together with a buffer solution, e.g. an alkaline buffer solution, such as a bicarbonate solution, such as 8.4% NaHCO3, pH 8.3, e.g. on a gauze.

It has been found that the speed of reaction is increased after application with 8.4% NaHCO3-solution soaked gauze compared to saline soaked gauze. This was observed by an higher adherence of the sponge to the tissue after 2 minutes in the case of the NaHCO3-application.

The present invention further provides a kit comprising a sponge of anyone claims1to5and a buffer solution, e.g. an alkaline buffer solution, such as a bicarbonate or carbonate, together with instructions for its use. The alkaline buffer solution preferably has a pH about 8, such as 8.3.

Another aspect of the present invention relates to a hemostatic composite comprising a water insoluble haemostatic material (matrix) and a hydrophilic polymeric cross-linker with reactive groups, said composite comprising pores which allow external fluids, especially human blood, to access into said composite. The haemostatic material may be any material mentioned above as “matrix of a biomaterial” which by itself already has a certain haemostatic property. Such materials are known in principle in the art as well as their haemostatic property. The composite material according to the present invention has pores which allow external fluids to access the inner part of the composite so that e.g, if applied to a wound, blood of this wound can enter the composite. The composite can get soaked by these pores. Practically important examples include non-woven or woven fabric of a haemostatic fiber or a porous haemostatic sponge. Preferably, this haemostatic material is a collagen sponge, a fabric of oxidized regenerated cellulose, a fibrin sponge or a gelatin sponge. It is specifically preferred, that the collagen sponge is essential native collagen (i.e. native collagen fiber structure is to a large extend preserved or regenerated by fibrillogenesis during processing).

The reactivity of the hydrophilic polymeric crosslinker in the composite according to the present invention is retained. This means that the reactive groups of the crosslinker have not yet reacted with the (surface of the) haemostatic material and are not hydrolyzed by water. This can be achieved by combining the hemostatic material with the crosslinker in a way which does not lead to reaction of the reactive groups of the crosslinker with the hemostatic material or with water, e.g. as disclosed herein by melting, spraying, soaking under inert conditions, etc. Usually, this includes the omitting of aqueous conditions (or wetting), especially wetting without the presence of acidic conditions (if crosslinkers are not reactive under acidic conditions). This allows the provision of reactive haemostatic materials. Preferably, the haemostatic composite according to the present invention contains a polyethylene glycol (PEG) as hydrophilic polymeric crosslinker with reactive groups, especially a PEG comprising two or more, preferably 4, reactive groups selected from succinimidylesters (—CON(COCH2)2), aldehydes (—CHO) and isocyanates (—N═C═O), especially preferred succinimidylesters, such as component COH102 as defined below of Coseal.

In a preferred embodiment the matrix material which forms the porous network of the sponge constitutes of between 1-50%, 1-10%, or about 3% of the dried porous sponge (w/w-%).

The matrix of a biomaterial, especially the collagen, according to the present invention in general is not soluble, in particular not water-soluble. However, since the sponge is be porous and/or hygroscopic, it is allowed to swell when it is brought together with aqueous fluids, especially blood, serum, plasma, etc. or other fluids present in wounds and takes up these fluids.

The hemostatic sponge according to the present invention is fluid absorbing. “Fluid absorbing” shall be considered as the physical process to hold fluids upon contacting which may or may not provoke swelling of the sponge. Preferably the sponge can hold an amount of fluid, in particular blood, of at least 1 time, at least 2 times, at least 4 times or at least 10 times and/or up to 100 times, up to 20 times or up to 10 of the dry weight of the sponge. The sponge material according to the present invention can take up fluids even under pressure.

The porous sponge material according to the present invention preferably has a pore size of 5 to 500 μm, preferably of 10 to 200 μm. This pore size can properly be adjusted in the course of production of the sponge biomaterial, especially by way of directing a drying process in the course of such production.

The sponge according to the present invention is preferably provided in a “ready-to-use” form so that it is directly applicable to a patient in need thereof, e.g. to a wound of this patient (whereafter crosslinking starts). The sponge according to the present invention is therefore packed into a sterile package which protects the sponge from contamination (e.g. by moisture or microorganisms) during storage. Before use, the package can be opened (preferably also under sterile conditions) and the sponge can directly be applied to the patient (“ready-to use”).

As already mentioned, the hydrophilic polymeric component is a hydrophilic crosslinker. According to a preferred embodiment, this crosslinker has more than two reactive groups for crosslinking (“arms”), for example three, four, five, six, seven, eight, or more arms with reactive groups for crosslinking. For example, NHS-PEG-NHS is an effective hydrophilic crosslinker according to the present invention. However, for some embodiments, a 4-arm polymer (e.g. 4-arms-p-NP-PEG) may be more preferred; based on the same rationale, an 8-arm polymer (e.g. 8-arms-NHS-PEG) may even be more preferred for those embodiments where multi-reactive crosslinking is beneficial. Moreover, the hydrophilic crosslinker according to the present invention is a polymer, i.e. a large molecule (macromolecule) composed of repeating structural units which are typically connected by covalent chemical bonds. Polymers according to the present invention should have a molecular weight of at least 1000 Da (to properly serve as crosslinkers for the sponge according to the present invention); preferably the crosslinking polymers according to the present invention has a molecular weight of at least 5000 Da, especially of at least 8000 Da.

For some hydrophilic crosslinkers, the presence of basic reaction conditions (e.g. at the administration site) is preferred or necessary for functional performance (e.g. for a faster crosslinking reaction at the administration site). For example, carbonate or bicarbonate ions (e.g. as a buffer with a pH of 7.6 or above, preferably of 8.0 or above, especially of 8.3 and above) may be additionally provided at the site of administration (e.g. as a buffer solution or as a fabric or pad soaked with such a buffer), so as to allow an improved performance of the sponge according to the present invention or to allow efficient use as a hemostatic and/or wound adherent material.

