MXPA97003589A - Elastina, biomaterials based on elastin and process for your producc - Google Patents

Abstract

The present inven relates to an elastin-based biomaterial and to a method for using same to effect tissue repair or replacement. The inven also relates to a method for securing the biomaterial to the tissue there are

Description

ELASTINA, ELASTIN BASED BIOMATERIALS AND PAPA PROCESS ITS PRODUCTION Technical Field The present invention relates to elastin and elastin-based biomaterials and to methods that use them in the repair and replacement of tissues. The invention also relates to methods for securing elastin and elastin-based biomaterials to existing tissue.

BACKGROUND OF THE INVENTION Elastin is an extracellular matrix protein that is ubiquitous in mammals. Elastin is found, for example, in the skin, in the blood vessels and tissues of the lung where they impart resistance, elasticity and flexibility. In addition, elastin, which is prevalent in the internal elastic lamina (IEL) and the external elastic lamina, can inhibit the migration of smooth muscle cells to the intima or tunica intima. It has been shown that elastin in the form of solubilized peptides inhibits the migration of smooth muscle cells in response to factors derived from platelets (Ooyama et al, Arteriosclerosis 7: 593 (1987)). Repeating hexapeptides of elastin attract bovine aortic endothelial cells (Long et al, J. Cell Physiol.140: 512 (1989)) and it has been shown that nonapeptides attract fibroblasts (USP 4,976,734). The present invention takes advantage of these physical and biochemical properties of elastin.

REF: 24675 Thirty to forty percent of atherosclerotic stenoses that are open with distention angioplasty persist as a result of the internal growth of the middle cells. Internal growth of smooth muscle to intima appears to be more prevalent in sections of the artery where the artery IEL is torn, broken or lost, as in severe dilatation injury from distension angioplasty, anastomosis of the vessels or other vessel trauma resulting in tearing or separation of the elastic lamina. While repair of the arterial wall is present immediately after the injury, the elastin structures IEL and EEL are not reorganized. Since these components play major structural and regulatory functions, their destruction is accompanied by the migration of muscle cells. There are also diseases that are associated with weakness in the vessel wall that result in aneurysms that can eventually rupture, as well as other events that are at least in part related to elastin abnormalities. Prosthetic devices such as vascular supports have been used with some success to overcome the problems of restenosis or re-narrowing of the vessel wall that results from the internal growth of muscle cells after injury. However, its use is frequently associated with thrombosis. In addition, prosthetic devices can exacerbate the underlying atherosclerosis. However, prostheses have been used.

Until recently, the primary methods available to secure a prosthetic material to tissue (or tissue to tissue) involved the use of sutures or staples. Fibrin glue A fibrin polymer polymerized with thrombin has also been used (mainly in Europe) as a tissue sealant and hemostatic agent. Laser energy has been shown to be effective in the arterial incisions of tissue welding, which is believed to occur through the fusion of fibrin, collagen and other proteins. The use of photosensitizing dyes improves the selective delivery of laser energy to the target site and allows the use of lower power laser systems, both factors reducing the extent of undesirable thermal trauma. The present invention combines the advantages of elastin-based products with the advantages of laser welding and provides a unique method of tissue repair and replacement. The invention enables tissue prostheses (particularly vascular prostheses) that are essentially free from the problems associated with prostheses known in the art.

OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION It is a general object of the invention to provide a method for effecting tissue repair or replacement. It is a specific object of the invention to provide an elastin-based biomaterial suitable for use as a support, for example a vascular support or as a conduit replacement. The biomaterial can also be used as a support or conduit that covers or coats. It is a further object of the invention to provide an elastin or elastin-based graft suitable for use in repairing the wall of the interior space of a tubular structure. It is another object of the invention to provide an elastin or elastin-based material suitable for use in the replacement or repair of tissue, for example in the replacement or repair of tissue, for example in the replacement or repair of the inner bladder. in the replacement of the intestine or esophagus or repair or replacement of the skin. It is also an object of the invention to provide a method for securing an elastin or elastin-based material to an existing fabric, without the use of sutures or staples. The present invention relates to a method of repairing, replacing or holding a section of a body tissue. The method comprises the positioning of an elastin or elastin-based biomaterial at the site of the section and the attachment of the biomaterial to the site or to the tissue surrounding the site. Adhesion is carried out by contacting the biomaterial and the site or tissue surrounding the site, at the point where the joint is to be made, with an agent that absorbs energy. Then the agent is exposed to an amount of energy absorbable by the agent, sufficient to adhere the biomaterial to the tissue site surrounding the site.

More specifically, an elastin or elastin-based material that can be fused to the fabric can be produced by using the process of the present invention, which comprises an elastin or elastin-based biomaterial layer and a tissue substrate having each first and second external surfaces and an energy-absorbing material applied to at least one of the external surfaces, the material that absorbs energy penetrates the biomaterial. The material that absorbs energy is energy absorbing within a predetermined range of wavelengths of light. The energy absorbing material is chosen such that when irradiated with light energy in the predetermined wavelength range, the intensity of that light will be sufficient to co-fuse one of the first and second outer surfaces of the elastin biomaterial or elastin base and the tissue substrate. Preferably, the first and second surfaces of the elastin or elastin-based biomaterial are principal surfaces. Normally, the energy absorbing material is indirectly irradiated by directing the light energy first through the elastin or elastin-based biomaterial or the tissue substrate and then into the energy absorbing material. In a preferred process of this invention, the energy absorbing material comprises a biocompatible chromophore, more preferably a dye that absorbs energy. In one form of the present invention, the energy absorbing material is substantially dissipated when the elastin-based or elastin-based biomaterial and the tissue substrate are fused together. In another form of this invention, the energy absorbing material comprises a material for dyeing the first surface or the second surface of the elastin or elastin-based material. The energy absorbing material can also be applied to one of the external surfaces of the biomaterial by impurifying a separate elastin layer with an energy absorbing material and then melting the separated elastin layer contaminated to the elastin material or to the base of the elastin. elastin In any case, the energy absorbing layer is preferably applied substantially uniformly to at least one of the outer surfaces, usually in a manner wherein the energy absorbing material substantially covers the entire outer surface of the elastin or elastin-based biomaterial. Some of the key properties which affect the process of the present invention with respect to the fusion of the elastin or elastin biomaterial and the tissue substrate include the magnitude of the wavelength, the absorption level and the intensity of the light during the irradiation with light energy of the energy absorbing material and the concentration of the energy absorbing material. These properties are arranged in such a way that the temperature during the irradiation with light energy during a period of time which causes the joint fusion of one of the first and second external surfaces of the elastin or elastin biomaterial and the tissue substrate is about 40 to 140 ° C and more preferably about 50 to 100 ° C. In addition, the average thickness of the material that absorbs energy in the preferred process of the invention is from about 0.5 to 300 microns. Additional objects and advantages of the invention will be clear from the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view of the application of laser energy to the biomaterial and the exposed original tissue. Figure 2 shows the placement of the elastin biomaterial to the artery. Figure 3 shows the use of the biomaterial as an intestinal patch. Figure 4 is an exploratory electron micrograph of the elastin-based biomaterial (prepared according to Rabaud et al., Using elastin, fibrinogen and thrombin) fused to the porcine aorta using a continuous wave diode laser. Figure 5 is a light microscopic graph of the elastin-based biomaterial fused to the porcine aorta using a pulsed diode laser. E = elastin biomaterial; A = aorta. Figure 6 is a light microscope photomicrograph of the elastin-based biomaterial derived from arterial digestion welded to the porcine carotid artery. E = elastin biomaterial; A = aorta.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to elastin-based biomaterials and methods for welding such biomaterials to the tissue with the use of laser energy. Elastin-based biomaterials suitable for use in the present invention can be prepared, for example, from elastin (eg, bovine nuchal ligament), fibrinogen and thrombin as described by Rabaud et al. (U.S. Patent 5,223,420). (See also Aprahamian et al, J. Biomed, Mat. Res. 21: 965 (1987), Rabaud et al., Thromb Res. 43: 205 (1986), Martin, Biomaterials 9: 519 (1988).) Biomaterials may have thrombogenic property associated in certain types of tissue repair. Elastin-based biomaterials suitable for use in the invention can also be prepared from elastin and lll-like collagen, also as described by Rabaud et al. (Lefebvre et al., Biomaterials 13 (1): 28-33 (1992 )). Such preparations are not thrombogenic and thus can be used for vascular support, etc. A further type of elastin-based biomaterial suitable for use in the present invention is prepared as described by Urry et al., (See, for example, U.S. Patents 4,132,746 and 4,500,700) (See also U.S. Patents 4,187,852, 4,589,882, 4,693,718. , 4,783,523, 4,870,055, 5,064,430, 5,336,256). Elastin matrices resulting from the digestion of elastin-containing tissues (eg arteries) can also be used. Digestion results in the separation of cells, proteins and fats but keeps the elastin matrix intact. The biomaterial used will depend on the particular application. The elastin-based biomaterial of the invention prepared from soluble elastin (see Raubad et al., Cited above) can be molded into an appropriate size and shape for any specific purpose. The molded biomaterial can be prepared as follows. Elastin (for example soluble elastin (molecular weight 12-32,000 daltons) is washed and dilated in pH buffer, fibrinogen or cryoglobulins (prepared, for example, according to Pool et al., New Engl. J. Med. 273 1965) are added to dilated elastin, followed by thiourea, with or without a protease inhibitor (such as aprotinin) and collagen.Thrombin is added with agitation and the resulting mixture is poured immediately into an appropriate mold. incubates (for example at 37 ° C) while allowing the polymerization of the fibrin / elastin material to proceed, advantageously over a period of between 15 to 1 hour, 30 minutes are preferred The reaction can be carried out at temperatures lower than 37 ° C, but the reaction proceeds more rapidly at 77 ° C. Heating the reaction to a temperature of more than 40 ° C, however, may result in the denaturing of thrombin. as long as it agita allows more time for mixing to occur. For polymerization to occur, it is important to have calcium and magnesium in the pH buffer and to use denatured thrombin.

Following the polymerization in the mold, the resulting biomaterial can be further crosslinked (or solidified) by using gamma radiation or an agent such as glutaraldehyde (a solution of glutaraldehyde, formic acid and picric acid is preferred). When radiation is used, the samples are advantageously subjected to gamma irradiation from a Cobalt 60 source. The irradiation amount may fluctuate for example from 10 to 100 MRAD, MRAD is preferred. It has been shown that the amount of gamma irradiation can affect the strength of the material (Aprahamian, J. Biomed, Mat. Res. 21: 965 (1987)). Biomaterial sheets that are of controlled thickness can be prepared by using the appropriate molds. The sheets of the biomaterial can be manufactured in thicknesses ranging, for example, from 200 microns to 5 mm. The sheets are generally made as thin as possible, to allow penetration of the laser energy while maintaining sufficient strength. By way of example, a sheet suitable for use as an intestinal patch can range in thickness from 200 microns to 5 mm, a thickness of approximately 2 mm is preferred. A patch that requires more resistance, such as a patch for use in the bladder is usually thicker. Arterial support or patches may be thinner (for example 100 microns - 1000 microns). The biomaterial prepared from elastic or insoluble soluble elastin fragments can also be molded into tubular segments by injecting the material, for example, into tubular molds. The crosslinking of the elastin solution present between the inner and outer tubes can be carried out before removal of the biomaterial from the mold or after the tubes are removed. Tubular segments of different internal and external diameters can be prepared, also as different lengths, by using this procedure by varying the diameters of the internal and external tubes. A mold of this type can be manufactured in virtually any size, the inner and outer tubes vary in diameter. A small tube for coronary artery support can be manufactured and used. A large tube of 2.5 - 12.7 cm in diameter, like an angularly welded patch for the anastomosis of the small intestine or colon. Various molding techniques and molding materials can be used; the above are only an example. As indicated above, the biomaterial suitable for use in the present invention can be prepared from tissue digests containing an elastin matrix. The tissues suitable for use as a starting material include arteries (for example coronary or femoral arteries, for example from the pig), umbilical cords, intestines, ureters, etc. Preferably, the matrix material is derived from the animal species in which the implantation is carried out, such that biocompatibility is increased. Any method of separation (digestion) of cellular material, proteins and fats from the original matrix, while leaving the extracellular elastin matrix intact can be used. These methods may involve a combination of acidic, basic, detergent, enzymatic, thermal or erosive media, as well as the use of organic solvents. These may include incubation in solutions of sodium hydroxide, formic acid, trypsin, guanidine, ethanol, diethyl ether, acetone, t-butanol and sonification. Normally digestion proceeds more quickly at higher temperatures. The optimum incubation temperature and time depend on the starting material and the digestion agent used and can be easily determined. The skilled artisan will appreciate that while the tubular segments result from the digestion of the tubular starting materials, those segments may be opened and configured to produce sheets suitable for use as tissue grafts. Alternatively, such segments can be opened and then reconstructed as tubular segments having a diameter different from the starting tissue. Preferably, however, when looking for tubular products, the starting material is selected to produce a tubular segment after digestion having the appropriate diameter, such that subsequent manipulations (other than length adjustment) are performed. can avoid The biomaterial of the invention, whether prepared from elastin powder or tissue digests, is normally secured to the existing tissue. Various techniques for effecting such a binding can be used, in which techniques recognized by the prior art are included. However, it is preferred that the biomaterial be ensured by using a source of tissue welding energy and an agent that absorbs the energy emitted by that source. Advantageously, the energy source is a source of electromagnetic energy, such as a laser and the absorption agent is a probe having an absorption peak at a wavelength corresponding to that of the laser. The elastin biomaterial material and the fabric to be welded have much less light absorption at this wavelength and the effect is therefore confined to an area around the dye layer. A preferred energy source is a laser diode having a dominant wavelength at about 808 nm and a preferred dye is indocyanine green (ICG), maximum absorbance 795-805 nm (see WO 91 / (, 4073). Laser / dye can also be used.It is preferred that the dye be applied to that portion of the biomaterial that is to be contacted and secured to the existing fabric.The dye can also be applied to the surface of the structure to which the elastin biomaterial is going to be welded or secured.The dye can be applied directly to the biomaterial or the surface of the biomaterial can be treated or coated first (eg primed) with a composition that controls the absorption of the dye into the biomaterial, in such a way The dye is maintained as a discrete coating layer, Alternatively, the dye can be adhered to the elastin biomaterial, in such a way that it is secured to the surface and prevented from s e filter the material. The dye can be applied in the form of a solution or the dye can be dissolved in or suspended in a medium which can then be applied as a thin sheet or film, preferably of uniform thickness and concentration of the dye. Tissue welding techniques employing a welding agent can be used. Such techniques are known (WO 91/04073).

Any proteinaceous material that is thermally denatured on heating can be used as the soldering agent (for example any whey protein such as albumin, fibronectin, von Willeb factor, vitronectin or any mixture of proteins or peptides). Welds comprising fibrinogen polymerized with thrombin are preferred, except where such materials would cause undesirable thrombosis or coagulation, such as with vascular spaces (within a tubular structure). The welds are selected in terms of their ability to impart greater adhesive strength between the biomaterial and the fabric. The welding must be non-toxic and generally biocompatible. In accordance with the present invention, the energy of the laser can be directed to the target site (for example the dye) directly from the laser by exposure of the tissue (for example during surgical procedures). In some cases, this is endovascular catheter treatments where open surgery exposure is not present, the laser energy is directed to the adhesion site via optical fibers. When ICG is used as the dye, dial media of approximately 800 nm can be used. Such wavelengths are not well absorbed by many tissues, particularly vascular tissues, therefore there will be a negligible effect on those tissues and the thermal effects will be confined to the dye layer. The biomaterial of the invention has similarly little optical absorbance in its waveband, compared to the dye that absorbs energy. Thus, the laser energy can pass either through the biomaterial or the original tissue and be absorbed by the dye layer as shown in figure 1. Once the surgeon has exposed the surface or vessel where the reinforcement or When the biomaterial is replaced, the dye-containing surface of the biomaterial is placed in contact with the original tissue at the site and the laser energy is delivered by directing the laser beam to the desired site. The absorbance of the dye layer (for example ICG) is ideally determined prior or concurrently, such that the optimum amount of light can be supplied for adhesion. Pressure can be used to ensure proper approximation of tissue and biomaterial. With a diode laser source, the diode laser itself or a capacitor or optic fiber based optical supply system can be placed against the material to ensure uniform light supply. In cases where a new elastin lining or new internal elastic lamina is required, for example after an open surgical endarterectomy, once the artery has been surgically cleaned from the atheroma or other injury, the biomaterial is then placed in its place, with the dye side down (see figure 2). The biomaterial can be deployed as a flat patch or as a tubular segment. A tubular segment may be hollow or may be filled with a material that supports the space within the tubular structure during placement and that melts with a low-energy heating or dissolves or separates with a variety of means. When necessary, a small number of surgical sutures (for example fixation points) can be used to juxtapose or add the edges of the vessel or to sew the vessel. Once the biomaterial is in place, the laser energy is directed through the vessel wall or through the biomaterial to the absorbent dye, the appropriate laser energy has been previously determined based on the absorbance measured in the biomaterial. . Alternatively, the dye can be applied at the time of surgery to the biomaterial or the vessel wall or both and then the laser energy can be delivered. In this mode, the absorbance can be determined at the time of surgery to the biomaterial or the vessel wall or both and then the laser energy can be supplied or with a feedback device that determines the suitability of the union or the thermal effect. (Figure 4 is a SEM of elastin-based biomaterial fused to the porcine aorta.) In addition to the above, the biomaterial of the invention can be used as a patch material for use in intestinal repairs or colon repairs which often do not heal well with current techniques, particularly when the patient has nutritional or other problems or when the patient is in shock , as in the case of multiple gunshot wounds or other abdominal injuries (see figure 3). The use of such a patch may, for example, seal the intestinal contents and thereby reduce the likelihood of peritonitis. In addition, a patch can be used on a solid organ, such as the liver, when lacerations have occurred. Similarly, the biomaterial of the invention can be used to repair or replace portions of the urinary system, that is, the calyces of the kidney or the urethra. The patch can also be used to seal a defect in the cardiac chamber, such as in the septal defect. Atrial, also like bronchial or rectal fistulas. The hyomaterial can also be used as a cerebrovascular patch for an aneurysm. can be sealed in place with marked laser fusion For applications where direct exposure is not possible or undesirable, a variety of catheter or endoscopic systems can be used to direct laser energy to the target site. The elastin-based biomaterials with which the invention relates can be used in a variety of other clinical and surgical equipment to effect tissue repair grafting. For the delivery of the biomaterial in the form of an intravascular support, the biomaterial can be preassembled in an expanded distention catheter. The distention catheter can be maneuvered to the desired arterial or venous site using standard techniques. Then the distension can be inflated, to compress the support (biomaterial) against the wall of the vessel and then the laser light can be supplied through the distension to seal the support in place (the dye can be present on the outer side of the biomaterial). Then the distension can be deflated and separated to leave the support in place. A protective sleeve (eg of plastic) can be used to protect the support during its passage to the vessel and then be removed once the support is in the desired location. The biomaterial of the invention can also be used as a biocompatible coating for a metal or synthetic support or support. In such cases, simple mechanical deployment can be used without the need for laser adhesion. The adhesion can be employed by laser, however, depending on the specific demands, for example, where inadequate mechanical adhesion is present, such as in the deployment of a support for abdominal aortic aneurysms. An alternative catheter-based vascular support deployment strategy employs temporary mechanical support with or without a distending device. One strategy of deploying the additional catheter-based vascular support employs a support or structure of thermally deformable metal (such as nitinol or other metal of similar type) or coating that is incorporated into the catheter tube under the support material. The support is maneuvered to the desired site, after which the deformable metal of the support is activated, in such a way that it juxtaposes or adds the support against the vessel wall. The laser light is supplied via a fiber optic system, also incorporated into the catheter assembly. The elastin-based biomaterial can also be used to replace portions of diseased or diseased or diseased vascular tissue such as the esophagus, the paracardium, the pleura of the lung, etc. The biomaterial can also be used as a skin replacement layer, for example in burn or wound treatments. As such, the biomaterial serves as a permanent bandage that acts as a structure for the growth of epithelial cells. The biomaterial can include antibiotics, coagulants or other desirable medications for various treatments that provide high local concentrations with minimal systemic drug levels. The elastin biomaterial can be deployed with a dye on the side of the tissue and then fused with the appropriate wavelength and laser energy. In addition to repairing the tubular body structures, the biomaterial of the present invention can also be used in the reconstruction of organs. For example, the biomaterial can be molded or otherwise configured as an appropriate bag for bladder reconstruction. The biomaterial of the invention can also be molded or otherwise configured to be suitable for the replacement of the esophagus. Again, the metal or synthetic mesh could also be associated with the implant if extra wall support is needed to control the passage of food from the pharynx to the stomach. This could be used for stenosis of the esophagus, repair of acid reflux for erosive esophagitis or more preferably to repair damaged segments of the esophagus during or after surgery or chemotherapy for esophageal carcinoma. For certain applications, it may be desirable to use the biomaterial of the invention in combination with a support material having strong mechanical properties. For those applications, the biomaterial can be coated on the support material (see description of the above support), for example by using the molding techniques described herein. Suitable support materials include polymers, such as woven polyethylene terephthalate (Dacron), teflon, polyolefin copolymer, polyurethane, polyvinyl alcohol or other polymer. In addition, a polymer that is a hybrid between a natural polymer, such as fibrin and elastin and a non-natural polymer such as a polyurethane, polyacrylic acid or polyvinyl alcohol can be used (see Giusti et al., Trends in Polymer Science 1: 261 (1993)). Such a hybrid material has the advantageous mechanical properties of the polymer and the desired biocompatibility of the elastin-based material. Examples of other prostheses that can be made from synthetics or metals coated with the elastin biomaterial or from the biomaterial / synthetic hybrids include heart valve rings and esophageal supports. The elastin-based prostheses of the invention can be prepared to include the medicament; which can be supplied via the prosthesis, to the particular sites of the body. For example, vascular supports can be produced to include drugs that prevent coagulation, such as heparin or antiplatelet drugs such as hirudin, drugs to prevent smooth muscle internal growth, or drugs to stimulate damaged endothelial esophageal segments during or after surgery or Chemotherapy for esophageal carcinoma. For certain applications, it may be desirable to use the biomaterial of the invention in combination with a support material having strong mechanical properties. For those applications, the biomaterial can be coated on the support material (see the above description of support), for example by using the molding techniques described herein. Suitable support materials include polymers, such as woven polyethylene terephthalate (Dacron), teflon, polyolefin copolymer, polyurethane, polyvinyl alcohol or other polymer. In addition, a polymer that is a hybrid between a natural polymer, such as fibrin and elastin and a non-natural polymer, such as polyurethane, polyacrylic acid or polyvinyl alcohol can be used (see Giusti et al., Trends in Polymer Science 1: 261 (1993)). Such a hybrid material has the advantageous mechanical properties of the polymer and the desired biocompatibility of the elastin-based material. Examples of other prostheses that can be made from synthetic materials or metals coated with biomateria! Elastin or biomaterial / synthetic hybrids include heart valve rings and esophageal supports. The elastin-based prostheses of the invention can be prepared to include the medicament that can be delivered via the prosthesis, to the sites of! private body. For example, vascular supports can be produced to include drugs that prevent coagulation, such as heparin or antiplatelet drugs such as hirudin, drugs to prevent smooth muscle internal growth, or drugs to stimulate endothelial growth. Vasodilators may also be included. Prostheses formed from the elastin-based biomaterial can also be coated with damaged esophageal segments of viable cells during or after surgery or chemotherapy for esophageal carcinoma. For certain applications, it may be desirable to use the biomaterial of the invention in combination with a support material having strong mechanical properties. For those applications, the biomaterial can be coated on the support material (see the above description of support), for example by using the molding techniques described herein. Suitable support materials include polymers, such as woven polyethylene terephthalate (Dacron), teflon, polyolefin copolymer, polyurethane, polyvinyl alcohol or other polymer. In addition, a polymer that is a hybrid between a natural polymer, such as fibrin and elastin and a non-natural polymer, ta! such as polyurethane, polyacrylic acid or polyvinyl alcohol can be used (see Giusti et al., Trends in Polymer Science 1: 261 (1993)). Such a hybrid material has the advantageous mechanical properties of the polymer and the desired biocompatibility of the elastin-based material. Examples of other prostheses that can be made from synthetic materials (or metals) coated with biomateria! Elastin or biomaterial / synthetic hybrids include rings for heart valves and esophageal supports. The elastin-based prostheses of the invention can be prepared to include the medicament; that can be supplied via the prosthesis, to the sites of! private body. For example, vascular supports can be produced to include drugs that prevent coagulation, such as heparin or antiplatelet drugs such as hirudin., medications to prevent the internal growth of smooth muscle or drugs to stimulate epdotelial growth. Vasodilators may also be included. The prostheses formed from the elastin-based biomaterial can also be coated with viable cells, preferably cells of the receptor. prosthesis device. Endothelial cells, preferably autologous (eg harvested during liposuction), can be seeded onto the elastin bioprosthesis prior to implantation (eg for indications of vascular support). Alternatively, the elastin biomaterial can be used as a means of replacing or repairing the skin, wherein the cultured skin cells can be placed on the biomaterial before implantation. Thus, the skin cells can be used to coat the elastin biomaterial. Certain aspects of the invention are described in greater detail in the non-limiting examples below.

EXAMPLE 1 Preparation of leaves of the elastin-based biomaterial from soluble peptides. Materials used for the production of the biomaterial: Phosphate pH buffer: The phosphate pH buffer solution used contained 1 mM sodium phosphate, 150 mM sodium chloride, 2 mM calcium chloride, 1 mM magnesium chloride, pH 7.4. Soluble elastin peptides: Bovine ligament nape elastin powder was obtained from Sigma, St. Louis, Missouri. The following procedure was used to obtain the soluble elastin peptides: 2.7 g of elastin powder were suspended in 35 ml of 1 M KOL solution in 80% ethanol. The suspension was stirred at 50 ° C for 2.5 hours. Then, 10 ml of deionized water were added and the solution was neutralized with 12 M concentrated HCl to pH 4. The solution was cooled to 4 ° C for 12 hours. The clear solution was decanted from the salt crystals and the supernatant was centrifuged for 15 minutes at 2000 R.P.M. The solution was then dialyzed against three changes of tap water at two-hour intervals and a 15-hour interval when using a PM 10,000 cut dialysis tube. Dialysis was continued with six changes of deionized water at two-hour intervals and one 15-hour interval. The resulting dialyzed product was lyophilized and stored at -20 ° C. The yield was 40%. Preparation of cryoglobulin: A modification of the Pool and Shannon method was used to produce the cryoglobulins (New Engl. J. Med. 273 (1965)). The cryoglobulins consisted mainly of fibrinogen (40 mg / ml) and fibronectin (10 mg / ml) (the concentrations of fibrinogen and fibronectin will vary). Briefly, pig blood was collected in a standard 500 ml blood collection bag containing adenine, citrate and dextrose anticoagulant. The blood was transferred to twelve 50 ml plastic centrifuge tubes and centrifuged for 15 minutes at 1500 R.P.M. Plasma was decanted from the erythrocyte layer and frozen at -70 ° C for 12 hours. Then the plasma was cooled to 4 ° C. The cryoglobulins were collected by centrifugation of the plasma at 4 ° C for 15 minutes at 1500 R.P.M. The supernatant was decanted and the cryoglobulins collected by separating the precipitate with a pasteur pipette. Each tube was also rinsed with 3 ml of a sodium citrate solution containing 0.9% NaCl and 0.66% sodium citrate. It was accumulated to cryoglobulins, frozen at -70 ° C, lyophilized and stored at -20 ° C until use.

Thiourea: Reactive grade urea was obtained from Sigma, St. Louis Missouri. A 0.5 mg / ml solution was used. Type I collagen. Soluble type I collagen was obtained. It consisted of preference of rat tail tendon by a modification of the Bornstein method. Two mg of collagen were heated in 0.6 ml of phosphate pH buffer at 60 ° C for 10 minutes until the collagen dissolved. Then it was cooled to 37 ° C and was used. Thrombin: Thrombin was obtained from bovine plasma of Sigma, in lyophilized form. When reconstituted with 1 ml of water the solution contained 106 NIH units per ml. Aprotinin: Bovine lung aprotinin was obtained from Sigma. It contained 15-30 trypsin inhibitory units (TIU) per ml.

Preparation: Six molds were prepared by gluing a 620 μm quartz fiber to one side of a 40 mm x 25 mm glass plate and adhering to a second glass plate the first time using a rubber band. Each mold thus constructed retained approximately 0.5 ml. The biomaterial was prepared by successively adding and mixing the following: 200 mg of soluble kapa-elastin or kapa-elastin powder in phosphate pH buffer (PB) (1 mM P041 150 mM NaCl, 2 mM Ca21, 1 mM Mg21 pH 7.4) at 37 ° C. 160 mg of cryoglobulin in 1 ml PB (37 ° C). 2 mg of collagen in 0.6 ml of PB (60 ° C, 37 ° C) 200) 11 thiourea (0.5 mg / ml) 200 CLI of aprotinin (5 units) An aliquot of 0.6n ml of the above solution was charged to a Test tube and 50 μl of thrombin solution (~ 6 units) was added. The resulting solution was immediately loaded into the mold. Certain of the resulting leaves were crosslinked with glutaraldehyde for 2 minutes.

Results: The leaves prepared as described above were slightly yellowish and opaque. The fixed sheets with glutaraldehyde were less resilient and were torn more easily than the non-fixed sheets. The fixed sheets of glutaraldehyde were subjected to microscopy of choice. These leaves had a less cohesive surface appearance at 100X and 1000X: Example 2: Welding of elastin-based biomaterial sheet tissue Pre-welding procedure: A 1 mg / ml solution of ICG was applied to the freshly obtained aorta of pig that had been carefully removed from the adventitia, washed in a sterile 0.9% NaCl solution and cut into 1 cm2 segments. The 1 mg / ml solution of ICG was applied to the area of the aorta gleam for approximately 3 minutes and was rinsed.

(The ICG was obtained from Sigma and contained 90% dye and 10% sodium iodide). It was found that the absorption coefficient measured at 780 nm with a 7.25 x 10"4 M solution was 175,000 M'1cm" 1. The maximum absorption shifts to 805 nm when the ICG binds to the whey proteins. (Landsman et al., J. Appl. Physiol. 40 (1976)). A small amount of cryoglobulins containing approximately 40 mg / ml of fibrinogen and 10 mg / ml of fibronectin doped with ICG was also applied to the biomaterial placed on it. The two materials were placed between two glass slides. This was submerged in a 0.9% saline solution. Welding procedure: The sheets of the biomaterial as described in Example 1 were equilibrated in phosphate pH buffer, pH 7.4 and were welded to the porcine aorta stained with ICG when using a gallium aluminum arsenide diode array laser . The maximum output was at 808 +/- 1.5 nm. The laser was coupled to a μm quartz fiber with polyethylene coating material. The laser energy was collimated with a focusing lens and coupled to the quartz fiber. The size of the point at the far end of the fiber could be varied from 1 mm to 4 mm by adjusting the distance between the focusing lens and the proximal end of the fiber. The laser operated continuously, the CW and the measured output at the far end of the fiber was 1.5 W. The quartz fiber was positioned directly above the glass slide, the biomaterial, the aorta. Before welding, the size of the laser spot was measured. The solder appeared to be present under the irradiated solution of 0.85 W but not at 1.32 W. Twenty seconds was a sufficient time for welding and 40 seconds caused a brown color change and the calcination of the biomaterial.

Example 3: Preparation of the elastin-based biomaterial from artery digest. Freshly cut sections of 4 cm porcine carotid artery were dissected and cleaned and washed in two changes of 0.9% saline overnight. The vessels were then placed in 0.5 M NaOH and subjected to sonification for 120 minutes (a modified method of Crissman, R. 1987) (Crissman, Rogert S. "Comparison of Two Digestive Techniques for Preparation of Vascular Elastic Networks for SEM Observation" , Journal of Electron Microscopy Techniques 6: 335-348 (1987)). Then the digested vessels were washed in distilled water and autoclaved at 107 ° C (225 ° F) for 30 minutes. The digested vessels appeared translucent, pearly white and crushed when removed from the water, indicating the absence of collagen and other structural support proteins. The welding of the artige digests to the porcine aorta was carried out by means of the following methods. A freshly cut porcine aorta was coated with 5 mJ / ml ICG for 5 minutes. The excess ICG solution was removed. Sections of 1 cm x 1 cm of elastin segments of digested carotid artery subjected to sonication with NaOH were placed on freshly stained aortas. An array of pulsed aluminum gallium arsenide diode lasers (Star Medical Technologies) was used to weld the segments. Pulses of five milliseconds of light from 790-810 to 2 Joules were emitted and applied to the tissue with a capacitor that created a uniform beam of 4 x 4 mm, which was placed on the elastin digest covered by a glass slide. Good welds were obtained with up to 10 impulses. A microscopic light photograph of the elastin digest welded to the porcine aorta is shown in Figure 6.

Example 4: Preparation of the elastin-based biomaterial and porcine aorta fusion Materials: Bovine nape elastin powder (Sigma St. Louis MO) was screened with 40 μm mesh and was dilated with phosphate buffer . Then the elastin fragments were reacted with 67 mg of fibrinogen (Sigma) in phosphate pH buffer, acid-soluble type I collagen, 2 mM (Sirgina), 2.8 mg of thiourea, Ca + 2 2 mM, Mg2 + 1 mM and 75 thrombin units were injected into molds and heated to 77 ° C. Sheets and 1 mm thick tubes of this biomaterial were removed and stored in 33% ethanol for later use. The indocyanine green dye (was dissolved in deionized water to provide a 1% solution and was applied to the surface of the freshly cut porcine aorta.) The dye was in place for 5 minutes and then the residual dye was removed. The elastin biomaterial was placed on the aorta stained with ICG and covered with a glass coverslip.Laser energy was applied with a condenser which collected the output of an array of gallium arsenide diode lasers emitting light at 800 nm in pulses of 5 milliseconds, points of 6 mm2 were irradiated with 2.89 Joules for 1-10 pulses which provided adequate welds, then the samples were bisected and fixed in formalin for microscopic study, Figure 5 is a microscopic light photography of Such welding is stained with an elastin stain.It is noted an excellent welding of the elastin biomaterial to the porcine aorta, without any detectable thermal damage or other damage to the biomaterial or to the aorta.

Example 5: Preparation of the elastin-based biomaterial and fusion to the porcine aorta. Materials: Elastin of the bovine ligament neck, porcine plasma fibrinogen and type I collagen soluble in rat tail tendon acid were obtained from Sigma Chemical Corp. (St. Louis, MO). Elastin was solubilized in KOL / 1% 80% ethanol at 50 ° C for 2.5 hours. (Hornebreck). The cryoprecipitates were obtained from porcine plasma according to the method of Pool and Shannon (Pool and Shannon). The fresh-cut porcine aorta was obtained from Carlton Packagin Co. (Cariton, Ore) and stored at -20 ° C until dissolved for use.

The elastin-fibrin biomaterials were prepared similarly to the methods developed by Rabaud (Rabaud). Elaborated patches of solubilized elastin and cryoprecipitates were prepared by successive addition with complete mixing of 100 mg of soluble elastin dissolved in 2 ml of phosphate buffer, 160 mg of lyophilized cryoprecipitate were dissolved in 1 ml of phosphate buffer , 2 mg of type I collagen dissolved in 0.6 ml of phosphate buffer and 0.2 ml of thiourea solution (0.5 mg / ml H20). 6 units of thrombin were added to aliquots of 0.5 ml of the mixture, completely mixed in a 1 ml syringe and injected into 4 cm2 glass molds. The molds were incubated at 37 ° C for 30 minutes and subjected to irradiation of MRAD (cobalt source). The biomaterial was stored at 4 ° C in EtOH at 33%. Before use, the biomaterial was washed several times with saline. Patches were also manufactured with insoluble elastin and fibrinogen. Sigma lyophilized elastin was passed through a 4000 U.S. mesh screen. (Tyler) before use. Only 40 μm or smaller particles were used. 28.0 mg of the filtered elastin were expanded and washed overnight in an excess phosphate buffer. The mixture was centrifuged (1000 R.P.M., 10 minutes) and the excess pH buffer was discarded. The dilated elastin was suspended in 2 ml of phosphate pH buffer. 67 mg of lyophilized fibrinogen dissolved in 1 ml of phosphate pH buffer was successively added to this suspension., 2 mg of type I collagen dissolved in 0.6 ml of phosphate buffer and 0.2 ml of thiourea solution (0.5 mg / ml of H20). Finally, 33 units of thrombin were added and the mixture was subjected to a vortex flow and poured rapidly into 3 cm x 7 cm molds. The molds were incubated at 37 ° C for 30 minutes, the material was stored at 4 ° C in 33% EtOH. Before use, the biomaterial was washed several times with saline. The soluble-cryoprecipitate elastin patch was fused to the porcine aorta by using an AlGaAr diode array laser that emits continuous-wave optical radiation at 808 nm. The freshly cut porcine aorta was washed in 0.9% NaCl and cut into 2 cm2 portions. Indocyanine green (Sigma) in aqueous concentrate of 1 or 5 mg / ml was applied to the aorta via a pasteur pipette, left undisturbed for 5 minutes and then stained. The tissue was then equilibrated in a 0.9% saline solution for 15 minutes to remove any unbound dye. Then the biomaterial was applied to the surface of the lumen of the aorta, the laser beam was directed to the surface of the biomaterial via a fused silicon fiber of 1 μm (Polymicro Technologies, Phoenix, Az) through a glass coverslip like is shown in figure 1. The six laser beams varied between 1 - 4 mm at offset distances. The laser output measured from the tip of the fiber was 1.5 Watts and the exposure times varied from 5 to 4 seconds.

The insoluble elastin-fibrinogen patch was fused to the porcine aorta using an AlGaAr diode array laser that emits pulsed optical radiation at 790-810 nm (Star Medical Technologies). Dissolved porcine aorta was prepared and diluted with 5 mg / ml aqueous ICG solution as previously described for the fresh cut aorta. After applying the biomaterial to the stained luminal surface of the aorta, laser radiation was directed to the biomaterial via a copper-coated condenser placed against a glass slide. The laser output was adjusted to 2 J and pulses of durations of 5 milliseconds.

EXAMPLE 6 Nerve elastin of bovine ligament, porcine plasma fibrinogen and type I collagen soluble in rat tail tendon acid were obtained from Sigma Chemical Corp. (St. Louis, MO). 1 mg of indocyanine green is dissolved in 1 ml of 24% human serum albumin. 67 mg of fibrinogen are dissolved in 1 ml of phosphate buffer (@ 37 ° C). Just before mixing, 16.6 units of thrombin are added to the indocyanine green solution. The mixtures are cooled to 4 ° C. The two mixtures are quickly combined and injected or poured into a 3 x 7 cm mold and incubated for 30 minutes at 37 ° C. The lyophilized elastin from Sigma is passed through a 400 U.S. mesh screen. (Tyler) before use. Only 40 μm or smaller particles were used. 210 mg of filtered elastin are expanded and washed overnight in an excess phosphate buffer. The mixture is subjected to centrifugation (1000 R.P.M., 10 minutes) and the excess of the pH-regulating solution is discarded. The expanded elastin is suspended in 1.5 ml of phosphate buffer. 67 ml of lyophilized fibrinogen are added successively to this suspension in 0.75 ml of pH-regulating solution, 2 mg of type I collagen are dissolved in 0.45 ml of pH-regulating solution and 0.15 ml of thiourea solution (0.5 mg / ml of H20). ). Finally, 26 units of thrombin are added and the mixture is subjected to swirling flow and poured rapidly onto the doped fibrin matrix with indocyanine green in the 3 cm x 7 cm molds. The molds are incubated again at 37 ° C for 30 minutes. When they are separated from the mold, the two layers are inseparable and the preparation produces a single patch. All of the documents cited above are hereby incorporated by reference in their entirety. Those skilled in the art will appreciate from a reading of this description that various changes in form and detail can be made without departing from the true scope of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (38)

1. Claims 1. An elastin or elastin biomaterial, fused to the fabric that includes an elastin or elastin-based biomaterial layer having first and second outer surfaces, characterized in that it comprises a material that absorbs energy applied to at least one of the external surfaces, the energy-absorbing material penetrates the elastin biomaterial or elastin, the energy absorbing material is energy absorbing within a predetermined range of wavelengths of light such that the first and second external surfaces of the Elastin or elastin-based biomaterial and a tissue substrate are fused together when the energy absorbing material is irradiated with light energy of sufficient intensity in the predetermined wavelength range.
2. 2. The biomaterial according to claim 1, characterized in that the first and second surfaces of the elastin biomaterial or elastin base are major surfaces.
3. 3. The biomatter according to any of the preceding claims, characterized in that the energy absorbing material is indirectly irradiated by directing the light energy first through the elastin or elastin biomaterial or the tissue substrate and then to the material that absorbs energy
4. 4. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material comprises a biocompatiblß chromophore.
5. 5. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material comprises an energy absorbing dye.
6. 6. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material is substantially dissipated when the elastin or elastin-based biomaterial and the tissue substrate are fused together.
7. 7. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material comprises a material for dyeing the first or second surface of the elastin or elastin-based biomaterial.
8. 8. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material is applied to one of the external surfaces of the biomaterial by impurifying a separate elastin layer with an energy absorbing material and then melting the layer of Separated elastin impurified to elastin or elastin based elastin.
9. 9. The biomaterial according to any of the preceding claims, characterized in that the temperature during irradiation with light energy for the period of time, which will cause the joint fusion of one of the first and second outer surfaces of the elastin biomaterial or based on elastin and the tissue substrate is approximately 40 to 140 degrees centigrade.
10. 10. The biomaterial according to any of the preceding claims, characterized in that the average thickness of the material that absorbs energy is about 0.5 to 300 microns.
11. 11. The biomaterial according to any of the preceding claims, characterized in that the magnitude of the wavelength, the energy level, the absorption and the intensity of the light during the irradiation with light energy of the material that absorbs energy and the concentration of the The energy absorbing material is arranged in such a way that one of the first and second outer surfaces of the elastin or elastin biomaterial and the tissue substrate are fused together at a temperature of about 40 to 140 ° C.
12. 12. A process for producing an elastin or elastin-based biomaterial fused to the fabric, which includes a layer of the elastin or elastin-based biomaterial having first and second outer surfaces, characterized in that it comprises: applying a material that absorbs energy to the first or second external surface, the material that absorbs energy penetrates the biomaterial, the material that absorbs energy is absorbing energy within a predetermined range of wavelengths of light, such that one of the first and second outer surfaces of the elastin or elastin biomaterial and a tissue substrate are fused together when the energy absorbing material is irradiated with light energy of sufficient intensity in the predetermined wavelength range .
13. 13. A prosthesis device that includes a support element comprising a support, a conduit or base, characterized in that it comprises an elastin or elastin-based biomaterial layer located on the support element.
14. 14. The prosthesis device according to claim 1, characterized in that the support element is formed of a metal, a polymer or a biological material.
15. 15. The prosthesis device according to any of the preceding claims, characterized in that the layer of the elastin or elastin-based biomaterial comprises a cover, coating or liner for the support element.
16. 16. The prosthesis device according to any of the preceding claims, characterized in that it is implantable in an artery, a vein, an esophagus, a liver, an intestine, a colon, an ureter, an urethra or a fallopian tube.
17. 17. The prosthesis device according to any of the preceding claims, characterized in that the elastin or elastin-based biomaterial is formed of an appropriate size and shape by molding.
18. 18. The prosthesis device according to any of the preceding claims, characterized in that the sheet is attached to the support element by grafting, by mechanical adhesion or by laser adhesion.
19. 19. The prosthesis device according to any of the preceding claims, characterized in that a medicament is incorporated into the layer of the elastin or elastin-based material, thereby decreasing the need for intravenous or oral medications.
20. 20. A process for producing a prosthesis device having a support element comprising a support, a conduit or a base, characterized in that it comprises: providing a layer of elastin or elastin-based biomaterial; and applying the layer of the elastin or elastin-based biomaterial to the support element to form the prosthesis device.
21. 21. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing layer is applied in a substantially uniform manner to at least one of the outer surfaces.
22. 22. The biomaterial according to any of the preceding claims, characterized in that the energy absorbing material substantially covers the entire outer surface.
23. 23. The biomaterial according to any of the preceding claims, characterized in that the temperature during irradiation with light energy for the period of time, which will cause the joint fusion of one of the first and second outer surfaces of the elastin biomaterial or elastin base and the tissue substrate is approximately 50 to 100 degrees centigrade.
24. 24. The process according to any of the preceding claims, characterized in that it also includes the step of providing first and second outer surfaces of the elastin or elastin-based biomaterial which are principal surfaces.
25. 25. The process according to any of the preceding claims, characterized in that it includes the step of indirectly irradiating the material that absorbs energy by directing the light energy first through the elastin biomaterial or elastin or tissue substrate and then to the material that absorbs energy
26. 26. The process according to any of the preceding claims, characterized in that the energy absorbing material comprises a biocompatible chromophore.
27. 27. The process according to any of the preceding claims, characterized in that the energy absorbing material comprises an energy absorbing dye.
28. 28. The process according to any preceding claim, claim 15, characterized in that it further includes the step of substantially dissipating the energy absorbing material when the elastin or elastin-based biomaterial and the tissue substrate are fused together.
29. 29. The process according to any of the preceding claims, characterized in that it further includes the step of dyeing the first and second surface of the elastin or elastin-based biomaterial with the energy absorbing material.
30. 30. The process according to any of the preceding claims, characterized in that it also includes the step of applying the energy absorbing material to one of the external surfaces of the biomaterial by impurifying a separate elastin layer with an energy absorbing material and then melting from the separated elastin layer impurified to the elastin or elastin based elastin.
31. 31. The process according to any of the preceding claims, characterized in that the energy absorbing layer is applied in a substantially uniform manner to at least one of the outer surfaces.
32. 32. The process according to any of the preceding claims, characterized in that it further includes the step of substantially covering the entire outer surface of the elastin or elastin-based biomaterial with the energy absorbing material.
33. 33. The process according to any of the preceding claims, characterized in that it further includes the step of irradiating the energy absorbing material with light energy at a temperature of about 40 to 140 degrees centigrade for a period of time which will cause the joint fusion of one of the first and second outer layers of the elastin or elastin-based biomaterial and the tissue substrate.
34. 34. The process according to any of the preceding claims, characterized in that it further includes the step of irradiating the energy absorbing material with light energy at a temperature of about 50 to 100 degrees centigrade for a period of time which will cause the joint fusion of one of the first and second outer layers of the elastin or elastin biomaterial and the tissue substrate.
35. 35. The process according to any of the preceding claims, characterized in that the average thickness of the energy absorbing material is about 0.5 to 300 microns.
36. 36. The process according to any of the preceding claims, characterized in that it also includes the step of adjusting the magnitude of the wavelength, the energy level, the absorption and the intensity of the light during the irradiation with light energy of the material that absorbs energy and the concentration of the energy-absorbing material, so that the first and second outer surfaces of the elastin or elastin-based biomaterial and the tissue substrate are maintained at a temperature of about 40 to 140 ° C, to fuse by this together the elastin or elastin biomaterial and the tissue substrate.
37. 37. A fused composite of living tissue - elastin-based biomaterial, characterized in that it comprises: an elastin or elastin-based biomaterial layer and a tissue substrate, each having first and second outer surfaces; an energy absorbing material, which is absorbent within a predetermined range of wavelengths, the energy absorbing material is applied to at least one of the first and second surfaces of the elastin biomaterial or elastin or the substrate of the tissue in an amount sufficient to directly fuse the biomaterial layer and the tissue substrate together; at least one of the first and second outer surfaces of the tissue substrate is directly fused to at least one of the first and second outer surfaces of the elastin biomaterial or elastin-based by irradiation of the energy absorbing material with emitted light energy in the predetermined wavelength range with a sufficient intensity which directly fuses the elastin or elastin-based biomaterial and the tissue substrate.
38. 38. A process for producing an elastin-fusionable biomaterial to the fabric, characterized in that it comprises: providing an elastin or elastin-based biomaterial layer and a tissue substrate having first and second outer surfaces; and applying an energy absorbing material, which is energy absorbing within a predetermined range of wavelengths of light, to one of the first and second outer surfaces of the elastin biomaterial or based on elastin or tissue substrate; positioning the first or second outer surfaces of the elastin or elastin biomaterial and the tissue substrate in contact with each other, such that the energy absorbing material is disposed between the elastin or elastin-based biomaterial and the tissue substrate; and irradiating the energy absorbing material with light energy in the predetermined wavelength range with sufficient intensity to coalesce together the first and second outer surfaces of the elastin or elastin-based biomaterial and the tissue substrate.