CA1339093C - Process for preparing bovine pericard materials and use thereof - Google Patents
Process for preparing bovine pericard materials and use thereofInfo
- Publication number
- CA1339093C CA1339093C CA000614535A CA614535A CA1339093C CA 1339093 C CA1339093 C CA 1339093C CA 000614535 A CA000614535 A CA 000614535A CA 614535 A CA614535 A CA 614535A CA 1339093 C CA1339093 C CA 1339093C
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- CA
- Canada
- Prior art keywords
- tissue
- pericard
- bovine
- process according
- bovine pericard
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
- A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
- A61L27/3683—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix subjected to a specific treatment prior to implantation, e.g. decellularising, demineralising, grinding, cellular disruption/non-collagenous protein removal, anti-calcification, crosslinking, supercritical fluid extraction, enzyme treatment
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
- A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
- A61L27/3604—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix characterised by the human or animal origin of the biological material, e.g. hair, fascia, fish scales, silk, shellac, pericardium, pleura, renal tissue, amniotic membrane, parenchymal tissue, fetal tissue, muscle tissue, fat tissue, enamel
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
- A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
- A61L27/3683—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix subjected to a specific treatment prior to implantation, e.g. decellularising, demineralising, grinding, cellular disruption/non-collagenous protein removal, anti-calcification, crosslinking, supercritical fluid extraction, enzyme treatment
- A61L27/3687—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix subjected to a specific treatment prior to implantation, e.g. decellularising, demineralising, grinding, cellular disruption/non-collagenous protein removal, anti-calcification, crosslinking, supercritical fluid extraction, enzyme treatment characterised by the use of chemical agents in the treatment, e.g. specific enzymes, detergents, capping agents, crosslinkers, anticalcification agents
Abstract
Disclosed is a process for preparing bovine pericard material by subjecting raw bovine pericard tissue to operations of wet-chemical processing, oxidative bleaching, washing out, de-greasing, drying and sterilizing, wherein the collagen contained in the bovine pericard is worked up by way of a definite sequence of process steps. The bovine pericard material obtained by the process according to the invention can be advantageously employed for implants and transplants in human and veterinary medicine.
Description
Process for Preparinq Bovine Pericard ~aterials and IJse Thereof The present invention relates to a process for preparing bovine pericard materials having excellent biocompatibility and an increased stability, and to the use of the materials thus prepared as transplants or 5 implants in human medicine and veterinary medicine.
From the beginning of this century it has been attempted in surgery to cover large tissue defects by means of transplants of collagenous connective tissue (Marchant, 1901: ~leinschmidt, 1914). Since 1954 human Dura mater is available as homologous transplant in lyophilized form and since 1973 in the form of a solvent-dried product. In many cases, human Dura, due to its good tissue compatibility, the absence of immuno-15 logic reactions and not least its high tensile strength at break has proven its value, so that this bio-material is successfully used even to-day. ~nfortunately, Dura mater, as a human transplant, is available only to a limited extent and, thus, by far cannot meet the demands 2 o of surgery . Also there are some indications, for example in neurosurgery and the ear, nose and thro t /
- -2- 1339a93 medicine, where Dura transplants frequently have proven to be somewhat to stiff and not the optimum in thick-ness .
The DE-OS 30 34 273 relates to a method for pre-paring collagen, said method been characterized in that natural insoluble collagen is treated with an aqueous solution of an alkali sulfate and/or alkali hydroxide, that the fat-free collagen is treated in an aqueous solution containing an alkali sulfate and optionally is washed with water, the collagen is dissolved in an aqueous solution, a small amount of a biologically active substance such as an antibiotic, a hormone or a spermizide is optionally added to the solution, said solution is frozen and the product is dried in vacuo.
However, said Offenlt:yul~y ~ rift [Public Unexamin-ed Patent Application] does neither anticipate the sub-j ect matter of the present invention nor render same obvious to the artisan.
The U.S. Patent No. 4,006,083 describes a sterile collagen product usable in surgery and having a felt or woven imitation fur structure, which product exerts a hemostatic action, has a high absorption capacity for body liquids, stimulates cell regeneration, has a high resorbability, substantialy is not rejected by body tissues and has optimum mechanical properties, which properties render said product capable of being used in the care of skin injuries or in skin lesions or in bone cavities .
However, the teaching of said U. S . Patent does neither anticipate the subj ect matter of the present invention nor render same obvious.
The U.S. Patent No. 4,502,159 descrlbes the pre-paration of a tubular prosthesis such as, for example, a vessel or ureter prosthesis. Said prosthesis is prepared by suturing the opposite corners of a pericard tissue using a biocompatible suture material. An exact description is provided of the suturing procedure. It is preferre~ to use bovine pericard which has similar extensibility properties as human tissue. The tubular tissue, once sutured, is tanned in a 0 . 5% solution of glutardialdehyde for 7 days. The smooth surface of the pericard material has been turned inside, while the basal membranes are on the outer surface. Sterilization is effected by preservation in formalin or by radiation sterilization of a physiological saline containing the pericard .
However, said U.S. Patent does not provide any information on isolation, purification and/or the physical and chemical properties of the tubular prosthesis thus prepared, so that the subject matter of the U.S. Patent cannot render obvious the subject matter of the present invention.
From these circumstances of prior art there arose necessarily a desire to provide a transplant or implant, respectively, which is available to a virtually unlimit-ed extent, which as much as possible includes all of the positive properties of the Dura mater and, in addition thereto, o~fers some further advantages when handled.
~oreover, it should be ensured that no germs dangerous to humans (HIV viruses, hepatitis viruses etc. ) could be entrained and introduced by the raw material, as is basically possible with human transplants.
.. ~f ~
. ~ , ~1 _ 4 _ 13~9~93 In consideration of all product-relevant para-meters, in bovine pericard - also designated as pericard hereinbelow - a biologic material has been found which in an almost optimum manner satisfied the reguirements set ~or an implant for covering human tissue defects.
It is the object of the present invention to create a process for the preparation of bovine pericard materials wherein the biological compatibility and stability of the product obtained thereby is improved.
It is a ~urther object o~ the present invention to provide new possible uses for this product.
Now it has been surprisingly found by experimental research that by means of a modified production process the resistance to biological degradation o~ the sclero-proteins contained in the bovine pericard and the bio-compatibility thereof may be ~nhAn~ ed even without an 21dehyde tanning ~uceduLe using formaldehyde or glutar-dialdehyde - like those described in the US-A-4, 502 ,159, WO 84/04669 published December 6,1984, and in the LJS-A-4,456,589.
The present invention relates to a process ~or preparing bovine pericard material by subjecting raw bovine pericard tissue to operations of wet-chemical processing, oxidative bleaching, washing out, de-greasing, drying and sterilizing, said process being characterized in that the wet-chemical processing o~ the bovine pericard tissue comprises the folIowing steps:
a) Soaking the bovine pericard tissue;
b) M~-rh~n;~Ally removing fat tissue and baszl membranes ~rom the surfacé of the bovine pericard tissue;
c) Treating the bovine pericard tissue with a diluted aqueous basic solution;
... :. , ,. ~
_ _ _ 5 _ 1339~93 d) Rinsing the bovine pericard tissue with demineralized water to remove residual base;
e) Treating the bovine pericard tissue with a diluted aqueous sodium chloride solution;
f) Rinsing the bovine pericard tissue with demineralized water to ~remove residual sodium chloride;
g) Treating the bovine pericard tissue with a complexing aqent;
h) Rinsing the bovine pericard tissue with demineralized water to remove residual complex-ing agent;
i) Treating the bovine pericard tissue with an acidic buffer system; and j ) Rinsing the bovine pericard tissue with demineralized water to remove residual acidic buffer system.
In a preferred embodiment of the present invention the measure according to feature b) is repeated sub-sequently to process step d) prior to process step e~.
Although the described measures in the wet-chemical processing may be readily carried out above room tempe-rature or below room temperature, it is preferred within the scope of the present invention to conduct all wet-chemical process steps at room temperature, that is between 15 ~C and 25 ~C.
The treatment in process step c) is preferably carried out in a diluted aqueous basic solution of sodium hydroxide, potassium hydroxide, lithium hydroxide and/or sodium carbonate. Particularly preferred is the use of a 2 to 2 . 59~ by weight aqueous sodium hydroxide solution which generally should act onto the bovine pericard tissue during a period of up to 16 hours, O . 50 to 1. 00 liters of the diluted basic solutions being used per 100 grams of bovine pericard tissue. Hereby, on the one hand, a good purification effect is attained which includes a complete deactivation as much as possible of enzymes and potential germs while, on the other hand, damage to the collagen-containing tissue is avoided.
After the treatment with the diluted aqueous basic solution the pericard tissue generally is strongly swollen to 2 to 5 times the initial volume.
The treatment in process step e) is preferably carried out with a 10 to 11% by weight sodium chloride solution, whereby a swelling condition of the collagen may be controlled which is favorable for further processing same. In contrast, lower concentrations in the sodium chloride solution will only cause insuffi-cient de-swelling o~ the collagen much swollen after the alkaline treatment. Higher sodium chloride concentrat-ions in the solution would cause an l~nn~ cs;~ry accumulation to occur of salt r~; n~rS in the bovine pericard tissue and are not meaningful already for this reason .
The treatment in process step g) is preferably carried out with a complexing agent as known to the artisan for complexing polyvalent metal ions which in part are present bound to proteins. In this case, a disodium EDTA solution has proven to be particularly preferable, which is present, for example, in a con-centration of from O . 3 to O . 5% by weight. Said complexing agent, in order to be able to display its ~ 1339093 full complexing action, must be adjusted to a basic pH
value in excess of 11. The treatment with the complex-ing agent should in general be carried out over a period of from O . 5 to 2 hours .
It is preferred to continue the rinsing operation in step h) until a weakly alkaline pH value of a maximum of 8 . 5 will have been reached.
For the treatment in process step i) there is preferably employed, as the acidic buffer system, an acetate buffeK system having a pH value of from 4.5 to 6 . O .
After the wet-chemical processing operation, the step following thereto of the oxidative bleaching is preferred to be carried out by bleaching the bovine pericard material with an aqueous solution containing hydrogen peroxide in an amount of less than 2% by weight, and particularly of about 1. 5% by weight. Said llydr OJ~ peroxide bleaching serves the purpose to oxid-atively destroy any accompanying substances of collagen without attacking the collagen itself. It has been shown that hydrogen peroxide concentrations in excess of 2. 0% by weight are not suitable within the scope of the invention, since they already cause noticeable damage to the collagen-containing bovine pericard tissue. The hydrogen peroxide treatment is usually carried out during a period from 0.5 to 2 hours, 0.5 to 1.0 liters of the hydrogen peroxide solution being used per 100 g of the bovine pericard tissue.
Subsequently to this operation of oxidative bleach-ing, residual hydrogen peroxide is removed in a per se known manner by exhaustive washing-out with water.
8 133gO93 Degreasing and drying of the bovine pericard tissue are carried out in such a manner that the pieces first are covered with a sufficient amount of acetone, and said solvent is replaced with a new batch 2 to 6 times within a period of from 12 to 24 hours. The bovine pericard ~i~sue having thus been dehydrated is then transferred to a Soxhlet apparatus, and the residual amounts of water and fat are removed by an exhaustive extraction. After the extraction the bovine pericard pieces are air-dried and then re-hydrated in demineral-ized water (swelling).
Thereafter, the bovine pericard material is lyo-philized and sterilized in an automatically controlled freeze-drier.
The preparation process as described hereinabove according to the invention is in a particular manner suitable to produce a product of consistent quality for use in the f ield of medicine .
The bovine pericard obtained according to the invention may be employed as transplant or implant in various f ields of veterinary medicine or human medicine well known to an artisan. In this context, reference may be made to the company brochure "LyoduraR zum homoo-plastischen Ersatz von Korperstrukturen" [ "Lyodura (R) for the homoplastic replacement of body structures" ] of the company B. Braun Melsungen AG from the year 1978 and the great number of literature references mentioned therein .
In the accompanying drawings:
Figure 1 is a graph showing by way of example the effect that can be achieved by the process according to the invention; and Figure~ 2 to 5 are photographic repre~entations which do, l. the ef fect of bovine pericard material prepared by the process of the invention as compared to commercially available ~ materials.
Evaluation of the ~n~ile strength at break ~ n the 511hrlltAn~" U8 i ~lantation test Figure 1 shows the tensile strength at break vs.
time of strips 10 mm wide of the pericard material obtained according to the invention and in comparison to that of the product Lyodura (R~ well-accepted in the market upon implantation under the dorsal skin of rats (values each averaged for 10 tested animals). In the test, in either case 50 of the strips were implanted and removed after different periods of time passed from the surgery, and the 1~ ~in;n~ tensile strength at break was measured. Curve A was dett~rm;ned with pericard prepared by the process according to the invention. Curve ~ was detPrm;n-~d with Lyodura(R) for comparison.
Over the observation period of 21 days no signific-ant difference can be det~r-n;n~d with respect to the tensile strength at break between the heterologous material pericard prepared according to the invention and the homologous material Lyodura (R); thereby it has been shown that said heterologous material constitutes an excellent substitute for the homologous material.
10_ 1339093 T a b l e:
Tensile strength at break of strips of pericard and of Dura (10 mm wide) upon implantation (n = 10 per group);
each point entered in the diagram has been based on 10 individual measurements.
Implantation Pericard according Lyodura (R) period to the invention (days) (Newton) (Newton) 0 25.0 + 9.4 23 + 10.0 100% + 38 92% + 40 24.1 + 7.9 22.8 + 9.1 96% + 32 91% + 36 4 19.0 + 9.0 19.2 + 8.5 76~ + 36 77% + 34 7 18.8 + 6.3 14 + 5.1 75% + 25 56% + 20 14 10.0 + 4.5 10.1 + 4.5 40% + 18 40% + 18 21 6.5 + 3.0 7.0 + 4.5 2696 + 12 28% + 18 Second line - value in %
0-Value of pericard = 100%
Evaluation of the biocompatibility in the subcutaneous implantation test I.
Subcutaneous implantations of pericard were carried out with altogether 58 rabits and 220 rats. Parameters of the investigation were the pathologic-anatomic f ind-ings and the histologic examination of the implants after stagewise periods of time from 7 days up to 12 months .
The pericard implants according to the invention were compared to lyophilized Dura, Lyodura (R) and acetone-dried Dura mater ~Tutoplast (R) ) . The inflammat-ion reaction and the implant condition were macroscopic-ally Ac~qq~d. Then the sampIes were fixed in 496 of formalin and subjected to a histologic examination.
The microarchitecture of the collagen skeleton was compared to that of non-implanted controls.
The histologic evaluation of the implants covers the invasion behavior of cells (connective tissue cells, immunocompetent cells), the bond implant-recipient (in-growth property), resorption and/or vitalization of the alien material and possible rejection reactions.
Results:
Upon examination of the devitalized samples prior to the implantation it was determined that same were absolutely free from cells or remainders of cell con-stituents. On the other hand, lyophilized and, more particularly, solvent-dried Dura mater exhibited some isolated nucleus material.
a) Microarchitecture of the implants:
It could be tlPtPrmi nPcl that the arrangement of the collagen fiber structure is important for the immigrat-ion behavior of connective tissue cells.
Straight tightly positioned collagen fiber bundles ( in solvent-dried Dura) hinder the revitalization . In the pericard and the Lyodura (R) mostly present as dissociated fibers the repopulation with cells from the connective tissue series i5 facilitated.
b) Vitality of the implant:
The pericard implant behaved as guide rail in the interstices of which the cells immigrate:
Already after one week, plenty of cells have immigrated to the implant which cells have diffusedly spread . They are f ibroblasts and histiocytic elements .
The vitality index increases from the first to the sixth week.
c) Infiltration of the implant by cells not belonging to the connective tissue series such as lymphocytes, macrophages, alien body giant cells.
The occurrence of said cells which in the pericard samples unexpectedly occurred at a lower number than in the Dura samples is not to be equated to a beginning re~ection reaction, but is to be understood as an immun-oinformative process. In contrast to the invasion by fibroblasts and histiocytes, these lymphocytes, macro-phages and giant cells seldom deeply penetrate into the - 13 - 1339~93 implant. Macrophages did more frequently occur where bleeding occurred into the wound bed. The cells (~y., Macr., GC) were counted, and an index was calculated which in the pericard sample put into clinical use ~1.43) was comparatively lower than in the Dura samples (lyophilized: 2.2; acetone-dried: 2.32). This phenomen-on is probably due to the fact that pericard is very well devitalized and does not contain any more cell or cell nucleus residues that might possible display an immunogenic action.
d) Acute infl ~ tion and rejection reactions No immunoreaction was detected in the pericard sample .
In summary it could be det~orm; n~l that the better performance of the pericard samples is due not only to the absence of rej ection reactions but also to the better vitality aspect, while here the somewhat lower thickness of the pericard samples plays a role.
II. Evaluation of biocompatibility and functionability of pericard as a Dura mater cerebralis substitute in the dog The implant, after three and six months post im-plantationem was well integrated so that it was no longer distinguishable from autochthonous Dura (re-vitalized by fibrocytes and traversed by blood vessels in the marginal zones). The inner side of the implant is coated with the same cell type as the autologous Dura. Fusions with the cerebral cor=tex did not exist.
~' - 14 - 1339093 This effect of the bovine pericard material pre-pared by the process according to the invention as compared to commercially available Dura materials i5 documented in the Figures 2 to 5 wherein Figure 2 shows pericard six weeks after subcutan-eous implantation to the rat. Well revitalized completely bland implant with vital f ibroblasts without lymphocytes; new formation of collagen.
Figure 3 shows solvent-dried Dura mater six weeks after subcutaneous implantation to the rat (comparison).
Local accumulation of lymphocytes; in the central area not yet vitalization with fibroblasts.
Figure 4 shows pericard twelve weeks after sub-cutaneous implantation to the rat. Good integration of implant and host tissue; no immunocompetent cells present .
Figure 5 shows solvent-dried Dura mater twelve weeks p. i. (comparison) . Local accumulation of lympho-cytes; the implant is mostly avital due to the dense f ibrous structure .
The process according to the invention is illu-strated hereinbelow by means of a working example for the preparati~n of the bovine pericard.
Workinq Example 1. Recovery of the raw material The bovine heart sacs (pericards) employed as the starting material, after the conventional meat inspect-ion by an official veterinarian in the abattoir, first are separated from attached organ parts and grossly rid of fat and connective tissue. Thereby, sheet-like pieces of approximately 30 cm x 15 cm in size and a weight of about one kilogram p=er piece are obtained.
The bovine pericards havinq been thus prepared are transported in a cold bag loaded with ice from the abattoir to the production site and, depending on the amount of the raw material recovered, int~ ; Ately stored there at below -20 ~C before they are further proces sed .
2. Wet-chemical processing The raw pericard pieces first are individually rinsed with purified water - usually soaked with running water - to remove adherent blood and water-soluble protein portions.
After soaking, all macroscopically visible residues of fat tissue and basal membranes are removed. This is followed by a treatment with 2% a~ueous sodium hydroxide solution at room temperature. The pericard pieces (5,000 grams) remain in the lye bath (37.5 liters) for a total of 16 hours. The removal therefrom is followed by a rinse process taking about 10 minutes in demineralized water, which process is repeated until the pH of the rinse run-off water has been reduced to below 8. This - 16 ~ 3~093 will be reached after about 1 hour. If any basal mem-branes and fat remainders will still be observable, then they will be finally removed in this process stage.
The much swollen pericard pieces are now transfer-red into 37 . 5 liters of a 10% aqueous saline to adjust the swelling state (partial deswelling~ as necessary for the further process steps. The NaCl treatment is carried out at room temperature. It is followed by a rinse process with demineralized water.
In order to remove any interfering heavy metal ions and any possible lime inclusions from the pericard material, the material is then subjected to a treatment with 37 . 5 liters of a EDTA solution adjusted to be weak-ly alkaline and having the concentration of O . 3 g in 100 ml. Then, the material is rinsed with demineralized water as in the preceding process steps to remove the excess of complexing agent and at the same time to bring the pH value to 8 . 5 . The one-time treatment now follow-ing with 37.5 liters of acetate buffer ~pH 4.8; compo-sition, per 100 ml: 59 parts by volume of a solution of o. 01 moles of sodium acetate plus 3 H2O in 100 ml and 41 parts by volume of 0. 01 moles of acetic acid in 100 ml~ serves the purpose of buffering all of the resi-dues, if any, left in the pericard tissue and to prepare a weakly acidic medium for the subsequent bleaching operation. Any excessive buffer substances are removed as described above by rinsing with demineralized water.
From the beginning of this century it has been attempted in surgery to cover large tissue defects by means of transplants of collagenous connective tissue (Marchant, 1901: ~leinschmidt, 1914). Since 1954 human Dura mater is available as homologous transplant in lyophilized form and since 1973 in the form of a solvent-dried product. In many cases, human Dura, due to its good tissue compatibility, the absence of immuno-15 logic reactions and not least its high tensile strength at break has proven its value, so that this bio-material is successfully used even to-day. ~nfortunately, Dura mater, as a human transplant, is available only to a limited extent and, thus, by far cannot meet the demands 2 o of surgery . Also there are some indications, for example in neurosurgery and the ear, nose and thro t /
- -2- 1339a93 medicine, where Dura transplants frequently have proven to be somewhat to stiff and not the optimum in thick-ness .
The DE-OS 30 34 273 relates to a method for pre-paring collagen, said method been characterized in that natural insoluble collagen is treated with an aqueous solution of an alkali sulfate and/or alkali hydroxide, that the fat-free collagen is treated in an aqueous solution containing an alkali sulfate and optionally is washed with water, the collagen is dissolved in an aqueous solution, a small amount of a biologically active substance such as an antibiotic, a hormone or a spermizide is optionally added to the solution, said solution is frozen and the product is dried in vacuo.
However, said Offenlt:yul~y ~ rift [Public Unexamin-ed Patent Application] does neither anticipate the sub-j ect matter of the present invention nor render same obvious to the artisan.
The U.S. Patent No. 4,006,083 describes a sterile collagen product usable in surgery and having a felt or woven imitation fur structure, which product exerts a hemostatic action, has a high absorption capacity for body liquids, stimulates cell regeneration, has a high resorbability, substantialy is not rejected by body tissues and has optimum mechanical properties, which properties render said product capable of being used in the care of skin injuries or in skin lesions or in bone cavities .
However, the teaching of said U. S . Patent does neither anticipate the subj ect matter of the present invention nor render same obvious.
The U.S. Patent No. 4,502,159 descrlbes the pre-paration of a tubular prosthesis such as, for example, a vessel or ureter prosthesis. Said prosthesis is prepared by suturing the opposite corners of a pericard tissue using a biocompatible suture material. An exact description is provided of the suturing procedure. It is preferre~ to use bovine pericard which has similar extensibility properties as human tissue. The tubular tissue, once sutured, is tanned in a 0 . 5% solution of glutardialdehyde for 7 days. The smooth surface of the pericard material has been turned inside, while the basal membranes are on the outer surface. Sterilization is effected by preservation in formalin or by radiation sterilization of a physiological saline containing the pericard .
However, said U.S. Patent does not provide any information on isolation, purification and/or the physical and chemical properties of the tubular prosthesis thus prepared, so that the subject matter of the U.S. Patent cannot render obvious the subject matter of the present invention.
From these circumstances of prior art there arose necessarily a desire to provide a transplant or implant, respectively, which is available to a virtually unlimit-ed extent, which as much as possible includes all of the positive properties of the Dura mater and, in addition thereto, o~fers some further advantages when handled.
~oreover, it should be ensured that no germs dangerous to humans (HIV viruses, hepatitis viruses etc. ) could be entrained and introduced by the raw material, as is basically possible with human transplants.
.. ~f ~
. ~ , ~1 _ 4 _ 13~9~93 In consideration of all product-relevant para-meters, in bovine pericard - also designated as pericard hereinbelow - a biologic material has been found which in an almost optimum manner satisfied the reguirements set ~or an implant for covering human tissue defects.
It is the object of the present invention to create a process for the preparation of bovine pericard materials wherein the biological compatibility and stability of the product obtained thereby is improved.
It is a ~urther object o~ the present invention to provide new possible uses for this product.
Now it has been surprisingly found by experimental research that by means of a modified production process the resistance to biological degradation o~ the sclero-proteins contained in the bovine pericard and the bio-compatibility thereof may be ~nhAn~ ed even without an 21dehyde tanning ~uceduLe using formaldehyde or glutar-dialdehyde - like those described in the US-A-4, 502 ,159, WO 84/04669 published December 6,1984, and in the LJS-A-4,456,589.
The present invention relates to a process ~or preparing bovine pericard material by subjecting raw bovine pericard tissue to operations of wet-chemical processing, oxidative bleaching, washing out, de-greasing, drying and sterilizing, said process being characterized in that the wet-chemical processing o~ the bovine pericard tissue comprises the folIowing steps:
a) Soaking the bovine pericard tissue;
b) M~-rh~n;~Ally removing fat tissue and baszl membranes ~rom the surfacé of the bovine pericard tissue;
c) Treating the bovine pericard tissue with a diluted aqueous basic solution;
... :. , ,. ~
_ _ _ 5 _ 1339~93 d) Rinsing the bovine pericard tissue with demineralized water to remove residual base;
e) Treating the bovine pericard tissue with a diluted aqueous sodium chloride solution;
f) Rinsing the bovine pericard tissue with demineralized water to ~remove residual sodium chloride;
g) Treating the bovine pericard tissue with a complexing aqent;
h) Rinsing the bovine pericard tissue with demineralized water to remove residual complex-ing agent;
i) Treating the bovine pericard tissue with an acidic buffer system; and j ) Rinsing the bovine pericard tissue with demineralized water to remove residual acidic buffer system.
In a preferred embodiment of the present invention the measure according to feature b) is repeated sub-sequently to process step d) prior to process step e~.
Although the described measures in the wet-chemical processing may be readily carried out above room tempe-rature or below room temperature, it is preferred within the scope of the present invention to conduct all wet-chemical process steps at room temperature, that is between 15 ~C and 25 ~C.
The treatment in process step c) is preferably carried out in a diluted aqueous basic solution of sodium hydroxide, potassium hydroxide, lithium hydroxide and/or sodium carbonate. Particularly preferred is the use of a 2 to 2 . 59~ by weight aqueous sodium hydroxide solution which generally should act onto the bovine pericard tissue during a period of up to 16 hours, O . 50 to 1. 00 liters of the diluted basic solutions being used per 100 grams of bovine pericard tissue. Hereby, on the one hand, a good purification effect is attained which includes a complete deactivation as much as possible of enzymes and potential germs while, on the other hand, damage to the collagen-containing tissue is avoided.
After the treatment with the diluted aqueous basic solution the pericard tissue generally is strongly swollen to 2 to 5 times the initial volume.
The treatment in process step e) is preferably carried out with a 10 to 11% by weight sodium chloride solution, whereby a swelling condition of the collagen may be controlled which is favorable for further processing same. In contrast, lower concentrations in the sodium chloride solution will only cause insuffi-cient de-swelling o~ the collagen much swollen after the alkaline treatment. Higher sodium chloride concentrat-ions in the solution would cause an l~nn~ cs;~ry accumulation to occur of salt r~; n~rS in the bovine pericard tissue and are not meaningful already for this reason .
The treatment in process step g) is preferably carried out with a complexing agent as known to the artisan for complexing polyvalent metal ions which in part are present bound to proteins. In this case, a disodium EDTA solution has proven to be particularly preferable, which is present, for example, in a con-centration of from O . 3 to O . 5% by weight. Said complexing agent, in order to be able to display its ~ 1339093 full complexing action, must be adjusted to a basic pH
value in excess of 11. The treatment with the complex-ing agent should in general be carried out over a period of from O . 5 to 2 hours .
It is preferred to continue the rinsing operation in step h) until a weakly alkaline pH value of a maximum of 8 . 5 will have been reached.
For the treatment in process step i) there is preferably employed, as the acidic buffer system, an acetate buffeK system having a pH value of from 4.5 to 6 . O .
After the wet-chemical processing operation, the step following thereto of the oxidative bleaching is preferred to be carried out by bleaching the bovine pericard material with an aqueous solution containing hydrogen peroxide in an amount of less than 2% by weight, and particularly of about 1. 5% by weight. Said llydr OJ~ peroxide bleaching serves the purpose to oxid-atively destroy any accompanying substances of collagen without attacking the collagen itself. It has been shown that hydrogen peroxide concentrations in excess of 2. 0% by weight are not suitable within the scope of the invention, since they already cause noticeable damage to the collagen-containing bovine pericard tissue. The hydrogen peroxide treatment is usually carried out during a period from 0.5 to 2 hours, 0.5 to 1.0 liters of the hydrogen peroxide solution being used per 100 g of the bovine pericard tissue.
Subsequently to this operation of oxidative bleach-ing, residual hydrogen peroxide is removed in a per se known manner by exhaustive washing-out with water.
8 133gO93 Degreasing and drying of the bovine pericard tissue are carried out in such a manner that the pieces first are covered with a sufficient amount of acetone, and said solvent is replaced with a new batch 2 to 6 times within a period of from 12 to 24 hours. The bovine pericard ~i~sue having thus been dehydrated is then transferred to a Soxhlet apparatus, and the residual amounts of water and fat are removed by an exhaustive extraction. After the extraction the bovine pericard pieces are air-dried and then re-hydrated in demineral-ized water (swelling).
Thereafter, the bovine pericard material is lyo-philized and sterilized in an automatically controlled freeze-drier.
The preparation process as described hereinabove according to the invention is in a particular manner suitable to produce a product of consistent quality for use in the f ield of medicine .
The bovine pericard obtained according to the invention may be employed as transplant or implant in various f ields of veterinary medicine or human medicine well known to an artisan. In this context, reference may be made to the company brochure "LyoduraR zum homoo-plastischen Ersatz von Korperstrukturen" [ "Lyodura (R) for the homoplastic replacement of body structures" ] of the company B. Braun Melsungen AG from the year 1978 and the great number of literature references mentioned therein .
In the accompanying drawings:
Figure 1 is a graph showing by way of example the effect that can be achieved by the process according to the invention; and Figure~ 2 to 5 are photographic repre~entations which do, l. the ef fect of bovine pericard material prepared by the process of the invention as compared to commercially available ~ materials.
Evaluation of the ~n~ile strength at break ~ n the 511hrlltAn~" U8 i ~lantation test Figure 1 shows the tensile strength at break vs.
time of strips 10 mm wide of the pericard material obtained according to the invention and in comparison to that of the product Lyodura (R~ well-accepted in the market upon implantation under the dorsal skin of rats (values each averaged for 10 tested animals). In the test, in either case 50 of the strips were implanted and removed after different periods of time passed from the surgery, and the 1~ ~in;n~ tensile strength at break was measured. Curve A was dett~rm;ned with pericard prepared by the process according to the invention. Curve ~ was detPrm;n-~d with Lyodura(R) for comparison.
Over the observation period of 21 days no signific-ant difference can be det~r-n;n~d with respect to the tensile strength at break between the heterologous material pericard prepared according to the invention and the homologous material Lyodura (R); thereby it has been shown that said heterologous material constitutes an excellent substitute for the homologous material.
10_ 1339093 T a b l e:
Tensile strength at break of strips of pericard and of Dura (10 mm wide) upon implantation (n = 10 per group);
each point entered in the diagram has been based on 10 individual measurements.
Implantation Pericard according Lyodura (R) period to the invention (days) (Newton) (Newton) 0 25.0 + 9.4 23 + 10.0 100% + 38 92% + 40 24.1 + 7.9 22.8 + 9.1 96% + 32 91% + 36 4 19.0 + 9.0 19.2 + 8.5 76~ + 36 77% + 34 7 18.8 + 6.3 14 + 5.1 75% + 25 56% + 20 14 10.0 + 4.5 10.1 + 4.5 40% + 18 40% + 18 21 6.5 + 3.0 7.0 + 4.5 2696 + 12 28% + 18 Second line - value in %
0-Value of pericard = 100%
Evaluation of the biocompatibility in the subcutaneous implantation test I.
Subcutaneous implantations of pericard were carried out with altogether 58 rabits and 220 rats. Parameters of the investigation were the pathologic-anatomic f ind-ings and the histologic examination of the implants after stagewise periods of time from 7 days up to 12 months .
The pericard implants according to the invention were compared to lyophilized Dura, Lyodura (R) and acetone-dried Dura mater ~Tutoplast (R) ) . The inflammat-ion reaction and the implant condition were macroscopic-ally Ac~qq~d. Then the sampIes were fixed in 496 of formalin and subjected to a histologic examination.
The microarchitecture of the collagen skeleton was compared to that of non-implanted controls.
The histologic evaluation of the implants covers the invasion behavior of cells (connective tissue cells, immunocompetent cells), the bond implant-recipient (in-growth property), resorption and/or vitalization of the alien material and possible rejection reactions.
Results:
Upon examination of the devitalized samples prior to the implantation it was determined that same were absolutely free from cells or remainders of cell con-stituents. On the other hand, lyophilized and, more particularly, solvent-dried Dura mater exhibited some isolated nucleus material.
a) Microarchitecture of the implants:
It could be tlPtPrmi nPcl that the arrangement of the collagen fiber structure is important for the immigrat-ion behavior of connective tissue cells.
Straight tightly positioned collagen fiber bundles ( in solvent-dried Dura) hinder the revitalization . In the pericard and the Lyodura (R) mostly present as dissociated fibers the repopulation with cells from the connective tissue series i5 facilitated.
b) Vitality of the implant:
The pericard implant behaved as guide rail in the interstices of which the cells immigrate:
Already after one week, plenty of cells have immigrated to the implant which cells have diffusedly spread . They are f ibroblasts and histiocytic elements .
The vitality index increases from the first to the sixth week.
c) Infiltration of the implant by cells not belonging to the connective tissue series such as lymphocytes, macrophages, alien body giant cells.
The occurrence of said cells which in the pericard samples unexpectedly occurred at a lower number than in the Dura samples is not to be equated to a beginning re~ection reaction, but is to be understood as an immun-oinformative process. In contrast to the invasion by fibroblasts and histiocytes, these lymphocytes, macro-phages and giant cells seldom deeply penetrate into the - 13 - 1339~93 implant. Macrophages did more frequently occur where bleeding occurred into the wound bed. The cells (~y., Macr., GC) were counted, and an index was calculated which in the pericard sample put into clinical use ~1.43) was comparatively lower than in the Dura samples (lyophilized: 2.2; acetone-dried: 2.32). This phenomen-on is probably due to the fact that pericard is very well devitalized and does not contain any more cell or cell nucleus residues that might possible display an immunogenic action.
d) Acute infl ~ tion and rejection reactions No immunoreaction was detected in the pericard sample .
In summary it could be det~orm; n~l that the better performance of the pericard samples is due not only to the absence of rej ection reactions but also to the better vitality aspect, while here the somewhat lower thickness of the pericard samples plays a role.
II. Evaluation of biocompatibility and functionability of pericard as a Dura mater cerebralis substitute in the dog The implant, after three and six months post im-plantationem was well integrated so that it was no longer distinguishable from autochthonous Dura (re-vitalized by fibrocytes and traversed by blood vessels in the marginal zones). The inner side of the implant is coated with the same cell type as the autologous Dura. Fusions with the cerebral cor=tex did not exist.
~' - 14 - 1339093 This effect of the bovine pericard material pre-pared by the process according to the invention as compared to commercially available Dura materials i5 documented in the Figures 2 to 5 wherein Figure 2 shows pericard six weeks after subcutan-eous implantation to the rat. Well revitalized completely bland implant with vital f ibroblasts without lymphocytes; new formation of collagen.
Figure 3 shows solvent-dried Dura mater six weeks after subcutaneous implantation to the rat (comparison).
Local accumulation of lymphocytes; in the central area not yet vitalization with fibroblasts.
Figure 4 shows pericard twelve weeks after sub-cutaneous implantation to the rat. Good integration of implant and host tissue; no immunocompetent cells present .
Figure 5 shows solvent-dried Dura mater twelve weeks p. i. (comparison) . Local accumulation of lympho-cytes; the implant is mostly avital due to the dense f ibrous structure .
The process according to the invention is illu-strated hereinbelow by means of a working example for the preparati~n of the bovine pericard.
Workinq Example 1. Recovery of the raw material The bovine heart sacs (pericards) employed as the starting material, after the conventional meat inspect-ion by an official veterinarian in the abattoir, first are separated from attached organ parts and grossly rid of fat and connective tissue. Thereby, sheet-like pieces of approximately 30 cm x 15 cm in size and a weight of about one kilogram p=er piece are obtained.
The bovine pericards havinq been thus prepared are transported in a cold bag loaded with ice from the abattoir to the production site and, depending on the amount of the raw material recovered, int~ ; Ately stored there at below -20 ~C before they are further proces sed .
2. Wet-chemical processing The raw pericard pieces first are individually rinsed with purified water - usually soaked with running water - to remove adherent blood and water-soluble protein portions.
After soaking, all macroscopically visible residues of fat tissue and basal membranes are removed. This is followed by a treatment with 2% a~ueous sodium hydroxide solution at room temperature. The pericard pieces (5,000 grams) remain in the lye bath (37.5 liters) for a total of 16 hours. The removal therefrom is followed by a rinse process taking about 10 minutes in demineralized water, which process is repeated until the pH of the rinse run-off water has been reduced to below 8. This - 16 ~ 3~093 will be reached after about 1 hour. If any basal mem-branes and fat remainders will still be observable, then they will be finally removed in this process stage.
The much swollen pericard pieces are now transfer-red into 37 . 5 liters of a 10% aqueous saline to adjust the swelling state (partial deswelling~ as necessary for the further process steps. The NaCl treatment is carried out at room temperature. It is followed by a rinse process with demineralized water.
In order to remove any interfering heavy metal ions and any possible lime inclusions from the pericard material, the material is then subjected to a treatment with 37 . 5 liters of a EDTA solution adjusted to be weak-ly alkaline and having the concentration of O . 3 g in 100 ml. Then, the material is rinsed with demineralized water as in the preceding process steps to remove the excess of complexing agent and at the same time to bring the pH value to 8 . 5 . The one-time treatment now follow-ing with 37.5 liters of acetate buffer ~pH 4.8; compo-sition, per 100 ml: 59 parts by volume of a solution of o. 01 moles of sodium acetate plus 3 H2O in 100 ml and 41 parts by volume of 0. 01 moles of acetic acid in 100 ml~ serves the purpose of buffering all of the resi-dues, if any, left in the pericard tissue and to prepare a weakly acidic medium for the subsequent bleaching operation. Any excessive buffer substances are removed as described above by rinsing with demineralized water.
3. Oxidative bleaching Subsequently to the wet-chemical processing, the pericard pieces are subj ected to an oxidative bleaching ~ ' - 17 _ 133g~93 operation taking one hour in 37 . 5 liters of a l . 5%
hydrogen peroxide solution. The bleaching process is carried out, as well as the preceding process steps are, at room temperature. Thereby, on the one hand, the efficiency of the purification operations is ensured while, on the other hand, a deterioration of the collagenous tissue is avoided.
hydrogen peroxide solution. The bleaching process is carried out, as well as the preceding process steps are, at room temperature. Thereby, on the one hand, the efficiency of the purification operations is ensured while, on the other hand, a deterioration of the collagenous tissue is avoided.
4. Washing out In order to remove any excess of reagent, the material is subsequently rinsed with demineralized water according to the conventional regimen.
5. Degreasing The rinsed bovine pericard pieces are placed in such an amount of acetone that the bovine pericard tissue was completely covered with acetone.
The solvent was three times replaced within 8 hours. The bovine pericard pieces thus dehydrated were then transferred to a Soxhlet apparatus and extracted with acetone for about 8 hours. After the extraction the pericard pieces were air-dried and then re-hydrated in a transportation vessel with demineral-ized water.
. Lyophilization Drying was effected in an automatically controlled freeze dryer. Freeze-drying in detail proceeds as follows .
~ . 13390 Lowering the temperature to +l ~C, lowering the temperature to -40 ~C, turning-on the vacuum, heating the trays to +40 ~C and drying with full vacuum.
7. Sterilization Sterilization is effected by radiation sterilizat-ion with 2 . 5 Mrad.
The solvent was three times replaced within 8 hours. The bovine pericard pieces thus dehydrated were then transferred to a Soxhlet apparatus and extracted with acetone for about 8 hours. After the extraction the pericard pieces were air-dried and then re-hydrated in a transportation vessel with demineral-ized water.
. Lyophilization Drying was effected in an automatically controlled freeze dryer. Freeze-drying in detail proceeds as follows .
~ . 13390 Lowering the temperature to +l ~C, lowering the temperature to -40 ~C, turning-on the vacuum, heating the trays to +40 ~C and drying with full vacuum.
7. Sterilization Sterilization is effected by radiation sterilizat-ion with 2 . 5 Mrad.
Claims (15)
1. A process for preparing bovine pericard material by subjecting raw bovine pericard tissue to operations of wet-chemical processing, oxidative bleaching, washing out degreasing, drying and sterilizing, characterized in that the wet-chemical processing of the bovine pericard tissue comprises the following steps:
a) Soaking the bovine pericard tissue in water;
b) Mechanically removing fat tissue and basal membranes from the surface of the bovine pericard tissue;
c) Treating the bovine pericard tissue with a dilute aqueous basic solution;
d) Rinsing the bovine pericard tissue with demineralized water to remove residual base;
e) Treating the bovine pericard tissue with a dilute aqueous sodium chloride solution;
f) Rinsing the bovine pericard tissue with demineralized water to remove residual sodium chloride;
g) Treating the bovine pericard tissue with a complexing agent for complexing polyvalent metal ions;
h) Rinsing the bovine pericard tissue with demineralized water to remove residual complexing agent;
i) Treating the bovine pericard tissue with an acidic buffer system;
and j) Rinsing the bovine pericard tissue with demineralized water to remove residual acidic buffer system.
a) Soaking the bovine pericard tissue in water;
b) Mechanically removing fat tissue and basal membranes from the surface of the bovine pericard tissue;
c) Treating the bovine pericard tissue with a dilute aqueous basic solution;
d) Rinsing the bovine pericard tissue with demineralized water to remove residual base;
e) Treating the bovine pericard tissue with a dilute aqueous sodium chloride solution;
f) Rinsing the bovine pericard tissue with demineralized water to remove residual sodium chloride;
g) Treating the bovine pericard tissue with a complexing agent for complexing polyvalent metal ions;
h) Rinsing the bovine pericard tissue with demineralized water to remove residual complexing agent;
i) Treating the bovine pericard tissue with an acidic buffer system;
and j) Rinsing the bovine pericard tissue with demineralized water to remove residual acidic buffer system.
2. The process according to claim 1, characterized in that the measure according to feature b) is repeated subsequently to process step d) prior to process step e).
3. The process according to claim 1, characterized in that the wet-chemical processing steps a) and c) through j) are conducted at room temperature, that is between 15°C and 25°.C
4. The process according to any one of claims 1 to 3, characterized in that the treatment in process step c) is carried out in a dilute aqueous basic solution containing at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide and sodium carbonate for a period of up to 16 hours.
5. The process according to any one of claims 1 to 3, characterized in that the treatment in process step c) is carried out in a dilute aqueous basic solution of 2 to 2.5% by weight sodium hydroxide for a period of up to 16 hours.
6. The process according to any one of claims 1 to 3, characterized in that the treatment in process step e) is carried out with a 10 to 11% by weight sodium chloride solution.
7. The process according to any one of claims 1 to 3, characterized in that the treatment in process step g) is carried out with a dilute disodium EDTA
solution in an aqueous alkaline medium pH ~ 11.
solution in an aqueous alkaline medium pH ~ 11.
8. The process according to any one of claims 1 to 3, characterized in that the treatment in process step g) is carried out with a dilute disodium EDTA
solution of 0.3 to 0.5% by weight in an aqueous alkaline medium pH ~ 11.
solution of 0.3 to 0.5% by weight in an aqueous alkaline medium pH ~ 11.
9. The process according to any one of claims 1 to 3, characterized in that the rinsing procedure in process step h) is continued until a weakly alkaline pH value of up to 8.5 has been reached.
10. The process according to any one of claims 1 to 3, characterized in that the treatment in process step i) is carried out with an acetate buffer system at a pH value of from 4.5 to 6.
11. The process according to any one of claims 1 to 3, characterized in that the treatment in process step i) is carried out with an acetate buffer system at a pH value of 4.8.
12. The process according to any one of claims 1 to 3, characterized in that the oxidative bleaching is effected with aqueous solutions containing hydrogen peroxide at a content of less than 2% by weight.
13. The process according to any one of claims 1 to 3, characterized that the oxidative bleaching is effected with aqueous solutions containing hydrogen peroxide at a content of less than 1.5% by weight.
14. The process according to any one of claims 1 to 3, characterized in that the operations of degreasing and drying are effected by acetone treatment at room temperature, Soxhlet extraction with acetone, re-hydration and freeze-drying.
15. Use of the bovine pericard materials obtained according to any one of claims 1 to 3 as transplants and implants in human and veterinary medicine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3835237A DE3835237C1 (en) | 1988-10-15 | 1988-10-15 | |
| DEP3835237.0 | 1988-10-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1339093C true CA1339093C (en) | 1997-07-29 |
Family
ID=6365247
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000614535A Expired - Fee Related CA1339093C (en) | 1988-10-15 | 1989-09-29 | Process for preparing bovine pericard materials and use thereof |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5413798A (en) |
| EP (2) | EP0438499B1 (en) |
| JP (1) | JP2624553B2 (en) |
| AT (1) | ATE106754T1 (en) |
| CA (1) | CA1339093C (en) |
| DE (2) | DE3835237C1 (en) |
| WO (1) | WO1990003811A1 (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2324958C (en) | 1998-03-23 | 2009-12-22 | Bio-Vascular, Inc. | Pericardial tissue implants and methods of making them |
| ES2234311T3 (en) * | 1998-09-30 | 2005-06-16 | Medtronic, Inc. | PROCEDURE THAT ALLOWS TO REDUCE THE MINERALIZATION OF A FABRIC USED FOR A TRANSPLANT. |
| DE19940426A1 (en) * | 1999-08-26 | 2001-03-01 | Tutogen Medical Gmbh | Process for dehydrating biological tissues for the production of canned grafts |
| US6312474B1 (en) * | 1999-09-15 | 2001-11-06 | Bio-Vascular, Inc. | Resorbable implant materials |
| US6893462B2 (en) * | 2000-01-11 | 2005-05-17 | Regeneration Technologies, Inc. | Soft and calcified tissue implants |
| US7078163B2 (en) * | 2001-03-30 | 2006-07-18 | Medtronic, Inc. | Process for reducing mineralization of tissue used in transplantation |
| DE10157182A1 (en) * | 2001-11-22 | 2003-06-05 | Matricel Gmbh | Process for the treatment of materials of biological origin and elastin product |
| DE10217779A1 (en) * | 2002-04-18 | 2003-11-13 | Co Don Ag | Preserved tissue matrix of a hollow organ, especially a blood vessel, process for the production and use thereof |
| US7144588B2 (en) | 2003-01-17 | 2006-12-05 | Synovis Life Technologies, Inc. | Method of preventing surgical adhesions |
| US7955788B2 (en) * | 2003-10-30 | 2011-06-07 | Medtronic, Inc. | Bioprosthetic tissue preparation with synthetic hydrogels |
| US20050266390A1 (en) * | 2004-06-01 | 2005-12-01 | Yuichiro Ueda | Processes for removing cells and cell debris from tissue and tissue constructs used in transplantation and tissue reconstruction |
| US7651387B2 (en) * | 2008-03-28 | 2010-01-26 | Southern Lights Ventures 2002 Limited | Apparatus and method for processing bovine pericardium |
| DE102008022319A1 (en) | 2008-04-30 | 2009-11-05 | Aesculap Ag | Implant, in particular for restoring and / or regenerating human and / or animal tissue |
| JP5424147B2 (en) * | 2009-06-26 | 2014-02-26 | 学校法人早稲田大学 | Method and device for holding biological tissue during storage processing, and biological tissue subjected to storage processing |
| US9211361B2 (en) | 2010-03-15 | 2015-12-15 | Kemal Schankereli | Thin collagen tissue for medical device applications |
| DE102011008604A1 (en) | 2011-01-14 | 2012-07-19 | Tutogen Medical Gmbh | Preparation of a graft of animal dermis with sodium sulfide solution |
| CN104524634B (en) * | 2014-12-17 | 2017-01-18 | 陕西佰傲再生医学有限公司 | Preparation method of tissue repair material |
| EP3693030A1 (en) | 2019-02-07 | 2020-08-12 | P+F Products + Features GmbH | Method for preparing biological tissue for surgical implantation |
| CN111420122A (en) * | 2020-04-30 | 2020-07-17 | 山东隽秀生物科技股份有限公司 | Biological membrane capable of inducing bone regeneration and preparation method thereof |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5043794A (en) * | 1973-08-22 | 1975-04-19 | ||
| US4006083A (en) | 1975-10-09 | 1977-02-01 | Caterpillar Tractor Co. | Pressure differential switch |
| US4066083A (en) * | 1976-06-03 | 1978-01-03 | Pentapharm A.G. | Sterile surgical collagen product |
| DE2854490C2 (en) * | 1978-12-16 | 1981-04-09 | B. Braun Melsungen Ag, 3508 Melsungen | Bone substitute material with improved biological stability based on collagen |
| US4279812A (en) * | 1979-09-12 | 1981-07-21 | Seton Company | Process for preparing macromolecular biologically active collagen |
| JPS5675152A (en) * | 1979-11-26 | 1981-06-22 | Matsuda Ika Kogyo | Reinforcing material for medical treatment |
| JPS5897365A (en) * | 1981-11-30 | 1983-06-09 | ヘモコン・ゲゼルシヤフト・ツ−ル・エントヴイツクルング・フオン・コラ−ゲンプロドウクテン | Production of surgical collagen fiber |
| US4456589A (en) | 1982-07-08 | 1984-06-26 | Genetic Laboratories, Inc. | Preparation of animal tissues for surgical implantation in human recipients |
| US4502159A (en) * | 1982-08-12 | 1985-03-05 | Shiley Incorporated | Tubular prostheses prepared from pericardial tissue |
| US4894063A (en) | 1983-05-24 | 1990-01-16 | Baxter International Inc. | Barrier layer for implantable tendons and ligaments |
| GB8413319D0 (en) * | 1984-05-24 | 1984-06-27 | Oliver Roy Frederick | Biological material |
| CA1254839A (en) * | 1984-08-14 | 1989-05-30 | Mark W. Torrianni | Retarded mineralization of implantable tissue by surface active betaines |
| SU1321420A1 (en) * | 1985-06-19 | 1987-07-07 | Московский научно-исследовательский институт микрохирургии глаза | Method of collagen coating for ophthalmological use |
| GB8618374D0 (en) * | 1986-07-28 | 1986-09-03 | Hsc Res Dev Corp | Biological vascular prostheses |
-
1988
- 1988-10-15 DE DE3835237A patent/DE3835237C1/de not_active Expired
-
1989
- 1989-09-29 CA CA000614535A patent/CA1339093C/en not_active Expired - Fee Related
- 1989-10-11 EP EP89911979A patent/EP0438499B1/en not_active Expired - Lifetime
- 1989-10-11 EP EP89118882A patent/EP0364871A1/en active Pending
- 1989-10-11 DE DE58907855T patent/DE58907855D1/en not_active Expired - Fee Related
- 1989-10-11 JP JP1511089A patent/JP2624553B2/en not_active Expired - Lifetime
- 1989-10-11 AT AT89911979T patent/ATE106754T1/en not_active IP Right Cessation
- 1989-10-11 WO PCT/EP1989/001202 patent/WO1990003811A1/en active IP Right Grant
-
1994
- 1994-04-06 US US08/223,826 patent/US5413798A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE3835237C1 (en) | 1989-12-28 |
| WO1990003811A1 (en) | 1990-04-19 |
| ATE106754T1 (en) | 1994-06-15 |
| EP0438499B1 (en) | 1994-06-08 |
| DE58907855D1 (en) | 1994-07-14 |
| JP2624553B2 (en) | 1997-06-25 |
| EP0364871A1 (en) | 1990-04-25 |
| EP0438499A1 (en) | 1991-07-31 |
| JPH04501077A (en) | 1992-02-27 |
| US5413798A (en) | 1995-05-09 |
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