WO2008097884A2

WO2008097884A2 - Processing skin from living donors

Info

Publication number: WO2008097884A2
Application number: PCT/US2008/052884
Authority: WO
Inventors: Manh-Dan Ngo
Original assignee: Manh-Dan Ngo
Priority date: 2007-02-02
Filing date: 2008-02-04
Publication date: 2008-08-14
Also published as: WO2008097884A3; EP2117462A1; EP2114136A2; WO2008097885A2; EP2114135A2; WO2008097882A1; CA2677305A1; CA2677229A1; CA2677308A1; WO2008097885A3

Abstract

In certain embodiments, the present invention relates to a process for preparing skin removed from a living human and removing cellular components and forming a decellular matrix having as major components collagens and elastins while disinfecting the tissue. In a particular embodiment, the process comprises the following: (1) removing hair from the skin; (2) decellularizing the skin including inspection for visual defects, trimming and soaking the tissue in a detergent and rinsing same with sterile water; (3) decontaminating the skin in an antibiotic composition containing peracetic acid; and (4) processing the tissue by cutting the tissue to size.

Description

PROCESSING SKIN FROM LIVING DONORS

RELATED APPLICATIONS

This application claims the benefit of priority of U.S. Provisional Application Serial Nos. 60/899,021, filed February 2, 2007; 60/899,020, filed

February 2, 2007; 60/899,018, filed February 2, 2007; and 60/924,249, filed May 4,

2007, the specifications of each of which are hereby incorporated by reference in their entirety.

FIELD OF INVENTION

The present invention is generally directed toward methods of treatment of allograft soft tissue taken from a living donor, including hair removal, decellularizing and disinfection for implantation into another human being.

BACKGROUND OF THE INVENTION

Techniques for restoring structure and function to damaged tissue are used routinely in the area of reconstructive surgery. Tissue transplantation is another way of restoring function by replacing or rebuilding the damaged tissue. However, problems exist when there is a transfer of biological material from one individual to another. Tissue rejection is a significant risk associated with transplantation, even with a good histocompatability match. Immunosuppressive drugs such as cyclosporin and FK506 are usually given to the patient to prevent rejection. These immunosuppressive drugs however, have a narrow therapeutic window between adequate immunosuppression and toxicity. Prolonged immunosuppression can weaken the immune system, which can lead to a threat of infection.

The advantages of retaining an acellular matrix, composed primarily of a collagenous component, have been explored by Klaus and Duhamel (WO 84/0488)) for the production of sterile body implants. In this method, a variety of tissues were extracted sequentially with non-ionic and ionic detergents to yield structures essentially free of cellular membranes, nucleic acids, lipids and cytoplasmic PATENT Atty. Docket No. 544945-204

components. The treatment consists of sequential extractions with a non-denaturing detergent and a denaturing detergent to form an acellular matrix of collagen.

U.S. Patent Number 4,776,853 relates to a process for preparing biological material for implant in a mammal's cardiovascular system, respiratory system or soft tissue. The process comprises: (1) isolating a desired tissue sample of the biological material from a donor; (2) extracting the tissue sample with an hypotonic buffer solution at a mild alkaline pH, the buffer solution including active amounts of proteolytic inhibitors and antibiotics; (3) extracting the tissue sample with a buffered solution having a high concentration of salt, the solution being at a mild alkaline pH and including a non-ionic detergent with protease inhibitors and antibiotics; (4) subjecting tissue sample to enzymatic digestion in a buffered saline solution, the enzymes consisting of purified protease-free dioxyribonuclease and ribonuclease;

(5) extracting the tissue sample with an anionic detergent at a mild alkaline pH; and

(6) storing the tissue sample in physiologic buffered solutions. Another soft tissue process is shown in U.S. Patent Number 6,734,018 which relates to toward a process for preparing an acellular soft tissue graft for implantation into a mammalian system. The process extracts a soft tissue sample with an extracting solution including one or more nonionic detergents and one or more endonucleases, to produce extracted tissue and treats the extracted tissue with a treating solution including one or more anionic detergents, to produce a treated tissue. The treated tissue is washed with a decontaminating solution including one or more decontaminating agents to produce the acellular soft tissue graft; and acellular soft tissue graft is then stored in a storage solution comprising one or more decontaminating agents. The soft tissue process of the '018 patent includes the steps of: isolating from a suitable donor a desired tissue sample of the biological material; extracting the tissue with mildly alkaline hypotonic buffered solution of an endonuclease such as Benzonase RTM and a nonionic detergent formulation such as Allowash Solution™ optionally treating the tissue with a hypertonic buffered salt solution; extracting and treating the tissue with a mildly alkaline hypotonic buffered solution of sodium PATENT Atty. Docket No. 544945-204 dodecylsulfate, optionally with 0.1 to 0.5 M sodium chloride rendering the solution hypertonic; washing the tissue with ultrapure water followed by a water solution of chlorine dioxide; and storage in a sealed container in isotonic saline, chlorine dioxide or 70% isopropanol. It can thus be seen that previous processes require extensive chemical treatment with a multitude of process steps in an attempt to obtain an acellular soft tissue specimen which has limited shelf life.

SUMMARY OF THE INVENTION The present invention relates to a process for use in the preparation of acellular (essentially lacking in living cells and/or non-living cells) soft-tissue implants that are derived from tissue products derived from the skin of living human donors. The decellularized grafts produced typically provide long-term durability and function when used in clinical applications. In certain embodiments, the present invention provides a process for preparing soft tissue for implant in a human and removes cellular components from tissue taken from living surgical donors while decontaminating the tissue. For example, in a particular embodiment, the process comprises the following: (1) obtaining from a living donor skin recovered from surgery; (2) removing hair from the recovered skin;

(3) processing and decellularizing the skin by soaking the tissue in sodium chloride and a detergent depending and rinsing same with sterile water to substantially remove the residual sodium chloride and detergent;

(4) decontaminating the skin by soaking the tissue in an antibiotic composition and rinsing same to remove to substantially remove residual chemicals to less than 1 ppm;

(5) processing the tissue by cutting the tissue to size; and

(6) packaging the tissue.

It is thus an object of the invention to provide acellular allograft dermis for implantation into a human being. PATENT Atty. Docket No. 544945-204

It is another object of the invention to provide acellular disinfected or decontaminated allograft dermis which is packaged for usage as an implant by a surgeon.

It is still another object of the invention to provide acellular disinfected or decontaminated dermis which can be stored for long periods of time for later use by a surgeon for implantation into a human being.

These and other objects, advantages, and novel features of the present invention will become apparent when considered with the teachings contained in the detailed disclosure along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic flow chart showing a soft tissue process;

DESCRIPTION OF THE INVENTION In certain embodiments, the present invention provides a method for the preparation of skin from living donors which is processed and decellularized.

For the purpose of this application, epidermis is the outer most layer of the skin and dermis is the layer of skin lying immediately under the epidermis and the term skin may refer to either epidermis, dermis or subcutaneous layers or all of the same, pending on the usage.

As used herein, the term "decontamination" refers to a process or treatment that renders a medical device, instrument, or environmental surface safe to handle. For example, according to OSHA, decontamination is "the use of physical or chemical means to remove, inactivate, or destroy bloodborne pathogens on a surface or item to the point where they are no longer capable of transmitting infectious particles and the surface or item is rendered safe for handling, use, or disposal" [29 CFR 1910.1030].

The term "disinfection" refers to the destruction of pathogenic and other kinds of microorganisms by physical or chemical means. Disinfection is generally less lethal than sterilization, because it destroys most recognized pathogenic PATENT Atty. Docket No. 544945-204 microorganisms, but not necessarily all microbial forms, such as bacterial spores.

An "acellular soft tissue" is a tissue-derived biomatrix structure that is made from any of a wide range of soft tissues by removing all, or substantially all, viable cells and all detectable subcellular components and/or debris generated by killing cells. As used herein, an acellular soft tissue lacking substantially all viable cells is one in which the concentration of viable cells is less than about 1 % (e.g., less than 0.1 %, 0.01 %, 0.001 %, 0.0001 %, 0.00001 %, or 0.000001 %) of that in the tissue or organ from which the acellular soft tissue was made.

The methods and related compositions described herein relate to treating soft tissue, and in particular embodiments, decellularizing dermal tissue obtained from living human donors. The novel methods described herein can be applied to any number of suitable tissue types, including dermis, fascia pericardia, dura, tendons, ligaments, and muscle.

Acellular soft tissue can be obtained from human sources, such as tissue from elective surgery, or may be obtained from non-human sources, such as non- human primates (e.g., monkeys, baboon, chimpanzees), pigs, cows, horses, goats, sheep, dogs, cats, rabbits, guinea pigs, gerbils, hamsters, rats, or mice. In further embodiments, where the soft tissue is from a non-human source, the non-human source is a genetically engineered non-human animal, e.g., one that has been genetically engineered to lack an immunogenic epitope of collagen-containing material, such as a terminal α-galactose moiety.

In certain embodiments, the process uses allograft human skin which has been previously taken from a living human donor undergoing surgery to remove excess skin and fat after excessive weight loss. Advantageously, the cells having been taken from a living human being are viable since the human donor is living as opposed to cadaveric skin sources. In certain embodiments, the soft tissue which is processed is full thickness skin which includes epidermis, dermis and subcutaneous layers. Suitable examples of skin for use in methods of the invention include skin that is obtained as the result of abdominoplasty, commonly known as "tummy tuck", a cosmetic surgery procedure to reshape and firm the abdomen; lipectomy; PATENT Atty. Docket No. 544945-204

panniculectomy; brachioplasty; thighplasty; and circumferential, a excision completely around a surface, such as a belt excision around the lower abdomen.

Skin obtained from a living donor is typically shipped from the donor site in a pouch containing sterilization solution such as antibiotics, alcohol or mixtures of same mixed with a decellularizing solution such as Sodium Chloride and is then frozen. This minimizes contamination of the tissue and begins the epidermal separation from the dermal skin layer. Generally, the skin is placed in the pouch shortly after surgery. The frozen skin is typically then taken from the freezer, the outer packaging (e.g., Kapak bag) is removed and thawed in a basin filled with sterile purified water. In certain embodiments, prior to processing, tissue is inspected for damage (holes or tears) and distinctive features (moles, warts, tattoos), which may be removed using a scalpel. Tissue is typically inspected for hair and the same may be removed using any one of a number of technique, including chemical removal using compositions such as (1) water, mineral oil, calcium thioglycolate, calcium hydroxide, ceteareth-20, sodium hydroxide, camellia oleifera extract, sunflower seed oil, fragrance, chromium hydroxide green and (2) alkaline soap and physical removal such as hot wax, hair inhibition, non-heating type laser hair removal in ultra short pulse (USP) range (at e.g., wavelength of 1552 nm and exposure time of 1.1 picosecond) and microdermabrasion. A visual inspection may be performed to ensure the skin tissue has uniform thickness. Thickness may be recorded using a thickness gauge. To identify the orientation (dermal or epidermal side) of tissue such as skin, the skin may be positioned such that, for example, the epidermis faces the processor and an incision may be cut into the upper left corner of each piece of tissue to indicate the epidermal side. In processing, the epidermal layer is removed and the dermis is typically decellularized using, for example, Sodium Chloride (NaCl) solution at a concentration of 0.1 - 1OM, preferably about IM with a pH ranging from 5.0 - 9.0, preferably 6.8 - 7.2, and is agitated, for example, at a speed of 65 rpm on an orbital shaker for 1-96 hours, preferably 12 hours to a maximum of 48 hours. After 12 hours, the container holding the skin is generally checked to ascertain if the PATENT Atty. Docket No. 544945-204 epidermal layers have been sloughed off. If not, the container may be checked every 2 hours until the epidermis has sloughed off. The dermis is then typically removed and placed on, for example, a cutting board with the epidermal side up, and any remaining epidermal layer are picked off and discarded as well as any remaining hairs. In some embodiments, the remaining dermis pieces are replaced in the tissue flasks, filled with sterile water and agitated on the orbital shaker for about 15 minutes. In some embodiments, the sterile water is refreshed and the rinse procedure is repeated one more time for a total of two rinses.

In further embodiments, once the final rinse (e.g., sodium chloride soak or sterile water rinse) is complete, the dermis pieces may be trimmed into shaped pieces, preferably rectangular, by removing all of the rough edges of each piece with a scalpel. The trimmed dermis pieces are then typically immersed in a detergent such as Triton X-100 solution having a concentration of 0.01 - 10.0%, preferably about 0.1% with a pH ranging from 4.5 - 8.5, preferably 6.2 - 7.0 and agitated on the orbital shaker for 1 - 96 hours, preferably 24 hours to 48 hours. In further embodiments, the dermis is then placed in tissue flasks filled with sterile water, and agitated on the orbital shaker at 65 rpm for 15 minutes. The sterile water is typically refreshed and the rinse procedure is generally repeated a minimum of 7 more times for a total of 8 water rinses. In some embodiments, a residual detergent test may be performed on the rinsate after the 6^l water rinse to ensure the detergent has been adequately removed.

In certain embodiments, the acellular dermis is disinfected in a solution containing a disinfection solution of e.g., 35% peracetic acid, ethano, e.g.,1 95% (undenatured), propylene glycol and sterile water. The disinfection mixture is generally stirred, e.g., with magnetic stir bar for at least 15 minutes or until homogenous. The dermis is then typically soaked under vaccum and agitated at 65 rpm for 30 minutes to 12 hours, preferably 4 hours, at 4⁰C to 4O⁰C preferably 20°C - 25°C. hi particular embodiments, the disinfection solution is formed with peracetic acid (v/v) 0.05% - 5.0%, preferably 0.5% - 0.7%; propylene glycol (v/v) 20% - 60%, preferably 37.5%; ethanol (undenatured) (v/v) 10% - 50%, preferably 23% to PATENT Atty. Docket No. 544945-204

26% and sterile water 30% to 40%, preferably 35%. The disinfection solution typically has a pH ranging from 2.0 - 5.0, preferably 3.2 - 3.8. In further embodiments, the disinfected dermis is subjected to a rinse series with sterile water followed with agitation at 65 rpm under vacuum; two 5-minute rinses, followed by two 10-minute rinses, followed by two 15-minute rinses for a total of 6 rinses or until the peracetic acid has been adequately remove. In some embodiments, after the last rinse, a residual test may be performed on the rinsate to ensure that the peracetic acid has been adequately removed with less than 1 ppm remaining on the tissue.

In further embodiments, disinfected dermis tissue is cut to a final size. If desired, the dermis can be perforated with holes about 1.2 mm in diameter spaced from each other 2 to 3 mm formed by a punch process. In particular embodiments, the tissue is dipped in 70% ethanol (e.g., specially denatured alcohol such as SDA- 3 C, which is 100 parts 190 proof ethanol and 5 parts isopropyl alcohol by volume.) and 30% water and packaged or treated to increase pore size and lyophilized. The following non-limiting examples further describe and enable one of ordinary skill in the art to make and use the present invention.

Example 1: Treatment of Dermis

Tissue which has been obtained from a living donor is shipped from the donor site in a pouch containing sterilization solution mixed with a decellularizing solution such as, for example, sodium chloride and then frozen.

Living donor tissue is then thawed and then rinsed to maintain moisture. The thawed tissue is processed by removing hair and is then decellularized using IM NaCl and 0.1% of Triton X-100. If desired at the time of decellularization one or more of the following protease inhibitors may be added; Aminoethylbenzenesulfonyl fluoride HCL (serine proteases) (25-100 :m, Aprotinin (broad spectrum, serine proteases) (7.5-30:m), Protease Inhibitor E-64 (cysteine proteases) (0.05-.0.20:m), Leupeptin, Hemisulfate (cysteine proteases) (0.05- .0.20:m), EDTA, Disodium (0.025-.0.10:m), and trypsin-like proteases, Pepstatin A PATENT Atty. Docket No. 544945-204

(Aspartic Proteases). Marmistat (MMP2). The tissue is processed and decellularized and is inspected visually for damage (e.g., holes or tears) and trimmed.

Once all blood and lipids are removed from the skin, the water is changed with clean sterile water. Defects (e.g., holes or tears) are removed from each piece of skin with a scalpel (epidermal side up during this process). Place each skin piece with the epidermal side up on the cutting board or flat surface, check the skin for damage (holes and initial tearing) and for distinctive features (mole, warts, tattoos) and cut these impurities off using a scalpel.

Each piece is checked for hairs and the hairs are removed chemically by application of chemical compositions such as water, mineral oil, calcium thioglycolate, calcium hydroxide, ceteareth-20, sodium hydroxide, camellia oleifera extract, sunflower seed oil, fragrance, chromium hydroxide green after which the skin is rinsed with water. The skin is positioned with the dermis side up (epidermis down) on the cutting board and rectangular skin pieces are cut by removing the rough edges of each piece with one or more uninterrupted cuts using a scalpel and ruler. An incision is cut into the left hand corner of each piece of skin indicating the epidermal side of the skin. A visual inspection is performed to make sure the tissue has a uniform thickness throughout the piece and regions with a visibly low or nonuniform thickness are removed. A thickness measurement is then performed using a thickness gauge. The skin is decellularized in a sterile tissue culture bottle filled with IL of IM NaCl. The bottle is sealed in a self-seal pouch and then placed the bottle on its flat side on the shaker with a set speed of 65 rpm for a period of 12 - 48 hours. The bottle(s) is checked after the first 12 hours to see if the epidermal layers have sloughed off. After the first 12 hour check, the bottle is checked every 2 hours until all epidermal layers have been sloughed. The bottles are removed from the shaker and the NaCl is emptied from the bottle(s). The skin is removed from the bottle and placed on the cutting board with the epidermal side up. Any remaining epidermal layers are removed with forceps and discarded leaving only the dermal layer (dermis). The bottles are rinsed with sterile water and the dermis is placed back into the bottle and filled with 1 L of 0.1 % Triton X- 100. PATENT Atty. Docket No. 544945-204

(Optionally, the bottles are instead filled with enough sterile water to submerge the tissue while the bottle is lying flat and the bottle is placed on the shaker which has a preset speed of 65 rpm. The shaker is set to run for 15 minutes. After running 15 minutes, the bottle(s) are removed and the water is changed with clean sterile water. This rinse is repeated one more time for a total of two times. The bottle(s),are removed from the shaker, emptied and then filled with IL of 0.1% Triton X-100).

The bottle containing the dermis is seated in a self-seal pouch and placed on the shaker set to the speed to 65 rpm's and allowed to shake for 24 to 48 hours. The shaker is stopped after 24 hours or a later time period, the dermis is removed from the bottles and place submerged in a container with sterile water to rinse off the Triton X-100. The tissue is again rinsed with a sterile water for 15 minutes at 65 rpm's for irrigation to rinse off the Triton X-100. The rinse is repeated 7 more times for a total of 8 times. Opionally, after rinsing a residual detergent test is performed to make sure that the detergent has been removed from the tissue so that less than lppm is found on the tissue.

The dermis is soaked in disinfection solution for about 4 hours. The disinfection solution preferably is composed of peracetic acid, ethanol, propylene glycol and sterile water and the dermis is soaked and agitated at 65 rpm under vaccum for about 4 hours at 20°C - 25°C. The disinfection solution contains peracetic acid (v/v), preferably 0.5% - 0.7%; propylene glycol (v/v), preferably 38.0%; ethanol (undenatured) (v/v), preferably 23%-26% and sterile water, preferably 35% - 36%. The solution has a pH ranging from ranging from about 3.2 - about 3.8. The canister stays on the shaker during the soak with the shaker set at 65 rpm. The dermis is initially rinsed in sterile water on the shaker at 65 rpm for 5 minutes and then rinsed 5 more times; 2^nd rinse for 5 minutes, 3^rd and 4^th rinse for 10 minutes and 5^th and 6^th rinse for 15 minutes. Optionally, after the 6th rinse, a test is performed for the presence of the peracetic acid. Less than 1 rpm must be present, otherwise additional rinses are required. The strips of dermis are taken out of the canister using forceps and placed PATENT Atty. Docket No. 544945-204 into a stainless steel basin. The basin is filled with water for irrigation to keep it moist. A wipe is placed on the top of a cutting surface and moistened with sterile water. The skin is taken from the basin and laid on the cutting surfa,ce epidermal side down (smooth side up) and inspected and measured. If the dermis is to be lyophilized the skin is placed in a double Tyvek® pouch and the tissue placed in a freezer at -70° until lyophilization.

Optionally, after the 6^l rinse or upon later removal from the lyophilization, the dermis tissue is cut to size and may be perforated with the perforations 10 spaced 2-3 mm apart with each perforation preferably having a diameter of about 1.2mm. The tissue may be lyophilized or is immersed in 70% ethanol and 30% water and packaged for storage in sterile foil.

The tissue for lyophilization is laid flat on screens and placed in double Tyvek® pouches and each Tyvek® pouch is sealed. The package is stored flat in the freezer to prevent the tissue from becoming wrinkled or deformed. Example 2: Treatment of Dermis

Tissue which has been obtained from a living donor is shipped from the donor site in a pouch containing, for example, disinfection solution mixed with a decellularizing solution such as sodium chloride and then frozen.

Living donor tissue is then thawed and then rinsed to maintain moisture. The thawed tissue is processed and decellularized using IM NaCl and 0.1% of Triton X- 100. If desired at the time of decellularization one or more of the following protease inhibitors may be added; Aminoethylbenzenesulfonyl fluoride HCL (serine proteases) (25-100 :m, Aprotinin (broad spectrum, serine proteases) (7.5-30:m), Protease Inhibitor E-64 (cysteine proteases) (0.05-.0.20:m), Leupeptin, Hemisulfate (cysteine proteases) (0.05-.0.20:m), EDTA, Disodium (0.025-.0.10:m), and trypsin- like proteases, Pepstatin A (Aspartic Proteases). Marmistat (MMP2). The tissue is processed and decellularized and is inspected for visual defects and trimmed.

Once all blood and lipids are removed from the skin, the water is changed with clean sterile water. Defects (e.g., holes, tears, warts, tattoos) are removed from each piece of skin with e.g., a scalpel (epidermal side up during this process). Place PATENT Atty. Docket No. 544945-204

each skin piece with the epidermal side up on the cutting board or flat surface, check the skin for damage (holes and initial tearing) and for distinctive features (mole, warts, tattoos) and cut these defects off using a scalpel.

Each piece is inspected for hairs and the hairs are removed physically by physical removals methods such as (1) hot wax, (2) hair inhibition, (3) non-heating type laser hair removal in ultra slow pulse (USP) range and (4) microdermabrasion. The skin is positioned with the dermis side up (epidermis down) on the cutting board and rectangular skin pieces are cut by removing the rough edges of each piece with one or more uninterrupted cuts using a scalpel and ruler. An incision is cut into the left hand corner of each piece of skin indicating the epidermal side of the skin. A visual inspection is performed to make sure the tissue has a uniform thickness throughout the piece and regions with a visibly low or non-uniform thickness are removed. A thickness measurement is then performed using a thickness gauge. The skin is decellularized in a sterile tissue culture bottle filled with IL of IM NaCl. The bottle is sealed in a self-seal pouch and then placed the bottle on its flat side on the shaker with a set speed of 65 rpm for a period of 12 - 48 hours. The bottle(s) is checked after the first 12 hours to see if the epidermal layers have sloughed off. After the first 12 hour check, the bottle is checked every 2 hours until all epidermal layers have been sloughed. The bottles are removed from the shaker and the NaCl is emptied from the bottle(s). The skin is removed from the bottle and placed on the cutting board with the epidermal side up. The epidermal layers are removed with forceps and discarded leaving only the dermal layer (dermis). The bottles are rinsed with sterile water and the dermis is placed back into the bottle. The bottles are then filled with 1 L of 0.1 % Triton X-100. Alternatively, the bottles are filled with enough sterile water to submerge the tissue while the bottle is lying flat and the bottle is placed on the shaker which has a preset speed of 65 rpm. The shaker is set to run for 15 minutes. After running 15 minutes, the bottle(s) are removed and the water is changed with clean sterile water. This rinse is repeated one more time for a total of two times. The bottle(s) are removed from the shaker, emptied and then filled with IL of 0.1% Triton X-100. PATENT Atty. Docket No. 544945-204

The bottle containing the dermis is seated in a self-seal pouch and placed on the shaker set to the speed to 65 rpm's and allowed to shake for 24 to 48 hours. The shaker is stopped after 24 hours or a later time period, the dermis is removed from the bottles and place submerged in a container with sterile water to rinse off the Triton X-100. The tissue is again rinsed with a sterile water for 15 minutes at 65 rpm's for irrigation to rinse off the Triton X-100. The rinse is repeated 7 more times for a total of 8 times. Optionally, after rinsing a residual detergent test is performed to make sure that the detergent has been removed from the tissue.

The dermis is soaked in disinfection solution for about 4 hours. The disinfection solution preferably is composed of peracetic acid, ethanol, propylene glycol and water and the dermis is soaked and agitated at 65 rpm under vacuum for about 4 hours at 2O⁰C - 25°C. The disinfection solution contains peracetic acid 35% (v/v), preferably 0.5% - 0.7%; propylene glycol (v/v), preferably 38.0%; ethanol 95% (undenarured) (v/v), preferably 23%-26% and sterile water, preferably 35% - 36%. The solution has a pH ranging from ranging from about 3.2 - about 3.8. The canister stays on the shaker during the soak with the shaker set at 65 rpm. The dermis is initially rinsed in sterile water on the shaker at 65 rpm for 5 minutes and then rinsed 5 more times; 2ⁿ rinse for 5 minutes, 3^r and 4* rinse for 10 minutes and 5^l and 6^l rinse for 15 minutes. Optionally, after the 6th rinse, a test is performed for the presence of the peracetic acid. Less than 1 rpm must be present, otherwise additional rinses are required.

The strips of dermis are taken out of the canister using forceps and placed into a stainless steel basin. The basin is filled with water for irrigation to keep it moist. A wipe is placed on the top of a cutting surface and moistened with sterile water. The skin is taken from the basin and laid on the cutting surfa,ce epidermal side down (smooth side up) and inspected and measured.

If the dermis is to be lyophilized the skin is placed in a double Tyvek® pouch and the tissue placed in a freezer at -70° until lyophilization.

Optionally, after the 6^th rinse or upon later removal from the lyophilization, the dermis tissue is cut to size and may be perforated with the perforations 10 spaced PATENT Atty. Docket No. 544945-204

2-3 mm apart with each perforation preferably having a diameter of about 1.2mm.

The tissue may be lyophilized or is immersed in 70% ethanol and 30% water and packaged for storage in sterile foil.

The tissue for lyophilization is laid flat on screens and placed in double Tyvek® pouches and each Tyvek® pouch is sealed. The package is stored flat in the freezer to prevent the tissue from becoming wrinkled or deformed.

While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. One skilled in the art will appreciate that numerous changes and modifications can be made to the invention, and that such changes and modifications can be made without departing from the spirit and scope of the invention. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.

Each patent, patent application, and publication cited or described in the present application is hereby incorporated by reference in its entirety as if each individual patent, patent application, or publication was specifically and individually indicated to be incorporated by reference.

Claims

PATENT Atty. Docket No. 544945-204What is claimed is:

1. A method for the treatment of skin obtained from a living donor to prepare the same for implantation into a human comprising:

(a) removal of hair from the skin; (b) decellularizing the skin to obtain soft tissue;

(c) disinfecting the soft tissue in disinfectant solution;

(d) rinsing the disinfection solution from the soft tissue to less than 1 ppm; and

(e) cutting the treated soft tissue to a specific size.

2. The method as claimed in claim 1 wherein said skin is obtained from an abdominoplasty.

3. The method as claimed in claim 1 wherein said skin is obtained from a lipectomy.

4. The method as claimed in claim 1 wherein said skin is obtained from a panniculectomy.

5. The method as claimed in claim 1 wherein said skin is obtained from a brachioplasty.

6. The method as claimed in claim 1 wherein said skin is obtained from a thighplasty.

7. The method as claimed in claim 1 wherein said skin is obtained from a circumferential.

8. The method as claimed in claim 1 wherein after step (a), decellularizing adding one or more of a group of the protease inhibitors consisting of one or more of the following protease inhibitors may be added; Aminoethylbenzenesulfonyl fluoride HCL (Serine Proteases), Aprotinin (broad spectrum, serine proteases), Protease Inhibitor E-64 (Cysteine Proteases), Leupeptin, Hemisulfate Cysteine Proteases and trypsin-like proteases, Pepstatin A (Aspartic Proteases). Marmistat (MMP2).

9. A method for the treatment of skin obtained from living donor tissue to prepare the same for implantation into a human comprisingf: PATENT Atty. Docket No. 544945-204

(a) removal of hair from the skin by application of a chemical solution;

(b) decellularizing the skin to obtain dermis tissue;

(c) disinfecting the dermis tissue in disinfectant solution;

(d) rinsing the disinfection solution from the dermis tissue to less than 1 ppm; and

(e) cutting the treated dermis tissue to a specific size.

10. A method for the treatment of skin obtained from living donor tissue to prepare the same for implantation into a human comprising the steps of:

(a) transporting the skin from the donor site in a disinfection and decellularizing solution;

(b) removal of hair from the skin;

(c) decellularizing the skin to obtain dermis tissue;

(d) disinfecting the dermis tissue in disinfectant solution;

(e) rinsing the disinfection solution from the dermis tissue to less than 1 ppm; and

(f) cutting the treated dermis tissue to a specific size.

11. A method for the treatment of skin obtained from living donor tissue to prepare the same for implantation into a human comprising:

(a) removal of hair from the skin by application of a chemical solution; (b) decellularizing the skin;

(c) disinfecting the skin in disinfectant solution;

(d) rinsing the disinfection solution from the tissue to less than 1 ppm; and

(e) cutting the treated tissue to a specific size.

12. The method as claimed in claim 11 wherein said chemical solution in

(a) is water, mineral oil, calcium thioglycolate, calcium hydroxide, ceteareth-20, sodium hydroxide, camellia oleifera extract, sunflower seed oil, fragrance, chromium hydroxide green.

13. The method as claimed in claim 11 wherein said chemical solution in (a) is alkaline soap. PATENT Atty. Docket No. 544945-204

14. The method as claimed in claim 11 wherein the decellurization step comprises soaking the skin in a NaCl solution and a detergent solution.

15. The method as claimed in claim 14 wherein said detergent is Triton X-100.

16. The method as claimed in claim 11 wherein said disinfection solution is a mixture including (v/v 0.5% to 0.7%) peracetic acid 35%, propylene glycol, ethanol and sterile water.

17. A method for the treatment of skin obtained from a living donor to prepare the same for implantation into a human comprising the steps of: (a) removal of hair from the skin by physical means;

(b) decellularizing the skin;

(c) disinfecting the skin in disinfectant solution;

(d) rinsing the disinfection solution from the tissue to less than 1 ppm; and (e) cutting the treated tissue to a specific size.

18. The method as claimed in claim 17 wherein said physical means is hot wax.

19. The method as claimed in claim 17 wherein said physical means is microdermabrasion.

20. The method as claimed in claim 17 wherein said physical means is non-heating type laser hair removal in ultra short pulse (USP) range.

21. The method as claimed in claim 17 wherein said physical means is hair inhibition.

22. The method as claimed in claim 17 wherein said physical means is hot wax.

23. The method as claimed in claim 17 wherein the decellurization step comprises soaking the skin in NaCl solution and a detergent solution.

24. The method as claimed in claim 23 wherein said detergent is Triton X-100.

25. The method as claimed in claim 17 wherein said disinfection solution PATENT Atty. Docket No. 544945-204

is a mixture including (v/v 0.5% to 0.7%) peracetic acid at 35%, propylene glycol, ethanol and sterile water.