A skin graft material and methods of making and using the same

Abstract

The present application relates to a kind of skin grafting materials and its preparation and use method, which is composed of carrier sheet, anvil sheet and repair liquid, without skin adhesive;When using, cut skin dermis layer is attached to anvil sheet, put into medical leather rolling machine, and cut into microskin grafting;Spray repair liquid on the cut microskin grafting, transfer to carrier sheet, paste in the place to be grafted, separate aluminum foil and take down, wrap with gauze.The skin grafting material provided by the present application can reduce the damage to new granulation when removing skin grafting material, has the effects of antibacterial and anti-inflammatory, promoting repair and healing, promoting cell proliferation, providing scaffold for cell crawling, hemostasis, absorbing exudate, reducing scar formation and pigmentation, etc., can effectively accelerate epithelialization in skin grafting area;The effect after recovery is good, can be used for burn and scald, mechanical trauma, diabetic foot and other wounds, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials, specifically relating to a graft material and its preparation and application methods. Background Technology

[0002] Currently, the skin graft material for conventional Mini-Eye Skin Grafting (MEEK) consists of a cork disc and aluminum foil-polyamide crepe gauze. After the autologous skin graft is cut and adhered to the crepe gauze with skin adhesive, it is applied to the wound and then bandaged with multiple layers of gauze. In actual surgical practice, it has been found that the cork disc in the MEEK graft material can shed cork fragments during skin graft cutting, posing a risk to wound repair. Simultaneously, the polyamide crepe gauze only serves a bandaging and fixation function during wound repair; if sterilization measures are inadequate, it can easily lead to bacterial invasion. This material generally has poor biocompatibility and poses a risk of damaging new granulation tissue during material removal.

[0003] Chinese invention patent application CN119488636 A discloses a skin graft material and its application method, consisting of a compressed sponge and a repair solution. The compressed sponge is selected from chitosan sponge, collagen sponge, or polyvinyl alcohol formaldehyde sponge; the repair solution is selected from physiological saline containing human epidermal growth factor and / or physiological saline containing superoxide dismutase. The application method involves attaching the cut skin graft epidermis to the compressed sponge, then placing it in a medical skin grafting machine to cut it into micro-skin grafts. The cut micro-skin grafts are then soaked in the repair solution until fully swollen and applied to the grafting site, and wrapped with gauze. The provided skin graft material reduces damage to newly formed granulation tissue during graft removal, has antibacterial effects, and improves post-graft scar hyperplasia and contracture. Simultaneously, the swollen sponge can slowly release the repair solution, promoting skin cell regeneration, accelerating epithelialization in the grafted area, and promoting wound healing. However, the shape of the compressed sponge after swelling is difficult to control in this patent application, resulting in uncontrollable distribution of the micro-skin grafts and a tendency for them to detach.

[0004] The risks.

[0005] Chinese utility model patent CN211985791U discloses an improved MEEK skin graft carrier, which includes a base layer and an extension layer stacked together. The base layer and the extension layer have several transverse and longitudinal folds. The portion enclosed by two adjacent transverse folds and two adjacent longitudinal folds forms the graft piece. The extension layer includes a silicone membrane and a collagen layer covering the silicone membrane. In use, a skin grafting machine is used to cut the dissected skin block into 3mm × 3mm micro-skin pieces. Then, the epidermis of the entire dissected skin block cut into micro-skin pieces is placed downwards on the graft carrier, with the dermis layer upwards, and the micro-skin pieces corresponding to the graft carrier. The transverse and longitudinal folds are then pulled apart and flattened, separating the micro-skin pieces. Finally, the base layer is removed, and the extension layer with the micro-skin pieces attached is placed at the site requiring skin grafting. The patent discloses a skin graft material that allows for controllable shape and proportion of the stretching of the graft. However, the patent does not solve the problem of potential chipping from the cork disc during the skin graft cutting process, nor does it address the issues of low success rate and inconvenient operation when using a cork disc to transfer micro-skin grafts.

[0006] Therefore, the current MEEK skin grafting technique, which uses cork trays as anvils and grafts, carries certain safety risks. It is necessary to make overall improvements to the grafts, anvils, and repair solutions. This means optimizing the composition and structure of the grafts, anvils, and repair solutions to improve the safety, ease of operation, and biocompatibility of MEEK skin grafting. Summary of the Invention

[0007] This invention provides a skin graft material that is convenient and safe to perform, has beneficial effects, good biocompatibility, does not require additional adhesives, and has antibacterial and anti-inflammatory properties, promotes repair and healing, promotes cell proliferation, provides a scaffold for cell migration, stops bleeding, absorbs exudate, and reduces scar formation and pigmentation. This accelerates epithelialization of the graft area, improves the aesthetics of the transplanted wound, and increases the skin's respiratory function.

[0008] The technical solution adopted in this invention is as follows:

[0009] A graft material is composed of a carrier, an anvil, and a repair solution. The carrier includes at least a bio-based material layer and a base layer. The bio-based material layer is one or more of carboxymethyl chitosan, bovine Achilles tendon type I collagen, or recombinant collagen. The carrier is prepared by electrospinning, air spinning, or freeze drying. The carrier has expandable folding area.

[0010] The anvil is selected from a sponge material that facilitates the cutting of miniature leather pieces and allows for easy transfer later; the density of the sponge is controlled at 270 kg / m³. 3 ~330kg / m 3 Dry water absorption 60-90%, compressive strength 100-180 kPa;

[0011] The repair solution is physiological saline containing epidermal growth factor and / or superoxide dismutase;

[0012] The skin graft material does not contain skin adhesive;

[0013] The purity of the carboxymethyl chitosan is ≥85%, the purity of bovine Achilles tendon type I collagen is ≥95%, and the purity of the recombinant collagen is ≥90%.

[0014] The base layer is aluminum foil, with dimensions of 180-220mm × 200-240mm and a thickness of 0.037mm ± 0.005mm;

[0015] The epidermal growth factor content in the repair solution is 100-200 U / ml;

[0016] The superoxide dismutase content in the repair solution is 500-1000 U / ml;

[0017] The sponge is made of polyethylene or polyurethane, with dimensions of 42±2mm×42±2mm and a thickness of 2.6±0.2mm;

[0018] The density of the sponge is 300 kg / m³. 3 Dry water absorption 80%, compressive strength 150 kPa;

[0019] The carrier is prepared as follows: the bio-based material is sprayed onto aluminum foil by electrospinning, air spinning or freeze drying, then pressed thin by a flattening machine and obtained by folding and cutting.

[0020] In the electrospinning method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. Specifically, when bovine Achilles tendon type I collagen is used, its mass percentage concentration is controlled at 8-12%; when carboxymethyl chitosan is used, the mass percentage concentration is 5-15%; and when recombinant collagen is used, the mass percentage concentration is 8-13%. The electrospinning voltage is 15-70 kV; the receiving distance is 10-25 cm; the temperature is 22-26℃; and the humidity is 30-50%.

[0021] In the described air spinning method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. Specifically, when bovine Achilles tendon type I collagen is used, its mass percentage concentration is controlled at 9-16%; when carboxymethyl chitosan is used, its mass percentage concentration is 5-30%; and when recombinant collagen is used, its mass percentage concentration is 8-15%. The airflow pressure is 0.05-0.3 MPa; the receiving distance is 10-45 cm; the temperature is 22-26℃; and the humidity is 30-50%.

[0022] In the freeze-drying method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. When bovine Achilles tendon type I collagen is selected, the mass percentage concentration is controlled at 0.1-0.6%; when carboxymethyl chitosan is selected, the mass percentage concentration is 1-3%; when recombinant collagen is selected, the mass percentage concentration is 0.2-0.4%. The thickness of the bio-based material solution is 1-5 mm. The freeze-drying process is as follows: Pre-freezing stage: First stage: 0℃ to -80℃, pre-freezing time 1-2 hours; Second stage: -20℃ to -45℃, pre-freezing time 2-3 hours; Sublimation drying stage: Temperature gradient is as follows: First stage: -20℃ to -5℃, drying time 6-18 hours; Second stage: 0℃ to 25℃, drying time 6-15 hours, vacuum degree: 20-45 Pa; Desorption drying stage: Temperature: 30-40℃, time: 1-6 hours, vacuum degree: ≤50 Pa.

[0023] The method of using the aforementioned skin graft material includes the following steps:

[0024] (1) The dermal layer of the cut skin piece is attached to the anvil and placed in a medical skin cutting machine to cut it into miniature skin pieces;

[0025] (2) Spray the repair fluid onto the cut micro-skin grafts without using skin adhesive, transfer them to the carrier, and press evenly for 2-3 seconds to make the micro-skin grafts adhere to the carrier.

[0026] (3) After unfolding the slide, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0027] The leather patch has a length × width of 42mm × 42mm, and the miniature leather patch has a length × width of 3mm × 3mm.

[0028] The adhesive force F1 between the anvil and the leather piece, the tearing force F2 of the cutting anvil, and the adhesive force F3 between the micro-leather piece and the carrier piece are all factors to consider. To achieve successful cutting of the leather piece without localized delamination between the leather piece and the anvil during the cutting process, it is necessary to control the density, water absorption rate, and compressive strength of the anvil material. The water absorption rate is directly related to the open-cell porosity of the sponge. This invention has found that density and open-cell porosity jointly affect compressive strength, but the relationship among the three is not linear. With a constant density, a higher open-cell porosity results in lower compressive strength, while with a constant open-cell porosity, a higher density results in higher compressive strength. Through verification, this invention has found that the sponge density is controlled at 27 kg / m³. 3 ~32kg / m 3With a compressive strength of 100-180 kPa and an open porosity (water absorption rate) in the range of 60-90%, it can be used as a preferred material for cutting boards, thus replacing cork trays. The advantages of this substitution are that, during the cutting process, using the sponge material of this invention ensures F1 > F2 without the use of adhesives, preventing localized peeling of the leather from the cutting board due to the tearing force, which is beneficial to the cutting operation. Furthermore, during the transfer of micro-leather pieces, using the sponge material of this invention ensures F1 < F3, thereby ensuring the micro-leather pieces are transferred smoothly. To improve the success rate of the transfer and prevent individual micro-grafts from failing or shifting in position on the first transfer, which could affect subsequent skin grafting processes, the selection of the carrier material in this invention is unique. Substances such as carboxymethyl chitosan, bovine Achilles tendon type I collagen, or recombinant collagen, after being impregnated or coated with the repair solution of this invention, exhibit good swelling and viscoelasticity. This provides better adhesion than traditional crepe paper carriers. Therefore, the adhesion of the sponge material of this invention lies precisely between the tearing force F2 during cutting and the adhesive force F3 between the carrier and the micro-graft, i.e., F2 < F1 < F3. Thus, the skin graft material of this invention, through the ingenious combination of carrier, anvil, and repair solution, achieves a complete replacement of the traditional "cork tray-adhesive-crepe paper carrier-repair solution" skin graft material system. This replacement significantly improves the outcome of skin grafting surgery.

[0029] This invention aims to provide a skin graft material that is convenient and safe to perform, has beneficial effects, and is highly biocompatible. It has antibacterial and anti-inflammatory properties, promotes repair and healing, promotes cell proliferation, provides a scaffold for cell migration, stops bleeding, absorbs exudate, reduces scar formation and pigmentation, and can reduce damage to newly formed granulation tissue during removal. Accelerating epithelialization of the grafted area is particularly important.

[0030] Furthermore, the beneficial effects of the above technical solution mainly lie in:

[0031] 1. This invention provides a reparative, absorbable, convenient, and safe skin graft material, composed only of a graft, an anvil, and a repair solution, without any skin adhesive. This skin graft material is absorbable by the human body and possesses antibacterial and anti-inflammatory properties, promotes repair and healing, promotes cell proliferation, provides a scaffold for cell migration, stops bleeding, absorbs exudate, and reduces scar formation and pigmentation. It can effectively accelerate epithelialization of the grafted area and reduce damage to newly formed granulation tissue during removal, resulting in good post-healing outcomes. It also has antibacterial and anti-inflammatory properties and promotes wound healing, which is beneficial for the healing of the grafted area. Compared to skin adhesives, it has high biocompatibility, reducing cytotoxicity, sensitization, irritation, genotoxicity, acute systemic toxicity, subchronic / chronic toxicity, blood compatibility, and immunotoxicity, further promoting the recovery of the grafted area.

[0032] 2. This invention provides a skin graft material that is reparative, absorbable, easy to use, and safe. The components work synergistically to construct a skin graft material combination and structure with good repair effects, simple operation, and safety. The carrier is prepared by electrospinning, air spinning, or freeze-drying, exhibiting excellent folding area expandability. While maintaining the biocompatibility of the main components of the carrier, such as carboxymethyl chitosan, bovine Achilles tendon type I collagen, or recombinant collagen, it further improves the skin grafting efficiency and repair effect during subsequent use. The anvil is selected from sponge, and its composition is a single polymer material. Micro-skin transfer does not require skin adhesives. Compared with traditional cork discs in existing technologies, it has higher biocompatibility in terms of cytotoxicity, sensitization, irritation, genotoxicity, acute systemic toxicity, subchronic / chronic toxicity, blood compatibility, and immunotoxicity. It also has a more uniform density, which is beneficial for operation and facilitates the carrying of skin grafts and subsequent transfer of skin grafts to the carrier.

[0033] 3. The skin graft material provided by this invention has high biological safety, including cytotoxicity, sensitization, irritation, genotoxicity, acute systemic toxicity, subchronic / chronic toxicity, blood compatibility, and immunotoxicity. It is simple to prepare, convenient to use, and easy to transport. At the same time, the material has high stability and has good antibacterial and anti-inflammatory effects on the affected area, promotes repair and healing, promotes cell proliferation, provides a scaffold for cell migration, stops bleeding, absorbs exudate, and reduces scar formation and pigmentation. It has broad market prospects. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described clearly and completely below with reference to specific embodiments. Unless otherwise specified, the equipment used in this embodiment is conventional equipment, the reagents used are all conventional reagents and are commercially available, and the operating methods used are all technical means known to those skilled in the art.

[0035] Example 1

[0036] (1) Preparation of slides: 3g of bovine Achilles tendon type I collagen (purity ≥95%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid in the freeze-drying tray, the solution was filled in, and after freeze-drying, a sponge was formed and attached to the aluminum foil. The sponge was then placed in a flattening machine to be thinned to 0.1mm and folded and cut. The area expansion ratio of the slides was 1:3. The specific parameters are as follows: thickness of the bio-based material solution: 3 mm; pre-freezing treatment: first stage: -5℃ pre-freezing time 1.5 hours; second stage: -40℃ pre-freezing time 2.5 hours; sublimation drying: first stage: -20℃ drying for 12 hours, vacuum degree 30 Pa; second stage: 0℃ drying for 8 hours, vacuum degree 25 Pa; desorption drying: 35℃ drying for 3 hours, vacuum degree 45 Pa, to obtain bovine Achilles tendon type I collagen solution.

[0037] (2) Preparation of repair solution: Take 25mg superoxide dismutase, 8ml human epidermal growth factor and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into spray bottle, where the content of superoxide dismutase is 500U / ml and the content of human epidermal growth factor is 100U / ml;

[0038] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0039] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil, which is selected from polyurethane foam material that is convenient for cutting leather pieces and easy for subsequent transfer; the density of the foam is controlled at 270 kg / m³. 3 The compressive strength is 100 kPa and the water absorption rate is 60%. It is cut into micro-skin pieces using a leather cutting machine. The micro-skin pieces are 3 mm long and 3 mm wide.

[0040] (5) Spray the repair fluid onto the cut micro-skin graft epidermis, transfer it to the bovine Achilles tendon type I collagen carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of bovine Achilles tendon type I collagen, unfold the carrier, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0041] Example 2

[0042] (1) Preparation of slides: 25g of carboxymethyl chitosan (carboxymethyl chitosan purity ≥85%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid on the freeze-drying tray, the solution was filled, and after freeze-drying, a sponge was formed and attached to the aluminum foil. The sponge was then placed in a flattening machine to be thinned to 0.1mm and folded and cut. The area expansion ratio of the slide was 1:4. The specific parameters are as follows: thickness of the bio-based material solution: 3 mm; pre-freezing treatment: first stage: -5℃ pre-freezing time for 1 hour; second stage: -40℃, pre-freezing time for 2.5 hours; sublimation drying: first stage: -20℃ drying for 10 hours, vacuum degree 50 Pa; second stage: 0℃ drying for 7 hours, vacuum degree 30 Pa; desorption drying: 35℃ drying for 6 hours, vacuum degree 18 Pa.

[0043] (2) Preparation of repair solution: Take 25mg superoxide dismutase, 8 ml human epidermal growth factor and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into spray bottle, the content of superoxide dismutase is 500U / ml and the content of human epidermal growth factor is 100U / ml;

[0044] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0045] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil, which is made of polyurethane foam material with a density of 300 kg / m³ that is convenient for cutting leather pieces and easy for subsequent transfer. 3 The compressive strength is 160 kPa, the water absorption rate is 70%, and it is cut into micro-skin pieces with a length of 3 mm and a width of 3 mm.

[0046] (5) Spray the repair solution onto the cut micro-skin graft epidermis, transfer it to the carboxymethyl chitosan carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of carboxymethyl chitosan, unfold the carrier, stick it to the skin grafting site, separate the aluminum foil and remove it, and wrap it with gauze.

[0047] Example 3

[0048] (1) Preparation of slides: 3g of recombinant collagen (purity ≥90%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid on a freeze-drying tray, the solution was filled in, and after freeze-drying, a sponge was formed and attached to the aluminum foil. The sponge was then placed in a flattening machine to be thinned to 0.1mm, folded and cut, and the area expansion ratio of the slide was 1:6. The specific process parameters are as follows: thickness of the bio-based material solution: 3 mm; pre-freezing treatment: rapid pre-freezing: -40℃ for 2 hours; staged temperature control: -40℃→-20℃→room temperature cycle freeze-thaw 2 times. Sublimation drying: first stage: -10℃ drying for 8 hours, vacuum degree 40 Pa; second stage: 10℃ drying for 8 hours, vacuum degree 30 Pa; desorption drying: 30℃ drying for 2 hours, vacuum degree 8 Pa;

[0049] (2) Preparation of repair solution: Take 25mg superoxide dismutase, 8 ml human epidermal growth factor and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into spray bottle, the content of superoxide dismutase is 500U / ml and the content of human epidermal growth factor is 100U / ml;

[0050] (3) Cutting leather pieces: The leather pieces are selected from the body skin. After the body skin is cut, it is cut into pieces with a length of 42mm and a width of 42mm.

[0051] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil. The anvil is made of polyurethane foam material that is convenient for cutting miniature leather pieces and easy for subsequent transfer. The foam density is 320 kg / m³. 3 The compressive strength is 180 kPa and the water absorption rate is 70%. It is cut into micro-skin pieces, each 3 mm long and 3 mm wide.

[0052] (5) Spray the repair solution onto the cut micro-skin graft epidermis, transfer it to the recombinant collagen carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of the recombinant collagen, unfold the carrier, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0053] Example 4

[0054] (1) Preparation of the carrier: 100g of bovine Achilles tendon type I collagen (purity ≥95%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid, the solution was filled in, and the solution was sprayed onto the aluminum foil by electrospinning. The solution was then pressed into a flattening machine to a thickness of 0.1mm and folded and cut. The area expansion ratio of the carrier was 1:4. The specific process parameters are as follows: voltage 65 kV, receiving distance 15 cm, fiber diameter 200-500 nm, temperature: 23℃, humidity: 40%.

[0055] (2) Preparation of repair solution: Take 25mg superoxide dismutase, 8 ml human epidermal growth factor and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into spray bottle, the content of superoxide dismutase is 500U / ml and the content of human epidermal growth factor is 100U / ml;

[0056] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0057] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil, which is selected from polyvinyl alcohol sponge material that is convenient for cutting leather pieces and easy for subsequent transfer; the density of the sponge is controlled at 270 kg / m³. 3 The compressive strength is 100 kPa and the water absorption rate is 70%. It is cut into micro-skin pieces using a leather cutting machine. The micro-skin pieces are 3 mm long and 3 mm wide.

[0058] (5) Spray the repair fluid onto the cut micro-skin graft epidermis, transfer it to the bovine Achilles tendon type I collagen carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of bovine Achilles tendon type I collagen, unfold the carrier, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0059] Example 5

[0060] (1) Preparation of the carrier: 120g of bovine Achilles tendon type I collagen (purity ≥95%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid, the solution was filled in, and the solution was sprayed onto the aluminum foil by air spinning. The solution was then placed in a flattening machine to be pressed to a thickness of 0.1mm, folded and cut. The area expansion ratio of the carrier was 1:8. The specific process is as follows: air pressure 0.12 MPa, receiving distance 30 cm, fiber diameter 200-500 nm, temperature: 23℃, humidity: 40%.

[0061] (2) Preparation of repair solution: Take 25mg superoxide dismutase, 8 ml human epidermal growth factor and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into spray bottle, the content of superoxide dismutase is 500U / ml and the content of human epidermal growth factor is 100U / ml;

[0062] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0063] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil, which is selected from polyvinyl alcohol sponge material with a density of 300 kg / m³ that is convenient for cutting leather pieces and easy for subsequent transfer. 3 The compressive strength is 160 kPa, the water absorption rate is 80%, and it is cut into micro-skin pieces with a length of 3 mm and a width of 3 mm.

[0064] (5) Spray the repair fluid onto the cut micro-skin graft epidermis, transfer it to the bovine Achilles tendon type I collagen carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of bovine Achilles tendon type I collagen, unfold the carrier, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0065] Example 6

[0066] (1) Preparation of slides: 3g of bovine Achilles tendon type I collagen (purity ≥95%) and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid on a freeze-drying tray, the solution was filled in, and after freeze-drying, a sponge was formed and attached to the aluminum foil. The sponge was then placed in a flattening machine to be thinned to 0.1mm, and then folded and cut. The area expansion ratio of the slides was 1:6. The specific parameters are as follows: Solution spreading thickness: 3 mm; Pre-freezing treatment: First stage: -5℃ pre-freezing time 1.5 hours; Second stage: -40℃, pre-freezing time 2.5 hours; Sublimation drying: First stage: -20℃ drying for 12 hours, vacuum degree 30 Pa; Second stage: 0℃ drying for 8 hours, vacuum degree 25 Pa; Desorption drying: 35℃ drying for 3 hours, vacuum degree 45 Pa;

[0067] (2) Preparation of repair solution: Take 25mg superoxide dismutase and 300ml physiological saline, mix and stir for 30 minutes until dissolved, pour into a spray bottle, wherein the superoxide dismutase content is 500U / ml;

[0068] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0069] (4) Cutting miniature leather pieces: The dermal layer of the cut leather pieces is attached to an anvil, which is selected from polyvinyl alcohol sponge material that is convenient for cutting leather pieces and easy for subsequent transfer, with a sponge density of 330 kg / m³. 3 The compressive strength is 180 kPa and the water absorption rate is 80%. It is cut into micro-skin pieces, each 3 mm long and 3 mm wide.

[0070] (5) Spray the repair fluid onto the cut micro-skin graft epidermis, transfer it to the bovine Achilles tendon type I collagen carrier, press evenly for 2 seconds, fix the micro-skin graft with the self-adhesion of bovine Achilles tendon type I collagen, unfold the carrier, attach it to the area to be grafted, separate the aluminum foil and remove it, and wrap it with gauze.

[0071] Comparative Example 1

[0072] (1) Prepare a cork tray material as an anvil. The cork tray is 42mm long and 42mm wide. Prepare aluminum foil-polyamide double crepe yarn with an expansion ratio of 1:3 after folding and pressing. The dimensions of the contact piece are 42mm long and 42mm wide.

[0073] (2) The skin pieces are selected from autologous skin. After the autologous skin is processed, it is cut into skin pieces with a length of 42mm and a width of 42mm.

[0074] (3) The cork tray is moistened with physiological saline, and the dermal side of the autologous skin is attached to the cork tray; the cork tray with the skin piece is placed in a medical skin rolling machine and cut into micro-skin pieces, the micro-skin pieces being 3mm long and 3mm wide; adhesive is sprayed onto the surface of the skin piece so that the surface of the skin piece comes into contact with the polyamide crepe yarn, the cork tray is removed, and all the micro-skin pieces are transferred to the polyamide crepe yarn;

[0075] (4) After stretching the polyurethane crepe yarn horizontally and vertically to expand it, trim the crepe yarn and remove the aluminum foil. Soak it in physiological saline for later use. Apply it to the area to be grafted and wrap the graft area with gauze.

[0076] As shown in Tables 1 and 2 below, Comparative Example 1 is prone to the risk of anvil cutting off or splintering during MEEK skin grafting surgery, posing a risk to surgical safety. Because the adhesion between the cork tray and the micro-graft cannot be controlled, adhesive needs to be sprayed onto the graft surface during graft transfer, increasing the number of steps and negatively impacting postoperative healing.

[0077] Comparative Example 2

[0078] (1) Preparation of slides: 3g of bovine Achilles tendon type I collagen and 1000ml of purified water were put into a mixing tank and stirred thoroughly to obtain a uniform solution. A 180mm×200mm×0.037mm aluminum foil was pre-laid on the freeze-drying tray, the solution was filled, and after freeze-drying, a sponge was formed and attached to the aluminum foil. The sponge was then placed in a flattening machine to be thinned to 0.1mm, and then folded and cut. The area expansion ratio of the slides was 1:3.

[0079] The specific parameters are as follows: Solution spreading thickness: 3 mm; Pre-freezing treatment: First stage: -5℃, pre-freezing time 1.5 hours; Second stage: -40℃, pre-freezing time 2.5 hours; Sublimation drying: First stage: -20℃, drying time 12 hours, vacuum degree 30 Pa; Second stage: 0℃, drying time 8 hours, vacuum degree 25 Pa; Desorption drying: 35℃, drying time 3 hours, vacuum degree 45 Pa;

[0080] (2) Preparation of repair solution: Take 300ml of physiological saline and pour it into a spray bottle;

[0081] (3) Cutting leather pieces: The leather pieces are selected from autologous leather. After the autologous leather is processed, it is cut into leather pieces with a length of 42mm and a width of 42mm.

[0082] (4) Cutting miniature leather pieces: Prepare a cork tray as an anvil. The cork tray is 42mm long and 42mm wide. Attach the dermal layer of the cut leather piece to the anvil and cut it into miniature leather pieces. The length of the miniature leather piece is 3mm and the width is 3mm.

[0083] (5) Spray repair fluid onto the cut micro-skin graft epidermis, transfer it to a bovine Achilles tendon type I collagen carrier, press evenly for 2 seconds, and fix the micro-skin graft with the self-adhesion of the bovine Achilles tendon type I collagen. Unfold the carrier, attach it to the site to be grafted, separate the aluminum foil and remove it, and wrap it with gauze. As shown in Tables 1 and 2 below, in this comparative example 2, there is a risk of the anvil chipping or falling off during the skin grafting operation, which poses a risk to the safety of the operation.

[0084] Comparative Example 3

[0085] Similar to Comparative Example 2, the difference lies in step (2): the repair solution consists of 25 mg superoxide dismutase, 8 ml human epidermal growth factor, and 300 ml physiological saline. These three are mixed and stirred for 30 minutes until dissolved, then poured into a spray bottle. The superoxide dismutase content is 500 U / ml, and the human epidermal growth factor content is 100 U / ml. Compared to Comparative Example 2, Comparative Example 3 shows slightly better repair results with the combined superoxide dismutase and human epidermal growth factor, but due to the use of a cork disc as the anvil, issues of surgical safety and low success rate of micro-graft transfer remain.

[0086] Comparative Example 4

[0087] The steps are the same as in Example 1, except that the density of the anvil sponge in Comparative Example 4 is controlled at 250 kg / m³. 3 The compressive strength is 90 kPa and the water absorption rate is 95%. In Comparative Example 4, the compressive strength of the sponge is too low, mainly because of its low density and relatively soft appearance, making it difficult to maintain its shape. Therefore, it is not easy to maintain the shape stability when cutting skin grafts, resulting in an unsatisfactory success rate in one slicing and affecting the convenience of preoperative operation.

[0088] Comparative Example 5

[0089] The steps are the same as in Example 1, except that the density of the anvil sponge in Comparative Example 5 is controlled at 350 kg / m³. 3 The compressive strength is 200 kPa and the water absorption rate is 50%. In Comparative Example 5, the compressive strength of the sponge is too high, mainly because the density is too high. Its appearance is relatively hard and lacks elasticity. Therefore, the adhesion of the leather pieces is not ideal when cutting the leather pieces, which affects the success rate of slicing in one go.

[0090] Example of effect 1

[0091] The skin grafting effects of the skin grafting materials obtained in Examples 1-6 and Comparative Examples 1-3 were studied. Skin grafting surgery was performed using the obtained skin grafting materials. The skin grafting effect, wound damage during removal, cell proliferation at the edge of the skin graft, and scar hyperplasia and contracture after healing were observed and recorded. Specific data are shown in Table 2 below.

[0092] Antibiotics were administered during the skin grafting process. One week later, the skin graft material was removed and the wound healing was observed. The healing process of the affected area and the post-healing scar hyperplasia and contracture were recorded. The experimental results are shown in Table 1.

[0093] Among them, 0-2 indicates that no damage was caused to the graft site when the graft material was removed; 3-4 indicates that the graft site was slightly damaged when the graft material was removed; 5-7 indicates that the graft site was damaged when the graft material was removed; and 8-10 indicates that the graft site was severely damaged when the graft material was removed.

[0094] 0-2 indicates no infection at the skin graft site; 3-4 indicates a minor infection at the skin graft site; 5-7 indicates an infection at the skin graft site; 8-10 indicates a severe infection at the skin graft site.

[0095] 0-2 indicates no hyperplasia or contracture of the scar at the skin graft site after healing; 3-4 indicates slight hyperplasia or contracture of the scar at the skin graft site after healing; 5-7 indicates hyperplasia or contracture of the scar at the skin graft site after healing; 8-10 indicates severe hyperplasia or contracture of the scar at the skin graft site after healing.

[0096] The standard for intact skin graft survival area and wound healing area is 100%; the cell proliferation rate at the edge of the skin graft is observed based on the distance between the skin grafts, and the standard for cell proliferation to the point where there is no distance between the skin grafts is 100%.

[0097] Table 1. Comparison of the safety and success rate of skin grafting surgery between Examples 1-6 and Comparative Examples 1-5.

[0098]

[0099] Note: According to actual operation requirements, the anvil is cut into 196 miniature leather pieces of 14*14. The number of miniature leather pieces successfully transferred in one go refers to the number of pieces successfully transferred in one go out of every 196 miniature leather pieces.

[0100] As shown in Table 1, the skin grafting material combinations used in Examples 1-6 consisted of a biological base layer carrier, a polymer sponge anvil, and a composite repair solution (superoxide dismutase and / or human epidermal growth factor combined with physiological saline). During clinical trials, these combinations demonstrated high ease of operation and success rates. Based on the statistical analysis of the number of successfully transferred 196 micro-skin grafts in a single procedure, Examples 1-6 all exceeded 194 grafts, achieving a success rate exceeding 98%. Furthermore, no material shedding or debris was observed during the slicing process using the skin grafting material combinations of Examples 1-6, indicating no surgical risk. In contrast, Comparative Example 1 used a skin grafting material combination of crepe de chine, cork trays, and physiological saline. Because cork trays exhibited shedding during actual clinical use, contaminating the skin grafts and repair solution system, and because the crepe de chine carrier material lacked absorbability and repair capabilities, the skin grafting material combination was more complex to operate clinically, especially during micro-skin graft transfer, requiring the application of adhesive to the carrier. The success rate of transferring skin grafts from the cork trays to the carriers was also significantly lower than that of the examples of this invention. Comparative Examples 2 and 3 replaced the slide material and repair solution, but due to the use of cork trays for the anvil, the actual use and operational results were still unsatisfactory. Therefore, the skin graft material combinations used in Comparative Examples 1-3 could not properly handle the relationship between the adhesion between the anvil and the skin graft, the adhesion between the micro-skin graft and the slide, and the tearing force caused by skin graft cutting, resulting in poor clinical operation results.

[0101] Table 2. Skin grafting effects of the grafting materials obtained in Examples 1-6 and Comparative Examples 1-3

[0102]

[0103] It should be noted that Comparative Examples 4-5 mainly illustrate the impact of skin graft materials on the convenience and success rate of skin grafting surgery. Generally, after selecting the skin graft material of this invention in clinical practice, the smooth operation is ensured. On this basis, the postoperative recovery of skin grafts is examined. As shown in Table 2 above, the postoperative repair effects of different skin graft material systems are compared to prove that the material system selection of this invention has superiority.

[0104] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A graft material, characterized in that: It consists of a slide, an anvil, and a repair solution; The carrier comprises a bio-based material layer and a base layer; wherein the bio-based material layer is composed of one or more of carboxymethyl chitosan, bovine Achilles tendon type I collagen, or recombinant collagen; the carrier is prepared by electrospinning, air spinning, or freeze drying; the carrier has expandable folding area. The anvil is selected from a sponge material that facilitates the cutting of miniature leather pieces and allows for easy transfer later; the density of the sponge is controlled at 270 kg / m³. 3 ~330kg / m 3 Dry water absorption 60-90%, compressive strength 100-180 kPa; The repair solution is physiological saline containing epidermal growth factor and / or superoxide dismutase; the skin graft material does not contain skin adhesive. The adhesive force between the anvil and the leather piece is F1, the tearing force of the cutting anvil is F2, and the adhesive force between the miniature leather piece and the carrier is F3, satisfying F2. <F1<F3。 2. The skin graft material according to claim 1, characterized in that: The purity of the carboxymethyl chitosan is ≥85%, the purity of bovine Achilles tendon type I collagen is ≥95%, and the purity of the recombinant collagen is ≥90%. The base layer is aluminum foil, with dimensions of 180-220mm × 200-240mm and a thickness of 0.037mm ± 0.005mm; The epidermal growth factor content in the repair solution is 100-200 U / ml; The superoxide dismutase content in the repair solution is 500-1000 U / ml.

3. The grafting material according to claim 1 or 2, characterized in that: The sponge is made of polyethylene or polyurethane, with dimensions of 42±2mm×42±2mm and a thickness of 2.6±0.2mm.

4. The skin graft material according to claim 1 or 2, characterized in that: The density of the sponge is 300 kg / m³. 3 It has a dry water absorption rate of 80% and a compressive strength of 150 kPa.

5. The skin graft material according to claim 1 or 2, characterized in that: The carrier is prepared as follows: bio-based material is sprayed onto aluminum foil by electrospinning, air spinning or freeze drying, then pressed thin by a flattening machine, and obtained by folding and cutting.

6. The skin graft material according to claim 5, characterized in that: In the electrospinning method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. Specifically, when bovine Achilles tendon type I collagen is used, the mass percentage concentration is controlled at 8-12%; when carboxymethyl chitosan is used, the mass percentage concentration is 5-15%; and when recombinant collagen is used, the mass percentage concentration is 8-13%. The electrospinning voltage is 15-70 kV; the receiving distance is 10-25 cm; the fiber diameter is 200-500 nm; the temperature is 22-26℃; and the humidity is 30-50%.

7. The skin graft material according to claim 5, characterized in that: In the described air spinning method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. Specifically, when bovine Achilles tendon type I collagen is used, the mass percentage concentration is controlled at 9-16%; when carboxymethyl chitosan is used, the mass percentage concentration is 5-30%; and when recombinant collagen is used, the mass percentage concentration is 8-15%. The airflow pressure is 0.05-0.3 MPa; the receiving distance is 10-45 cm; the fiber diameter is 200-500 nm; the temperature is 22-26℃; and the humidity is 30-50%.

8. The skin graft material according to claim 5, characterized in that: In the freeze-drying method, the bio-based material raw material is selected from one of bovine Achilles tendon type I collagen, carboxymethyl chitosan, and recombinant collagen. Specifically, when bovine Achilles tendon type I collagen is used, the mass percentage concentration is controlled at 0.1-0.6%; when carboxymethyl chitosan is used, the mass percentage concentration is 1-3%; and when recombinant collagen is used, the mass percentage concentration is 0.2-0.4%. The thickness of the bio-based material solution is 1-5 mm. The freeze-drying process is as follows: Pre-freezing stage, first stage: 0℃ to -80℃, pre-freezing time 1-2 hours; second stage: -20℃ to -45℃, pre-freezing time 2-3 hours; The temperature gradient during the sublimation drying stage is as follows: Stage 1: -20℃ to -5℃, drying time 6-18 hours; Stage 2: 0℃ to 25℃, drying time 6-15 hours, vacuum degree: 20-45Pa. During the drying stage, the temperature is 30-40℃, the time is 1-6 hours, and the vacuum degree is ≤50Pa.

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