CN2830409Y - tissue engineered peripheral nerve graft - Google Patents

Abstract

The utility model discloses a tissue engineering peripheral nerve graft to provide a surgical graft for repairing nerve defect with wider application range and better quality. The tissue-engineered peripheral nerve graft described in the utility model includes a scaffold used to connect the two broken ends of the nerve and seed cells with the function of promoting nerve regeneration. The seed cells are attached to the scaffold to form a three-dimensional structure with imitation nerve and biological activity. complex. The scaffold is a bundle microfilament structure composed of microfilaments made of biodegradable materials, and its outer surface is covered with a film to form a tubular scaffold. The seed cells are adult stem cells. The utility model is a tissue-engineered peripheral nerve graft in the true sense, which not only provides a bionic channel for the regenerated nerve fibers to pass through the nerve defect area, but also its internal seed cells can promote nerve regeneration, so it can be used for repairing For longer-distance nerve defects, the effect of nerve repair is significantly improved, and the clinical application range is wider.

Description

tissue engineered peripheral nerve graft

technical field

The utility model relates to a surgical graft, in particular to a nerve graft used for repairing peripheral nerve defects.

Background technique

Peripheral nerve injury and the nerve defect caused by the injury are common clinical disabling diseases. The repair of peripheral nerve injuries caused by various accidents has always been a difficult problem in neurosurgery. There are nearly 1 million new cases in my country every year, of which about 450,000 cases need to be repaired by implanting nerve grafts. At present, the sources of neural grafts are very scarce, and there is an urgent need for research and development of neural substitutes.

The development of nerve grafts at home and abroad has been stuck on catheters with imitation nerve structures. At present, the artificial products developed are tubular medical materials that connect the two stumps of nerves, which are so-called "artificial nerve tubes" or "artificial nerve tubes". Artificial Nerve Grafts". In the Chinese patent "medical artificial nerve graft and its preparation method" (patent number: 01108208.9), a biological catheter made of chitosan material is disclosed. The biological catheter is embedded with a fiber scaffold, and the fiber scaffold material is polyglycolic acid or polylactic acid; in the Chinese patent application "artificial nerve tube" (application number: 00810000.4), "artificial nerve tube" (application number: 99807035.1), "artificial nerve tube" (application number: 97199928.7) all disclose the The tube formed by decomposing the absorbent material has fine fibrous collagen in the lumen, and the interstices are filled with laminin.

The above-mentioned existing products are all catheters made of degradable biomaterials, which can "bridge" the defective nerves after implantation in the body, but the above-mentioned products only provide a "bridge" or a "bridge" for the growth of regenerated nerve axons. The "channel" itself has no biological activity, cannot provide the necessary internal environment for nerve growth, and has no effect on promoting nerve regeneration.

Modern medicine has confirmed that Schwann cells play an extremely important role in the growth of human nerves. They attach to and surround axons to form myelin sheaths and promote the extension and maturation of axons. Because the above-mentioned existing products do not provide Schwann cells necessary for nerve regeneration or active cells with similar functions, when new axons grow near the stump, they can only rely on the body's own Schwann cells to grow together. Not only is it very slow, but the migration of the Schwann cells in the body itself has a certain limit. If the Schwann cells cannot enter, or enter very little, the growth of the nerve will be greatly affected. If it is applied clinically, it can only repair short distances. Generally, the nerve defect is not more than 15mm. Clinically, such a short-distance nerve defect can often be sutured directly, without the need for these nerve grafts. For longer-distance nerve defects, even if the above-mentioned catheter is "bridged", the regenerated nerve axons cannot reach the distal stump, and the function of the damaged nerve cannot be restored, so the repair effect is very unsatisfactory.

In recent years, the emergence of tissue engineering has brought new hope for the repair of tissue damage. Tissue engineering is a science that uses the principles and methods of engineering and life sciences to study the relationship between normal and diseased mammalian tissue morphology and function, and to develop biological substitutes for repairing damaged tissue morphology and function. It is a science in the field of biotechnology. important content. Specifically, the principle of bionics is used to prepare complexes with specific three-dimensional structures and biological activities to create tissues with normal physiological functions, which can be used to replace the shape and function of human defective tissues. The emergence of tissue engineering marks that medicine will enter a new stage of using artificial tissue and organ transplantation to repair defects and reconstruct functions from the existing autologous or allogeneic tissue and organ transplantation model.

The above-mentioned existing products have no biological activity, and are not tissue-engineered peripheral nerve grafts in the true sense, which is the root cause of the unsatisfactory effect of the existing products in nerve repair.

Contents of the invention

The purpose of the utility model is to provide a tissue-engineered peripheral nerve graft, which is used for repairing nerve defects after peripheral nerve damage.

The tissue engineered peripheral nerve graft described in the utility model includes a scaffold used to connect the two broken ends of the nerve and seed cells with the function of promoting nerve regeneration, and the scaffold is a bundle composed of microfilaments prepared from biodegradable materials The outer surface is covered with a layer of film to form a tubular scaffold, and the seed cells are evenly attached to the bundle-like microfilament structure to form a complex with a three-dimensional neuromimetic structure and biological activity.

The biodegradable material used to prepare the stent can be a synthetic degradable material, or a natural biodegradable material, or a material prepared by combining the two. The synthetic degradable material is selected from one or more combinations of polylactic acid, polyglycolic acid, polycaprolactone and copolymers thereof; the natural biodegradable material is selected from collagen, chitosan, alginic acid one or a combination of more than one.

In order to further enhance the adhesion of the scaffold to the seed cells and promote nerve regeneration and vascularization of the graft, the surface of the microfilament can be coated with substances that can promote cell adhesion, nerve regeneration and vascularization of the graft.

Another solution is to make microfilaments contain substances that can promote cell adhesion, nerve regeneration and graft vascularization in the preparation of microfilaments, and the substances can be gradually released during the degradation of microfilaments.

The aforementioned substances that can promote cell adhesion, nerve regeneration, and graft vascularization can be extracellular matrix (ECM), including collagen, aminoglycans, and glycoproteins; they can also be various growth factors.

The microfilaments have a diameter of 5-50 μm. Preferably it is 10 to 20 μm. According to the diameter of the nerve to be repaired by the patient, a bundled microfilament structure composed of microfilaments of suitable diameter and quantity is selected, which can provide sufficient attachment sites for seed cells without hindering the growth of regenerated nerve axons.

The membrane may be a semipermeable membrane. The membrane allows nutrients such as oxygen molecules, proteins, carbohydrates, etc. to enter the membrane, so that the tissue metabolic waste and microfilament degradation products in the membrane can be discharged out of the membrane, and at the same time prevent the growth of fibrous connective tissue in the body and avoid damage to nerves. adverse effects on regeneration.

The film can also be a film made of biodegradable materials. The biodegradable material may be a synthetic degradable material, or a natural biodegradable material, or a material prepared by combining the two. The synthetic degradable material is selected from one or more combinations of polylactic acid, polyglycolic acid, polycaprolactone and copolymers thereof; the natural biodegradable material is selected from collagen, chitosan, alginic acid one or a combination of more than one. The membrane is a porous membrane with a certain degree of permeability, and the pore size is preferably 5-25 μm, allowing nutrients such as oxygen molecules, proteins, carbohydrates, etc. Discharge out of the membrane, and at the same time prevent the growth of fibrous connective tissue in the body, avoiding adverse effects on nerve regeneration.

The seed cells are adult stem cells. Bone marrow mesenchymal stem cells or adipose stem cells are preferred.

Peripheral nerves are composed of nerve cells, Schwann cells, connective tissue, blood vessels, lymphatic vessels, and special supporting cells. A nerve cell (neuron) is composed of a cell body and a protruding cell process. The end of the cell process repeatedly branches and contacts the neuron. The axon is one of the longest and most important cell processes that can extend to the effector . Schwann cells wrap around axons to form nerve fibers. Tens of thousands of fibers gather together to form nerve bundles, and one or several nerve bundles are linked together by connective tissue to form peripheral nerves. When a peripheral nerve is ruptured and a defect occurs, a graft is needed to "bridge" the defective nerve segment, and new nerve axons grow into the graft from the proximal stump, and grow toward the distal stump under the guidance of Schwann cells. Modern medicine has confirmed that Schwann cells play an extremely important role in the growth of human nerves. They attach to and surround axons to form myelin sheaths and promote the extension and maturation of axons. The inventors have successfully attached adult stem cells to the scaffold and transplanted them into the body. In the in vivo environment, the adult stem cells were induced to become cells with the morphology and function characteristics of Schwann cells, named "Schwann-like cells". These cells should be human One of the most suitable seed cells used in the tissue engineered nerve designed for the repair of peripheral nerve injury, its proliferation in vivo paves the way for the regeneration of nerve axons.

The existing so-called "artificial nerve tubes" or "artificial nerve grafts" are only "bridges" or "channels" provided for the growth of regenerated nerve axons, while the tissue engineered peripheral nerve grafts described in the utility model have The breakthrough advantage is the use of "planting" biologically active seed cells on the scaffold connected to the stump of the nerve, which can be induced to differentiate into Schwann's cells in the in vivo environment with the morphology and function The characteristic "Schwann-like cells" have the characteristics of attached growth. The Schwann-like cells can adhere, migrate, and proliferate on the surface of the scaffold to form an artificial neural tissue with a special three-dimensional structure and active cells. Both the scaffold and the seed cells are essential components of the peripheral nerve graft described in the utility model, thereby constituting a real tissue engineered peripheral nerve graft.

When the utility model is applied, the tissue-engineered peripheral nerve graft is implanted into the nerve defect site of the human body, and the newborn axons growing from the stump of the nerve start to grow into the bracket and extend and mature in the bracket. During this process, the seed cells attached to the scaffold continue to proliferate and migrate in the direction of the regenerated axon, forming a "Schwann-like cell" band, waiting for the arrival of the new axon, and growing in the new axon. During the process, the seed cells are equivalent to the "guide" that "welcomes" the newborn axons, providing the necessary nutrition and induction. The newborn peripheral nerve axon has one after another Schwann-like cells to "meet" it, surround the axon, form a myelin sheath, and make it functionally mature. At the same time, the scaffold made of biodegradable materials is also degrading continuously, giving way to the space for the growth of nerve fibers, which will eventually be replaced by new nerve fibers. The in vivo degradation rate of the scaffold matches the growth rate of the nerve fibers, avoiding compression of the nerve fibers. Membranes prepared with semipermeable membranes can also be completely absorbed by the body.

Because the growth of peripheral nerves must be "escorted" by Schwann cells. Existing nerve graft products only provide scaffolds and do not provide Schwann cells or active cells with similar functions. When new axons grow from the proximal stump, they can only rely on the body's own Schwann cells to grow together. The process is not only very slow, but also the migration of the Schwann cells in the body itself has a certain limit. If the Schwann cells cannot enter, or enter very little, the growth of the nerve will be greatly affected. If it is applied clinically, it can only repair short The distance of the nerve defect is generally not more than 15 mm. Clinically, such a short-distance nerve defect can often be sutured directly, without the need for these nerve grafts. For nerve defects with a longer distance, such as more than 3 cm, even if the above-mentioned catheter is "bridged", the regenerated nerve axons cannot reach the distal stump, and it is difficult to restore the function of the damaged nerve, so the repair effect is very unsatisfactory. However, the utility model adopts the combination structure of seed cells and scaffolds, which not only provides a bionic channel for the regenerated nerve fibers to pass through the nerve defect area, but also its internal seed cells can promote nerve regeneration, so it can be used to repair longer The effect of nerve repair is significantly improved and the scope of clinical application is wider.

Description of drawings

Fig. 1 is the structural representation of the utility model.

FIG. 2 is a schematic cross-sectional view along line A-A of FIG. 1 .

FIG. 3 is an enlarged schematic view of part B in FIG. 2 .

FIG. 4 is an enlarged schematic view of part C in FIG. 1 .

Fig. 5 is a schematic diagram of the application of the utility model.

Detailed ways

The tissue engineered peripheral nerve graft described in the utility model, as shown in Figure 1 to Figure 3, comprises a support 1 for connecting the two broken ends of the nerve and a seed cell 2 with the function of promoting nerve regeneration, and the seed cell 2 is attached to On the scaffold 1, a complex with a three-dimensional neuromimetic structure and biological activity is formed. The scaffold 1 is a bundled microfilament structure 11 composed of microfilaments 13 made of biodegradable materials, and its outer surface is covered with a layer of membrane 12 to form a tubular stent. As shown in FIG. 4 , the seed cells 2 are mainly attached to the surface of microfilaments 13 . In actual products, the seed cells 2 can also be attached to other parts of the scaffold 1 , such as the membrane 12 . As shown in FIG. 5 , when repairing a nerve defect, the tissue-engineered peripheral nerve graft described in the present invention is implanted between the proximal stump 3 and the distal stump 4 .

In actual products, the microfilaments contained in the bundle-like microfilament structure are extremely small. Figures 1 to 5 are microscopic schematic diagrams, and their proportions do not represent the proportions of actual products.

The seed cell 2 described in the utility model is an adult stem cell. Adult stem cells include a variety of stem cells, such as bone marrow mesenchymal stem cells and adipose stem cells. The following examples use bone marrow mesenchymal stem cells and adipose stem cells as seed cells to illustrate:

Embodiment one:

Use biodegradable materials to prepare microfilaments 13, and assemble them into bundled microfilament structures 11, and prepare membranes 12 with biodegradable materials or semipermeable membranes, wrap the membranes 12 on the bundled microfilament structures 11 to form scaffolds 1, and Reserve after sterilization. Bone marrow is extracted from the patient's body (such as ilium and tibia), bone marrow mesenchymal stem cells are isolated, and the isolated bone marrow mesenchymal stem cells are used as seed cells 2 and co-cultured with sterilized bundle-like microfilament structures 11 in vitro to make the seeds The cells 2 are evenly distributed on the bundled microfilament structure 11, and finally the bundled microfilament structure 11 is covered with a membrane 12 to form a tubular structure, that is, the bone marrow mesenchymal stem cells and biodegradable materials described in the present invention are obtained. Tissue engineered peripheral nerve grafts. In clinical use, the tissue engineered peripheral nerve graft described in the present invention is implanted into the peripheral nerve defect to be repaired, and the adult stem cells are induced to differentiate into "like Schwann cells" in the in vivo environment. Proliferate and migrate along the growth direction of regenerated axons. After the peripheral nerve is broken, new axons grow out from the proximal end of the nerve, close to the Schwann-like cells, and the Schwann-like cells surround the axons, form myelin sheaths, provide nutrients to the axons, and guide the axons to the distal end of the nerve. The end grows and connects with the distal end 4 of the nerve fiber. During this process, Schwann-like cells function as Schwann cells, while scaffold 1 is continuously degraded or absorbed by the body, and finally replaced by regenerated nerve fibers.

In this embodiment, the biodegradable material is made of synthetic degradable material, or natural biodegradable material, or a combination of both. The synthetic degradation material is selected from one or more combinations of polylactic acid, polyglycolic acid, polycaprolactone and their copolymers. The natural biodegradable material is selected from one or more combinations of collagen, chitosan and alginic acid.

In this example, according to the diameter of the nerve to be repaired by the patient, a bundled microfilament structure composed of microfilaments of suitable diameter and quantity is selected, which can provide sufficient attachment sites for the seed cells without hindering the regeneration of the nerve axis Sudden growth.

When the utility model is applied, the selected microfilament diameter has nothing to do with the diameter of the repaired nerve, but the number and length of the microfilaments required to form the bundled microfilament structure are determined according to the diameter of the repaired nerve and the length of the nerve defect. . The diameter of the microfilament is usually designed to be 5-50 μm.

In order to further enhance the adhesion of the scaffold to the seed cells, and promote nerve regeneration and graft vascularization, the surface of the microfilaments described in this example can be coated with substance.

In this embodiment, in the preparation of the microfilaments, the microfilaments can also contain substances that can promote cell adhesion, nerve regeneration and graft vascularization, and the substances can be gradually released during the degradation process of the microfilaments.

The aforementioned substances that can promote cell adhesion, nerve regeneration, and graft vascularization can be extracellular matrix (ECM), including collagen, aminoglycans, and glycoproteins; they can also be various growth factors.

Embodiment two:

Use biodegradable materials to prepare microfilaments 13, and assemble them into bundled microfilament structures 11, and prepare membranes 12 with biodegradable materials or semi-permeable membranes, wrap the membranes 12 on the bundled microfilament structures 11 to form scaffolds 1, and Reserve after sterilization. Adipose tissue is extracted from the fat-rich part of the patient's body (such as the abdominal wall), and the adipose stem cells are separated, and the separated adipose stem cells are used as seed cells 2 and co-cultured with the sterilized bundle-like microfilament structure 11 in vitro, so that the seed cells 2 are evenly distributed On the fascicular microfilament structure 11, finally wrap the fascicular microfilament structure 11 with a membrane 12 to form a tubular structure, that is, the tissue-engineered peripheral nerve graft constructed from adipose stem cells and biodegradable materials described in the present utility model is obtained thing. In clinical use, the tissue-engineered peripheral nerve graft described in the present invention is implanted into the peripheral nerve defect to be repaired, and the adult stem cells are induced to differentiate into "like Schwann cells" in the in vivo environment. Proliferate and migrate along the growth direction of regenerated axons. After the peripheral nerve is broken, new axons grow out from the proximal stump of the nerve, close to the Schwann-like cells, and the Schwann-like cells surround the axons, form myelin sheaths, provide nutrients to the axons, and guide the axons to the distal end of the nerve. The end grows and connects with the distal end 4 of the nerve fiber. During this process, Schwann-like cells function as Schwann cells, while scaffold 1 is continuously degraded or absorbed by the body, and finally replaced by regenerated nerve fibers.

In this embodiment, the biodegradable material is made of synthetic degradable material, or natural biodegradable material, or a combination of both. The synthetic degradation material is selected from one or more combinations of polylactic acid, polyglycolic acid, polycaprolactone and their copolymers. The natural biodegradable material is selected from one or more combinations of collagen, chitosan and alginic acid.

In this example, according to the diameter of the nerve to be repaired by the patient, a bundled microfilament structure composed of microfilaments of suitable diameter and quantity is selected, which can provide sufficient attachment sites for the seed cells without hindering the regeneration of the nerve axis Sudden growth.

When the utility model is applied, the selected microfilament diameter has nothing to do with the diameter of the repaired nerve, but the number and length of the microfilaments required to form the bundled microfilament structure are determined according to the diameter of the repaired nerve and the length of the nerve defect. . The diameter of the microfilament is usually designed to be 5-50 μm.

In order to further enhance the adhesion of the scaffold to the seed cells, and promote nerve regeneration and graft vascularization, the surface of the microfilaments described in this example can be coated with substance.

In this embodiment, in the preparation of the microfilaments, the microfilaments can also contain substances that can promote cell adhesion, nerve regeneration and graft vascularization, and the substances can be gradually released during the degradation process of the microfilaments.

The aforementioned substances that can promote cell adhesion, nerve regeneration, and graft vascularization can be extracellular matrix (ECM), including collagen, aminoglycans, and glycoproteins; they can also be various growth factors.

The above detailed description is a specific description of a feasible embodiment of the utility model, but the embodiment is not intended to limit the patent scope of the utility model, and any equivalent implementation or change that does not depart from the spirit of the utility model shall be Included in the patent scope of the present utility model.

Claims (5)

1, tissue engineered peripheral nerve graft, it is characterized in that: comprise the support (1) that is used to connect neural two broken ends of fractured bone and have the seed cell (2) that promotes the neurotization function, described support (1) is the pencil microfilament structure of being made up of microfilament (13) (11) of biodegradable material preparation, its outside surface coats a skim (12), form tubular bracket, seed cell (2) evenly adheres to and is on the pencil microfilament structure (11), forms to have imitative neural three-dimensional structure and bioactive complex body.

2, tissue engineered peripheral nerve graft according to claim 1, it is characterized in that: described microfilament (13) surface scribbles the material that can promote cell adhesion, neurotization and graft vascularization, perhaps contains the material that can promote cell adhesion, neurotization and graft vascularization in the microfilament (13).

3, tissue engineered peripheral nerve graft according to claim 1 and 2 is characterized in that: the diameter of described microfilament (13) is 5～50 μ m.

4, tissue engineered peripheral nerve graft according to claim 1 is characterized in that: described seed cell (2) is an adult stem cell.

5, tissue engineered peripheral nerve graft according to claim 4, it is characterized in that: described adult stem cell is a bone marrow interstital stem cell, perhaps fat stem cell.

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