PL218618B1 - Prosthesis for the regeneration of peripheral nerve and method for manufacturing the prosthesis for the regeneration of peripheral nerve - Google Patents

Description

Description of the invention

The present invention relates to a peripheral nerve regeneration prosthesis and a method of manufacturing a peripheral nerve regeneration prosthesis.

Peripheral nerve injuries are a common form of trauma resulting primarily from accidents such as road accidents, agricultural accidents, tumor resection, or the undesirable effects of various types of surgery. The effect of this is not only the loss of motor skills, but also the atrophy of the reddened muscles. A common phenomenon accompanying peripheral nerve injuries is also the development of neuropathic pain particularly resistant to pharmacological treatment. Without any protection, fibers in the proximal segment of a ruptured nerve regrow spontaneously and chaotically, almost always forming neuromas or micronuromas. Therefore, it is necessary to properly secure the resulting nerve stump, and an ideal connection would be to recreate the primary nerve pathway.

Three methods are used for surgical treatment of damaged peripheral nerves: direct connection of the ends of the broken nerve, autograft, and the use of various natural or synthetic materials to restore the neural connection.

The first method of nerve reconstruction has a major disadvantage, as it can only be used for defects shorter than 1 cm. Reconstruction, as well as healing, should proceed without nerve tension and without tension in the tissues surrounding the nerve.

The so-called "Gap-injuries" when a break in the continuity of a nerve prevents it from being sutured immediately. In order to supplement the defect, the so-called “Bridging most often with a fragment of the harvested nerve, mostly cutaneous, with autogenous veins and muscle fibers, which, however, causes additional injury to the patient. The disadvantages of autografts have led to the development of several alternative techniques, such as those using nerve regeneration prostheses made of synthetic or natural materials.

Patent US 4,778,467 discloses nerve prostheses in the form of a polyurethane tube coated on the outside with silicone, protecting against the loss of significant amounts of trophic substances and fluids from the inside to the outside of the prosthesis.

From US patent 5,092,871 peripheral nerve prostheses are known in the form of a tube with a diameter of 0.5-30 mm made of polytetrafluoroethylene (PTFE).

From US patents 5,026,381, US 4,963,146, US 5,019,087 as well as from J. Peripher Nerv Syst., Vol. 1, 1996, pp. 53-64, J Reconstr. Microsurg., Vol. 9, 1993, pp. 415-420; Ann Neurol., Vol. 51, 2002, pp. 69-81, artificial connections for repairing damaged peripheral nerves made of biodegradable collagen are known. These prostheses have the shape of microporous, multilayer tubes with a diameter of 1-10 mm.

The journal Neurosci Lett., Vol. 259, 1999, pp. 75-8 describes peripheral nerve prostheses made of lyophilized alginate gel in a polyglycolide mesh sheath.

From the publications in Brain Res., Vol. 128, 2005, pp. 1897-1910 and Microsur., 2008, pp. 238-242 and pp. 471-479, prostheses in the form of a chitosan tube and polyglycolide acid are known.

However, from the publication in: Brain Research, Vol. 993, 2003, pp. 111-123, Sci., Technol. Adv. Mater., Vol. 4, 2003, pp. 261-268 and Biomaterials, Vol. 24, 2003, pp. 3285-3292, hydroxyapatite-chitosan tube prostheses with circular or triangular cross-section are known.

From the publication in Tsinghua Science and Technology, Vol. 10, 2005, pp. 435-438 porous, two-layer chitosan tubes are known for the prosthesis of peripheral nerves.

From US Patent No. 4,534,349, combinations of nerves of polyglycolic acid, polylactic acid, polyesteramides and their copolymers and mixtures are known. These prostheses are in the form of longitudinally opened, porous tubes 0.1-10 mm in diameter, with a rough inner surface.

From Pain., Vol. 117, 2005, pp. 251-258, Brain Res., Vol. 868, 2000, pp. 315-328; Polym. Eng. Sci., Vol. 47, 2006, pp. 1461-1467 and J. Thorac Cardiovasc Surg., Vol. 133, 2007, pp. 726-732, biodegradable peripheral nerve connections in the form of microporous braided polyglycolic acid tubes coated with cross-linked collagen.

Patent US 7,135,040 discloses prostheses for the reconstruction of peripheral nerves in the form of braided, biodegradable tubes made of a copolymer of L-lactic acid and glycolide (10:90) and chitosan.

PL 218 618 B1

US patent 6,090,117 discloses temporary nerve connections in the form of tubes made of lactic acid copolymers filled with collagen gel with the addition of laminin and growth factor, in which collagen fibers are additionally immersed.

The peripheral nerve regeneration prosthesis according to the invention is characterized by a cylindrical core made of microcrystalline chitosan with an average molecular weight of 200,000 - 400,000, a degree of deacetylation of 80 - 90%, 7 - 13 through channels parallel to the core axis and evenly spaced on a circle or circles, centered on the core axis, placed in a sleeve with an internal diameter equal to the core diameter and a thickness of 0.04 - 1 mm, made of DL - lactide / glycolide copolymer with a 75/27 molar ratio or of microcrystalline chitosan with average molecular weight 200,000 - 400,000, degree of deacetylation 80 - 90%. The core is placed in the sleeve so that the sleeve protrudes beyond both ends of the core.

The method of producing a prosthesis for peripheral nerve regeneration consists in that an aqueous suspension of microcrystalline chitosan at pH is injected into a silicone mold with a circular cross-section, in which the smooth polypropylene fibers are placed under tension, parallel to the axis of the mold, evenly on a circle or concentric circles. = 7 - 7.15 containing 2.0 - 3.0% by weight of microcrystalline chitosan with an average molecular weight of 200,000 - 400,000 and a degree of deacetylation of 80 - 90%. Then it is frozen at -20 ° C to -25 ° C for 15-20 minutes, the silicone mold is removed and the formed cylindrical core is freeze-dried for 24-48 hours at -20 ° C to -25 ° C under a pressure of 10-57 Pa. The core, after removing the polypropylene fibers from it, is placed in a sleeve with an internal diameter equal to the core diameter and a thickness of 0.04 - 1 mm, made of DL - lactide / glycolide copolymer with a molar ratio of 75/25 or from an aqueous suspension of microcrystalline chitosan at pH = 6, 0-6.2, containing 1.6-1.8 wt.% Microcrystalline chitosan with an average molecular weight of 200,000-400,000 and a degree of deacetylation of 80-90%, the core being positioned so that the sleeve protrudes beyond both ends of the core.

The advantage of the method according to the invention is the use of polymers in the form of microcrystalline chitosan and a lactic acid-based copolymer for the production of biocompatible and resorbable polymers in the body.

The multi-channel nerve prosthesis is used in the treatment of peripheral nerve injuries in humans, which has been confirmed in preclinical studies conducted in animals in vivo. It allows for a radical reduction in the intensity of neuropathic pain and the reconstruction of the missing fragment of the nerve.

The following non-limiting examples illustrate the invention.

Example I. In a silicone mold with a length of 7 mm and a circular cross-section with a diameter of 2 mm, 7 smooth polypropylene fibers with a diameter of 0.2 mm were placed under tension, parallel to the axis of the mold, distributed evenly on a circle centered on the axis of the mold. An aqueous suspension of microcrystalline chitosan at pH = 7 containing 2.47 wt.% Was injected into the mold. Polymer with w = 320,000 and 81% deacetylation degree. The filled mold was frozen at -25 ° C for 15 minutes, then the mold was removed and the formed core was freeze-dried for 24 hours at -25 ° C. The fibers were then removed from the core to obtain a cylindrical core 7 mm in length and 2 mm in diameter having 7 channels 0.22 mm in diameter. An aqueous gel-like suspension of microcrystalline chitosan, pH = 6.1 - 6.2, containing 1.7 wt. of polymer with an ow = 320,000 and 81% deacetylation degree, with the addition of glycerin in a weight ratio of 1: 0.4, poured onto a Teflon mold, then the resulting film was dried at room temperature for 24 hours, neutralized for 30 minutes with an aqueous solution of sodium carbonate with a concentration of 1% by weight with the addition of 1% by weight of glycerin. The membrane was then washed with glycerin water and freeze-dried for 24 hours at -25 ° C and 0.1-0.57 mbar. A sleeve with an internal diameter of 2 mm was made from a dried film with a thickness of 0.08 - 0.1 mm, in which the core was placed so that the sleeve protrudes 4 mm beyond both its ends.

The usefulness of the produced peripheral nerve prosthesis has been confirmed in preclinical studies conducted on animals in in vivo conditions. Immunohistochemical studies using confocal microscopy showed the regrowth of regenerative nerve fibers into 7 channels located in the core of the prosthesis.

P r z x l a d II. An aqueous suspension of microcrystalline chitosan was injected into a silicone mold 10 mm long with a circular cross-section of 2 mm in diameter, in which, under tension, parallel to the axis of the mold, 13 smooth polypropylene fibers with a diameter of 0.2 mm, distributed evenly on a circle centered on the mold axis with a pH = 7, containing 2.89 wt. of a polymer with a = 280,000 and a degree of deacetylation of 80.0%. The filled mold was frozen as in example 1, na4

After that, the mold was removed and the formed core was freeze-dried and the fibers were removed from the core as in Example 1. A cylindrical core 10 mm in length and 2 mm in diameter having 13 channels 0.23 mm in diameter was obtained. 75/25 molar ratio of DL-lactide / glycolide copolymer solution in 1,4-dioxane at 3% by weight. with the addition of polyethylene glycol 600 in the amount of 4% by weight. with respect to the copolymer, poured onto a Teflon mold. The resulting film was first dried at room temperature for 24 hours and then at 50 ° C under a pressure of 0.07 MPa for 4 days. A dried film with a thickness of 0.045 mm was used to make a sleeve with an internal diameter of 2 mm, into which the core was placed so that the sleeve protruded 6 mm beyond both its ends.

The usefulness of the produced peripheral nerve prosthesis has been confirmed in preclinical studies conducted on animals in in vivo conditions. Immunohistochemical studies using confocal microscopy showed the regrowth of regenerating nerve fibers into 13 channels in the core of the prosthesis.

Claims (2)

1. A prosthesis for the regeneration of a peripheral nerve consisting of a core placed in a sleeve, characterized in that a cylindrical core made of microcrystalline chitosan with an average molecular weight of 200,000 - 400,000, degree of deacetylation 80 - 90%, 7 - 13 through channels parallel to the core axis and evenly spaced on a circle or concentric circles, centered on the core axis, is placed in a sleeve with an internal diameter equal to the core diameter and a thickness of 0.04 - 1 mm made of DL - lactide / glycolide copolymer with a molar ratio of 75 / Or from microcrystalline chitosan with an average molecular weight of 200,000-400,000, a degree of deacetylation of 80-90%, the sleeve protruding beyond both ends of the core. Method for the production of a prosthesis for peripheral nerve regeneration, characterized in that an aqueous suspension of microcrystalline chitosan is injected into a silicone mold with a circular cross-section, in which, under tension, parallel to the axis of the mold, smooth polypropylene fibers are uniformly placed on a circle or concentric circles pH = 7.0 - 7.15 containing 2.0 - 3.0% by weight of microcrystalline chitosan with an average molecular weight of 200,000 - 400,000 and a degree of deacetylation of 80 - 90%, and then the whole is frozen at a temperature of -20 ° C to -25 ° C for 15 - 20 minutes, the silicone mold is removed and the formed cylindrical core is freeze-dried for 24 - 48 hours at -20 ° C to -25 ° C at a pressure of 10 - 57 Pa, then the core is dried removing polypropylene fibers from it, placed in a sleeve with an internal diameter equal to the diameter of the core and a thickness of 0.04 - 1.0 mm, made of DL - lactide / glycolide copolymer with a molar ratio of 75/25 or of an aqueous suspension of mi crocrystalline chitosan pH = 6.0 - 6.2 containing 1.6 - 1.8% by weight of microcrystalline chitosan with an average molecular weight of 200,000 - 300,000 and a degree of deacetylation of 80 - 90%, with the core placed so that the sleeve protrudes beyond both ends of the core.