Surgery – Instruments – Surgical mesh – connector – clip – clamp or band
Reexamination Certificate
1998-09-01
2001-04-10
Jackson, Gary (Department: 3731)
Surgery
Instruments
Surgical mesh, connector, clip, clamp or band
C264S029300
Reexamination Certificate
active
06214021
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to repairing injured nerves. More particularly, the invention relates to a guidance channel or conduit, as well as a method, for promoting nerve regeneration.
Various prostheses and nerve grafts have been proposed for repairing severed nerves. Typical prostheses include synthetic tubular bodies having a single lumen through which nerve regeneration is intended to occur. These nerve guidance devices are surgically inserted into the gap between the proximal and distal nerve stumps in an effort to promote nerve growth.
Conventional nerve guidance channels are often unsuccessful. When a nerve is injured, Schwann cells stimulate the growth of the regenerating nerve fibers by dividing and producing the trophic substances responsible for nerve growth. Accordingly, Schwann cells appear to play an important role in the regeneration of nerve tissue in an injured or severed nerve. One cause of failure in conventional nerve prostheses and grafts appears to be due to a lack of support for a sufficient number of Schwann cells to ensure successful nerve regeneration.
Accordingly, there is a need for an improved nerve prosthesis for promoting increased and reliable nerve regeneration between the distal and proximal stumps of a severed nerve.
It is, therefore, an object of the present invention to provide an effective nerve guidance channel for promoting nerve regeneration.
It is another object of the present invention to provide a nerve guidance channel which provides increased surface area for Schwann cell adherence.
It is also an object of the present invention to provide a more flexible and preferably biodegradable prosthesis that does not cause discomfort or require surgical removal.
It is a further object of the present invention to provide a nerve guidance channel or conduit that permits increased control over the direction of growth of regenerating nerve fibers.
SUMMARY OF THE INVENTION
The present invention is directed to a guidance channel or conduit and a method for promoting nerve regeneration. The guidance channel includes a body constructed of a biocompatible polymeric material and having a first end for connection to a proximal stump of a severed nerve and a second end for connection to a distal stump of the severed nerve. The body includes a plurality of internal lumens extending between the first and second end to facilitate rejoining of the proximal and distal stumps of the severed nerve by providing increased surface area for Schwann cell adherence.
In a preferred embodiment, the guidance channel is constructed of a bioresorbable or biodegradable material, such as poly-L-lactic acids, poly-lactic-coglycolic acid polymers, poly-glycolic acid polymers, and polycaprolactones. The guidance channel can include between 5 and 5000 lumens. The inner diameter of each lumen is can be between approximately 2 and 500 microns.
In accordance with a further aspect of the present invention, Schwann cells are incorporated within the lumens of the nerve guidance channel body. The Schwann cells can adhere to the interior surfaces of the lumens.
In accordance with another aspect of the present invention, the body of the nerve guidance channel is constructed of a porous membrane structure which contains a plurality of pores for permitting fluids and nutrients to pass through the body of the guidance channel to reach the internal lumens. In this manner, Schwann cells and regenerative nerve tissue within the internal lumens are able to receive nutrients and oxygen during nerve regeneration. It is preferable for the pores to be sized to inhibit the growth of regenerative nerve tissue through the pores.
The method of the present invention provides for promoting nerve regeneration between the severed stumps of a nerve. The method includes the steps of providing a guidance channel constructed of a polymeric material and having a plurality of internal lumens extending between the first end and the second end of the guidance channel, connecting the proximal stump of the nerve to the first end of the guidance channel, and connecting the distal stump of the nerve to the second end of the guidance channel such that nerve regeneration occurs within the plurality of lumens of the guidance channel between the severed stumps of the nerves.
In accordance with a further aspect of the present invention, the method includes the step of lining the lumens of the plurality of lumens with Schwann cells.
A method of manufacturing a multi-lumen nerve guidance channel in accordance with present invention includes the steps of preparing a polymer solution comprising a polymer and a solvent, injecting the polymer solution into a mold to form the body of the nerve guidance channel, the mold including a plurality of wires for forming a plurality of internal lumens within the body, solidifying the polymer solution by freezing the body, and drying the body by sublimation to form a plurality pores within the body.
In accordance with another aspect of the present invention, the manufacturing method includes the step of adjusting the concentration of the solvent within the polymer solution to control the size and number of pores formed within the body.
A method for manufacturing a polymeric prosthesis for use in tissue engineering and regeneration in accordance with present invention includes the steps of preparing a polymer solution by dissolving a polymer in a solvent, injecting the polymer solution into the mold cavity, solidifying the polymer solution by freezing the polymer solution in the mold to form the polymeric prosthesis, and drying the polymeric prosthesis by sublimation. The injection molding process of the present invention permits the fabrication of biocompatable and biodegradable polymer prosthesis with controlled, precise dimensions, high tolerances, and controlled porosity. Polymeric prostheses manufactured according to the injection molding method of the present invention can be used in the tissue engineering and regeneration of a wide range of tissue types, including structural tissues, such as bone, muscle, or cartilage, and specialized tissues such as organ tissue, including brain and liver tissue, and breast tissue.
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Hadlock Theresa Anne
Sundback Cathryn
Bui Vy Q.
Children's Medical Center Corporation
Engellenner Thomas J.
Jackson Gary
Nutter & McClennen & Fish LLP
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