Abstract:
Delivery devices and methods related thereto may be used in humans for spinal delivery of cells, drugs or vectors. The patient population may include patients with spinal traumatic injury, amyotrophic lateral sclerosis, multiple sclerosis, spinal ischemia and any other spinal neurodegenerative disorders which will require spinal cell, vector or drug delivery. Unlike conventional methods which require multiple injection sites to make multiple, localized substrate deliveries, the delivery devices and methods of the present invention may allow for multiple substrate delivery locations with homogeneous substrate delivery with a single injection site.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims benefit of U.S. Provisional Application having application number 60/915,743 filed May 3, 2007, which is hereby incorporated by reference herein in its entirety. 
     
    
     STATEMENT OF GOVERNMENT INTEREST 
       [0002]    This invention was made with government support under contract awarded by the National Institute of Health (NIH). The government has certain rights in the invention. 
     
    
     BACKGROUND OF THE INVENTION 
       [0003]    The present invention generally relates to a drug or cell delivery system and more specifically, to a drug or cell delivery system for multisegmental injection of substrate and/or cells into an animal or human. 
         [0004]    Currently used devices employ multiple vertical spinal cord injections to deliver cells into multiple spinal cord segments. (Feron et al., Brain, 2005: 128: 2951-2960.) The risk of secondary spinal cord injury resulting from multiple vertical injections is high as it can lead to a mechanical trauma of otherwise intact and functional spinal cord tissue. 
         [0005]    Previous devices developed for multiple depositions of cells into brain tissue have used plastic injection cannulas which bends after exiting the guide needle and therefore do not permit deposition of the injectate in a single plane (if measured against the guide needle). See  FIG. 2C  of Brecknell and Fawcett, Experimental Neurology, 1996; 138: 338-343. 
         [0006]    The second type of device which was developed for brain injections describes the use of a rigid type of guide needle which can hold a specific angle (shape) and can be used for guided placement of flexible injection needle or possibly for injections. See page 1498—Material and Methods section of Cunningham et al., Neurosurgery, 2004; 54: 1497-1507. 
         [0007]    As can be seen, there is a need for apparatus and methods for delivering a substrate into the spinal cord of a mammal while minimizing the number of required injection sites. 
       SUMMARY OF THE INVENTION 
       [0008]    In one aspect of the present invention, a device for the delivery of a substrate into a spinal cord comprises a guide needle having an inside diameter; an injection needle fitting into the inside diameter of the guide needle; a stepping motor advancing the injection needle into and within the spinal cord; and a chamber containing the substrate or cells in fluid communication with the injection needle. 
         [0009]    In another aspect of the present invention, a method for multisegmental delivery of a substrate or cells into a spinal cord comprises advancing a guide needle into the spinal cord; advancing an injection needle through the guide needle into the spinal cord; and withdrawing the injection needle while delivering the substrate or cells into the spinal cord. 
         [0010]    In a further aspect of the present invention, a method for homogenous delivery of a substance into a spinal cord comprises advancing a guide needle into spinal parenchyma at an angle of about 45 degrees; advancing an injection needle through the guide needle horizontally into spinal parenchyma; initiating delivery of the substance or cells after the injection needle is fully inserted into spinal parenchyma (up to 1-3 inches); and continuing delivery of the substance or cells while the needle is withdrawn from spinal parenchyma using a computer-controlled stepping motor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1A  is a graphical representation of a drug delivery system according to the present invention nearly fully injected into spinal segments; 
           [0012]      FIG. 1B  is a graphical representation of the drug delivery system of  FIG. 1A  partially withdrawn from the spinal segments; 
           [0013]      FIG. 1C  is a graphical representation of the drug delivery system of  FIG. 1A  nearly fully withdrawn from the spinal segments; 
           [0014]      FIG. 1D  is a graphical representation of the drug delivery system of  FIG. 1A  after the injection is completed; and 
           [0015]      FIG. 2  is a flow chart describing a method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0017]    As used herein, the term “substrate” refers to any injectable substance, including but not limited to cells, drugs, viruses, plasmids, growth factors and the like. The substrate may any suitable form of matter, including a liquid, a suspension, a gel, an encapsulated solid, a nanoparticle suspension, a slow- or extended-release polymer composition and the like. 
         [0018]    As used herein, the term “mammal” refers to any class of warm-blooded higher vertebrates that includes humans. 
         [0019]    As used herein, the term “horizontal” refers to a direction of the spinal column when a subject is lying supine or prone. In other words, horizontal may be described as along the long axis of the spine. The term “vertical” refers to a direction from about 45 degrees to about 90 degrees relative to the horizontal direction. 
         [0020]    Broadly, the present invention may permit a multisegmental injection of cells or any diffusible substances (such as drugs, growth factors or any other injectable substance) into spinal cord in large animal species and in humans. The present invention may provide methods and apparatus so that one vertical spinal cord puncture may be required to permit a multisegmental (up to 4-6 spinal segments) delivery of a substrate. 
         [0021]    Conventional devices employ multiple vertical spinal cord injections to deliver cells, drugs, vectors or the like into spinal cord parenchyma. In a typical setting, multiple injections (up to several hundred) are required to achieve a satisfactory cell, drug or vector delivery to multiple spinal segments (Feron et al., Brain, 2005: 128: 2951-2960.). The device of the present invention, after exiting the guide needle, the injection needle may retain a fixed angle, thus permitting a well controlled placement in a given plane over 1-3 inches from the tip of the guide needle. 
         [0022]    The device of the present invention may permit the number of vertical injections to be reduced to about less than 20, typically less than 10, and even more typically to within a range of about 6 to 10. In addition, because of a continuous cell delivery during the process of the needle withdrawal, a much more homogeneous distribution of substrate can be achieved in the multiple spinal cord segments. The device of the present invention may use a stepping motor to withdraw the needle, thus permitting a homogenous injectate delivery over the whole injection trajectory. 
         [0023]    Referring to  FIG. 1A , a device  10  of the present invention may include two separate elements, a guide needle  12  and an injection needle  14 . The guide needle  12  may be from about 27 to about 30 gauge, typically from about 100 to about 400 micrometers in diameter, and may be made from stainless steel or other non-corrosive material. The guide needle  12  may be from about 2 to about 4 inches long. The lower 2-3 inches of the needle may have a bend  16 , the bend  16  curving circularly at an angle of about 45 degrees. The upper 3-4 inches of the needle may be attached firmly to a micromanipulator  18  which may be used to place the guide needle into a specific spinal cord region localized in the gray  22  or white matter. 
         [0024]    The injection needle  14  may be made of stainless steel, polycarbonate, synthetic quartz polymer or other flexible material tubing between about 34 to about 30 gauge and may be from about 5 to about 7 inches long. One end of the needle (internal end  20 ) may be advanced into the spinal cord tissue (e.g., the gray matter  22 ) through the guide needle  12  and used for injection of a substrate  24 , such as cells or any diffusible substances (see  FIG. 1B ). The other end (i.e., external end  26 , about 1-2 inches) may be attached to a stepping motor  28 . The stepping motor  28  may be used for advancement of the injection needle  14  into spinal parenchyma (e.g., gray matter  22 ) through the guide needle  12 . The external end  26  of the injection needle  12  may be connected to a syringe  30  using polyethylene tubing  32 . Injections may be performed by using a digital microinjector (not shown). 
         [0025]    Referring now to  FIGS. 1B ,  1 C and  1 D, the guide needle  12  may be advanced into spinal parenchyma (e.g., gray matter  22 ) through the dorsal horn (e.g., spinal segment number  4 ) of the spinal cord  32  at an injection angle (not shown) of about a 45 degree angle relative to horizontal. The tip (not shown) of the guide needle  12  may be targeted into the spinal regions to be injected with substrate  24 . The tip of the guide needle  12  may have a bend  19  at an angle of about 45 degrees, which, along with the injection angle, may result in the tip of the guide needle  12  pointing in a substantially horizontal direction along the spinal cord  36  when inserted into a subject. The bend  19  in the tip may be formed along the guide needle  12  within the last 0.5 inches thereof, typically within the last 0.1-0.2 inch thereof. The spinal region may be gray matter  22  (dorsal horn, intermediate zone or ventral horn) or any region of the white matter. 
         [0026]    After positioning of the guide needle  12 , the injection needle  14  may be advanced horizontally into spinal parenchyma (e.g., gray matter  22 ) in dorso-caudal or caudo-rostral direction. The distance of the injection needle  14  advancement can be up to about 1 to about 3 inches. 
         [0027]    After the targeted spinal segment is reached with the tip (internal end  20 ) of the injection needle  14 , the injection of substrate  24  may be initiated using, for example, a microinjector (not shown). During the course of the injection, the injection needle may be gradually withdrawn, as shown by arrow  34 , thereby permitting a homogenous multisegmental delivery of substrate  24  into the targeted areas (spinal segments  1 - 4 ), as shown in  FIG. 1D . 
         [0028]    Referring to  FIG. 2 , there is shown a flow chart of a method  40  for multisegmental delivery of a substance (e.g., substrate  24 ) into a spinal cord (e.g., spinal cord  36 ). The method may include a step  42  of advancing a guide needle (e.g., guide needle  12 ) into spinal parenchyma (e.g., gray matter  22 ). The guide needle may be bent at the injection end at an angle of about 45 degrees. The method may include a further step  44  of advancing an injection needle (e.g., injection needle  14 ) through the guide needle to exit the guide needle horizontally into spinal parenchyma. The injection needle may be injected through one or several spinal segments. The method may also include a step  46  of withdrawing the injection needle while delivering the substance into the spinal cord. This withdrawal during delivery may provide not only multisegmental delivery of the substance, but may also provide for a homogenous delivery of the substance. Conventional methods may fail to provide the multisegmental delivery or the homogenous delivery of the substance into the spinal column. 
         [0029]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.