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 . 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 . as used herein , the term “ mammal ” refers to any class of warm - blooded higher vertebrates that includes humans . 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 . 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 . 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 . 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 . referring to fig1 a , 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 . 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 fig1 b ). 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 ). referring now to fig1 b , 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 . 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 . 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 fig1 d . referring to fig2 , 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 . 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 .
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 .