as used herein , the use of the singular includes the plural and visa versa unless expressly stated otherwise . that is , “ a ” and “ the ” are to be construed as referring to one or more of whatever the word modifies . as used herein , “ catheter ” refers to a tube that can be inserted into a body cavity , duct or vessel allowing for the injection of fluids , access to internal organs by surgical instruments , e . g ., a needle , or the placement of implantable medical devices , e . g ., a stent . a catheter can be a thin , flexible tube , i . e ., a soft catheter , or a larger solid tube , i . e ., a hard catheter . as used herein , “ needle ” refers to a hollow tube with a sharp distal end used to inject substances into a tissue . as used herein , “ needle catheter ” refers to a catheter in which a needle is disposed such that the needle can be delivered to a site within the body in order to inject a therapeutic material into a target tissue . as used herein , “ tissue ” generally refers to any group of cells that in the aggregate perform the same function and specifically refers to tissues that receive blood through a dedicated arterial system , such tissues including the lungs ( pulmonary artery ), liver ( hepatic artery ), kidneys ( renal artery ) and heart ( coronary artery ). as used herein , “ lumen ” refers to a cavity of a tubular structure including an organ such as a blood vessel or a device such as a catheter or catheter handle . as used herein , “ reversibly deformable material ” refers to any material that can be repeatedly induced to change shape upon the application of a specific stimulus to the material , e . g ., pressure or heat , yet upon removal of the stimulus will return to its original shape . it is to be understood that a stimulus appropriate for the present invention includes sliding the knob over the rod , as depicted in fig1 a and 1b . examples of reversibly deformable materials suitable for the present invention include , without limitation , nitinol , stainless steel , cobalt chromium , nylon , urethane , polyurethane , polyvinylchloride and polyester . as used herein , “ operatively coupled ” refers to the attachment of a needle of the invention to either the proximal hub or the fluid lumen of the needle catheter through direct or indirect means , respectively . for example , it is possible for the needle to be coupled to the proximal hub directly , e . g ., through adhesive bonding , thermal welding or press fitting . alternatively , it is possible for the needle to be coupled to the fluid lumen indirectly such that the needle would attach to an intermediate component , e . g ., the proximal hub , which in turn would be coupled to the fluid lumen , as depicted in the figures herein . as used herein , “ adhesive bonding ” refers to a method where two materials , e . g ., metals , plastics or composites , are joined using an adhesive , e . g ., glue or epoxy . as used herein , “ thermal welding ” refers to a method where two materials , e . g ., metals , plastics or composites , are joined by heating one or both of the materials and fusing the materials together so that upon cooling , the materials are effectively bonded together . as used herein , “ press fitting ” refers to the attachment of two components by friction . for example , the proximal end of a needle can be compressed so that it fits into a slightly larger component orifice , e . g ., a proximal hub , at which point the proximal end of the needle is allowed to return to its normal size , thereby being held tight by the orifice . as used herein , “ substantial ” or “ substantially ” refers to a characteristic of the object of the adverb by which it is understood that the object is not a perfect example as such would be immediately envisaged by the reader . rather , when modified by the word “ substantially ,” the object of the modifier would be considered close enough to those of ordinary skill in the art to warrant the object designation . as used herein , “ substantially coiled ” refers to the shape of a needle that resembles a spiral or corkscrew shape . as used herein , “ substantially bowed ” refers to the shape of a needle that resembles a bow or curved shape . as used herein , “ substantially wave - shaped ” refers to the shape of a needle that resembles a sinusoidal curve . the present invention relates to a needle catheter that includes a needle made of a reversibly deformable material . the needle is positioned within the catheter such that it can be delivered to a site within a body in a retracted position but upon being positioned at the target tissue is able to be extended to inject cells or any biologic or therapeutic substance into the tissue . fig1 a - b show a first aspect of the invention . fig1 a shows a knob and handle section of needle catheter 100 of the invention . hollow handle 102 includes proximal end 104 , distal end 106 and lumen 108 extending from proximal end 104 to distal end 106 . movable knob 110 is disposed on rod 112 which is positioned adjacent to distal end 106 of handle 102 such that knob 110 can slide back and forth along rod 112 . needle 114 is positioned inside of handle 102 and the proximal end of needle 114 is operatively coupled to proximal hub 116 which is positioned in proximal end 104 of handle 102 . at proximal hub 116 , needle 114 is operatively coupled to fluid lumen 118 . when knob 110 is positioned on rod 112 adjacent to distal end 106 , needle 114 will be in a substantially coiled shape , as shown in fig1 a . it is in this position that distal end 120 of catheter 100 can be moved through the vasculature to a target tissue since needle 114 will be in a retracted position . when knob 110 is moved along rod 112 to become positioned away from distal end 106 , needle 114 will straighten , to some extent as depicted in fig1 b , so that the sharp distal end of needle 114 can penetrate a tissue once the catheter is in position . it is to be understood that both before and after knob 110 is moved , fluid , e . g ., a therapeutic substance , can flow from fluid lumen 118 through proximal hub 116 and into needle 114 . it has been determined that the coil of the needle does not significantly change the fluid dynamics within the needle . because needle 114 is made of a reversibly deformable material , when knob 110 is moved back into a position adjacent to distal end 106 , i . e ., the position depicted in fig1 a , needle 114 will reform into a substantially coiled shape . it is to be understood that needle 114 can be used any number of times for the delivery of fluids and that after the needle is extended it will return to is original shape . fig2 and fig3 show alternative embodiments of the invention . fig2 depicts knob 210 and handle section 202 of needle catheter 200 of the invention in which needle 214 is present in a substantially waved formation . fig3 depicts another embodiment of the invention in which needle 314 is substantially bowed . it is to be understood , however , that when knob 210 or 310 is moved along rod 212 or 312 away from distal end 206 or 306 needle 214 and 314 will straighten , to some extent as depicted in fig1 b , so that the sharp distal end of the needle can penetrate a tissue once the catheter is in position . when knob 210 and 310 are moved back into a position adjacent to distal end 206 or 306 of the handle , needle 214 and 314 will reform into either a substantially waved or a substantially bowed shape , respectively . it is to be understood that the needle catheter components depicted in fig1 , 2 and 3 are the same , e . g ., knob 110 is the same as knob 210 and 310 . needles 114 , 214 and 314 , however , are different as depicted in fig1 a , 2 and 3 . another aspect of the present invention relates to a method for delivering therapeutic materials into heart tissue that involves providing a needle catheter according to the invention , providing a therapeutic material and administering the therapeutic material into the heart tissue . the therapeutic material , also referred to herein as a drug or biologic material , can include cells as well as an antiproliferative agent , an anti - inflammatory agent , an antineoplastic , an antimitotic , an antiplatelet , an anticoagulant , an antifibrin , an antithrombin , a cytostatic agent , an antibiotic , an anti - allergic agent , an anti - enzymatic agent , an angiogenic agent , a cyto - protective agent , a cardioprotective agent , a proliferative agent , an abc a1 agonist , an antioxidant or any combination thereof . it is to be understood that methods of using a needle catheter according to the invention for the administration of therapeutic materials to heart tissue will be easily ascertainable to those skilled in the art from the disclosures herein . while particular embodiments of the present invention have been shown and described , it will be obvious to those skilled in the art that changes and modifications can be made without departing from this invention in its broader aspects . therefore , the appended claims are to encompass within their scope all such changes and modifications as fall within the true spirit and scope of this invention .