Abstract:
An infusion container includes a main body portion with side walls, and top and bottom portions. The bottom portion has an included angle, the included angle being between 30-120 degrees. The included angle serves to channel cells to be infused into a patient out of the container, to reduce waste and damage to the cells. A method of infusion is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The infusion of donor cells such as islet cells requires that the cells be maintained in some type of container prior to infusion into the patient. Typically, the cells are placed in solution into a flexible sterile container. An outlet port of the container is connected to a flexible conduit which delivers the cells and solution to a catheter for infusion. Some cells become collected at the horizontal bottom of the square or rectangular shaped container, and do not pass through the outlet port. Valuable cells are thereby lost in the infusion process, or time is lost as the container is manipulated to cause the cells to pass from the container. The loss of time and manipulation of the cells increases the risk of injury to the cells. 
       SUMMARY OF THE INVENTION 
       [0002]    An infusion container comprises a main body portion comprising side walls, and top and bottom portions. The bottom portion has an included angle, the included angle being between 30-120 degrees. In another aspect, the included angle is between 40-100 degrees. In yet another aspect, the included angle is between 50-80 degrees. The included angle can be about 60 degrees. An outlet can be provided through which the contents exit the container. The outlet can be of any suitable design. 
         [0003]    The side walls can comprise a flexible material such that the container will be in the nature of a bag. The side walls can comprise a substantially transparent or translucent material. The container can comprise a material that is oxygen permeable. The container can comprise a material that is carbon dioxide permeable. 
         [0004]    The container can comprise at least one port for the introduction of material into the bag. The at least one port can be selected from the group consisting of a luer lock, a spike entry port, and an injection port. 
         [0005]    A method of infusing cells according to the invention comprises the steps of providing an infusion container, the infusion container having a main body portion with side walls, and top and bottom portions, the bottom having an included angle, the included angle being between 30-120 degrees. A liquid solution and cells to be infused into a patient are placed into the container. The cells and solution are allowed to exit the container through an outlet in the bottom portion, whereby the cells will directed by the included angle to the outlet. The infusion container may also be used to transport and culture islet cells in the incubator due to its high gas permeability characteristics. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    There is shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention can be embodied in other forms without departing from the spirit or essential attributes thereof. 
           [0007]      FIG. 1  is a side elevation of an infusion container according to the invention. 
           [0008]      FIG. 2  is a side elevation of an infusion container according to an alternative embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0009]    There is shown in  FIG. 1  an infusion container  10  according to the invention. The container  10  can comprise side walls such as opposing front and rear side main body panels  12  joined at side edges  14  thereof. A tubular side wall or seamless construction is also possible. The container  10  further has a top portion  16  and bottom portion  20 . The bottom portion  20  defines an included angle  24 . The included angled  24  permits cells and other solid and viscous materials to readily drain from the infusion container  10  through a suitable outlet port  30 . The outlet port  30  is positioned substantially at the vertex of the included angle  24 . 
         [0010]    The shape and capacity of the container can be varied, provided that the bottom of the container has the included angle construction of the invention. The sides of the included angle  24  need not be linear, curved or sloping sides are possible, provided that the outlet port is below the sides when the infusion container is in use and that the surface is shaped so as to permit cells to effectively leave the container. Therefore, the term vertex as used herein generally refers to the point where the sides of the bottom portion  20  converge, which will generally be the lowest point of the container when it is positioned upright. 
         [0011]    The included angle  24  can be any suitable angle which facilitates the egress of material from the infusion container  10 . In one embodiment, the included angle is between about 30-120 degrees. In another embodiment, the included angle is between about 40-100 degrees. In still another embodiment, the included angle  24  is between about 50-80 degrees. The included angle can be between about 55-65 degrees, and can be about 60 degrees. 
         [0012]    The dimensions and capacity of the container can be varied. In one aspect, the container has a capacity of between about 500 ml and 1 L, and for pancreatic cell transplantation purposes a capacity of about 600 ml is useful. 
         [0013]    The container  10  can be constructed from a material that is permeable to oxygen and to carbon dioxide. In this manner, cells within the container can receive oxygen and carbon dioxide can be removed from the container  10 . This will facilitate the continued viability of the cells. The permeability of the material to oxygen is selected to deliver oxygen at least at the minimum consumption rate that is required by the cells contained within the containers, and will depend on the amount of cells that are in the container  10 . In the particular case of pancreatic islet cells, for example, this rate is about 7.2×10 −8  mol/(cm 3 ·s) at 37° C. The rate of transfer of gases into or from the container can be varied for the oxygen demand and number of cells intended to be placed within the container, by suitable methods such as changing the thickness of the container material, the composition of the container material, and the size and geometry of the container. An oxygen permeability of between about 50-500 cm 3 /(100 in 2 *24 hr*atm@25° C.) is desirable for many types of cells, and an oxygen permeability of between about 98-293 cm 3 (100 in/ 2 *24 hr*atm.@25° C.) can be useful. Children and adults, as well as differently sized people in general, can require differing amounts of cells for an islet cell transplantation, and the more cells that are placed within a same size container, generally the greater the oxygen permeability that will be required. Since islet cells are considered to be one of the most oxygen demanding cells (since they are metabolically active), then designs that are satisfactory for these types of cells should also be satisfactory for many other kinds of biological cell types. 
         [0014]    The container is preferably transparent or translucent in part to permit visual inspection of the contents. A suitable container material is ES-4000™, a flexible vinyl film manufactured by Solvay Draka Inc. of Commerce, Calif. ES-4000 has an O 2  transmission of 146 cm 3 /(100 in 2 *24 hr*atm@25° C.). The container material can have any suitable thickness. The thickness of the container material will affect flexibility and the permeability to oxygen and carbon dioxide, and the thickness can be adjusted accordingly. In one aspect the material thickness is about 0.015 inches. 
         [0015]    The container  10  can be provided with various ports for the introduction of materials into the container. One such port is a female Luer lock  40 . The female Luer lock  40  is adapted to connect to a male fitting for the introduction of material into the container  10 , and can be covered by a cap  42  until ready for use. Another suitable port is the spike entry port  44 . Yet another is an injection cap  48 . The injection cap  48  has an elastomeric material as a covering which permits a syringe needle to be placed through the material to introduce materials into the container  10 . The elastomeric material seals when the needle is withdrawn. Other ports or apparatus used with infusion containers are possible. A tab  50  with a slit  52  or other suitable structure can be provided to permit the container  10  to be hung from a support. Various valve and port constructions can similarly be provided with the outlet port  30 , such as the spike outlet port  56  with cap  58 , to control egress of the contents of the container through the outlet. 
         [0016]    The infusion container  10  can be used for other purposes due to its high gas permeability characteristics. The infusion container  10  can also be used to transport and culture islet cells in the incubator, and the permeability of the container will permit gas exchange through the container so as to foster cell maintenance and growth. 
         [0017]    An alternative container design is shown in  FIG. 2 . The container  60  includes top  64 , sides  68 , and bottom  72 . The bottom  72  is formed from curved sides that slope to the outlet port  76 . A plurality of inlet ports  78 ,  80  and  82  can be provided at the top  64 . Hanging rings  86  can be provided at sides of the top  64  to permit the hanging of the container from a suitable support. 
         [0018]    The permeability and size of the container can be selected so as to provide the gas exchange necessary for maintenance and growth if desired for the intended contents. In one embodiment the oxygen permeability, and volume of the container are selected such that the flow rate of oxygen into the container is sufficient to satisfy the oxygen demand of the cells inside the container. The oxygen permeability in one embodiment is selected using atmospheric pO 2  at a given temperature. 
         [0019]    The following example will be provided for the case of pancreatic cell transplantation, however, it will be appreciated that the invention has utility for a variety of different kinds of cells and organs. In this example, in order for islet cells to survive inside the infusion container, the oxygen transmission rate through the container film has to be greater than the oxygen consumption rate of the islet cells. It has been shown that a pO 2 &lt;40 mmHg leads to hypoxia in islet cells. Therefore, it is assumed that a 50% higher pO 2  inside the container (60 mmHg pO 2 ) will be sufficient to maintain the cells. Also, it is assumed that outside the container the pO 2  is 142 mmHg (21% of 760 mmHg after accounting for 5% CO 2  and moisture at 37.0° C. inside an incubator).
   Therefore, the ΔpO 2  is: p 0   2     incubato{dot over (r)}   :=142 mmHg
       ΔpO 2 :=pO 2     incubato  r     =pO 2  bag   ΔpO 2 :=pO 2     incubato  r     =pO 2  bag   ΔpO 2 =82 mmHg
 
Both the transmission and oxygen consumption parameters need to be adjusted at the same (actual) temperature. The oxygen transmission rate for ES-4000 film is given at 25.0° C. Therefore, this calculation is an approximation.
   
       
 
         [0024]    Starting with the ES-4000 film oxygen transmission rate: 
         [0000]    
       
         
           
             TR 
             := 
             
               
                 146 
                 · 
                 
                   
                     
                       cm 
                       3 
                     
                     
                       100 
                       · 
                       
                         in 
                         2 
                       
                       · 
                       24 
                       · 
                       hr 
                       · 
                       atm 
                     
                   
                    
                   
                       
                   
                   @ 
                   
                       
                   
                    
                   25.0 
                 
               
                
               
                   
               
                
               
                 C 
                 . 
               
             
           
         
       
     
         [0025]    It is known that for an ideal gas, the standard molar volume is the volume that is occupied by one mol of substance (in gaseous form) at standard temperature and pressure (STP) of 273.15 K (H 2 O freezing temperature) and 101325 Pa (1 atm). It is 22.42 L/mol and is directly related to the universal gas constant R in the ideal gas law. 
         [0000]    Therefore, the volume occupied by one mol of a gas at 25.0° C. and 1 atm is: 
         [0000]    
       
         
           
             T 
             := 
             
               298.15 
                
               
                   
               
                
               K 
             
           
         
       
       
         
           
             R 
             := 
             
               8.314570 
               · 
               
                 
                   N 
                   · 
                   m 
                 
                 
                   K 
                   · 
                   mol 
                 
               
             
           
         
       
       
         
           
             P 
             := 
             
               101325 
                
               
                 N 
                 
                   m 
                   2 
                 
               
             
           
         
       
       
         
           
             MV 
             = 
             
               2.447 
               × 
               
                 10 
                 4 
               
                
               
                 
                   cm 
                   3 
                 
                 mol 
               
             
           
         
       
       
         
           
             MV 
             := 
             
               
                 R 
                 · 
                 T 
               
               P 
             
           
         
       
     
         [0026]    This factor can be used to turn cm 3  of oxygen to mol of oxygen at the given temperature and pressure. Therefore we can express the oxygen transmission rate of the container in terms of 
         [0000]    mol/cm 2  sec mmHg 
         [0000]    
       
         
           
             Tx 
             := 
             
               TR 
               MV 
             
           
         
       
       
         
           
             Tx 
             = 
             
               1.538 
               × 
               
                 10 
                 
                   - 
                   13 
                 
               
                
               
                 mol 
                 
                   
                     cm 
                     2 
                   
                   · 
                   s 
                   · 
                   mmHg 
                 
               
             
           
         
       
     
         [0027]    The transmission rate can be multiplied times the ΔpO 2  (based on the assumption) to express the transmission rate in terms of mol/cm 2 ·sec 
         [0000]    
       
         
           
             Tx 
             := 
             
               
                 
                   TR 
                   · 
                   Δ 
                 
                  
                 
                     
                 
                  
                 
                   p 
                    
                   O 
                 
                  
                 
                     
                 
                  
                 2 
               
               MV 
             
           
         
       
       
         
           
             Tx 
             := 
             
               1.261 
               × 
               
                 10 
                 
                   - 
                   11 
                 
               
                
               
                 mol 
                 
                   
                     cm 
                     2 
                   
                   · 
                   sec 
                 
               
             
           
         
       
     
         [0000]    The infusion container can have a surface area of (one side): 
         [0000]      A:=206·cm 2    
         [0000]    The transmission rate of the container then becomes (assuming oxygen transmission occurring throughout top and bottom film): 
         [0000]    
       
         
           
             
               IB 
               OTR 
             
             := 
             
               
                 
                   
                     Tr 
                     · 
                     Δ 
                   
                    
                   
                       
                   
                    
                   p 
                    
                   
                       
                   
                    
                   
                     
                       O 
                        
                       2 
                     
                     · 
                     A 
                   
                 
                 MV 
               
               · 
               2 
             
           
         
       
       
         
           
             Both 
              
             
                 
             
              
             sides 
           
         
       
       
         
           
             
               IB 
               OTR 
             
             = 
             
               5.195 
               × 
               
                 10 
                 
                   - 
                   9 
                 
               
                
               
                 mol 
                 s 
               
             
           
         
       
     
         [0028]    This oxygen transmission rate can be compared to the oxygen consumption rate of islet cells. For a preparation to be “transplantable”, there have to be approximately 4,000-6,000 IEQ/kg. This means (assume a 70 kg average person), to treat diabetes, anywhere from 280,000-420,000 IE need to be transplanted. Assuming a 350,000 IE preparation is placed inside the container. 
         [0000]      IE:=30000( 
         [0000]    One IE islet tissue mass is equivalent to a spherical islet of 150 μm in diameter 
         [0000]    
       
         
           
             r 
             := 
             
               75 
               · 
               
                 10 
                 
                   - 
                   6 
                 
               
               · 
               m 
             
           
         
       
       
         
           
             
               V 
               IE 
             
             := 
             
               
                 4 
                 3 
               
               · 
               π 
               · 
               
                 r 
                 3 
               
             
           
         
       
       
         
           
             
               V 
               IE 
             
             = 
             
               1.767 
               × 
               
                 10 
                 
                   - 
                   6 
                 
               
                
               
                 cm 
                 3 
               
             
           
         
       
     
         [0000]    Therefore the volume of the islet cell preparation would be: 
         [0000]      V prep :V IE IE 
         [0000]      V prep =0.53 cm 3    
         [0029]    From literature, the maximum oxygen consumption rate of islet cells is: 
         [0000]    
       
         
           
             
               IC 
               OCR 
             
             := 
             
               7.2 
               · 
               
                 10 
                 
                   - 
                   8 
                 
               
               · 
               
                 mol 
                 
                   
                     cm 
                     3 
                   
                   · 
                   sec 
                 
               
             
           
         
       
       
         
           
             
               Prep 
               OCR 
             
             = 
             
               3.817 
               × 
               
                 10 
                 
                   - 
                   8 
                 
               
                
               
                 mol 
                 s 
               
             
           
         
       
     
         [0000]    Therefore the total of 300,000 IE would have an O 2  consumption rate of: 
         [0000]      Prep OCR :=IC OCR ·V prep    
         [0030]    The infusion container oxygen transmission rate can be compared to the islet cell preparation oxygen consumption rate, as follows: 
         [0000]    
       
         
           
             
               IB 
               OTR 
             
             = 
             
               5.195 
               × 
               
                 10 
                 
                   - 
                   9 
                 
               
                
               
                 mol 
                 s 
               
             
           
         
       
       
         
           
             
               Prep 
               OCR 
             
             = 
             
               3.817 
               × 
               
                 10 
                 
                   - 
                   8 
                 
               
                
               
                 mol 
                 s 
               
             
           
         
       
     
         [0000]    The preparation consumes oxygen at a higher rate than the container can transmit. Since IB OTR &lt;Prep OCR , it means that if 300,000 IE are placed inside the infusion container, the islet cells will start having hypoxic or anoxic cores and they will die. Accordingly, only about 40,000 IE can be safely placed inside the infusion container for cell culturing. 
         [0031]    A method of infusing cells according to the invention comprises the steps of providing an infusion container, the infusion container having a main body portion with side walls, and top and bottom portions, the bottom portion having an included angle, the included angle being between 30-120 degrees. A liquid solution and cells to be infused into a patient are placed into the container. The cells and solution are allowed to exit the container through an outlet at a vertex of the bottom portion, whereby the cells will directed by the included angle to the outlet. The infusion container  10  may also be used to transport and culture islet cells in the incubator due to its high gas permeability characteristics. 
         [0032]    This invention can be embodied in other forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be had to the following claims rather than the foregoing specification as indicating the scope of the invention.