Sickle cell therapeutic treatment

A sickle cell therapeutic treatment is provided by means of continuous flow red blood cell carbamylation. In a substantially continuous process, whole blood is removed from a patient and is directed to a red cell separator chamber of a seal-less type centrifuge. The whole blood is centrifuged and the red blood cells to be treated are removed from the red cell separation chamber and are directed to a reaction chamber. An anti-sickle agent, such as cyanate solution, is introduced into the reaction chamber and is mixed with the red blood cells to be treated. The mixed anti-sickle agent and red blood cells are transferred to a wash chamber in the centrifuge where they are washed, by centrifugation, and the washed, treated red blood cells are combined with the plasma that was separated in the red cell separation chamber and the combination is returned to the patient.

BACKGROUND OF THE INVENTION 
This invention concerns a novel system for treating sickle cell disease 
and, more particularly, a substantially continuous system for 
carbamylating red blood cells to therapeutically treat sickle cell 
disease. 
Sickle cell disease concerns a human blood disorder in which the red blood 
cells contain hemoglobin S, which is an abnormal hemoglobin. On occasion, 
the hemoglobin S cells change from the normal disc shape to a crescent 
shape, and these cells are designated sickle cells. There are presently 
certain known methods of treating sickle cell disease with an 
extracorporeal carbamylation method. 
One prior art method of treating sickle cell disease by carbamylating red 
blood cells utilizes a batch process by which a predetermined amount of 
whole blood is removed from the patient, the whole blood is treated and 
thereafter the treated blood is reinfused. This prior art method requires 
the steps of erythropheresing the patient with blood bags, separating the 
red blood cells with centrifugation and carbamylating the cells by short 
incubation with an anti-sickle agent, such as a cyanate solution, washing 
the otherwise toxic carbamylating agent with manual centrifugation and 
decanting, reconstituting the carbamylated cells with plasma, reinfusing 
the reconstitate, and repeating this batch process as many times as 
possible during one day. 
In the batch processing described in U.S. Pat. No. 3,833,724, a unit of the 
patient's blood is removed into a bag containing acid-citrate-dextrose 
(ACD). The blood is then centrifuged and the plasma is returned to the 
patient. The recovered red cells are incubated with an aqueous solution of 
sodium cyanate (0.001 M to 0.01 M) at about 37.degree. C. for about one to 
two hours. The cells are then washed to remove any unreacted cyanate and 
the resulting carbamylated cells are then reintroduced into the patient. 
The aforesaid type of batch treatment process is labor intensive and time 
consuming. Typically, no more than three patients can be treated in one 
day at one blood treatment center. Because of the batch nature of the 
process, patients are treated relatively inefficiently, typically having 
less than 20 percent of their cells carbamylated. The process is merely a 
treatment that prevents sickling of those cells which have been 
carbamylated. As these cells age and deteriorate, they are replaced by new 
sickle-able cells which must then be likewise treated. 
We have discovered that a continuous sickle cell treatment process would 
increase the efficiency of treating sickle cell disease. While in the 
batch processing extracorporeal blood volumes must be kept low, this 
problem is overcome using continuous processing. 
It is, therefore, an object of the present invention to provide a novel 
system for treating sickle cell disease utilizing continuous flow red 
blood cell carbamylation. 
Another object of the present invention is to provide a red blood cell 
carbamylation process that is simple in operation and does not require the 
removal of substantial extracorporeal blood volumes. 
A further object of the present invention is to provide a continuously 
flowing centrifugal system to partition red blood cells to be treated from 
the whole blood of a sickle cell patient, and to treat the red blood cells 
with anti-sickle agents, to wash these agents from the red blood cells and 
to finally return the red blood cells to the patient. 
Other objects and advantages of the present invention will become apparent 
as the description proceeds. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a process is provided for 
treating sickle cell disease including the step of withdrawing whole blood 
substantially continuously from a patient. During the withdrawal of the 
whole blood, the whole blood is directed to a red cell separator, red 
blood cells to be treated are separated from the plasma by centrifugation, 
the centrifuged, separated red blood cells to be treated are directed to a 
reaction chamber, an anti-sickle agent is introduced into the reaction 
chamber and is mixed with the red blood cells to be treated, the mixture 
is directed to a wash chamber, a washing medium is introduced into the 
wash chamber and the mixture is washed by centrifugation, and the washed, 
treated red blood cells are removed from the centrifuge and are directed 
back to the patient. 
In the illustrative embodiment, the plasma is separated from the red blood 
cells and the plasma is directed back to the patient. The red blood cells 
to be treated are also separated in the red cell separator from the white 
cells and platelets. 
In the illustrative embodiment of the present invention, a seal-less 
centrifuge is provided having a red cell separation chamber and a separate 
wash chamber. Means are provided for pumping a patient's whole blood to 
the red cell separation chamber. A plasma removal conduit is coupled to 
the red cell separation chamber and a red blood cell removal conduit is 
also coupled to the red cell separation chamber. Means are provided for 
pumping the red blood cells in the red blood cell removal conduit to a 
reaction chamber. 
Means are provided for introducing an anti-sickle agent to the reaction 
chamber whereby the anti-sickle agent and the red blood cells are mixed in 
the reaction chamber. Means are provided for removing the mixture from the 
reaction chamber and for pumping the mixture into a wash chamber. A 
washing medium is introduced to the wash chamber and a conduit is provided 
for removing the washed, treated red blood cells and for directing the 
washed and treated red blood cells back to the patient. 
In the illustrative embodiment, the red blood cell removal conduit is 
coupled to a location within the red cell separation chamber that 
substantially prevents removal of white cells and platelets. To this end, 
the red cell removal conduit is located within the red cell separation 
chamber at a position generally below the location at which the white 
cells and platelets are collected during centrifugation. 
A more detailed explanation of the invention is provided in the following 
description and claims, and is illustrated in the accompanying drawings.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT 
Referring to the drawings, a sickle cell therapeutic treatment system is 
shown therein in which whole blood is withdrawn from a patient 1 via 
flexible plastic tubing 2 which is coupled to the vein of the patient by 
means of a conventional needle assembly 3. The blood is pumped by a 
peristaltic pump 4 which operates on tubing 5 and which also pumps an 
anti-coagulant solution in tubing 6 from a source 7 of anti-coagulant 
solution. As illustrated, the anti-coagulant solution is pumped to mix 
with the whole blood in tubing 5. 
In the drawings, the portion within the dashed lines represents the portion 
within the rotor assembly 8 of a centrifuge. Thus the centrifuge rotor 
assembly 8 is multi-chambered and includes a red cell separation chamber 
9, a reaction chamber 10 and a wash chamber 11. Each of these chambers may 
comprise a flexible bag or a rigid container having inlet and outlet ports 
which are strategically located to enable the receipt of or removal of 
predetermined fractions of the centrifugate. 
Thus the whole blood, with anti-coagulant added, which is flowing in line 5 
is coupled to a lower portion 12, preferably the bottom port of red cell 
separation chamber or bag 9. Side ports 13 and 14 of chamber or bag 9 are 
coupled to outlet tubing 15 which removes the red blood cells to be 
treated while an upper port 16 is coupled to tubing 17 which carries the 
plasma. 
During centrifugation, the plasma, which is the least dense, will be 
located adjacent the top of chamber 9, and the red blood cells that are 
most desired to be carbamylated will be adjacent the bottom of chamber 9 
because they have a higher specific gravity than those red blood cells in 
which carbamylation is undesired, such as the red blood cells that include 
granulocytes, lymphocytes, reticulocytes, and platelets. If desired, 
tubing 17 could be located with respect to chamber 9 so that tubing 17 
would collect and transport the plasma and less dense red blood cells, 
including the red blood cells having granulocytes, lymphocytes, 
reticulocytes and platelets, and the white blood cells. 
The red blood cells to be treated flow in tubing 15 and are pumped by 
peristaltic pump 18 to reaction chamber 10. A solution of anti-sickle 
agent 19 is pumped via line 20 by peristaltic pump 18 and is mixed with 
the red blood cells to be treated. 
In the illustrative embodiment, reaction chamber 10 is located within 
centrifuge rotor assembly 8 so that the anti-sickle agent and the red 
blood cells to be treated are mixed through centrifugation. The mixing is 
enhanced by introducing the cells and anti-sickle agent at the bottom 21 
of reaction chamber 10, which reaction chamber could comprise a solution 
bag or rigid container. The anti-sickle agent or the carbamylating agent 
may be a cyanate solution or any other type of anti-sickle agent that is 
known in the art, with it being understood that the specific type of 
carbamylating agent is not considered as part of the invention. 
The waste is withdrawn via tubing 22 which is coupled at an upper portion 
23 of reaction chamber 10, while the treated red blood cells are withdrawn 
via tubing 24 that is connected to ports 25, 26, which are at a lower 
level of the reaction chamber 10. 
A peristaltic pump 27 pumps the treated red blood cells in tubing 24 to a 
lower port 28 of wash chamber 11. A wash solution 29 is pumped by 
peristaltic pump 27 via tubing 30 to mix in line 24 and thus mix with the 
treated red blood cells. The waste is withdrawn from an upper port 31 of 
chamber 11 via tubing 32 while the washed, treated red blood cells are 
withdrawn from middle level ports 33, 34 via tubing 35. The washed, 
anti-sickle agent-treated red blood cells which flow in tubing 35 meet, at 
junction 36, the plasma that is flowing in tubing 17, for return to the 
patient via tubing 37 and needle assembly 38. 
Referring to FIG. 2, the sickle cell treatment system of the invention may 
be utilized in conjunction with a seal-less centrifugation apparatus such 
as that described in U.S. Pat. No. 4,113,173 or as described in the 
co-pending application of Herbert M. Cullis and James H. De Vries, Ser. 
No. 843,296, filed Oct. 18, 1977, and assigned to the present assignee. It 
is preferred that a seal-less centrifuge be used to alleviate leakage and 
contamination problems. 
The centrifugation apparatus of FIG. 2 includes a rotor drive assembly 60 
to which a rotor assembly or carriage 61 is journaled by means of a hollow 
support shaft 62. The rotor drive assembly 60 is itself journaled to a 
stationary hub assembly 63 by means of a vertical drive shaft 64. A guide 
sleeve 65 is mounted on the rotor drive assembly. 
The red cell separation chamber 9 and the wash chamber 11 of the treatment 
system are seated on the rotor assembly 61. If desired, reaction chamber 
10 could also be seated on rotor assembly 61. Fluid communication is 
established between the chambers, which rotate with the rotor assembly, 
and the non-rotating portions of the processing system, by means of the 
umbilical cable 42 which is seen to extend from a central location along 
the axis of rotation of the rotor downwardly through the center of the 
drive shaft 62, radially outwardly through guide sleeve 65, and upwardly 
to a fixed axially aligned position established by a support arm 67. 
Umbilical cable 42 includes plasma removal conduit 17, red cell removal 
conduit 15, waste removal conduits 22 and 32, and conduits 24 and 35. 
The routing of the umbilical cable 42, together with the rotor assembly 61 
and rotor drive assembly 60 being driven in the same direction with a 
speed ratio of 2:1, establishes fluid communication with chambers 9 and 11 
without the cable becoming twisted. Instead, the umbilical cable is 
subjected only to flexing, or repeated partial twists about its axis 
through angles not in excess of 180 degrees, as the rotor assembly 61 
rotates. 
A 2:1 speed ratio is obtained between the rotor and rotor drive assembly by 
means of two pairs of idler pulleys 68 mounted on rotor drive assembly 60 
and a drive belt 69. The drive belt is routed over these pulleys and into 
engagement with a stationary ring-type pulley 70 mounted on hub 63 at one 
end, and a rotor drive pulley 71 carried on the bottom end of the rotor 
drive shaft 62 at its other end. As the rotor drive assembly 60 is rotated 
clockwise by means of a motor 72 and drive belt 73 driving drive shaft 64, 
drive belt 69 establishes a clockwise rotation of rotor assembly 61. 
Assuming that stationary pulley 70 and rotor drive pulley 71 have the same 
diameter, the rotational speed of rotor assembly 61 will be exactly twice 
that of rotor 60 by reason of the combined effect of the direct 1:1 drive 
relationship of pulleys 70 and 71 and the planetary motion of pulleys 68 
about the axis of rotation of rotor drive assembly 61. 
The sickle cell treatment system of the invention may be manufactured as a 
single disposable unit in which umbilical cable 42 is included. To install 
this system in the apparatus, the free end of the umbilical cable may be 
threaded downwardly from support arm 67 through the hollow support sleeve 
65 and then upwardly through the hollow rotor support shaft 62. The other 
end of the cable is then connected to the other components of the system. 
Since the system remains sealed when installed, all possibility of 
compromising the sterility of the system is avoided. After use, the entire 
flow system may be removed from the apparatus and disposed of. 
The processing can be operated continuously with the maximum patient time 
being approximately four hours at a process rate of 30 ml per minute. 
Using this process, the cells may be subjected to approximately two 
atmospheres of pressure at approximately 20.degree. to 25.degree. C. Under 
these conditions, the solubility of oxygen in fluids is substantial, which 
is believed to inhibit sickling during treatment. Carbamylation may be 
performed in chamber or bag 10 with the centrifuge rotor assembly 8 in an 
elutriation process with the carbamylating agent being the elutrient. 
Incubation times may be relatively short, with approximately two minutes 
residence time within the chamber being adequate. 
Although an illustrative embodiment of the invention has been shown and 
described, it is to be understood that various modifications and 
substitutions may be made by those skilled in the art without departing 
from the novel spirit and scope of the present invention.