Systems, methods and control laws for cell harvesting
The methods of harvesting cells are provided, wherein the methods comprise introducing a processing material and a source material into a processing loop. The processing loop comprises a processing chamber and a filtering device. The processing material and the source material are circulating through the processing chamber and the filtering device, wherein the processing chamber has a mass; balancing an influx of the processing material into the processing chamber with a permeate flux of the filtering device to maintain the mass of the processing chamber at a constant value; and collecting the cells in a collection chamber. Cell harvesting devices are also provided for processing and harvesting cells using a control law to balance the mass of the processing chamber through the entire process.
1. A method of harvesting cells in an automated fashion from a fluidic material in a processing loop of a cell harvesting device comprising a processing chamber having an overall capacity, a filtering device, and a network of input and output lines each operatively coupled to one of a source pump, a buffer pump, and a permeate pump, said method comprising:
circulating the fluidic material through the processing loop and maintaining the mass of the fluidic material in the processing chamber at a constant value defined as a setpoint, the maintaining step further comprising:
measuring a rate of change of a mass of the processing chamber;
directing the influx of the fluidic material by the source pump or the buffer pump;
estimating a permeate flux of the filtering device by:
q
W
e
(
t
)
=
γ
ω
s
(
t
)
-
d
m
p
(
t
)
d
t
,
or
q
We
(
t
)
=
β
ω
W
(
t
)
where q We (t) is the estimated permeate flux, ω s (t) is the velocity of the source pump, γ is a calibration constant of the source pump, dm p (t)/dt is the rate of change of the mass of the processing chamber, β is a calibration constant of the permeate pump, and ω W (t) is the Velocity of the Permeate Pump;
adjusting, in real time, a flow rate of the source pump or the buffer pump directing the influx based on the estimated permeate flux and a feedback term configured to adjust for errors or variations introduced by one or more system components of the cell harvesting device;
concentrating the cells by increasing permeate flux of the filtering device relative to the influx of the fluidic material into the processing chamber; and
collecting the concentrated cells in a collection chamber,
wherein the fluidic material comprises a source material, a processing material or a combination thereof; and
wherein the flow rate through the source pump or buffer pump directing the influx, q Sd (t), is determined using a control law:
q Sd ( t )= q We ( t )− k{m p ( t )− m pd }
where m pd is the setpoint, k>0 is a feedback gain, q We (t) is the estimated permeate flux, and −k{m p (t)−m pd } is the feedback term.
2. The method of claim 1 , wherein the processing material is selected from a liquid media, a buffer, or a combination thereof.
3. The method of claim 1 , wherein the source material comprises cells in a liquid media or buffer.
4. The method of claim 1 , wherein the source material has a total volume less than or equal to the overall capacity of the processing chamber, the method further comprising a prior step of loading the total volume of the source material to the processing loop.
5. The method of claim 1 , further comprising a prior step of concentrating the source material when the source material has a total volume greater than a desired volume of the processing chamber, and wherein the desired volume of the processing chamber is less than or equal to the overall capacity of the processing chamber.
6. The method of claim 1 , further comprising a prior step of washing the cells by introducing the fluidic material and balancing the influx of the fluidic material into the processing chamber with the permeate flux of the filtering device to maintain the mass of the fluidic material in the processing chamber at the constant value defined as the setpoint.
7. The method of claim 1 , further comprising prior steps of introducing the processing material to the processing loop to rinse the processing loop before or after introducing the source material.
8. The method of claim 1 , wherein the filtering device comprises a hollow fiber filter having a pore diameter in a range from about 0.1 to 1 pm and an inner fiber diameter of 200 to 2000 pm and a fiber count of 4 to 400.
9. The method of claim 1 , wherein the processing loop is further operatively coupled to a source chamber and a buffer chamber and connections to the source chamber and buffer chamber comprise optical sensors to determine presence of a liquid in the connections.
10. The method of claim 9 , further comprising introducing sterile air directly or indirectly to the source chamber, the buffer chamber or a combination of both.
11. The method of claim 1 , wherein the method is independent of an initial sample volume of the fluidic material.
12. The method of claim 11 , wherein the source material comprises cells in a liquid media or buffer.
13. The method of claim 11 , further comprising loading the total mass of the source material to the processing loop prior to circulating the fluidic material, wherein the total mass of the source material is less than or equal to the overall capacity of the processing chamber.
14. The method of claim 11 , further comprising concentrating the source material prior to circulating the fluidic material, when the source material has a total mass greater than the desired mass of the processing chamber.
15. The method of claim 11 , further comprising washing the cells by introducing the fluidic material and balancing the influx of the fluidic material with the permeate flux of the filtering device to maintain the mass of the fluidic material in the processing chamber at the constant value.
16. The method of claim 11 , further comprising a prior step of introducing the processing material to the processing loop to rinse the processing loop before or after introducing the source material.
17. A method of controlling a mass of a fluidic material in a processing chamber of a cell harvesting device in an automated fashion, wherein the cell harvesting device comprises a processing loop comprising a filtering device, the processing chamber, and a network of input and output lines each operatively coupled to one of a source pump, a buffer pump, and a permeate pump, the method comprising:
circulating the fluidic material through the processing loop and maintaining the mass of the processing chamber at a constant value defined as a setpoint, the maintaining step further comprising:
measuring a rate of change of a mass of the processing chamber;
estimating a permeate flux of the filtering device by:
q
W
e
(
t
)
=
γ
ω
s
(
t
)
-
d
m
p
(
t
)
d
t
,
or
q
W
e
(
t
)
=
β
ω
W
(
t
)
where q We (t) is the estimated permeate flux, ω s (t) is the velocity of the source pump, γ is a calibration constant of the source pump, dm p (t)/dt is the rate of change of the mass of the processing chamber, β is a calibration constant of the permeate pump, and ω W (t) is the velocity of the permeate pump; and
setting a flow rate through the source pump or the buffer pump, q Sd (t), which is determined using a control law:
q Sd ( t )= q We ( t )− k{m p ( t )− m pd }
where m pd is the setpoint, k>0 is a feedback gain, q We (t) is the estimated permeate flux, and −k{m p (t)−m pd } is a feedback term.
18. The method of claim 17 , wherein the feedback term minimizes one or more errors in the estimation of the permeate flux, a source or buffer pump flux, an electrical noise, a mechanical noise or combinations thereof.