Perfusion Bioreactor With Filtration Systems

Abstract

The disclosure provides a filtration system for a cell culture apparatus and a method of cell culture. The filtration system comprises a bioreactor vessel and two or more alternating tangential flow (ATF) filters connected in parallel. A failure in either filter is detected by an in-line sensor, and an automated response system functions to sequester the malfunctioning filter by stopping the flow of liquid media through the filter. Media flow through the remaining operable filters can be increased so that the rate of perfusion through the bioreactor remains relatively unchanged. Such a system may prevent issues that arise from ATF filter failures in conventional perfusion bioreactors, thereby improving the long-term viability of cell cultures.

What is claimed is: 
     
         1 : A perfusion cell culture apparatus comprising:
 (a) a bioreactor vessel configured to receive liquid media;   (b) a first filtration assembly in fluid communication with the bioreactor vessel, wherein the first filtration assembly comprises:
 (i) a first filtration system; 
 (ii) a first harvest pump connected in series with the first filtration system, wherein the first harvest pump is configured to pump the liquid media from the bioreactor vessel through the first filtration system; and 
 (iii) a sensor, wherein the sensor is configured to interact with the liquid media inside the first filtration assembly; and 
   (c) a second filtration assembly configured to operate in parallel with the first filtration assembly, wherein the second filtration assembly is in fluid communication with the bioreactor vessel, and wherein the second filtration assembly comprises:
 (i) a second filtration system; and 
 (ii) a second harvest pump connected in series with the second filtration system, wherein the second harvest pump is configured to pump the liquid media from the bioreactor vessel through the second filtration system; and 
   (d) a controller, wherein the controller executes operations comprising:
 (i) receiving, from the sensor, information indicative of an operational state of the first filtration system; 
 (ii) determining, based on at least the received information, whether the first filtration system is in an operable state; and 
   (iii) responsive to a determination that the first filtration system is not in an operable state, causing the first harvest pump to stop pumping liquid media through the first filtration system.   
     
     
         2 : The perfusion cell culture apparatus of  claim 1 , wherein at least one of the first filtration system and the second filtration system comprises an alternating tangential flow filter. 
     
     
         3 : The perfusion cell culture apparatus of  claim 1 , wherein at least one of the first filtration system and the second filtration system comprises a tangential flow filter. 
     
     
         4 : The perfusion cell culture apparatus of  claim 1 , wherein each of the first filtration system and the second filtration system comprise a pore size of about 0.1 micron to about 1 micron. 
     
     
         5 : The perfusion cell culture apparatus of  claim 1 , wherein the sensor comprises a pressure sensor, and wherein determining that the first filtration system is not in an operable state comprises determining that a pressure in the first filtration assembly is greater than a threshold value. 
     
     
         6 : The perfusion cell culture apparatus of  claim 1 , wherein the sensor comprises a capacitance sensor. 
     
     
         7 : The perfusion cell culture apparatus of  claim 1 , wherein the sensor comprises an optical sensor. 
     
     
         8 : The perfusion cell culture apparatus of  claim 1 , wherein the controller is further configured to:
 responsive to the determination that the first filtration system is not in an operable state, cause the second harvest pump to increase a flow rate of liquid media through the second filtration system.   
     
     
         9 : The perfusion cell culture apparatus of  claim 8 , wherein causing the second harvest pump to increase the flow of liquid media through the second filtration system comprises approximately doubling the flow rate. 
     
     
         10 : The perfusion cell culture apparatus of  claim 1 , wherein the controller is further configured to:
 responsive to the determination that the first filtration system is not in an operable state, output a notification.   
     
     
         11 : The perfusion cell culture apparatus of  claim 10 , wherein the notification comprises a visual alert or an auditory alert. 
     
     
         12 : The perfusion cell culture apparatus of  claim 1 , further comprising an isolation valve connected in series with the first filtration assembly, wherein the valve is configured to control the flow of liquid media through the first filtration assembly, and wherein the controller is further configured to:
 responsive to the determination that the first filtration system is not in an operable state, close the isolation valve.   
     
     
         13 : The perfusion cell culture apparatus of  claim 1 , wherein the first filtration assembly further comprises a guard filter connected in series with the first filtration system, wherein the guard filter is connected downstream of the first filtration system and the sensor. 
     
     
         14 : The perfusion cell culture apparatus of  claim 13 , wherein the guard filter comprises a pore size of about 0.1 micron to about 1 micron. 
     
     
         15 : The perfusion cell culture apparatus of  claim 1 , further comprising a capture operation configured to collect product from the liquid media, wherein the capture operation is in fluid communication with the bioreactor vessel by way of at least the first filtration assembly. 
     
     
         16 : The perfusion cell culture apparatus of  claim 15 , wherein the capture operation comprises a periodic continuous counter-chromatography skid. 
     
     
         17 : A perfusion cell culture apparatus comprising:
 (a) a bioreactor vessel configured to receive liquid media;   (b) a filtration assembly in fluid communication with the bioreactor vessel, wherein the filtration assembly comprises:
 (i) a filtration system; 
 (ii) a harvest pump connected in series with the filtration system, wherein the harvest pump is configured to pump the liquid media from the bioreactor vessel through the filtration system; and 
 (iii) a sensor, wherein the sensor is configured to interact with the liquid media inside the filtration assembly; and 
   (c) a controller, wherein the controller executes operations comprising:
 (i) receiving, from the sensor, information indicative of an operational state of the filtration system; 
 (ii) determining, based on at least the received information, whether the filtration system is in an operable state; and 
 (iii) responsive to a determination that the filtration system is not in an operable state, causing the harvest pump to stop pumping liquid media through the filtration system. 
   
     
     
         18 : The perfusion cell culture apparatus of  claim 17 , wherein the filtration system comprises an alternating tangential flow filter. 
     
     
         19 : The perfusion cell culture apparatus of  claim 17 , wherein the filtration system comprises a tangential flow filter. 
     
     
         20 : The perfusion cell culture apparatus of  claim 17 , wherein the filtration system comprises a pore size of about 0.1 micron to about 1 micron. 
     
     
         21 : The perfusion cell culture apparatus of  claim 17 , wherein the sensor comprises a pressure sensor, and wherein determining that the filtration system is not in an operable state comprises determining that a pressure in the filtration assembly is greater than a threshold value. 
     
     
         22 : The perfusion cell culture apparatus of  claim 17 , wherein the sensor comprises a capacitance sensor. 
     
     
         23 : The perfusion cell culture apparatus of  claim 17 , wherein the sensor comprises an optical sensor. 
     
     
         24 : The perfusion cell culture apparatus of  claim 17 , wherein the controller is further configured to:
 responsive to the determination that the filtration system is not in an operable state, output a notification.   
     
     
         25 : The perfusion cell culture apparatus of  claim 24 , wherein the notification comprises a visual alert or an auditory alert. 
     
     
         26 : The perfusion cell culture apparatus of  claim 17 , further comprising an isolation valve connected in series with the filtration system, wherein the isolation valve configured to control the flow of liquid media through the filtration assembly, and wherein the controller is further configured to:
 responsive to the determination that the filtration system is not in an operable state, close the isolation valve.   
     
     
         27 : The perfusion cell culture apparatus of  claim 17 , further comprising a guard filter connected in series with the first filtration assembly, wherein the guard filter is connected downstream of the first filtration assembly. 
     
     
         28 : The perfusion cell culture apparatus of  claim 27 , wherein the guard filter comprises a pore size of about 0.1 micron to about 1 micron. 
     
     
         29 : The perfusion cell culture apparatus of  claim 17 , further comprising a capture operation configured to collect product from the liquid media, wherein the capture operation is in fluid communication with the bioreactor vessel by way of at least the filtration assembly such that the harvest pump is configured to pump the liquid media through the filtration system and into the capture operation. 
     
     
         30 : The perfusion cell culture apparatus of  claim 29 , wherein the capture operation comprises a periodic continuous counter-chromatography skid. 
     
     
         31 : The perfusion cell culture apparatus of  claim 29 , wherein the controller is further configured to:
 responsive to the determination that the filtration system is not in an operable state, cause the capture operation to stop collecting product from the liquid media.   
     
     
         32 : The perfusion cell culture apparatus of  claim 17 , wherein the filtration assembly further comprises a waste valve connected in series with the filtration system, wherein the waste valve is configured to divert the liquid media into a waste collection system, and wherein controller is further configured to:
 responsive to the determination that the filtration system is not in an operable state, open the waste valve.   
     
     
         33 : A method of culturing cells, the method comprising:
 (a) at least partially filling a bioreactor vessel with cells and liquid media, wherein the bioreactor vessel is in fluid communication with a first filtration system and a second filtration system connected in parallel with the first filtration system;   (b) pumping liquid media from the bioreactor vessel through the first filtration system using a first harvest pump, wherein the first harvest pump is connected in series with the first filtration system;   (c) pumping liquid media from the bioreactor vessel through the second filtration system using a second harvest pump, wherein the second harvest pump is connected in series with the second filtration system;   (d) receiving, from a sensor configured to interact with the liquid media, information indicative of an operational state of the first filtration system;   (e) determining, based on at least the received information, whether the first filtration system is in an operable state; and   (f) responsive to a determination that the first filtration system is not in an operable state, causing the first harvest pump to stop pumping liquid media through the first filtration system.   
     
     
         34 : The method of  claim 33 , wherein at least one of the first filtration system and the second filtration system comprises an alternating tangential flow filter. 
     
     
         35 : The method of  claim 33 , wherein the sensor comprises a pressure sensor. 
     
     
         36 : The method of  claim 35 , wherein the received information comprises information relating to a pressure of liquid media downstream of the first filtration system. 
     
     
         37 : The method of  claim 35 , wherein the received information comprises information relating to a transmembrane pressure across the first filtration system. 
     
     
         38 : The method of  claim 35 , wherein determining whether the first filtration system is in an operable state comprises determining that a pressure of the liquid media is above a predetermined threshold value. 
     
     
         39 : The method of  claim 33 , wherein pumping liquid media from the bioreactor vessel through the first filtration system comprises pumping liquid media at a first flow rate, wherein pumping liquid media from the bioreactor vessel through the second filtration system comprises pumping liquid media at a second flow rate, and wherein the first flow rate is approximately equal to the second flow rate. 
     
     
         40 : The method of  claim 33 , further comprising:
 responsive to the determination that the first filtration system is not in an operable state, causing the second harvest pump to increase a flow rate of liquid media through the second filtration system.   
     
     
         41 : The method of  claim 40 , wherein causing the second harvest pump to increase a flow rate of liquid media through the second filtration system comprises approximately doubling the flow rate of liquid media through the second filtration system. 
     
     
         42 : The method of  claim 33 , further comprising:
 responsive to a determination that the first filtration system is not in an operable state, outputting a notification.