Systems, methods, and devices for removing circulating tumor cells from blood
Filtering systems, methods, and devices, particularly adapted for apheresis of cellular bodies and more specifically for apheresis of circulating tumor cell bodies (CTCs) employs a cross-flow channel. Systems and methods as well as devices for such a system are described. Embodiments include a cylindrical filter that employs a thin micro-machined porous filter membrane with a regular array of pores and reliably pass blood while trapping CTCs.
1. A method of removing circulating tumor cells (CTCs) from whole blood, the method comprising:
for a first duration, continuously flowing and recirculating whole blood along and parallel to a first side of a filter membrane while withdrawing filtrate that has passed through to a second side of the filter membrane opposite the first side such that red blood cells from the whole blood pass through the filter membrane without a rise in transmembrane pressure exceeding 100 torr over the first duration
wherein the filter membrane has an array of pores, each pore tapering with respect to a thickness direction of the filter membrane from one of the first and second sides to the other of the first and second sides, and
said one of the first and second sides has a greater open area than said other of the first and second sides of the filter membrane.
2. The method of claim 1 , wherein each pore tapers with respect to the thickness direction from the first side to the second side such that the first side has a greater open area than the second side of the filter membrane.
3. The method of claim 1 , wherein each pore tapers with respect to the thickness direction from the second side to the first side such that the second side has a greater open area than the first side of the filter membrane.
4. The method of claim 1 , wherein the array of pores are sized so as to obstruct passage of CTCs therethrough.
5. The method of claim 1 , wherein the continuously flowing whole blood and withdrawing filtrate are such that an average shear rate through the pores of the filter membrane is less than 350 s−1 for circular pores having a minimum diameter in a range of 5.5-7.5 μm.
6. The method of claim 1 , wherein the continuously flowing whole blood and withdrawing filtrate are such that a shear rate at each point across the first side of the filter membrane is between 500 s−1 and 1000 s−1.
7. The method of claim 1 , wherein the continuously flowing whole blood and withdrawing filtrate are such that shear rate at each point across the first side of the filter membrane is greater than an average shear rate through the pores of the filter membrane.
8. The method of claim 1 , wherein the continuously flowing and recirculating is of a volume of 20 ml to 500 ml.
9. The method of claim 1 , further comprising:
collecting retentate that has not passed through the filter membrane.
10. The method of claim 1 , further comprising:
withdrawing the whole blood from a patient during the continuously flowing and recirculating; and
injecting the filtrate into the patient.
11. The method of claim 10 , wherein
the first duration is at least one hour.
12. The method of claim 10 , wherein
the withdrawing the filtrate that has passed through to the second side of the filter membrane is at a flow rate of 5-80 ml/min.
13. The method of claim 10 , wherein
the injecting the filtrate into the patient is at a flow rate of 100 ml/min.
14. The method of claim 10 , wherein
recirculation of the whole blood along and parallel to the first side of the filter membrane is at a flow rate of 1-10 ml/min.
15. The method of claim 1 , wherein
the first duration is at least one hour.
16. The method of claim 1 , wherein
the first duration is between 1 and 4 hours.
17. The method of claim 1 , wherein
the continuously flowing and recirculating is of a volume between 4 and 6 liters.
18. The method of claim 1 , wherein
the continuously flowing and recirculating is of a volume between 8 and 18 liters.
19. The method of claim 1 , wherein
the withdrawing the filtrate that has passed through to the second side of the filter membrane is at a flow rate of 5-80 ml/min.