High efficiency microfluidic purification of stem cells to improve transplants

A method for purifying leukocytes for therapeutic use from a sample comprising leukocytes and erythrocytes, the method comprising:

• (a) providing a sample comprising erythrocytes and leukocytes, wherein the sample volume is at least 100 ml and less than 300 mL;
• (b) separating said erythrocytes from said leukocytes by deterministic lateral displacement on a microfluidic device, wherein said microfluidic device comprises posts with one or more non-rounded vertices, wherein said posts are organized into an array of rows and columns such that adjacent posts form a gap through which fluid may pass and adjacent columns are offset from one another to form an array direction that differs from the flow direction of the device by a tilt angle (c) and wherein the array has a critical diameter such that, when said sample is flowed through the device, leukocytes travel in the array direction and erythrocytes travel in the direction of fluid flow;
• (c) collecting a product from said microfluidic device, wherein:
• i) the product comprises leukocytes;
• ii) relative to the sample applied to the device, the product is depleted in erythrocytes;
• and iii) the product comprises less than 10% erythrocytes;
• wherein the device is operated at a flow rate of at least 100 ml per hour and a linear flow rate of 5 mm/sec to 150 mm/sec, and wherein greater than 90% of the leukocytes collected in the product are viable.