A Secondary Plasma Device for Collection of Cell-free Nucleic Acids from Blood Plasma During Extracorporeal Blood Processing by Clinical Apheresis Machines

A secondary plasma device (SPD) for use with extracorporeal blood processing systems having an extracorporeal blood tubing circuit wherein the SPD is capable of collecting circulating, cell-free nucleic acids (cfNA) directly from plasma separated from a subject's blood by the extracorporeal blood processing system, the SPD comprising:

• a sterile capsule having:
• an inlet port,
• an outlet port, and
• a filtration/adsorption medium positioned within the capsule a filtration/adsorption medium,
• wherein the inlet port is configured to connect to the tubing circuit at a point distal to a hemoseparator and prior to a plasma collection reservoir or a treated plasma bag, in fluid communication with plasma previously separated from formed elements of subject's blood such that the plasma enters the SPD through the inlet port under pressure and contacts the filtration/adsorption medium prior to exiting through the outlet port,
• wherein the outlet port is configured to connect to a return path portion of the tubing circuit leading back to the subject;
• wherein the filtration/adsorption medium bears a fixed positive charge at physiological pH, thereby configured to function as an anion exchange substrate which captures cfNA from the previously-separated plasma passing through the SPD;
• and
• wherein the filtration/adsorption medium is configured to collect cfNA in quantities of at least 10-fold more than an amount of cfNA recoverable from a 5 ml venipuncture blood draw specimen.