(177v) High Magnetic Energy Gradient Quadrupole Magnet to Fractionate Oxirase-Deoxygenated Low Iron Label-Less RBCs from Aged Blood Donations

In the United States, around 13.1 million units of blood are needed per year. Although 6.8 million donors give 13.6 million units of blood per year, there is still a great challenge for hospitals to maintain a reliable supply given the 42-day expiration from the date of drawing and match the donor and recipient antigen types (A,B,O). Commercial storage mediums (saline containing adenine, glucose, citrate and phosphate), such as AS-3 have shown to limit cell lysis to 0.8% of cells and have at least 75% of cells be retained in the recipient’s body at the end of 6 weeks. However, little attention is directed towards potential fractionation methods to remove unwanted cell debris and the 25% of cells that are removed from the recipient’s body within the first 24 hours after transfusion.

Split flow lateral transport thin (SPLITT) channel is field that utilizes a thin channel with a high surface area to aspect ratio to separate macromolecules. Thus far, SPLITT devices have been designed to separate objects by utilizing gravitational, electrical, magnetic or acoustic fields and transporting the particles or cells of interest perpendicular to the direction of flow.

Dr. Chalmers’s lab at The Ohio State University has previously published the binary separation performance of a SPLITT Neodymium-Iron-Boron quadrupole magnet with a maximum field of 1.36 T and constant gradient of 286 T/m. A thin cylindrical channel in the center of the magnet has a constant ∇B²and cause paramagnetic cells to migrate radially outwards. this device can separate non stem glioblastoma cells from stem cells and also separate unlabeled, deoxygenated, paramagnetic red blood cells (RBCs) from diamagnetic polystyrene (PS) microspheres with high purity of RBCs in the enriched outlet. The next phase of this research is to separate the iron-rich (and presumably healthier) fraction and iron-poor red blood cells from a 525 mL unit of stored blood. The liquid sample delivery mechanism to this quadrupole magnet and channel has been improved using Fluigent flow sensors and nitrogen pressure controllers to meet this large volume.

Previously, RBCs have been converted from their diamagnetic, oxygenated state to paramagnetic, deoxygenated or met state by two methods. A reaction with sodium nitrite will permanently convert the oxyhemoglobin into methemoglobin. This irreversible method is convenient from an experimental perspective but not feasible for future clinical trials because the met-RBCs lose their ability to carry oxygen. Alternatively, the RBCs may be passed through a nitrogen-supplied hollow fiber deoxgenator that will reversibly convert RBCs into the paramagnetic state. However, the entire system must be purged with nitrogen and sealed from the outside environment. Recent data has shown that oxyrase, an enzyme used in aerobic cell cultures, is able to deoxygenate the carrier fluid as well as the RBCs and is reversible upon transferring to an oxyrase-free carrier.