Morgan Geiger

In the United States, ∼30,000 units of red blood cells (RBCs) are transfused daily to patient recipients. These RBCs are stored in one of multiple variations of media known as additive solutions, all of which contain glucose at concentrations well above physiological levels. Recently, strategies for storage of the RBCs in normoglycemic versions of the additive solutions whose glucose levels are maintained with periodic boluses of glucose were developed, resulting in benefits to the stored RBCs. Here, we describe a system capable of semiautonomous, Wi-Fi-enabled control of glucose delivery using a microperistaltic pump for maintenance of physiological concentrations of glucose in a closed RBC storage system. The RBCs stored in these normoglycemic conditions demonstrated reduced lysis and reduced hemoglobin glycation in comparison to those of the currently used hyperglycemic additive solutions. Furthermore, a novel single cell technique using pressure-induced conductivity mapping showed an improved Young’s modulus for those RBCs stored in normoglycemic solutions. These quantitative measurements of the RBCs’ chemical and physical properties coincide with improvements in cell functionality. Specifically, determinations of RBC-derived ATP using a 3D-printed microfluidic device show an increased release of ATP for RBCs stored in normoglycemic solutions in comparison to hyperglycemic storage, even for cells that were 2 weeks past a storage expiration of 42 days.

Within hyperglycemic blood storage, proteins on the red blood cell (RBC) membrane undergo glycation to form advanced glycated end products (AGEs).

Multiple sclerosis (MS) is an inflammatory disease characterized by damage to the myelin sheath surrounding axons in the central nervous system. While the exact mechanism of this destruction is unknown, excess nitric oxide (NO) and adenosine triphosphate (ATP) have been measured in tissues and fluids obtained from people with MS. Here, incubation of interferon-beta (IFN-β), an MS drug with an unknown mechanism of action, with red blood cells (RBCs) obtained from people with MS provide evidence of a potential hypermetabolic state in the MS RBC that is decreased with IFN-β intervention. Specifically, binding of all three components of an albumin/C-peptide/Zn²⁺ complex to MS RBCs was significantly increased in comparison to control RBCs. For example, the binding of C-peptide to MS RBCs was significantly increased (3.4 ± 0.1 nM) compared to control RBCs (1.6 ± 0.2 nM). However, C-peptide binding to MS RBCs was reduced to a value (1.6 ± 0.3 nM) statistically equal to that of control RBCs in the presence of 2 nM IFN-β. Similar trends were measured for albumin and Zn²⁺ binding to RBCs when in the presence of IFN-β. RBC function was also affected by incubation of cells with IFN-β. Specifically, RBC-derived ATP and measurable membrane GLUT1 were both significantly decreased (56 and 24%, respectively) in the presence of IFN-β. Collectively, our results suggest that IFN-β inhibits albumin binding to the RBC, thereby reducing its ability to deliver ligands such as C-peptide and Zn²⁺ to the cell and normalizing the basal hypermetabolic state.

The pancreatic β‐cells of healthy individuals secrete insulin and C‐peptide, a 31‐amino acid peptide, in a 1:1 mole ratio. However, the β‐cells of people with type 1 diabetes (T1D) are damaged or destroyed. Therefore, exogenous insulin is required for people with T1D to survive. Even with regular insulin treatments, patients develop complications such as retinopathy, neuropathy, and nephropathy. Research from our group demonstrates that C‐peptide increases microvascular blood flow, therefore, it could be a useful tool to decrease these complications due to poor blood flow. However, the unknown C‐peptide receptor and mechanism has been a major roadblock in utilizing C‐peptide as a therapeutic. Utilizing ELISA, our group has demonstrated that approximately 1,800 C‐peptide molecules bind per red blood cell (RBC) in the presence of albumin. Without albumin, there was no detectable C‐peptide binding per RBC. Rather than C‐peptide solely binding to a RBC receptor, we hypothesize that C‐peptide binds to RBCs through an albumin/C‐peptide complex receptor. Bovine serum albumin (BSA) binding per RBC was detectable through an attached gamma decay radiolabel ( ^99m Tc). A binding saturation experiment was conducted to examine the specific binding of BSA to RBCs with and without C‐peptide. The specific binding curves revealed that albumin saturates at 14,021 ± 1489 BSA molecules/RBC with a K _d of 1.07 (±0.19) × 10 ⁻⁷ M and a B _max of 1.94 (±0.06) × 10 ⁻⁸ M, or 13,900 receptor molecules/RBC. Whereas, in the presence of C‐peptide and zinc, albumin saturates at 16,696 ± 1479 BSA molecules/RBC with a K _d of 1.91 (±0.09) × 10 ⁻⁷ M and a B _max of 2.50 (±0.03) × 10 ⁻⁸ M, or 17,900 receptor molecules/RBC. At saturation, the additional 2,700 BSA molecules binding per RBC in the presence of C‐peptide and zinc indicates that an albumin receptor exists on RBCs as well as a separate albumin/C‐peptide complex receptor. Support or Funding Information: NIH