Research

Blood Banking

Approximately 13.6 million units of whole blood and red blood cells (RBCs) are collected in the United States per year. RBCs are collected into anticoagulants such as citrate phosphate dextrose (CPD), separated, and then stored in an additive solution (AS-1, AS-3, etc.). These additive solutions serve to preserve the viability of the RBCs throughout the 6-week storage period at 2-6 °C. However, during storage, the RBCs undergo irreversible metabolic and physiological damages including diminished adenosine triphosphate (ATP) release, increased oxidative stress, reduced deformability, and other storage lesions. The Spence lab believes that hyperglycemic storage of RBCs contributes to the storage lesion problem. Interestingly, all FDA approved anticoagulants and additive solutions contain glucose concentrations at least 8 times greater than physiological levels. The Spence lab is investigating how normoglycemic RBC storage can aid in alleviating issues regarding storage lesions.

One important area of storage lesion research involves the formation of advanced glycated end-products (AGEs). Our hypothesis is that there are increased amounts of AGE modifications on the RBC membrane surface due to hyperglycemic conditions. There are limited studies showing consistent measurements of the RBC conditions over the entirety of storage time. Our group is utilizing new storage conditions and “feeding” regimes to store blood for 43 days and measure carboxymethyl-lysine (CML), carboxyethyl-lysine (CEL), and reduced glutathione (GSH). We are developing various analytical techniques and utilizing UPLC-MS/MS to separate and quantify these AGEs. Our group has designed, developed, and validated an automated glucose feeding system that maintains sterility and can dispense precise microliter volumes of concentrated glucose into stored RBCs completely autonomously. Using this feeding device with much larger volumes of stored RBCs (>20 mL) in commercially available blood collection bags, we have successfully been able to maintain physiologically relevant levels of glucose (4-6 mM) without any manual intervention.

Liu et al. Ⓒ Lab on a Chip

Multiple Sclerosis

The Spence lab has been investigating the involvement of blood cells in multiple sclerosis (MS) for over 10 years. MS is a chronic inflammatory disease affecting the central nervous system. Some of our first results in this area of research showed that the red blood cells (RBCs) of MS patients release more adenosine triphosphate (ATP) than healthy controls. ATP in the blood stream increases the amount of nitric oxide (NO) released from endothelial cells, which then decreases the integrity of the blood-brain-barrier (BBB), which is knowns to break down in MS.  

Combined with results from our diabetes studies showing that C-peptide increases ATP release from RBCs, we then looked at the binding of C-peptide to RBCs, finding that the RBCs of MS patients bind significantly more C-peptide than those of healthy controls. We are continuing this research and believe that this may lead to a new diagnostic for MS, a disease that is notoriously hard to diagnose. Additionally, we are now starting to investigate the pharmacodynamic properties of the RBC, regarding glucose transport with and without the disease modifying treatment, interferon-β (INF-β). We will also be continuing to look at C-peptide and Zn2+ binding to the RBCs, GLUT1 content, glucose uptake, and lactate production. 

Jacobs et al. Ⓒ ACS Chemical Neuroscience

Type 1 Diabetes

Type 1 diabetes (T1D) is an autoimmune disease afflicting over 8 million people worldwide. It is characterized by the destruction of pancreatic β-cells and subsequent disruption in the production of insulin. While modern insulin pumps, continuous glucose monitors, and fast-acting insulins allow T1D patients to maintain normal glucose levels, myriad chronic complications (e.g., peripheral nerve damage, vision issues, etc.) persist. This suggests the existence of some missing link in the therapies used to treat T1D.

The Spence Lab has spent over a decade investigating one promising candidate for this missing link: C-peptide. This peptide is produced with insulin in the pancreatic β-cells and co-secreted in equimolar amounts. Therefore, just like insulin, individuals with T1D also produce little to no C-peptide. Research by both the Spence Lab and others has elucidated the potential benefits of C-peptide replacement in T1D. Despite this, there have been few attempts at readministering C-peptide as a therapeutic.

Ex vivo, C-peptide has been shown to specifically bind to red blood cells (RBCs). While insulin itself has no effects on RBCs, C-peptide appears to enhance their glucose metabolism, allowing them to produce more adenosine triphosphate (ATP). Downstream, this extra ATP increases nitric oxide (NO) production in blood vessels. Being a potent vasodilator, NO can help improve blood flow throughout the body. Impaired blood flow is a hallmark of T1D and is implicated in the causes of many complications. We believe a C-peptide based therapy may help to restore blood flow in individuals with T1D, thereby helping to mitigate some of the chronic complications that occur even with modern treatments.

Supported by:

National Institute of Neurological Disorders and Stroke National Heart, Lung, and Blood Institute Helmsley Charitable Trust