2013 Grant Recipients/Scholars
Stella T. Chou, MD
The Children's Hospital of Philadelphia
Perelman School of Medicine at the University of Pennsylvania
"Red Blood Cell Generation From Human Induced Pluripotent Stem Cells: A New Tool for Transfusion Medicine"
Although most red blood cell, or RBC, transfusions are uneventful, alloimmunization remains a significant complication, particularly for patients with sickle cell disease. These patients often form antibodies for which reagent RBCs are not widely available, making antibody identification a challenge. Testing for these antibodies may require sending samples to a reference immunohematology laboratory. To ensure that such testing is more widely available, Stella T. Chou, MD, and colleagues are proposing to use donor-derived induced pluripotent stem cells, or iPSCs, to produce panels of customized iPSC-derived reagent RBCs.
Chou was first author of a paper in "Blood" this year, showing that patients with sickle cell disease have a high degree of Rh variation, which contributes to an increased risk of Rh alloimmunization.
"The goal of this project, first, as proof of principle, is to see if we can generate RBCs that either lack high-prevalence Rh antigens or express variant Rh, and then to test whether we can use these RBCs as blood bank reagents," she said.
If successful, the proposed work could make testing for these Rh variants more widely accessible to blood banks, improving transfusion safety.
"Currently, the reference labs depend heavily on rare donors for these types of variants," Chou said. "If we are successful in creating these cell lines, which can be grown and expanded in labs, this could provide a virtually limitless supply."
William Janssen, MD
National Jewish Health, University of Colorado Denver
"Degradation of the Pulmonary Endothelial Glycocalyx in Transfusion-Related Acute Lung Injury"
Blood vessels are lined with a kind of "sugar coating" called the glycocalyx, said William Janssen, MD. The aim of his research under the NBF grant is to test the hypothesis that degradation of this pulmonary endothelial glycocalyx is required for the development of transfusion-related acute lung injury, or TRALI. He and his coworkers have developed a "two-hit" mouse model of TRALI to test this hypothesis.
"We think that during TRALI there is a first 'hit' from systemic insult that leads to degradation of the glycocalyx," he said. "When that initial insult happens, the glycocalyx is shed and the endothelial cells are no longer covered by this protective layer. Then when the endothelial cells are exposed, they can become a site of injury upon a second 'hit,' the exposure to blood products during transfusion."
The researchers propose to use intravital microscopy, a technique that enables individuals to see the pulmonary microvasculature and its associated glycocalyx in vivo in real time. This will allow them to assess the role of the glycocalyx in TRALI development.
"The nice thing about this new imaging technology of intravital microscopy is that it will allow us to study the function of this fragile glycocalyx barrier in a living organism, whereas a more common study technique such as histology would damage the glycocalyx," Janssen said.
If, as hypothesized, the shedding of the glycocalyx constitutes a first hit in TRALI, then components of the glycocalyx circulating in the blood could serve as a biomarker for risk, he explained.
George J. Murphy, PhD
Boston University Medical Center, Center for Regenerative Medicine
"Pluripotent Stem Cells in the Modeling of Blood Disease and the Development of Potentially Transfusable Human Red Blood Cells and Platelets"
With this NBF grant, George J. Murphy, PhD, and colleagues are hoping to turn a historical bad guy into an agent for good. Murphy was senior author of a paper in "Blood" this year describing a surprising new role for a notorious cell-surface receptor that has primarily been studied for its role in environmental chemical-induced toxicity — the aryl hydrocarbon receptor, or AhR. The researchers found that this receptor also plays an important role in hematopoiesis; under their NBF grant, they propose to explore the possibility of manipulating the receptor to generate healthy or disease-specific progenitor cells.
"Many labs can make iPSCs. What this grant proposes is to use these cells to make blood, and historically that has been very difficult to do," Murphy said. "We have found that if we modulate this AhR we can make many more differentiated progenitor cells from these iPSCs, a great increase in the number of cells from what has been done before."
The researchers hope to create iPSCs from patients with various blood diseases to help study the ways that these diseases develop. They also aim to make healthy blood cells.
"We are using bioreactors in which we can grow large numbers of cells," Murphy said. "At the same time we are working on trying to get the cells to fully mature to an end-stage RBC, that beautiful biconcave cell."
If successful, he hopes the work will advance toward the ultimate goal of generating Good Manufacturing Practice-grade RBCs and platelets.
Robert B. Neuman, MD
Fellow, Cardiovascular Disease Clinical Research Track
Emory University School of Medicine
"Physiologic Effects of RBC Storage in Chronic Transfusion Recipients: Vasoreactivity, Exercise Capacity, and Oxygen Consumption"
Transfusion of red blood cells (RBC) is a common intervention aimed at preventing mortality and morbidity in anemic and bleeding patients. However, older stored RBC units, termed storage-aged RBCs (saRBCs) may have functional defects that impair their efficacy and could actually harm transfused patients. Among the saRBC storage changes of interest are those that reduce nitric oxide (NO) bioavailability. NO is a crucial vasodilator in the microcirculation, the vascular circuit that increases blood flow (and O2 delivery) to local tissues with high oxygen demands. We have found that saRBCs (>21 days old) exert significant vasoinhibitory effects: saRBCs but not fresh RBCs (stored < 10 days) significantly inhibit nitric oxide (NO)-mediated vasodilation in hospitalized transfused patients. These adverse effects of saRBCs are consistent with effects we observed using in vitro aortic ring assays. We hypothesize that an interplay between NO deficient saRBCs and patients with underlying endothelial dysfunction leads to insufficient NO bioavailability which results in poor tissue perfusion and adverse effects. The proposed studies will test our hypothesis that saRBCs (>21 days of storage), but not fresh RBCs (< 10 days of storage), will impair NO-mediated vasodilation and result in reduced exercise tolerance and oxygen consumption in an ambulatory transfusion-dependent adult population.
Sean Stowell, MD, PhD
Emory University School of Medicine
"Characterization of Immunity and Tolerance Following RBC Transfusion"
Patients who receive repeat transfusions often develop RBC-specific alloantibodies that decrease the therapeutic efficacy of transfusions and limit the availability of compatible RBCs. Unlike with organ transplantation, however, no immune suppression methods are available to prevent RBC alloimmunization. Sean Stowell, MD, PhD, and colleagues have developed a mouse model to examine the induction and consequences of RBC alloimmunization.
The researchers previously have observed that the density of the Kell antigen on the surface of RBCs affects alloimmunization, and that RBCs with low or high densities of Kell antigens can induce tolerance in Kell-negative recipients. Using the mouse model, they propose to examine factors responsible for the development of tolerance after transfusion with low-density and high-density Kell antigens. The group also will examine how marginal zone B cells mediate RBC alloimmunization.
"Although phenotype-matching protocols reduce rates of RBC alloimmunization, patients who undergo chronic transfusion therapy continue to develop RBC alloantibodies. Our studies are aimed at trying to understand, at a mechanistic level, what factors regulate RBC alloimmunization with the ultimate goal of identifying prophylactic agents designed to actively prevent RBC alloimmunization," Stowell said. "If we can understand mechanistically how patients make RBC alloantibodies, then hopefully we can discover unique targets that we can favorably modulate to prevent this from occurring."
NBF grants are funded through the generous contributions of the NBF Council on Research & Development (CORD) members:
American Red Cross
Fenwal, A Fresenius Kabi Company
New York Blood Center
1985 - 2013 Scientific Research Grant Recipients/Scholars