2012 Grant Recipients/Scholars
Stephanie Eisenbarth, MD, PhD
Yale University, Laboratory Medicine and Internal Medicine
Identifying Innate Immune System Pathways Critical for RBC Alloimmunization
Every unit of allogeneic red blood cells, or RBCs, contains numerous antigens that are foreign to the recipient of the transfusion. Why do some, but not all patients, become alloimmunized after transfusion? Under this NBF grant, Eisenbarth and colleagues will examine the very early stages after transfusion of allogeneic RBCs, seeking to "nail down the critical antigen-presenting cell that dictates when you get an alloimmune T-cell response to RBCs," she said.
"What I would like to do is identify that critical step that dictates what happens subsequently — Do you have an alloimmune response or not? — to see whether we can intervene in that process," said Eisenbarth.
Preliminary work in her laboratory has investigated the role of a NOD-like receptor, called Nlrp10, in the generation of alloantibodies to RBC antigens. The proposed work will further examine the role of this receptor using an animal model.
"Animal models can be powerful in terms of what kinds of questions you can address in transfusion medicine," Eisenbarth said. "This project is focused on one particular pattern recognition receptor, and a genetically modified knockout mouse for that molecule was only made in the last three years. So the ability to do this work is due to a confluence of having good transfusion models with the right knockouts to address this question."
Michael J. Nemeth, PhD
Roswell Park Cancer Institute, Department of Medicine
Improving Bone Marrow Transplantation Through Targeting Hematopoietic Stem Cell Quiescence
An ongoing challenge in the field of bone marrow transplantation, or BMT, is managing the toxic side effects of the conditioning regimen — the myeloablative drugs or radiation — given to prepare the host tissue for transplant. But reducing the dose of conditioning agents can result in inefficient engraftment of donor hematopoietic stem cells, or HSCs. With his NBF grant, Nemeth hopes to make the clinical application of BMT more tolerable for patients and increase the patient base that can benefit from the therapy.
"We're looking at some of the basic biology of the stem cell to try to figure out whether there are better ways to prepare the host for receiving a BMT that don't rely on low doses of nonspecific drugs, but instead target the stem cell itself," he said.
Building on previous in vitro work, Nemeth and colleagues will test the hypothesis that inhibiting the Ryk receptor inhibits HSC quiescence in vivo and allows engraftment of donor HSCs without myeloablation.
"No one has shown how this receptor works in stem cell biology," he said. "One part of the grant will be figuring that out, and a second part will be sort of a preclinical approach, to see whether we can target it as well."
Anand Padmanabhan, MD, PhD
BloodCenter of Wisconsin
Role of IgA and IgM Immunoglobulins in Heparin-Induced Thrombocytopenia and Thrombosis
Heparin-induced thrombocytopenia and thrombosis, or HIT, is a serious side effect of heparin administration that occurs in a small percentage of patients exposed to this widely used anticoagulant. How this immunologic response is triggered is not fully understood. Padmanabhan and colleagues aim to study the mechanism by which it occurs.
Blood samples from patients who experience HIT can contain several classes of antibodies, including immunoglobulin, or Ig, G, IgA and IgM. Current diagnostic tests focus on IgG, under the belief that IgA and IgM are clinically insignificant in HIT, explained Padmanabhan.
"We are a major referral center for HIT testing. Rroutinely we get samples that are strongly positive for IgA, and may or may not be positive for IgG, and the clinical story of these patients is consistent with HIT," he said. "My research seeks to understand if indeed these other types of antibodies are important. If they are, this has huge diagnostic implications."
In the proposed research, the investigators will evaluate the ability of IgA and IgM antibodies in promoting clotting by activation of platelets and monocytes and compare the ability of the three types of HIT antibodies, IgG, IgA and IgM, to promote heparin-dependent clearance of human platelets in an animal model, the NOD/SCID mouse.
"The hope is that this work will lead to better diagnostic testing, correctly diagnosing who has HIT and who doesn't, so that heparin is appropriately withheld in those with HIT," said Padmanabhan. "Also, this could open the door for different ways to think about treatment."
Tracey L. Papenfuss, DVM, MS, PhD
The Ohio State University, Department of Veterinary Biosciences
Development of Myeloid Derived Suppressor Cell Therapy for the Treatment of Inflammatory Disease
Inflammation helps to maintain and restore the body's homeostasis, but dysregulated, chronic inflammation contributes to the development and progression of many diseases. Under this NBF grant, Papenfuss and colleagues propose to generate a certain type of immunoregulatory immune cells in vitro to investigate their use in treating inflammatory disease.
"My laboratory is looking at how to induce a specific population of regulatory myeloid cells, termed myeloid-derived suppressor cells, or MDSC, in order to treat an inflammatory disease model of multiple sclerosis," Papenfuss said.
MDSCs are a recently described immune cell population best known for their ability to suppress immune function in cancer patients. Less understood is whether these cells can be used to treat inflammatory disease. The investigators have developed a method to generate large quantities of MDSCs using the hormone retinoic acid, and they will evaluate the anti-inflammatory abilities of cell therapy using retinoic acid-generated MDSC cell therapy in an in vivo inflammatory autoimmune disease model. They will also investigate the mechanisms by which these MDSCs inhibit helper T-cell responses.
Research into the potential therapeutic applications of regulatory myeloid cells is "only in its infancy," said Papenfuss. "Our work will provide a useful system and method for generating large numbers of the regulatory myeloid cell population of MDSC and demonstrate the potential utility of regulatory myeloid cell therapy to treat numerous inflammatory diseases."
Henrique Veiga-Fernandes, DVM, PhD
Instituto de Medicina Molecular, Immunobiology Unit; Lisbon, Portugal
Modulation of RET Signaling in Hematopoietic Stem Cell Transplantation
Challenges in HSC transplantation include poor engraftment efficiency and low yield of HSCs from sources such as cord blood. Therefore, finding new biological targets that promote HSC engraftment or sustained HSC survival is an important goal in transfusion medicine and cellular therapy. Veiga-Fernandes and colleagues hypothesize that the neurotrophin receptor RET is critical to HSC function, and they propose to study its effect in mouse and human cells.
"We have done some preliminary experiments demonstrating that if we genetically turn on that molecule in HSCs, we can get improved transplantation and improved survival of HSCs in mice," he said. "We now want to explore specifically how to activate that signal pathway in HSCs, aiming to improve either the efficiency of transplantation of those cells or the expansion in vitro of those cells."
The researchers were surprised to find that neurotrophins may have an effect on or be produced by HSCs, said Veiga-Fernandes.
"This is a family of molecules that hasn't been explored at all in the field of HSCs, and it seems to have a critical function for survival of HSCs, at least in mouse models. It remains to be determined whether that is the case in human models," he said.
A challenge in the proposed work will be working with the human cells. "Because we are dealing with small populations of cells, with readouts that are technically difficult, it will be a big challenge to control for the heterogeneity from donor to donor," he said.
Jianhua Yu, PhD
Ohio State University, Wexner Medical Center
Preclinical Studies of the Combination of Recombinant Human FLT3 Ligand and AMD3100 to Mobilize Allogeneic Blood Cell Grafts for Transplantation
Peripheral blood stem cell mobilization by granulocyte colony stimulating factor is the most common method used to collect donor HSCs for transplantation. However, this method of mobilizing HSCs has been associated with a high risk of chronic graft-versus-host disease, or GVHD, and, in young patients and those with severe aplastic anemia, worse survival. Yu and colleagues propose to investigate the use of two clinical-grade drugs, Flt3 ligand and plerixafor, to mobilize a more favorable balance of HSC, conventional T-cells, regulatory T-cells and natural killer, or NK, cells. They theorize that this approach will optimize favorable graft-versus-leukemia effects while mitigating deleterious GVHD reactions.
"The purpose of this study is to reduce GVHD and leukemia relapse, the two critical complications during HSC transplantation, thereby improving leukemia treatment," said Yu.
The two drugs have been studied separately, but not together, he said. Previous work at the Wexner Medical Center and other institutes has shown that Flt3 ligand increases NK cells and that plerixafor can suppress GVHD and quickly mobilize HSCs.
"Our preliminary data show that this combination can mobilize cells with a higher percentage of stem cells and more NK cells in the peripheral blood, while CD8 T-cells were decreased," said Yu. "We therefore hypothesize that the two-drug combination will promote fast engraftment, suppression of GVHD and prevention of leukemia relapse."
NBF grants are funded through the generous contributions of NBF Council on Research & Development (CORD) members:
American Red Cross
Blood Systems/United Blood Services
New York Blood Center
1985 - 2012 Scientific Research Grant Recipients/Scholars