Cynthia E. Dunbar, M.D.

Senior Investigator

Molecular Hematopoiesis Section

NHLBI

Building 10, Room 4-5132
10 Center Drive
Bethesda, MD 20814

301-496-5093

dunbarc@nhlbi.nih.gov

Research Topics

Hematopoiesis—the development and differentiation of stem cells into multiple types of blood cells—occurs throughout life, and its dysfunction is associated with low blood counts or leukemia. Dr. Dunbar’s research focuses on understanding the process of hematopoiesis in vivo, as well as on optimizing and improving the safety of gene transfer into primary hematopoietic cells for therapeutic purposes. Her goals are synergistic: insight into the control of hematopoiesis is required to successfully manipulate and genetically modify hematopoietic cells; conversely, genetic marking of hematopoietic stem and progenitor cells has provided novel insights into lineage relationships, stem cell dynamics, and stem cell numbers in vivo that are applicable to gene therapy, stem cell transplantation, and other clinical interventions.

For over twenty-five years, Dr. Dunbar’s laboratory has had the privilege of utilizing a rhesus macaque transplantation model. Her facility is one of only a handful worldwide able to successfully support non-human primates through stem cell transplantation. This model provides unique and highly relevant insights into hematopoiesis and has resulted in successful optimization of gene and cell therapy approaches later translated successfully into human clinical trials. Her studies also encompass informative in vitro, murine, and human xenograft models.

Dr. Dunbar and her colleagues have mapped the number, frequency, and output of individual stem and progenitor cells over time in the rhesus macaque model, via a quantitative, informative and high-throughput genetic barcoding approach. Novel and biologically/clinical relevant findings regarding clonal stability, frequency, lifespan, geographic location, and lineage bias have been generated utilizing this approach.  The approach has offered direct evidence for peripheral expansion and long-term persistence of natural killer cell clones, beginning to elucidate a mechanism for NK cell memory.

In addition, Dr. Dunbar’s team has developed a number of new gene therapy vector systems for high efficiency transduction of monkey and human hematopoietic stem and progenitor cells. The growing evidence that integrating gene therapy vectors can activate adjacent proto-oncogenes, both from human clinical trials and from primate studies in Dr. Dunbar’s laboratory, has spurred intense investigation into the process of vector integration into the genome. Dr. Dunbar has been a leader in this research for the past fifteen years. Her laboratory continues to optimize vector and transduction approaches that can retain the therapeutic potential of stem cell gene therapies while avoiding genotoxic events. Most recently, her laboratory has focused on developing, testing and optimizing gene-editing technologies such as CRISPR/Cas9 to engineer hematopoietic stem and progenitor cells and create relevant disease models in rhesus macaques.

Dr. Dunbar’s laboratory has also developed induced pluripotent stem cells (iPSC) in the rhesus model, and is investigating whether their use in regenerative medicine approaches can be made safe and effective. Her group developed the first non-human primate autologous teratoma model, and demonstrated functional bone regeneration in vivo from rhesus macaque iPSC.  Active research directions include testing of in vivo cardiac and hepatic regeneration from rhesus macaque iPSC.

Dr. Dunbar’s recent clinical work has focused on strategies to expand human hematopoietic stem cells in vivo, most notably in a trial of the stem cell stimulatory cytokine analog eltrombopag for the treatment of patients with severe refractory aplastic anemia. This trial resulted in the first FDA approval for new drug to treat aplastic anemia in over 30 years.  Her group has also used human iPSC to model bone marrow failure disorders, including GATA2 deficiency and telomeropathies, in order to gain insights into pathophysiology and investigate new treatment approaches. 

Biography

Cynthia Dunbar earned a B.A. magna cum laude in the history of science from Harvard University in 1980 and a M.D. magna cum laude from Harvard Medical School in 1984. She subsequently completed her internal medicine internship and residency at Boston City Hospital and hematology fellowship training at the University of California, San Francisco. She came to the NHLBI as a postdoctoral fellow in the laboratory of Arthur Nienhuis in 1987, became an independent Investigator in 1993, and has been Head of the Molecular Hematopoiesis Section since 2000. Dr. Dunbar has received numerous awards for teaching, mentorship, and research, including the NIH Clinical Center Distinguished Clinical Teacher Award, the John Decker Memorial Lectureship, and the Brigham and Women's Hospital Moloney Award and Lectureship. She served as the program director for the NIH/NHLBI clinical hematology fellowship program for 17 years.  She has authored more than 230 peer-reviewed scientific and review articles, and has given numerous invited lectures and presentations about her work. Dr. Dunbar served as Editor-in-Chief of the journal Blood, the flagship publication of the American Society of Hematology, from 2007-2012. She is a member of the American Society for Clinical Investigation, a Master of the American College of Physicians, and is the current President member of the American Society for Cell and Gene Therapy. 

Selected Publications

  1. Desmond R, Townsley DM, Dumitriu B, Olnes MJ, Scheinberg P, Bevans M, Parikh AR, Broder K, Calvo KR, Wu CO, Young NS, Dunbar CE. Eltrombopag restores trilineage hematopoiesis in refractory severe aplastic anemia that can be sustained on discontinuation of drug. Blood. 2014;123(12):1818-25.

  2. Wu C, Li B, Lu R, Koelle SJ, Yang Y, Jares A, Krouse AE, Metzger M, Liang F, Loré K, Wu CO, Donahue RE, Chen IS, Weissman I, Dunbar CE. Clonal tracking of rhesus macaque hematopoiesis highlights a distinct lineage origin for natural killer cells. Cell Stem Cell. 2014;14(4):486-99.

  3. Olnes MJ, Scheinberg P, Calvo KR, Desmond R, Tang Y, Dumitriu B, Parikh AR, Soto S, Biancotto A, Feng X, Lozier J, Wu CO, Young NS, Dunbar CE. Eltrombopag and improved hematopoiesis in refractory aplastic anemia. N Engl J Med. 2012;367(1):11-9.

  4. Hong SG, Winkler T, Wu C, Guo V, Pittaluga S, Nicolae A, Donahue RE, Metzger ME, Price SD, Uchida N, Kuznetsov SA, Kilts T, Li L, Robey PG, Dunbar CE. Path to the clinic: assessment of iPSC-based cell therapies in vivo in a nonhuman primate model. Cell Rep. 2014;7(4):1298-309.

  5. Winkler T, Hong SG, Decker JE, Morgan MJ, Wu C, Hughes WM 5th, Yang Y, Wangsa D, Padilla-Nash HM, Ried T, Young NS, Dunbar CE, Calado RT. Defective telomere elongation and hematopoiesis from telomerase-mutant aplastic anemia iPSCs. J Clin Invest. 2013;123(5):1952-63.


This page was last updated on September 1st, 2016