Program in Hematopoietic Stem Cells


The IRM Program in Hematopoietic Stem Cells consists of basic science and clinical investigators from Penn’s Schools of Medicine, Veterinary Medicine, and Engineering and Applied Science.

The Program investigates the fundamental properties of normal and malignant adult hematopoietic stem cells, the origin of hematopoietic cells in the embryo, and the use of hematopoietic stem cells in the clinic.  Hematopoietic stem cells are the paradigm for understanding the fundamental properties of adult stem cells, and for clinical stem cell therapy.  Bone marrow transplantation is the standard of care treatment for a variety of malignant and benign hematological diseases, thus this program provides an important clinical perspective to all IRM researchers.


  • Clinical program members demonstrated that blockade of the CCR5 receptor prevented visceral graft versus host disease in allogeneic hematopoietic stem cell transplants  (Reshef, et al.: 2012 New England Journal of Medicine).
  • IRM investigators discovered that hemogenic stem cells differentiate from hemogenic endothelial cells in the embryo, and that hemogoenic endothelial cells are functionally heterogeneous  (Chen, et al., 2009 Nature; Chen, et al.: 2011 Cell Stem Cell).
  • IRM researchers showed that human leukemic stem cells are rare in acute myelogenous leukemia, and described a phenotypic plasticity that was not previously appreciated  (Sarry, et al.: J Clin Invest, 2011).


  • Improved treatment protocols for allogeneic hematopoietic stem cell transplants that improve treatment outcomes and reduce morbidity.
  • Applying lessons learned from the study of hematopoietic stem cells toward producing them from ES/iPS cells, and expanding or maintaining them in vitro.
  • Establishing a drug development pipeline at Penn for all IRM researchers.

Nancy A. Speck, Ph.D., is Associate Director of the IRM, Professor of Cell and Developmental Biology, and Co-Director of the Hematological Malignancies Program at the Abramson Cancer Center.  She studies Runx1, a protein essential for the formation of hematopoietic stem cells in the embryo, that is frequently mutated in leukemia.The goal of her work is to understand hematopoietic stem cell formation in the embryo in order to guide efforts to produce hematopoietic stem cells from ES/iPS cells in vitro. 
Warren S. Pear, M. D., Ph.D., the Gaylord P. and Mary Louise Harnwell Professor of Pathology & Lab Medicine.  Dr. Pear identified genes that are responsible for lymphocyte development and differentiation.