Jump to Main Content


Statement in Support of All Avenues of Stem Cell Research

As an organization of physicians who care for desperately ill patients and scientists devoted to understanding the basic mechanisms of disease and discovering new therapies, the American Society of Hematology (ASH) is excited about the scientific potential of all avenues of stem cell research, particularly human embryonic stem cells (hESC), adult stem cells, and induced pluripotent cells (iPS) derived by gene modifications of adult cells.


Human embryonic stem cells (hESC) are the fundamental precursor to all cells in the body and may be able to develop into blood, bone, skin, skeletal and cardiac muscle, cartilage, brain, liver, pancreas, and other specialized cells. Researchers are able to cultivate these cells from fertilized embryos that are leftover from in vitro fertilization clinics and would otherwise have been discarded. Adult stem cells can be derived from several different adult tissues, including bone marrow and blood (mobilized peripheral blood and umbilical cord blood), but are more differentiated than embryonic stem cells, and probably have less ability to form cells of all body tissues than do embryonic stem cells. Induced pluripotent cells (iPS) can be reprogrammed outside the body towards an embryonic stem cell-like state and can be manipulated to develop into different kinds of specialized body cells. However, there is still much to be understood about these cells, including their potential therapeutic usefulness.

Recent studies in adult stem cell research have shown promise, but because these cells are not as pliable as hESC, they may not be as useful for therapeutic interventions. Because of the ability of hESC to differentiate into most, if not all, tissues and cells in the body, research into the transplantability and differentiation of hESC appears to have the greatest potential to lead to important therapies for a large number of intractable diseases.

In August 2001, the Bush Administration set a policy for federal funding of hESC research. President Bush declared that federal research funds could only be used on hESC lines created before that date, arguing that this policy would prevent the creation and subsequent destruction of new embryos solely for the purpose of extracting stem cells.

At the time, several of the President’s scientific advisors believed that there were approximately 78 viable cell lines in existence and they would be sufficient for investigators to advance the hESC field. However, in practice only 21 hESC lines were available to researchers and these lines were not all at the same stage of developmental activity or capability. Additionally, in 2001, researchers only had the technology to grow hESC using mouse “feeder cell” lines and many of the stem cell lines available to researchers under the Bush Administration policy were found to be contaminated with mouse cells or mouse cell products.

In March 2009, President Obama issued an executive order expanding the use of federal funding for hESC research by allowing inclusion of more stem cells lines derived under strict ethical guidelines established by the National Institutes of Health (NIH). As a result of the Obama Administration policy, 76 hESC lines were available for federally funded research as of October 2010.

However, an August 2010 federal court ruling prohibiting federal funding of hESC research has cast uncertainty over the future of research in this field and the development of therapies for patients who need them the most. Without legislation codifying the Obama Administration policy, it is likely there will be continued litigation and disruption of hESC research.

ASH Policy

ASH believes that stem cell research offers a significant degree of promise and hope to the approximately 100 million Americans suffering from deadly and debilitating diseases, including cancer, stroke, heart attack, Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, diabetes, and traumatic brain and spinal cord injury. At this time, there is sufficient evidence to conclude that research into both embryonic and adult stem cell research, and other approaches that allow for the creation of pluripotent cells, is warranted to reach the goal of developing new therapies for patients with devastating diseases.

Researchers must continue to have access to all types of stem cells, particularly hESC, in order to fully understand and determine the true potential of each type of stem cell. The Society supports federal funding of all avenues of stem cell research under National Institutes of Health (NIH) federal research guidelines and with appropriate public oversight. ASH plans to continue to build the necessary consensus among scientists, policymakers, and the public that all forms of stem cell research need to be pursued vigorously to ensure the health and well-being of all Americans.

To this end, ASH endorses efforts to expand the list of hESC lines that are eligible for federal research funding, as well as legislative and regulatory changes that would permit broad development and utilization of hESC for research and potential therapeutic purposes. The previous lack of hESC lines eligible for federal funding created roadblocks in this field and slowed medical and scientific progress.

With the possibility of fewer opportunities for federal funding in hESC research available once again, efforts outside of the federal government’s oversight, control, and peer review mechanisms may gain prominence. Furthermore, several foreign countries encourage and/or actively invest in hESC research, thereby posing the potential of loss of American scientific prominence in this emerging field, possible emigration of the best and brightest American scientists, and diminution in the number of talented foreign graduate students, postdoctoral fellows, and senior scientists who otherwise would come to the U.S. for their training and to conduct research in this important area of scientific inquiry. Congress must act definitively by passing legislation to make the issue of federal funding for hESC research unambiguous, removing the possibility of repeated litigation intended to disrupt this important research and permanently allowing NIH-supported hESC research to continue.

ASH firmly believes that with more hESC lines available for federal funding, new opportunities will become available for scientific advancement. Likewise, with the ability to conduct research on additional hESC lines, more investigators will be attracted to careers in stem cell research in the United States. The Society believes that more U.S. researchers using new hESC lines should ultimately equate to further scientific and medical progress that is beneficial to patients.

ASH supports the position that the large number of fertilized embryos that are currently leftover in clinics from in vitro fertilization procedures—if used according to all appropriate informed consent and donation practices—are a rich, genetically-diverse source of potential hESC lines. ASH’s only criteria for new embryonic stem cell lines are that they are derived under the ethical guidelines established by NIH, that the individual cells have growth and differentiation capabilities, and be made available at reasonable costs to investigators at NIH, academic health centers, and research institutes throughout the nation and world.

ASH enthusiastically supports the continued development of the field of stem cell research and pledges the Society’s enduring commitment to move the science forward to help patients.

Founded in 1958, ASH represents over 16,000 clinicians and scientists committed to the study and treatment of blood and blood-related diseases. These diseases encompass malignant hematologic disorders such as leukemia, lymphoma, and myeloma; and non-malignant conditions including anemia and hemophilia; and congenital disorders such as sickle cell anemia and thalassemia. In addition, hematologists have been pioneers in the fields of bone marrow transplantation, gene therapy, and many drugs for the prevention and treatment of heart attacks and strokes.