Frequently Asked Questions

What are stem cells and why do we hear so much about them?

Scientists have known of the existence of stem cells - the foundation of every organ, tissue, and cell within the human body - for over a century. Yet it has been only since the late 1990s, when human embryonic stem cells were first cultured in the laboratory, that the field of stem cell research has become the focus of intense scientific interest, sociopolitical controversy, and therapeutic potential.

Like a blank microchip that can be programmed to perform many different tasks, stem cells are undifferentiated, 'blank' cells that do not yet have a specific physiological function. When the proper conditions occur in the body or in the laboratory, stem cells begin to develop into specialized tissues and organs. Stem cells are also distinguished from other cells by their ability to self-renew-in other words, to divide and give rise to more stem cells.

Why is stem cell research so important?

Stem cells are the source of all tissues of the body, and understanding their properties is fundamental to our understanding of human biology in health and disease. In particular, stem cells offer the possibility of a renewable source of replacement cells to treat a wide variety of diseases and disabilities, including diabetes, neurological disease, cardiovascular disease, blood disease and many other conditions. Defective stem cells also appear to underlie many forms of cancer, and by understanding their properties it should be possible to develop new types of anti-cancer therapy.

What is the difference between embryonic and adult stem cells?

Some organs contain stem cells that persist throughout adult life and contribute to the maintenance and repair of those organs. Not every organ has been shown to contain stem cells, however, and generally adult stem cells have restricted developmental potential, in that their capacity for proliferation is limited and they can give rise only to a few cell types. Embryonic stem cells, by contrast, can divide almost indefinitely and can give rise to every cell type in the body, suggesting that they may be the most versatile source of cells for transplantation therapy.

Why is there so much controversy surrounding embryonic stem cell research?

At present, the only known way to derive embryonic stem cells involves the destruction of a blastocyst-stage embryo. Some people are opposed to this research because they consider the blastocyst to be morally equivalent to a human individual.

What is the source of embryos used for making embryonic stem cells?

The human embryonic stem cell lines that have been created at Harvard are derived from frozen embryos left over after in vitro fertilization (IVF) treatment. These early stage embryos were donated, with informed consent, by patients who had completed their treatment. In the future, Harvard researchers also hope to derive embryonic stem cells by somatic cell nuclear transfer.

What is somatic cell nuclear transfer?

Somatic cell nuclear transfer (SCNT), sometimes known as 'therapeutic cloning,' involves transferring a nucleus from a donor cell, such as a skin cell, into an unfertilized egg. The injected egg is then induced to divide, and when it reaches a few hundred cells, the so-called blastocyst stage, it can be used to derive embryonic stem cells that are genetically identical to the original donor. No sperm is involved, and, therefore, no fertilization occurs in this procedure. Moreover, because the blastocyst is not implanted in a uterus, no pregnancy is established. SCNT has great therapeutic promise because the resulting stem cells could be transplanted into the original donor and would be recognized as 'self', thereby avoiding the problems of rejection and immunosuppression that occur with transplants from unrelated donors. In addition to providing a source of material for transplantation therapy, SCNT can also be used to make stem cells that carry disease genes. These cells could provide a powerful new tool for studying the basis of human disease and for discovering new drugs.

What is the difference between therapeutic and reproductive cloning?

Reproductive cloning involves creating an embryo by nuclear transfer and then implanting it into a uterus and allowing it to establish a pregnancy. This has been achieved for sheep and several other mammalian species. It is not known whether it could be made to work in humans, but the vast majority of researchers in the field are strongly opposed to attempting such an experiment. Many countries and some US states have already enacted legislation that permits therapeutic cloning while prohibiting reproductive cloning. Harvard supports a proposal to enact similar legislation in Massachusetts.

How is human embryonic stem cell research affected by the current policies of the Bush administration?

Under administration policy, only stem cell lines created before August 9, 2001 can be studied using federal funds. Although it was originally claimed that more than 60 lines would meet this eligibility criterion, most researchers in the field consider this to be an overestimate. NIH currently lists only 22 lines that are available for distribution to researchers. These federally approved lines are limited in their utility for a variety of reasons, including lack of genetic diversity, chromosomal abnormalities, poor growth characteristics, exposure to - and potential contamination by - mouse feeder cells, and commercial restrictions. Therefore, if the therapeutic potential of embryonic stem cells is to be realized, researchers must also work with non-approved lines. This cannot be done using NIH funding (the main source of research funds for most academic labs in the US), and so private philanthropic support is essential to the future of this field.

When will stem cell research lead to new disease cures?

Stem cell-based therapies are already in widespread clinical use, in the form of bone marrow and cord blood transplants. These procedures, which save many lives every year, demonstrate the validity of stem cell transplantation as a therapeutic concept. We are optimistic that similar successes will be possible with other types of stem cells for other diseases, but it is impossible to predict how soon this will happen, given the many technical challenges that must be overcome. The only safe prediction is that the sooner we begin, the sooner we will reach our goal.

Have embryonic stem cells been used to treat any diseases in humans?

Not yet. Although embryonic stem cell research has shown great potential, the field is still very new; human embryonic stem cells were first identified in 1998. Moreover, in the US and some other countries, progress has been slowed by funding restrictions and political controversies.

Why create a Stem Cell Institute at Harvard?

Stem cells represent an extraordinary opportunity and challenge that involves areas of expertise not encompassed in any one discipline, department or school. For example, basic biology must interface with medical expertise if the promise of this field is to be fully realized. At the same time, clinical and laboratory scientists must engage with those attuned to the political, societal and ethical implications of the research. The excessively politicized and emotional debate engendered by stem cell research requires a champion institution whose tradition of rational deliberation can balance the voices of opinion with a strong counterweight of exceptional science. Harvard, with its tradition of academic excellence, its diversity of basic and clinical expertise, and its strong links to a thriving local biotechnology community, is exceptionally well positioned to play such a role and to establish itself as the world's leading center for stem cell research.

What types of research does HSCI support?

HSCI supports research into all aspects of stem cell biology, including both embryonic and adult stem cells. Our primary emphasis is on the search for new therapies for serious diseases, including, among others, diabetes, neurological disease, cardiovascular disease, blood disease and cancer.

What is the source of HSCI funding?

HSCI is supported primarily by private philanthropic donations. These donations allow us to support a wide range of research activities that could not be supported from other sources such as NIH funding. In future, we also expect to apply to NIH and other funding agencies for support of activities that are eligible for such funding.

Where can I learn more about HSCI activities?

Further details of our research programs and other activities are given throughout this web site and in our annual report, available here in PDF format.

How can I donate money to the HSCI?

Since many of our research activities are not eligible to receive federal funding, the HSCI depends upon philanthropic support. To learn more about how to support our programs, please visit our Ways to Give section by clicking here.