Revised October 12, 2012
The International Society for Stem Cell Research (ISSCR) congratulates Dr. Shinya Yamanaka and Dr. John Gurdon for their scientific achievements recognized by this year’s Nobel Prize in Physiology or Medicine. The work of these two scientists established that it is possible to “turn back the clock” on adult cells so that they can be reprogrammed to an embryonic-like “pluripotent” state that allows them to grow and make all adult cell types. Their work is a vital foundation for accelerating efforts to better understand complex and intractable human diseases and to turn stem cell science into stem cell therapy for many terrible human diseases for which we currently lack effective treatments. While the importance of Gurdon’s and Yamanaka’s research is enormous, it does not remove the imperative to pursue all forms of stem cell research, including research with adult stem cells and human embryonic stem (ES) cells to improve understanding and treatment of human diseases.
Human Embryonic Stem Cells are the Prototype “Gold Standard” Pluripotent Cell
Yamanaka’s recent and exciting advances demonstrate that it is possible to reprogram cells in adult human tissues into cells that very closely resemble, but may not be identical to, ES cells. Along with recent progress on redirecting cell fate to enhance tissue repair, these experiments have captured the imagination of the scientific community worldwide. While many scientists are very optimistic about the future of this new research, some people in political circles have incorrectly interpreted this enthusiasm as a verdict that research on human ES cells is no longer necessary. This conclusion is not yet scientifically justified.
At present, and in the foreseeable future, there is a strong scientific and medical consensus that continued research on all types of stem cells is critical to developing research strategies that will ultimately provide new therapies. Supporting all forms of stem cell research is in the best long-term interests of a broad spectrum of patients with debilitating diseases and injuries. In fact, predictions about what might or might not be possible cannot substitute for careful and rigorous research to discover what strategy will provide the most successful therapeutic intervention for a given disease or condition. The basic tools for these discoveries include human ES cells, which remain the benchmark for assessing pluripotency and the ability of cells to develop into all the different cell types of the body.
Induced Pluripotent Stem (iPS) Cells
Research efforts on ES cells, iPS cells and reprogramming of adult or tissue stem cells are not alternative or mutually exclusive pathways to discovery, but are in fact complementary and synergistic. It is important to remember that the recent success in reprogramming adult human cells into cells that closely resemble ES cells would not have occurred without the last decade of human ES cell research. Although ES cells and these newer iPS cells were both first discovered in the mouse, the human versions of these cells require different conditions to sustain their growth. It was only through research on human ES cells that scientists determined the necessary conditions for iPS cells. Had we relied only on information from studies in the mouse, the recent attempts at deriving human iPS cells would have failed. It is still controversial whether human iPS cells differ in clinically significant ways from human ES cells. In the meantime, vital research on human ES cells must continue.
In the few years in which human ES cells have been available for experimental and preclinical research, human ES cells have already entered human clinical trials. Trials have already started, or will soon start, with cells derived from human ES cells to promote retinal regeneration, recovery after stroke, spinal cord injury, blood diseases, heart diseases, diabetes, and other conditions. There is considerable value in continuing to develop therapies based on the human ES cell lines that have already been in clinical development for years and have years of analysis and safety information. One cannot replace an existing cell line in research or clinical development without a significant additional investment in time and at considerable additional cost.
Read the related Summary Points.
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The International Society for Stem Cell Research is an independent, nonprofit membership organization established to promote and foster the exchange and dissemination of information and ideas relating to stem cells, to encourage the general field of research involving stem cells and to promote professional and public education in all areas of stem cell research and application.