Announcements about major steps in stem cell research are now fairly common. How much longer until this research yields actual therapies? A special section in the latest issue of Science looks at the path toward the clinic that stretches ahead. The articles discuss how the stem-cell field is making progress toward medical advances—both in the research and policy domains—while continuing basic research using animal model systems to understand stem cell biology.
"The steps between early research results on stem cells and possible medical applications of stem cells are full of twists and turns, and occasional missteps, among the many advances," said Pam Hines, Senior Editor at Science. "With this special issue we hoped to highlight some of the most recent thought about the scientific advances and the ethical complexity that characterizes stem cell research today."
Highlights from the issue include:
Stem Cell Tourism v. Medical Innovation: Though the clinics around the world that currently offer unproven stem-cell-based therapies to desperate patients are certainly objectionable, we should take a breath and think before condemning all forms of stem cell tourism, according to a Perspective article by Olle Lindvall of University Hospital in Lund, Sweden and Insoo Hyun of Case Western Reserve University School of Medicine.
Experts must distinguish clearly between exploitative stem-cell tourism and legitimate attempts at medically innovative stem-cell-based interventions, the authors say. They argue that the standard clinical trials process, by itself, may not be able to deliver results, for reasons such as poor availability of cells or limited number of patients. For the last 40 years, for example, only 10 to 20 percent of all surgical techniques were developed through a clinical trials process, they say.
Lindvall and Hyun urge guidelines for determining whether innovative stem cell treatments should be used outside the normal clinical trials system. The procedures should include a written plan, they say, and show rational and preclinical evidence of efficacy and safety. The procedures also should be subjected to peer review and involve few seriously ill patients. When possible, medical innovation should also be followed by clinical trials.
NIH's New Stem-Cell Research Guidelines: New draft guidelines issued by the National Institutes of Health, which will govern the federal funding of human stem cell research, do have positive aspects, according to Policy Forum authors Mary Majumder of Baylor College of Medicine and Cynthia Cohen of Georgetown University. But they say additional issues must be resolved in the final guidelines, including questions about previously approved stem cell lines, informed consent, oversight and research embryos.
The Cancer Stem Cell Paradigm: Despite considerable controversy surrounding the idea of cancer stem cells—in which mutations can transform normal adult stem cells into harmful cells that give rise to cancerous tumors—research in this area is revealing potential targets for cancer therapy, Jeffrey Rosen of Baylor College of Medicine and Craig Jordan of University of Rochester School of Medicine say in a Review article. It has been difficult to figure out why cancer stem cells seem more numerous in some tumors than others, but controversy over this question has led researchers to explore areas that were not previously the focus of cancer therapeutics. For example, a variety of signaling pathways known to be important for stem-cell self-renewal now show promise as targets for cancer therapies.
Back to Basics (Research): Studies of wound-repairing cells in relatively simple animals such as planarians, fish and amphibians are shedding light on how mesenchymal stem cells operate in mammals and how these cells might be used to treat chronic diseases in which wound repair is deficient, as Thaddeus Stappenbeck and Hiroyuki Miyoshi of Washington University School of Medicine explain in another Review article. And, new technologies are helping researchers parse the complicated ways in which a stem cell interacts with its environment, according to another Review article by Dennis Discher of the University of Pennsylvania and colleagues.
Finally, in a new study, Ewa Wandzioch of Fox Chase Cancer Center and colleagues have detailed the dynamic signaling pathways that lead to the formation of the pancreas and liver in mammals, and they say it might help to explain the incomplete programming seen in various stem cell differentiation experiments in the past.