A team of researchers headed by Thomas Skutella (pictured), director of the Center for Regenerative Biology and Medicine in Germany, has made a major breakthrough in stem cell research. This scientists in Tübingen, with first author Sabine Conrad and in cooperation with colleagues from the University Department of Urology, director Prof. Arnulf Stenzl, present their study on isolating pluripotent human stem cells, providing a true alternative to ethically controversial embryonic stem cells.
The experimental material stems from immature human germ cells from the adult testicle. The samples were obtained from orchiectomies or biopsies performed at the Department of Urology. Skutella and his team then found the right combination of culture conditions, media, and additional growth factors to induce the spontaneous generation of pluripotent cells. Pluripotent cells are not yet differentiated, which means that, in principle, they have the capacity to transform themselves into almost every cell type present in the body. In this respect they resemble embryonic stem cells. Thanks to this pioneering work done in Tübingen, testicular cells are the first and at present the only known source of naturally occurring adult human pluripotent stem cells. This alone is already a remarkable achievement, but the team’s work is crowned by their success in further cultivating the cells to produce cell lines which remain stable and reproduce well over a long period of time in culture.
The cells also stood up to the test for pluripotency, the current international gold standard: After being injected into mice with genetic immunodeficiency, the cells form teratomas. These special tumors contain cells of all three germ layers that are formed in the early developmental stages of the embryo. In addition, the scientists were able to show that a regulatory network of pluripotent genes is active in these cells – further proof of a developmental potential similar to that of embryonic stem cells. In the Tübingen laboratories, the pluripotent cells could already be differentiated into a variety of different tissue-forming cells such as those found in the nervous system, muscles, bone, and pancreas.
Skutella is not only a department director at the university’s Anatomy Institute but is also director of the Center for Regenerative Biology and Medicine ZRM. He is pleased that the door to regenerative and individual medicine has opened up even more with the publication of these new results. The scientists and physicians associated with Tübingen’s ZRM have great hopes that these pluripotent cells can serve as a basis from which specific replacement tissues can one day be cultivated to help ill and injured patients. Because such tissues are based on the patient’s own cell material, rejection, and immune reactions can be largely avoided. In addition, the new pluripotent cells are produced without genetic engineering techniques such as the introduction of genetic material from viruses into the cell nucleus. This eliminates one more hurdle to medical application in patients.
However, further intensive research is needed before the new results are translated into actual therapies, according to Skutella.
Illustration: Center for Regenerative Biology and Medicine.
Center for Regenerative Biology and Medicine News Release (10/10/08)
USA Today (10/08/08)
AZ Star Net (10/09/08)
Los Angeles Times (10/09/08)
Abstract (Nature, Published online 8 October 2008)