WASHINGTON (Reuters) - Using just three genes, California researchers have transformed mouse skin cells directly into nerve cells called neurons.
Here are some questions and answers about the field and about this experiment by a team from Stanford University, which was reported in the journal Nature:
They took ordinary mouse skin cells and used viruses to “infect” them with a variety of different genes known to be active in nerve cells. Eventually the team, headed by Thomas Vierbuchen and Marius Wernig, found three genes that would change a skin cell into a nerve cell.
Scientists are trying to find ways to regenerate the human body, to repair injuries and cure disease. Currently, once a cell in the body has differentiated — become a skin cell or a brain cell or a blood cell — it will not turn into another kind of cell. Powerful but immature cells called stem cells still have this ability and scientists have been trying to harness their abilities, but methods so far are cumbersome and inefficient.
This method offers the possibility of skipping several steps, including using human embryos, to transform ordinary cells directly without first taking them back to the stem cell stage.
Not yet. The researchers have only done their experiment in mice and say they are struggling to get human cells to do the same thing. In addition, they have only created one cell type — neurons. It will likely take years to find the genes needed to make liver cells, heart cells, blood cells or bone cells. In addition, stem cells have abilities that these cells don’t have: they proliferate well in lab dishes and are virtually immortal. The new cells behave like ordinary cells, do not grow well in the lab and eventually die off.
This is unclear. Regenerative medicine is a promising field in which doctors hope to someday be able to help the body repair itself. Some companies are working with so-called adult stem cells, which have a limited ability to form new types of cells and tissues. For instance, Aastrom Biosciences Inc is testing cardiac stem cells that can produce a variety of different cells that make up heart tissue.
Other companies such as Geron Corp and Advanced Cell Technology are working with human embryonic stem cells, made using human fetuses, which have the ability to morph into any and all cell types.
Some hope to use a representative sample of stem cells in a bank that could be used as a source of closely matched tissue to repair or replace organs, tissue or blood. Others are pursuing more closely matched tailored therapies.
Researchers are also working with embryonic-like stem cells called induced pluripotent stem cells from ordinary skin cells. But this technology is far newer than embryonic stem cell technology and scientists are not entirely sure it is safe.
Some companies in the stem cell sector include Stemcells Inc, NeuralStem, Reneuron Group Plc, Osiris Therapeutics Inc, Neostem Inc, Cytori Therapeutics Inc, iZumi Bio Inc and International Stem Cell Corp, which seeks to create stem cells using human eggs only in a process called parthenogenesis.
Editing by David Storey