October 1, 2007

Versatile Stem Cells Isolated From Adult Mouse Testes

Cluster of oval-shaped cells Stem cells derived from adult mouse testes. Dr. Shahin Rafii, Weill Cornell Medical College.

Researchers have developed a way to efficiently isolate cells from mouse testes that have the potential to become almost any type of cell in the body. If the feat can be reproduced in humans, it may provide an alternative to human embryonic stem cells for therapeutic organ regeneration.

Human embryonic stem cells, even after many months growing in culture dishes, have the potential to form any cell type, from muscle to nerve to blood. Researchers hope to learn how to use these versatile cells to repair tissues and organs throughout the body. Some people, however, have ethical objections to the use of embryonic stem cells. Stem cells from adults have more limited potential. They can transform into the cells needed to maintain and repair the tissue in which they are found, but not into other types of tissue. Last year, German researchers showed that there are cells in adult mouse testes that, like embryonic stem cells, can become many different cell types in the body.

Dr. Shahin Rafii of Weill Cornell Medical College and his colleagues reported in the September 20, 2007, issue of the journal Nature that they have identified the highly specialized mouse cells, called adult spermatogonial progenitor cells, responsible for giving rise to these versatile stem cells. The researchers established cultures of the progenitor cells in the laboratory. They found that the cells maintain a protein on their surface called GPR125 that allows them to be easily identified and tracked throughout the process of stem cell creation.

The researchers showed that the stem cells, when injected into embryos, incorporated into tissues throughout the body. They were also able to coax the cells into becoming contractile cardiac tissue in the laboratory and functional blood vessels in mice.

Rafii said in a statement, "It appears that these specialized GPR125-positive spermatogonial cells could be an easily obtained and manipulated source of stem cells with a similar capability to form new tissues that we see in embryonic stem cells."

This research, which was supported by NIH's National Heart, Lung and Blood Institute (NHLBI) along with the Howard Hughes Medical Institute and Ansary Stem Center for Regenerative Medicine, demonstrates an easily obtained and manipulated source of stem cells with a capability similar to that of embryonic stem cells.

Rafii's team is currently trying to use GPR-125 to isolate stem cells from human testes. For male patients, this could provide a readily available source of stem cells without the ethical issues raised by embryonic stem cells. It would also avoid potential problems of tissue transplant rejection, since the cells come from the patient's own body. The group has also begun pursuing a similar effort in ovaries.

— by Harrison Wein, Ph.D.

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