Researchers control stem-cell growth

MU scientists have learned to control growth and maintain a more consistent stem-cell culture.
Thursday, June 30, 2005 | 12:00 a.m. CDT; updated 6:12 p.m. CDT, Friday, July 18, 2008

In the scientific pursuit to discover the workings of human cells in an effort to cure disease, MU researchers have made a small, but possibly significant, advance in understanding one of the smallest components of the human body.

MU researchers Michael Roberts, Toshihiko Ezashi and Padmalaya Das have discovered that by lowering the amount of oxygen in the environment in which a stem cell is growing, researchers can control how cells in a human embryonic stem-cell culture divide, allowing scientists to possibly replicate human tissues more efficiently.

The results of the study were published in the March issue of the magazine Proceedings of the National Academy of Sciences of the United States of America.

Stem cells have the potential to fight diseases caused by damaged cells and tissues by controlling the division and growth of stem cells to create replacement tissues and organs. Left alone in a culture dish, without manipulation, stem cells can randomly become any tissue in the body.

“Human stem cells do have this capacity to go off into any direction,” said Roberts, director of MU’s Life Sciences Center. “I’m confident we have been able to overcome real troublesome, spontaneous growth in a cell culture.”

MU researchers have learned how to control growth and maintain a more consistent stem-cell culture.

“If the cell concentration is more homogenous, all the cells are the same status, same condition, we can more efficiently create a certain tissue,” said Ezashi, an MU assistant researcher.

The university is not engaged in somatic cell nuclear transfer procedures involving human embryonic stem cells, but researchers are working toward making human stem cells more viable for scientists working on projects including cardiovascular disease, diabetes and Parkinson’s disease.

MU purchased a federally approved stem line, one of 22, from WiCell lines at the University of Wisconsin-Madison for $5,000 in 2003. MU received the line of stem cells in a 150 milliliter vial about the size of a pinky finger. In the vial, not viewable to the naked eye, was a frozen stem-cell culture, “which have the capacity to divide indefinitely,” Roberts said.

Once unfrozen, stem cells will begin to divide slowly and become visible within six to seven days. It takes continuous effort to maintain the consistency of dividing cells and the cell culture. Layers of inconsistent cells must be separated from the culture — a process that wastes time and cells, Ezashi said.

Based on prior embryonic research, Roberts hypothesized that if the oxygen level was lowered to imitate the environment of a uterus, the growing stem cells would not begin to form a specific tissue or organ.

In general, stem-cell cultures have been grown in an environment with a 21 percent oxygen level. By lowering the oxygen level to 5 percent, cells divide just as rapidly but will maintain the potential to form into any cell or tissue in the human body.

Roberts plans to use the research to continue studying the early stages of placenta formation, how an embryo develops and why some pregnancies fail by studying what causes the stem cells of an embryo to first begin to change. Being able to control the growth of stem cells will help Roberts look for what causes a stem-cell culture to change and become an embryo.

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