Stem cell like progenitor cells could be key to aging slowly: Study

By Dr. Ananya Mandal, MDJan 4 2012

In new research on mice, scientists have found that stem cells could help slow the aging process. This new research was conducted on mice that had been bred to have progeria, a disorder that causes premature aging. Mice with the condition typically live only 21 to 28 days instead of the usual two years.

Researchers from the University of Pittsburgh took 17-day-old mice with progeria and injected them with stem cell-like cells called stem/progenitor cells that they had taken from the muscle tissue of younger, healthier mice. Mice injected with these cells lived two to three times longer than expected. The full results appear in the journal Nature Communications.

Progenitor cells have the capacity of becoming many kinds of cells, but are more limited than stem cells and cannot divide and reproduce indefinitely. Their main role is to replace cells lost by normal cell death.

One of the researchers, Dr. Johnny Huard, a professor in the Departments of Orthopaedic Surgery and of Microbiology and Molecular Genetics, at the Pitt School of Medicine, says he and his team were amazed with the results. “We were mind boggled with this,” Huard told CTV News. “We had mice at 45 days and they looked so good, we thought the lab facility had mixed them up with the healthy mice,” said Huard, who is also the director of the Stem Cell Research Center at Pitt.

He says some of the mice lived 75 days, which is three times as long as would be expected in mice with this advanced aging. Not only did the treated mice live longer, they were also in better general health that the untreated mice with progeria. Normally, mice with the condition lose muscle mass in their hind limbs as they age, and begin to tremble and move slowly and awkwardly. But the mice that got the shots of stem/progenitor cells were more like normal mice, and they grew almost as large.

At end of the study the researchers found new blood vessel growth in the brains and muscle of the treated mice, even though large numbers injected stem/progenitor cells weren't detected in those tissues. They did find small amounts of new stem cells in the organs of the mice, but their numbers were so low, “they could not explain the huge effect in these animals,” Huard said.

Laura Niedernhofer associate professor in Pitt's Department of Microbiology and Molecular Genetics and the University of Pittsburgh Cancer Institute (UPCI) and co-author said, “Our experiments showed that mice that have progeria, a disorder of premature aging, were healthier and lived longer after an injection of stem cells from young, healthy animals…That tells us that stem cell dysfunction is a cause of the changes we see with aging.”

The next step was to try to understand how the stem/progenitor cells were helping the mice. The team conducted experiments in petri dishes in a lab, placing stem/progenitor cells alongside cells from aged mice animals. After a few days, they discovered the cells from the aged mice appear renewed.

Huard says that suggests the healthy cells secreted something in the dish that helped revive the older stem cells in the same dish. “This leads us to think that healthy cells secrete factors to create an environment that help correct the dysfunction present in the native stem cell population and aged tissue,” Dr. Niedernhofer said. “In a culture dish experiment, we put young stem cells close to, but not touching, progeria stem cells, and the unhealthy cells functionally improved.” The team is conducting more research in hopes of better understanding the protein or substance that might have been secreted.

The researchers hope that there could be a time, for example, when an older adult could be injected with progenitor cells or stem cells that had harvested from their own body at age 20 and then re-injected into them. For now, much more research is needed on both the short and long term effects of the treatments.

The project was funded by grants from the National Institutes of Health.