HMS Researcher Makes Stem Cell Advances

A scientist from Harvard Medical School (HMS) has helped develop a technique for increasing the number of stem cells in mice, an advance which could ease bone marrow transplants for cancer patients and improve recovery from injury.

Stem cells play a key part in bone marrow transplants, but because the cells reproduce in small numbers within the body, there aren’t enough naturally-produced stem cells for patients who need them.

“Limiting numbers [of stem cells] has been a problem in bone marrow transplants and in trying to expand their use,” said David Scadden, associate professor of medicine at HMS and one of the researchers involved with the study. “Getting more stem cells is key, or needing fewer transplants is key.”

Scadden worked with Laura Calvi of the University of Rochester Medical School and Gregor Adams of the Massachusetts General Hospital Cancer Center. The project combined Scadden’s interest in the interaction between stem cells and other cells with Calvi’s research on the relationship between bone and bone marrow.

Looking at cells that create new bone—known as osteoblasts—in mice, the researchers discovered that mice with a protein that generates more osteoblasts also had more stem cells.

“Osteoblastic cells appear to provide a particular support to hematopoietic stem cells,” Calvi said. “If you particularly alter osteoblastic cells, you can affect stem cells.”

The researchers discovered that parathyroid hormone (PTH), an FDA-approved hormone for treating osteoporosis, had the same effect as the mice’s protein, increasing the number of stem cells. Mice treated with PTH who underwent bone marrow transplants had a 100 percent survival rate in the study.

“If this pans out to be useful in humans, we might be able to use fewer stem cells or expand stem cells. That opens a whole new area of approach to stem cells,” Scadden said.

Increasing the number of available stem cells could improve healing after injury and provide stem cells for leukemia patients who have trouble finding donors, according to Scadden.

After about two years of work on this project, the researchers said they are about to begin clinical trials to figure out what PTH’s impact will be on human stem cells. Calvi and Scadden do not expect the impact of PTH to be different for humans than it was for mice.

The researchers also said they plan to do further research on stem cells. They hope to find a way to increase the number of stem cells in umbilical cord blood, since there are currently too few of them to use them for bone marrow transplants in adults.

For Calvi, the results of this study were the solution to a problem she had been focusing on.

“We have a really neat model,” she said. “We were not expecting such a finding initially. Serendipity really played a role in this finding.”