Researchers have devised a way to help blood cells regenerate faster, by stimulating a particular type of stem cell to secrete growth factors that help blood cell precursor cells differentiate into mature blood cells. This could help repopulate blood cells in cancer patients who receive bone marrow irradiation.

Patients with blood cancers such as leukemia and lymphoma are often treated by irradiating their bone marrow to destroy the diseased cells. After the treatment, patients are vulnerable to infection and fatigue until new blood cells grow back.

MIT researchers have now devised a way to help blood cells regenerate faster. Their method involves stimulating a particular type of stem cell to secrete growth factors that help precursor cells differentiate into mature blood cells.

Using a technique known as mechanopriming, the researchers grew mesenchymal stem cells (MSCs) on a surface whose mechanical properties are very similar to that of bone marrow. Este induced the cells to produce special factors that help hematopoietic stem and progenitor cells (HSPCs) differentiate into red and white blood cells, as well as platelets and other blood cells.

"You can think about it like you are trying to grow a plant," says Krystyn Van Vliet, the Michael and Sonja Koerner Professor of Materials Science and Engineering, a professor of biological engineering, and associate provost. "The MSCs are coming in and improving the soil so that the progenitor cells can start proliferating and differentiating into the blood cell lines that you need to survive."

In a study of mice, the researchers showed that the specially grown MSCs helped the animals to recover much more rapidly from bone marrow irradiationVan Vliet is the senior author of the study, which appears in the October 24 issue of the journal  Stem Cell Research and Therapy.

The paper's lead author is recent MIT Ph.D. recipient Frances Liu. Other authors are Singapore-MIT Alliance for Research and Technology (SMART) postdoc Kimberley Tam, recent MIT Ph.D.ecipient Novalia Pishesha, and former SMART postdoc Zhiyong Poon, now at Singapore General Hospital.

Cellular drug manufacturers

MSCs are produced throughout the body and can differentiate into a variety of tissues, including bone, cartilage, muscle, and fat. They can also secrete proteins that help other types of stem cells differentiate into mature cells.

"They act like drug factories," Van Vliet says. "They can become tissue lineage cells, but they also pump out a lot of factors that change the environment that the hematopoietic stem cells are operating in."

When cancer patients receive a stem cell transplant, they usually receive only HPSCs, which can become blood cells. Van Vliet's team has shownpreviously that when mice are also given MSCs, they recover faster. However, in a given population of MSCs usually, only about 20% produces the factors that are needed to stimulate blood cell growth and bone marrow recovery.