A new growth factor stimulates the division of hematopoietic cells
Researchers at Duke University Medical Center (Durham, North Carolina), working under the leadership of John Chute, identified a new growth factor that stimulates the proliferation of hematopoietic stem cells not only in culture, but also in the conditions of the body. The results of the work, published on March 21 in the preliminary on-line version of the journal Nature Medicine in the article "Pleiotrophin regulates the expansion and regeneration of hematopoietic stem cells", will help specialists overcome one of the most difficult barriers to the introduction of cell therapy into clinical practice: the small number of stem cells and their unwillingness to divide.
In experiments on stem cells isolated from the bone marrow of mice, the authors demonstrated that the addition of a natural growth factor – pleiotropin (Greek pleion – more numerous, tropos – direction) to the culture stimulates cell proliferation and leads to a tenfold increase in their population.
After that, the researchers injected pleiotropin into mice in which the division of hematopoietic bone marrow cells was suppressed by radioactive irradiation. This led to a tenfold increase in the population of bone marrow cells of mice in the experimental group compared to the number of cells inhabiting the bone marrow of animals in the control group.
In addition, the researchers found that in the culture of human cord blood cells, pleiotropin increases the number of stem cells that can take root in the bone marrow of immunodeficient mice.
The not fully formed system of factors of tissue compatibility of cord blood cells facilitates the selection of donor stem cells for patients in need of cell transplants, compared with the search for a compatible adult bone marrow donor, even among the patient's relatives. However, the number of stem cells in a portion of cord blood is very limited (today, in the vast majority of cases, such transplants are suitable only for transplanting small children). Unfortunately, until now, scientists have not been able to find growth factors that would ensure the production of large populations of cord blood cells sufficient for the treatment of adults.
According to Chute, the data obtained should expand the scope of umbilical cord blood transplants, whose cells can be transplanted to adult patients who do not have compatible donors.
In addition, systemic administration of pleiotropin is a very promising method of restoring the bone marrow and immune system of patients who have undergone chemotherapy and /or radiotherapy for the treatment of various malignant diseases.
In order to test the ability of pleiotropin to increase the likelihood of malignancy of hematopoietic cells, the authors carry out long-term observation of animals of the experimental group. At the time of publication, six months after the introduction of the growth factor, none of the mice showed signs of developing malignant tumors.
Currently, researchers are conducting experiments aimed at finding out the need for pleiotropin for normal growth and development of stem cells and decoding the biological mechanisms it triggers. Chute also notes that additional animal trials are needed before clinical trials of pleiotropin can begin.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Duke University Medical Center: Newly-Identified Growth Factor Promotes Stem Cell Growth, Regeneration.
24.03.2010