Stem Cell Researchers Reverse Aging of Blood
By reversing, or reprogramming, the stem cells that produce blood, Lund University researchers have succeeded in rejuvenating the blood of mice. Their results suggest that most of the negative aging effects are not caused by primary DNA damage which would be permanent, but are in fact reversible because they are based on epigenetic factors which are programmed over time and can also be reprogrammed.
Stem cells are the source of all the cells in the body, since they can divide an unlimited number of times, and each time, one of the resulting cells remains a stem cell while the other matures into the type of cell needed by the body, for example a blood cell.
The composition of blood is one example of how it ages and the difference between blood from a young person and an old person is well known. Blood contains a certain mix of B- and T-lymphocytes and myeloid cells. "In older people, the number of B- and T-lymphocytes falls, while the number of myeloid cells increases", explained Martin Wahlestedt, a doctoral student in stem cell biology at the Faculty of Medicine at Lund University and lead author of a forthcoming article in the journal Blood.
When an elderly person is affected by leukemia, the cancer often has its origin in the myeloid cells, of which the elderly have more. Being able to "restart" the blood, as Martin and his colleagues have done in their studies on mice, presents interesting possibilities for future treatment.
"Our aging process is a consequence of changes in our stem cells over time", said Wahlestedt.
"Some of the changes are irreversible, for example damage to the stem cells' DNA, and some could be gradual changes, known as epigenetic changes, that are not necessarily irreversible, even if they are maintained through multiple cell divisions. When the stem cells are reprogrammed, as we have done, the epigenetic changes are cancelled."
Wahlestedt stressed that the science is still only at the stage of basic research, far from a functioning treatment. However, the research group is pleased with the results, because they indicate that it may not primarily be damage to DNA that causes blood to age, but rather the reversible epigenetic changes.
"A critical factor that gives an indication of whether the procedure is going to work or not is the age of the bone marrow donor. By reversing the development of the stem cells in the bone marrow, it may be possible to avoid negative age-related changes."