Like it or not, the blood of young people and older people is different. Can the blood of an older person be rejuvenated and made young again?
In an article published recently by the scientific journal Blood, a research group at Lund University in Sweden details a series of experiments in which they rejuvenated the blood of mice by reversing, or re-programming, the blood cell-making stem cells.
Stem cell populations throughout the body form and replace cells in the body and help repair organs. Stem cells have the capability to divide an unlimited number of times, and when they divide, one cell remains a stem cell and the other matures into another cell type needed by the body.
Martin Wahlestedt, a doctoral student in stem cell biology at the Faculty of Medicine at Lund University, and principal author of the article explained, “Our ageing process is a consequence of changes in our stem cells over time.” Wahlestedt continued, “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 re-programmed, as we have done, the epigenetic changes are cancelled.”
Shinya Yamanaka was awarded the Nobel Prize in Medicine last year for this very discovery.
Blood composition changes as we age. For example, blood from a young person contains a certain mix of B- and T-lymphocytes and myeloid cells, but in older people, according to Wahlestedt, “In older people, the number of B- and T-lymphocytes falls, while the number of myeloid cells increases.” Therefore, when an elderly person is affected by leukemia, the cancer usually originates in the myeloid cells, since the elderly have more myeloid cells. Being able to refurbish the blood, as Martin and his colleagues have done in their mouse studies, therefore, presents interesting possibilities for future treatment.
“There is a lot of focus on how stem cells could be used in different treatments, but all that they are routinely used for in clinical work today is bone marrow transplants for diseases where the blood and immune systems have to be regenerated”, said Martin Wahlestedt, continuing: “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.”
Even if the composition of the blood in old and young mice is remarkably like that in young and elderly people, Martin Wahlestedt stressed that at this stage; the technology is only at the basic research stage and is far from a functioning treatment. 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.