Vampires. They like drinking the blood of young victims, folklore tells us, because it helps rejuvenate their shriveling, thousand-year-old bodies. Last year a study out of Stanford University indicated that the basic idea has some merit: Infusions of young blood, scientists found, while not exactly the same as drinking it, could help revive cognitive function and stimulate neurogenesis in older brains.
Though the study was conducted in mice, it was promising news for old humans with degenerative brain diseases like Alzheimer’s. Promising, that is, on the assumption that there would always be enough young blood to keep the old folks thriving. Lucky for us young folks who feel we’ve been bled enough by our elders lately, a new study in the journal Blood (what a name!) reveals that scientists at Lund University in Sweden have successfully reprogrammed the blood-producing stem-cells in old mice to produce younger blood on their own. With luck, humans will be next.
Stem cells, like most other cells, reproduce by division, and when they divide, the DNA in their nuclei deteriorate a little bit each time—a process known as replicative senescence. (One notable exception may be neurons, which, a recent study suggests, may only die because their host bodies die.) That DNA deterioration—the result of shortening telomere chains—seems so far to be irreversible.
But cells age in other ways, too, and these so-called “epigenetic” changes can be reversible if scientists reprogram an organism’s stem cells.
Older blood, for example, contains fewer B- and T-lymphocytes than young blood—two types of white blood cell crucial to a healthy immune system—and more myeloid cells, which are often the origin of leukemia. For the new study, the researchers were able to manipulate the gene expressions of those blood-producing stem cells in mice to reverse that epigenetic aging process.
Martin Wahlestedt, a doctoral student in stem cell biology at Lund and the study’s principal author, noted that one clear application, if the results are ever reproduced in humans, pertains to bone marrow transplants, which are performed when a patient’s blood and immune system need regeneration.
“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,” Wahlestedt said in a statement released by the university. "By reversing the development of the stem cells in the bone marrow, it may be possible to avoid negative age-related changes.”
But given the discoveries made with regard to young blood and brain science last year, the implications are more exciting still. And one can only imagine that having younger, healthier blood and a sturdier immune system must be advantageous in all sorts of other ways—not least of all by simply helping old people with weak immune systems better fight disease. That fountain of youth just keeps getting closer.