The research noted here, in which scientists transplant young stem cells into old mice, is a logical exploration of the bounds of the possible along the lines of parabiosis studies, in which the circulatory systems of old and young individuals are linked. The results demonstrate that regular cell transplants incorporating young bone marrow stem cells can extend life when provided to older individuals, provided there is a close genetic match between donor and recipient. Without that match there was no effect on life span:
The method of lifespan extension that is a practical application of the informational theory of aging is proposed. In this theory, the degradation (error accumulation) of the genetic information in cells is considered a main cause of aging. According to it, our method is based on the transplantation of genetically identical (or similar) stem cells with the lower number of genomic errors to the old recipients. For humans and large mammals, this method can be realized by cryopreservation of their own stem cells, taken in a young age, for the later autologous transplantation in old age.
To test this method experimentally, we chose laboratory animals of relatively short lifespan (mouse). Because it is difficult to isolate the required amount of the stem cells (e.g., bone marrow) without significant damage for animals, we used the bone marrow transplantation from sacrificed inbred young donors, males and females of 1.5-3 months. Bone marrow transplantation (2 × 10^6 cells) was performed with the intervals of 3 months to the death of the animal. Experiments were started at age of 7-8 months for the recipients of the first and the second experimental groups and at age of 6-10 months for those of the third group.
It is shown that the lifespan extension of recipients depends on level of their genetic similarity (syngeneity) with donors. We have achieved the lifespan increase of the experimental mice by 34% when the transplantation of the bone marrow with high level of genetic similarity was used. The value of lifespan increase in our experiments varies from 34% for high-level syngeneic transplantation to 0% for allogeneic transplantation.