Research Paper Volume 14, Issue 6 pp 2507—2512

Evaluation of the effect of age of the younger mice on the rejuvenation of the older mice by heterochronic parabiosis

Yushi Suzuki1, , Kento Takaya1, , Shiho Watanabe1, , Marika Otaki1, , Hikaru Kono1, , Kazuo Kishi1, ,

  • 1 Department of Plastic and Reconstructive Surgery, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan

Received: January 7, 2022       Accepted: March 15, 2022       Published: March 21, 2022
How to Cite

Copyright: © 2022 Suzuki et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Heterochronic parabiosis is used to study the systemic effects of aging and involves surgically connecting two animals of different ages such that they have common blood circulation. Although this technique has been prevalent for a long time, there is no scientific consensus on the age of the animals that should be used. We hypothesized that the younger the animal, the greater would be its rejuvenating effect. Hence, to test this hypothesis, we created parabiosis of 67-week-old mice with younger mice of different ages (4-week-old and 8-week-old). We evaluated the changes in appearance and the expression IL-1A, IL-6, and Cdkn2a (p16) in the liver, kidney, brain, and skin. These cytokines belong to the senescence-associated secretory phenotype (SASP) factors, and are indicators of aging. Although we did not find any significant changes in the appearance of the mice, we found statistically significant differences in some SASP factors between the liver of the 4-week-old and 8-week-old pairs. However, overall, compared to the 8-week-old mice, the 4-week-old does not exert a significantly higher rejuvenation effect on the older mice. Hence, we concluded that the rejuvenation of older mice during heterochronic parabiosis might not be affected by the exact age of the younger mice.


SASP: senescence-associated secretory phenotype; IL: interleukin.