A new method for swapping young and old mouse blood is described in Nature Communications this week. A single blood exchange between mice of different ages is shown to alter tissue function within a matter of days. The transfusion system may be a useful tool for studying tissue ageing.
Previous work has shown that components of young blood can rejuvenate old tissues, whereas old blood has detrimental effects on young tissues. However, these experiments often relied on heterochronic parabiosis, a complicated surgical procedure during which the circulation of two animals is connected for several weeks. In addition to sharing blood, other components are shared, including organs, which means that old mice get access to younger lungs, immune system, heart, liver and kidneys and young mice have to maintain an additional old body. Irina Conboy and colleagues designed a simplified blood transfusion system to exchange only blood between mice, removing the influence of shared organs on outcomes of blood swapping.
The team showed that young blood enhances repair of injured old muscles, whereas old blood inhibited the formation of new brain cells and liver cell regeneration in young mice. These effects were measured within six days of the blood exchange. Generally, the inhibitory effects of old blood were more pronounced than the beneficial effects of young blood.
The authors propose the blood exchange system reported here has several practical advantages over heterochronic parabiosis, such as being quicker and less invasive, and could enable well-controlled future studies to identify blood-borne factors that contribute to tissue ageing or rejuvenation.