UC Berkeley scientists and a research foundation recently collaborated to further examine the relationship between blood and the aging process as part of a study published Nov. 22 in the scientific journal Nature Communications.

The study was conducted by campus researchers with the Conboy Lab — run by UC Berkeley bioengineering professor Irina Conboy — and received about $500,000 in funding from the National Institutes of Health, the Strategies for Engineered Negligible Senescence Research Foundation, Rogers’ Family and Calico. By transferring blood from old mice to young mice and vice versa, researchers gained new insights into the impact of blood’s age on organ regeneration.

The researchers were the first in the field of aging research to study the effect of blood transfer between two separate organisms, said collaborating campus researcher Michael Conboy, who is married to Irina. Earlier studies used a method called parabiosis, in which scientists would cut open the sides of two animals to be anatomically joined together so that they’re connected to each other’s circulatory system, kidneys and liver.

“It’s like living with another person literally attached,” said one of the campus researchers, Ranveer Gathwala, describing parabiosis.

Using this method, the laboratory found in a 2005 study that the older of the two mice undergoing parabiosis demonstrated improved regeneration, while the younger showed a decreased ability to regenerate. The experiment, however, was susceptible to the influence of several factors besides the exchange of young and old blood, including the older mouse’s ability to access the younger mouse’s organs, which might also impact regeneration in the older mouse.

The recent study narrowed down the research to the effects of blood on aging by using a pump that exchanged only blood between young and old mice. Researchers concluded that while blood from younger mice does improve liver and blood regeneration in older mice, the effect of the older mouse’s blood is much more detrimental for the younger mouse’s liver, muscle and brain, Gathwala said.

“(This finding) calls in the question of what the real value is of young blood as a medicine versus neutralizing the stuff in the old blood as a medicine,” Michael Conboy said.

According to UC Berkeley integrative biology professor George Brooks, another expert on aging, the new study is consistent with prior research on brain cell regeneration by other campus scientists.

According to Michael Conboy, many scientists in the field of aging research focus their studies on young blood and the idea that it has a positive effect on aging. Gathwala said, however, that scientists should instead focus on the impact of old blood on aging because young blood mainly appears to display positive effects by diffusing old blood.

“You have a pool of bad blood in an old organism,” Gathwala said. “If you dilute that, it’s not as bad.”

It is safer to filter “garbage” out of the old blood of individuals and re-enter it into circulation — which triggers no immune response in the individual — than to transfuse young blood into an older person, Michael Conboy said. For every one unit of transfused blood a person receives, there is a 1 percent chance that the person will suffer complications, such as immune responses that cause holes to form in blood vessels, Michael Conboy said.

Not only is filtering aging compounds in blood safer than transfusing blood between organisms, it is also a more feasible method to counter the aging process, Gathwala said. He added that there is existing technology designed to filter out the negative components in blood.

“There’s a doctor in San Francisco who wants to give it a trial right now,” Michael Conboy said. “MDs can do it tomorrow.”

The effects of blood filtering, however, remain to be studied. Michael Conboy said that future research will filter out aging-related compounds in old blood and “see if we can make blood less old.”