A UC Berkeley study published May 30 found evidence that removing certain blood factors may reverse aging in mice.

Some members of the research team were involved in a 2005 study where conjoining young and old mice led to reversed effects on aging in the old mice. The study’s results contributed to a popular theory that “young blood” can be used therapeutically to produce age-reversing effects. The new study, however, helps disprove this theory, as it suggests that the reversal of aging effects is caused by diluting “old blood.”

The approach to the study was adopted from a therapy approved by the U.S. Food and Drug Administration known as therapeutic plasma exchange. The study aimed to analyze blood cells from young and old mice by removing a portion of their blood and replacing it with a solution of isotonic normal saline and albumin, a protein found in blood.

“Our hypothesis going into this study was: What if we just remove these factors somehow and see what kind of effect it has on tissue generation and promoting the function of these resident stem cells and tissues in muscle, liver and brain?” said campus graduate student and study co-author Melod Mehdipour.

After replacing blood from old mice with the saline and albumin solution, the team observed multiple beneficial effects in the old mice, including a significant increase in muscle regeneration and wound healing, as well as a decrease in liver fibrosis and fatty deposits in aged livers.

The team also observed similar effects in human blood samples.

“We’ve also seen a lot of very interesting proteomics changes in human and mouse samples that we’ve interrogated that largely show that there are very, very similar changes with respect to the type of proteins being exchanged,” Mehdipour said.

The researchers found that the benefits of plasma exchange came from removing “old blood” and diluting it with the saline and albumin solution. Campus rising senior and study co-author Michael Lieb, however, added albumin to human blood samples that had not been through a plasma exchange and saw no age-reversing impacts.

This helped the team to conclude that the albumin served primarily to replenish the extracted blood, but it did not provide the age-reversing benefit the team observed.

“It is important clinically because, in the past decade or so, when everybody jumped into this boat of young blood, millions of dollars and years of clinical trials were dedicated to using young blood or young blood products,” said campus professor of bioengineering and co-author Irina Conboy. “Those were without success.”

The team plans to continue researching the impacts of plasma exchanges on aging, and is working on starting clinical trials in humans.