Young human serum requires bone marrow for skin rejuvenation effects

A new research paper featured on the cover of Volume 17, Issue 7 of Aging (Aging-US) was published on July 25, 2025, titled "Systemic factors in young human serum influence in vitro responses of human skin and bone marrow-derived blood cells in a microphysiological co-culture system."

The study, led by first author Johanna Ritter and corresponding author Elke Grönniger from Beiersdorf AG, Research and Development Hamburg, shows that components in young human blood serum can help restore youthful properties to skin, but only when bone marrow cells are also present. This discovery highlights the role of bone marrow in supporting skin health and may allow for novel approaches aimed at slowing or reversing visible signs of aging.

The research explored how factors present in blood serum, already known to influence aging in animal studies, act on human cells. Using an advanced system that mimics human circulation, the researchers connected a 3D skin model with a 3D bone marrow model. They found that young human serum alone was not enough to rejuvenate skin. However, when bone marrow cells were present, these serum factors changed the activity of those cells, which then secreted proteins that rejuvenated skin tissue.

"Interestingly, we detected a significant increase in Ki67 positive cells in the dynamic skin model co-cultured with BM model and young serum compared to the model co-cultured with BM and old serum, indicating an improved regenerative capacity of the tissue."

Detailed analysis indicated that young serum stimulated the bone marrow to produce a group of 55 proteins, with 7 of them demonstrating the ability to boost cell renewal, collagen production, and other features associated with youthful skin. These proteins included factors that improved energy production in cells and reduced signs of cellular aging. Without the interaction between skin and bone marrow cells, these rejuvenating effects did not occur.

This finding explains why earlier experiments in mice, where young and old animals shared a blood supply, showed rejuvenation across organs. It suggests that bone marrow-derived cells are critical messengers that transform signals from blood into effects on other tissues, including the skin.

While these results are preclinical and not from human trials, they offer a starting point for new strategies in regenerative medicine and skin care. By identifying specific proteins that may carry rejuvenating signals, the study points to a new way to address age-related changes. Researchers emphasize that further studies will be needed to confirm these effects in humans and to test how these proteins can be safely and effectively applied in future therapies.

Overall, this research is an important step in understanding how young blood serum factors influence human tissue and could guide the development of novel methods to maintain healthier skin as people age.