Wounds in the elderly heal faster than young people, and there are fewer scars, because there is a compound called stromal cell-derived-factor-1 (SDF-1) in the blood of the elderly, University of Pennsylvania School of Medicine Leung and colleagues demonstrated that blocking this substance can affect skin scar formation and tissue regeneration in mice and humans.

In the study, researchers pierced the ears of mice of different ages (equivalent to humans from 12 to 70 years old). Old mice did not form scars and closed holes, while young mice had obvious scars. Then, the researchers exchanged the blood of the young mice with the old mice, then pierced the ears, and found that the ears of the old mice also became scarred. They concluded that the substance that caused the scar must be in the blood.

When the researchers analyzed blood gene products, they found that 13 genes were quite different. Among them, SDF1 is the key suspect. Previous studies have shown that it plays a role in scarring of the skin, liver and lungs. The researchers created a mouse model that lacks SDF1 in the skin. When the function of SDF1 is inactivated, the ears of young mice also begin to regenerate skin, behaving just like old mice.

"This is a rare example. Aging actually improves the body's ability to heal itself, rather than weakening it," Leung said. "When we are young, we secrete a lot of SDF1 into the blood to promote scar formation. As we age, we gradually lose this ability and instead allow tissue regeneration."

In order to prove it again, the researchers replaced the blood of the young mice lacking SDF1 with the old mice. This time, the two mice, whether they were young or old, showed no scars. They also stabbed human skin cultured in the laboratory with a scalpel, proving that human skin healing is also affected by SDF1 expression.

EIAAB SCIENCE INC, WUHAN has developed SDF1 protein, antibody and ELISA kit.