Strips of dried placenta help wounds heal with less scarring

Skin wounds heal with less scarring when thin sheets of dried human placenta are applied as dressings, according to research in mice and people.

The placenta’s healing properties have been known since at least the early 1900s, when the tissue was sometimes applied to burns to reduce scarring. However, the treatment fell out of favour due to the potential risk of disease transmission.

Now, with new ways to safely sterilise and preserve placentas, such dressings are once again gaining attention. In particular, researchers have been investigating the healing properties of the amniotic membrane, the innermost layer of the placenta that faces the fetus during pregnancy and contains a rich variety of growth factors and immune-modulating proteins.

Several US companies have started harvesting amniotic membranes from placentas donated after planned Caesarean sections. They peel this thin membrane from the rest of the placenta, freeze-dry it, cut it to standard sizes, package it and sterilise it with radiation. This preserves its growth factors and other healing substances, while destroying any pathogens. The resulting tissue paper-like sheets can then be used as wound dressings.

To find out whether these reduce scarring, Geoffrey Gurtner at the University of Arizona and his colleagues made surgical incisions on the backs of anaesthetised mice, and used a device to pull at the sides of the wounds and slow the healing process.

When the wounds were left untreated, they healed poorly, with large, lumpy scars. In contrast, when human amniotic membrane dressings were applied, the wounds healed much better, with thinner, flatter, barely visible scars. The dressings didn’t trigger adverse reactions in the mice due to the placenta having “immune privilege”, a state that prevents attack from the immune system.

Some US surgeons and physicians are already experimenting with using amniotic membrane dressings on people’s wounds, since the Food and Drug Administration permits their clinical use. For example, they are being applied to surgical wounds and chronic, non-healing ones caused by conditions like diabetes.

A study that came out in June 2025 gave us an idea of how well these dressings work in real-life clinical settings. Ryan Cauley at Beth Israel Deaconess Medical Center in Boston and his colleagues combed through a large US-wide database of anonymous patient health records, from which they identified 593 people who had received amniotic membrane dressings to treat chronic wounds or burns and compared them with 593 similar individuals who had been given other treatments.

The researchers found that the wounds treated with amniotic membrane dressings were less likely to become infected and to develop thick, raised scars, known as hypertrophic scars. This validates the growing popularity of these dressings, although Cauley and his colleagues note in their paper that “additional prospective, randomized studies with extended follow-up periods are warranted to validate these findings”.

Meanwhile, other groups are exploring the potential of placental tissue to heal organs other than the skin. For example, in 2023, Hina Chaudhry at the Icahn School of Medicine at Mount Sinai in New York City and her colleagues found that injections of placental cells repaired heart injuries in mice, suggesting they may one day be used to treat damage from heart attacks.