Doctors have found a way to use 3D printing technology to create human skin grafts in the laboratory that have been proven to heal wounds faster than traditional grafts.

Skin grafts are performed when a person has suffered severe burns or ulcers, and after surgery to remove cancer. Typically, they require surgeons to remove skin from an undamaged part of the body and tape it to wounds.

Grafts taken from the patient or a deceased donor are often temporary or leave unattractive scars, but scientists at Wake Forest University in North Carolina have developed a near-perfect replica of human skin for the first time to help the flesh regenerate in the most serious diseases. wounds.

The bioprinted skin, tested in mice and pigs, is made using human skin cells designed to be used as ink for a 3D printer-like device. The printer produced human-like thick skin that, when transplanted, effectively formed new blood vessels and helped regenerate and repair the structure.

Skin is one of the most commonly transplanted organs in the US, with an estimated 160,000 transplants performed each year. But the current standard for transplantation has serious drawbacks, including a limited supply of healthy tissue that can be transplanted, cost and unattractive scarring.

Bioprinted skin was grafted onto wounds in mice and monitored for 90 days, alongside a control group that received a hydrogel graft and a group that received traditional wound dressings and nothing else. The bioprinted skin grafts helped the wounds heal by sending healing skin cells to the wound site instead of forcefully pulling the skin together (contraction)

The bioprinter is shown using human skin cells to generate square patches of human-like skin

Some examples of the bioprinted skin grafts are shown

Creating full-thickness skin with a bioprinter has not been possible until now. If scaled up properly, the technology could potentially help 160,000 people needing skin grafts every year

The Wake Forest researchers developed skin in the laboratory that mimicked the biological composition of human skin using six types of human skin cells: epidermal keratinocytes, melanocytes, dermal fibroblasts, dermal papilla cells of the follicle, dermal microvascular endothelial cells and adipocytes.

The cells were placed in vials containing a specific type of ink used to print biological materials such as organ tissue.

That ink was then used to create a three-by-three-inch patch of skin consisting of the three layers that make up healthy human skin: the epidermis, dermis, and hypodermis.

The three layers together form the so-called ‘full thickness’ skin, and creating it using 3D printing has been impossible until now, the researchers said.

Using six different human cells to develop the pieces of skin that would be used on mice was also crucial in ensuring that the printed graft would function in the same way as natural human skin when healing wounds.

One shortcoming of previous attempts to develop bioprinted skin, the researchers said, was that they contained only two cell types.

The scientists conducted a similar proof-of-concept experiment in four pigs using four different human cell types to validate their theory that bioprinting full-thickness skin grafts could be applied to real wounds in a laboratory setting.

The researchers tested their bioprinted skin on four mice, with another four receiving a control treatment without the bioprinted skin graft, and the final four receiving a standard bandage.

Pictures of the healing process were taken every week for three weeks. By day 14, the wounds in mice covered with the bioprinted skin were completely closed.

At the same time, the wounds of mice that received the control graft or traditional dressings had closed only 64 percent.

The human cells used in the skin grafts helped accelerate the migration of epithelial cells to the wound site, the ultimate marker for healing known as epithelialization.

Approximately 160,000 skin graft procedures are performed in the US each year.  This can be challenging because doctors may not be able to remove the amount of healthy skin needed from one part of a person to repair a wound elsewhere on the body.  Grafts can also go terribly wrong, potentially leading to infection and amputation

Approximately 160,000 skin graft procedures are performed in the US each year. This can be challenging because doctors may not be able to remove the amount of healthy skin needed from one part of a person to repair a wound elsewhere on the body. Grafts can also go terribly wrong, potentially leading to infection and amputation

Mice that received bioprinted skin grafts had the fastest healing period compared to other groups.  Researchers attribute this to the bioprint's unique ability to direct healing cells to the wound site, allowing the wound to heal cleanly without restricting mobility in the surrounding skin area.

Mice that received bioprinted skin grafts had the fastest healing period compared to other groups. Researchers attribute this to the bioprint’s unique ability to direct healing cells to the wound site, allowing the wound to heal cleanly without restricting mobility in the surrounding skin area.

The wounds in mice that underwent the bioprinted skin grafts also showed signs of forming distinct human-like patterns of ridges and grooves that anchor layers of skin together. This was remarkable because normal mouse skin has a very different flat, thin appearance.

Scientists also created full-thickness skin wounds in laboratory pigs. Like the mice, some pigs received either a control skin graft, the newly designed bioprinted skin graft, or traditional wound dressing with bandages, without any additional grafting. Their healing status was monitored twice a week for 28 days.

All pigs, regardless of which treatment they received, saw their wounds completely closed by day 28. One big difference, however, was that pigs given the bioprinted graft saw their wounds heal through epithelialization rather than contraction, which pulls the surrounding tissue inward. leading to the formation of an unattractive scar.

The process of epithelialization also typically lends itself to faster healing and a lower risk of loss of mobility due to tighter skin, as well as less scarring.

Dr. Anthony Atala, director of the Wake Forest Institute for Regenerative Medicine and co-author of the study, said: ‘Comprehensive skin healing is a significant clinical challenge, affecting millions of people worldwide, with limited options.

“These results show that creating full-thickness, human-like bioengineered skin is possible, promoting faster healing and more natural-looking results.”